Dissertations / Theses on the topic 'Inorganic P'
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Woolley, Martin Fraser. "The synthesis and polymerisation of some conjugatively extended p-xylylenes." Thesis, Durham University, 1991. http://etheses.dur.ac.uk/5985/.
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This thesis describes studies directed towards the preparation of new conjugatively extended p-xylylenes through in situ 1,6- or 1,8-Hoffmann elimination reactions of trimethylammonium salts. The polymers arising from these highly reactive compounds were analysed in order to determine whether or not the extra conjugation had been involved in the polymerisation process. A number of fascinating by-products were also isolated which were useful in determining the structural unit orientation in the related polymer chains. Chapter 1 highlights the areas of p-xylylene chemistry of relevance to the general theme of this thesis. Chapter 2 describes the in situ synthesis and consequent polymerisation of vinyl-extended p-xylylene from two different trimethylammonium salts. An in-depth analysis of the polymers and the two cyclic dimers produced is also included. Chapter 3 describes the in situ synthesis and polymerisation of phenyl-extended p-xylylene from two different trimethylammonium salts. Once again, an analysis of die polymer structures and the identification of the two cyclic trimers is also included. Chapter 4 describes attempts to extend the polymerisation reactions of Chapters' 2 and 3 to produce water-soluble precursor polymers from bis-sulphonium salts. Chapter 5 describes attempts to synthesise novel polymeric materials from fluorinated monomers. Chapter 6 gives experimental details for Chapters 2-5.
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Aris, Damian R. "Macrocyclic complexation of selected neutral and cationic p-block metal species." Thesis, University of Warwick, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.369455.
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Youngman, Paul Kenneth. "Electron correlation effects in some S and P states of helium and lithium." Thesis, University of Leicester, 1986. http://hdl.handle.net/2381/35838.
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In Section (I), the origins and nature of the correlation problem are discussed, and two approaches to its solution are outlined. Some of the methods by which correlation effects in the ground state of helium have been analysed in the past are briefly reviewed. In Section (II.1), position-space correlation effects in the 21S, 23S, 21P and 23P states of helium are studied. The investigation is performed by examining the effects of correlation on various radial, angular and interparticle distribution functions and expectation values; where possible, comparisons are made with the ground state. For each of the four excited states studied, it was found that correlation causes a significant inward movement of electron density from the outer regions of the atom, due to a reduction in nuclear shielding. In the light of the results obtained in position space, a3 parallel momentum-space investigation of the 23S, 21P and 23P states was performed, and the results are presented in Section (II.2). Differences between the interparticle correlation properties of the three states were rationalised by considering the varying interactions between the radial and angular components of correlation in each instance. For 23S and 21P, as for the ground state, radial and angular correlation have opposing effects on the interparticle momentum distributions; for 23P, on the other hand, the two effects act together. In Section (III), a partitioning technique used previously to examine correlation effects in individual electron pairs within many-electron atoms is applied to a momentum-space study of the (1s2 2s)2S and (1s2 2p)2P states of lithium. For both states, the effects of correlation observed in the K-shell electron pairs show a strong resemblance to those found in Li+. As for the excited states of helium, the rationalisation of the behaviour of, and differences between, the interparticle correlation properties of the intershell electron pairs was achieved by considering the varying interactions between the radial and angular components of correlation in each instance.
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Navarrete, Gatell Eric. "Synthesis and gas sensing properties of inorganic semiconducting, p-n heterojunction nanomaterials." Doctoral thesis, Universitat Rovira i Virgili, 2021. http://hdl.handle.net/10803/672438.
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En aquesta tesis utilitzant principalment Aerosol Assited Chemical Vapor Deposition, AACVD, com a metodologia de síntesis d'òxid de tungstè nanoestructurat s'han fabricat diferents sensors de gasos. Per tal d'estudiar la millora en la selectivitat i la sensibilitat dels sensors de gasos basats en òxid de tungstè aquest s'han decorat, via AACVD, amb nanopartícules d'altres òxids metàl·lics per a crear heterojuncions per tal d'obtenir un increment en la sensibilitat electrònica, les propietats químiques del material o bé ambdues. En particular, s'han treballat en diferents sensors de nanofils d'òxid de tungstè decorats amb nanopartícules d'òxid de níquel, òxid de cobalt i òxid d'iridi resultant en sensors amb un gran increment de resposta i selectivitat cap al sulfur d'hidrogen, per a l'amoníac i per a l'òxid de nitrogen respectivament a concentracions traça. A més a més, s'han estudiat els mecanismes de reacció que tenen lloc entre les espècies d'oxigen adsorbides a la superfície del sensor quan interactua amb un gas. I també s'ha treballat en intentar controlar el potencial de superfície de les capes nanoestructurades per tal de controlar la deriva en la senyal al llarg del temps, quan el sensor està operant, a través d'un control de temperatura.En esta tesis utilizando principalmente Aerosol Assited Chemical Vapor Deposition, AACVD, como metodología de síntesis de óxido de tungsteno nanoestructurado se han fabricado diferentes sensores de gases. Para estudiar la mejora en la selectividad y la sensibilidad de los sensores de gases basados en óxido de tungsteno estos se han decorado, vía AACVD, con nanopartículas de otros óxidos metálicos para crear heterouniones para obtener un incremento en la sensibilidad electrónica, las propiedades químicas del material o bien ambas. En particular, se han trabajado en diferentes sensores de nanohilos de óxido de tungsteno decorados con nanopartículas de óxido de níquel, óxido de cobalto y óxido de iridio resultante en sensores con un gran incremento de respuesta y selectividad hacia el sulfuro de hidrógeno, para el amoníaco y para el óxido de nitrógeno respectivamente a concentraciones traza. Además, se han estudiado los mecanismos de reacción que tienen lugar entre las especies de oxígeno adsorbidas en la superficie del sensor cuando interactúa con un gas. Y también se ha trabajado en intentar controlar el potencial de superficie de las capas nanoestructuradas para controlar la deriva en la señal a lo largo del tiempo, cuando el sensor está trabajando, a través de un control de temperatura.
In this thesis, using mainly Aerosol Assited Chemical Vapor Deposition, AACVD, as a synthesis methodology for nanostructured tungsten oxide, different gas sensors have been manufactured. To study the improvement in the selectivity and sensitivity of gas sensors based on tungsten oxide, they have been decorated, via AACVD, with nanoparticles of other metal oxides to create heterojunctions to obtain an increase in electronic sensitivity, in the chemical properties of the material or at the same time in both. Particularly, we have worked on different tungsten oxide nanowire sensors decorated with nanoparticles of nickel oxide, cobalt oxide and iridium oxide resulting in sensors with a large increase in response and selectivity towards hydrogen sulfide, for ammonia. and for nitrogen oxide respectively at trace concentrations. In addition, the reaction mechanisms that take place between oxygen species adsorbed on the sensor surface when it interacts with a gas have been also studied. Furthermore, efforts have been put on trying to control the surface potential of the nanostructured layers to control the drift in the signal over time, when operating the sensors, through temperature control.
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Contreras, Julio Santiago. "Inorganic spectroscopic methods / A. K. Brisdon. Oxford: Oxford University Press, 1998. 91 p." Revista de Química, 2013. http://repositorio.pucp.edu.pe/index/handle/123456789/101365.
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Contreras, Julio Santiago. "Optoelectronic proporties of inorganic compounds / D. M. Roundill, J. P. Fackler ed. New York: Plenum Press, 1999. xv, 412 p." Revista de Química, 2013. http://repositorio.pucp.edu.pe/index/handle/123456789/100319.
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Wilcock, Steven M. "Investigation of the Sn-P bond and related studies." Thesis, University of Sussex, 2011. http://sro.sussex.ac.uk/id/eprint/6948/.
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This thesis reports the synthesis and analysis of a number of organometallic compounds, focusing primarily on novel structures containing Sn and P atoms. Chapter 1 contains a literature review examining the different structural and bonding properties and reactions of C4H4, P4 and P2C2R2. Chapter2 describes the ability of the P2C2tBu2 ligand to cause a reductive elimination in Sn(IV) species. Several different products from the reaction between Me2SnCl2 and Cp2Zr(P2C2tBu2) are determined, and mechanisms for their interconversion are proposed. The synthesis of Sn(P2C2Ad2) is reported along with its unprecedentedly low frequency 119Sn NMR spectroscopic chemical shift. Chapter 3 contains attempts to produce transition metal complexes with phosphaalkyne based ligands. The crystal structure of a complex containing Fe and Zr centres with two P2C2Ad2 rings is reported along with analysis of its paramagnetism. Mechanisms for the exchange of P2C2R2 rings and chlorides are also proposed. Chapter 4 details the synthesis of a range of CpnSnIm species and a comparison of their solid and solution state structures using X-ray diffraction and NMR spectroscopy. Reactions between these compounds and P(SiMe3)3 or LiP(SiMe3)2 are performed in order to explore the possibility of forming a Sn-P multiple bond. Chapter 5 outlines the synthesis of bicyclic systems based on C6H4-1,2-(PH2)2 and Sn and Ge dialkyls. The effect of alkyl group bulk on product structure is investigated. Chapter 6 explores the reaction between C6H4-1,2-(PH2)2 and P(SiMe3)3 in which an exchange of H and SiMe3 groups occurs. The mechanism of the reaction is elucidated by the introduction of a catalytic proton source.
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Vennström, Marie. "Crystal Chemistry of the Ti3Sn-D, Nb4MSi-D and Pd-Ni-P Systems." Doctoral thesis, Uppsala universitet, Institutionen för materialkemi, 2003. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-3466.
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Future energy systems based on hydrogen as energy carrier require reliable ways for storing hydrogen gas in safe, clean and efficient ways. Metal hydrides absorb hydrogen gas reversibly, making them suitable for storage applications. Investigations of the crystal structures of these materials contribute to an understanding of the factors which can influence the absorption. Three systems, Ti3Sn-D, Nb4MSi-D (M=Co or Ni) and Pd-Ni-P, have been investigated in this thesis. Various solid state synthesis techniques have been used for sample preparation. The crystal structures have been studied using x-ray and neutron diffraction techniques. Three metal hydride phases were found in the Ti3Sn-D system upon hydrogenation. Deuterium occupies titanium octahedra and the applied deuterium pressure induces the phase transitions. The distances between the deuterium atoms increase from 2.47 Å in orthorhombic Ti3SnD0.80 to 4.17 Å in cubic Ti3SnD. The Nb4MSi-D system (M=Co or Ni) readily absorbs deuterium at room temperature and 90 kPa deuterium pressure to give a deuterium content of Nb4MSiD~2.5. Two interstitial voids, both coordinated by four niobium atoms arranged in a tetrahedral configuration, accommodate deuterium atoms. Two ternary phases and a solid solution of nickel in Pd3P have been synthesised and the crystal structures determined. PdNi2P is orthorhombic and crystallises in the MgCuAl2-type structure: an ordered derivative of the Re3B-type structure. Pd8Ni31P16 is a tetragonal high-temperature phase stable at 700°C with 110 atoms in the unit cell. Pd2.7Ni0.3P0.94 has the cementite-type structure with mixed occupancy of palladium and nickel at one of the two non-equivalent crystallographic metal positions.
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Spry, Marcus P. "Synthesis and structural studies of macrocyclic complexes of the p-block (Sb, Ge, Te, O) and lanthanide (La, Ho, Er, Tm and Pr) elements." Thesis, University of Warwick, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.340984.
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Lubuna, Beegum Shafeek. "Organic-Inorganic Hetero Junction White Light Emitting Diode : N-type ZnO and P-type conjugated polymer." Thesis, Linköping University, Department of Science and Technology, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-11195.
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The purpose of this thesis work is to design and fabricates organic-inorganic hetero junction White Light Emitting Diode (WLED). In this WLED, inorganic material is n- type ZnO and organic material is p-type conjugated polymer. The first task was to synthesise vertically aligned ZnO nano-rods on glass as well as on plastic substrates using aqueous chemical growth method at a low temperature. The second task was to find out the proper p- type organic material that gives cheap and high efficient WLED operation. The proposed polymer shouldn’t create a high barrier potential across the interface and also it should block electrons entering into the polymer. To optimize the efficiency of WLED; charge injection, charge transport and charge recombination must be considered. The hetero junction organic-inorganic structures have to be engineered very carefully in order to obtain the desired light emission. The layered structure is composed of p-polymer/n-ZnO and the recombination has been desired to occur at the ZnO layer in order to obtain white light emission. Electrical characterization of the devices was carried out to test the rectifying properties of the hetero junction diodes.
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Sellappan, Raja. "Light emitting diodes based on n-type ZnO nanorods and p-type organic semiconductors." Thesis, Linköping University, Department of Science and Technology, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-11197.
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The aim of this thesis work was to fabricate a hybrid LED using organic-inorganic ZnO materials. The goal of the project was to get an efficient white light emission from zinc oxide (ZnO) nanorods active layer. Since most of the organic materials are good for hole mobility and most of the inorganic materials are good for electron mobility, it is possible to fabricate a high performance heterostructure electroluminescence device from organic-inorganic materials. This thesis work was an attempt towards fabricating such a high electroluminescence LED from hybrid materials in which polymer acts as a p-type material and ZnO acts as a n-type material. The growth mechanism of ZnO nanorods using low-temperature aqueous solution method has been studied and nanorods (NRs) growth was examined with scanning electron microscope (SEM). Optimum hole injection polymers have been studied. Finally, the fabricated device was characterized using parameter analyzer. The fabricated device worked as a diode i.e. it rectified current as expected and the desirable light emission has almost been achieved.
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Anber, Mohammed al. "Organic and, or inorganic p-conjugated [pi-conjugated] units in the synthesis of multinuclear transition metal complexes." [S.l. : s.n.], 2003. http://deposit.ddb.de/cgi-bin/dokserv?idn=97031387X.
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Pham, Ngoc Duy. "Efficiency enhancement in solution-processed organic-inorganic perovskite solar cells." Thesis, Queensland University of Technology, 2019. https://eprints.qut.edu.au/133985/1/Ngoc%20Duy_Pham_Thesis.pdf.
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Organic-inorganic lead halide perovskite is a promising candidate in the photovoltaic field due to the combined merits of impressive power conversion efficiencies and relatively cost-effective solution processes. Despite its remarkable success, there is still room for further improvement. This thesis aims to investigate the impacts of morphological microstructure and elemental composition of organic-inorganic lead halide perovskite light absorber on power conversion efficiency, stability and current-voltage hysteresis behaviour of perovskite solar cells.
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Vennström, Marie. "Crystal Chemistry of the Ti3Sn-D, Nb4MSi-D and Pd-Ni-P Systems." Doctoral thesis, Uppsala University, Department of Materials Chemistry, 2003. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-3466.
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Future energy systems based on hydrogen as energy carrier require reliable ways for storing hydrogen gas in safe, clean and efficient ways. Metal hydrides absorb hydrogen gas reversibly, making them suitable for storage applications. Investigations of the crystal structures of these materials contribute to an understanding of the factors which can influence the absorption.
Three systems, Ti3Sn-D, Nb4MSi-D (M=Co or Ni) and Pd-Ni-P, have been investigated in this thesis. Various solid state synthesis techniques have been used for sample preparation. The crystal structures have been studied using x-ray and neutron diffraction techniques.
Three metal hydride phases were found in the Ti3Sn-D system upon hydrogenation. Deuterium occupies titanium octahedra and the applied deuterium pressure induces the phase transitions. The distances between the deuterium atoms increase from 2.47 Å in orthorhombic Ti3SnD0.80 to 4.17 Å in cubic Ti3SnD.
The Nb4MSi-D system (M=Co or Ni) readily absorbs deuterium at room temperature and 90 kPa deuterium pressure to give a deuterium content of Nb4MSiD~2.5. Two interstitial voids, both coordinated by four niobium atoms arranged in a tetrahedral configuration, accommodate deuterium atoms.
Two ternary phases and a solid solution of nickel in Pd3P have been synthesised and the crystal structures determined. PdNi2P is orthorhombic and crystallises in the MgCuAl2-type structure: an ordered derivative of the Re3B-type structure. Pd8Ni31P16 is a tetragonal high-temperature phase stable at 700°C with 110 atoms in the unit cell. Pd2.7Ni0.3P0.94 has the cementite-type structure with mixed occupancy of palladium and nickel at one of the two non-equivalent crystallographic metal positions.
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Jordens, Kurt. "Hybrid Inorganic-Organic Materials: Novel Poly(Propylene Oxide) Based Ceramers, Abrasion Resistant Sol-Gel Coatings for Metals, and Epoxy-Clay Nanocomposites. With an Additional Chapter On: Metallocene Catalyzed Linear Polyethylene." Diss., Virginia Tech, 1999. http://hdl.handle.net/10919/30194.
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The sol-gel process has been employed to generate hybrid inorganic-organic network materials. Unique ceramers were prepared based on an alkoxysilane functionalized soft organic oligomer, poly(propylene oxide) (PPO), and tetramethoxysilane (TMOS). Despite the formation of covalent bonds between the inorganic and organic constituents, the resulting network materials were phase separated, composed of a silicate rich phase embedded in a matrix of the organic oligomer chains. The behavior of such materials was similar to elastomers containing a reinforcing filler. The study focused on the influence of initial oligomer molecular weight, functionality, and tetramethoxysilane, water, and acid catalyst content on the final structure, mechanical and thermal properties. The sol-gel approach has also been exploited to generate thin, transparent, abrasion resistant coatings for metal substrates. These systems were based on alkoxysilane functionazized diethylenetriamine (DETA) with TMOS, which generated hybrid networks with very high crosslink densities. These materials were applied with great success as abrasion resistant coatings to aluminum, copper, brass, and stainless steel. In another study, intercalated polymer-clay nanocomposites were prepared based on various epoxy networks montmorillonite clay. This work explored the influence of incorporated clay on the adhesive properties of the epoxies. The lap shear strength decreased with increasing clay content. This was due to a reduction in the toughness of the epoxy. Also, the delaminated (or exfoliated) nanocomposite structure could not be generated. Instead, all nanocomposite systems possessed an intercalated structure.
The final project involved the characterization of a series of metallocene catalyzed linear polyethylenes, produced at Phillips Petroleum. Polyolefins synthesized with such new catalyst systems are becoming widely available. The influence of molecular weight and thermal treatment on the mechanical, rheological, and thermal behavior was probed. Although the behavior of this series of metallocene polyethylenes was not unlike that of traditionally catalyzed materials, this work is one of the first comprehensive studies of these new linear polyethylenes. The main distinction between the metallocene and traditional Ziegler-Natta catalyzed polyethylenes is the narrow molecular weight distributions produced by the former (for this series of materials, 2.3< Mw  Mn <3.6).Ph. D.
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Sala, Román Xavier. "New Ruthenium complexes containing N, P and S-donor type of ligands: coordination chemistry, characterization and application to asymetric and non-asymetric catalysis." Doctoral thesis, Universitat de Girona, 2007. http://hdl.handle.net/10803/8043.
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Síntesi de nous complexos de Ruteni amb lligands no quirals que tenen per fórmula [Ru(phen)([9]aneS3)X] (on X = H2O, py i MeCN). Caracterització espectroscòpica electroquímica i estructural d'aquesta família de complexos. Estudi de les seves propietats catalítiques en front a l'oxidació de substrats orgànics com l'alcohol benzílic en reaccions d'electrocatàlisi. Avaluació cinètica dels mecanismes de substitució entre els complexos Ru-py i Ru-MeCN. Generació d'un interruptor molecular foto-induït.Síntesi de nous complexos quirals de Ru atropoisomèricament purs amb lligands oxazolínics que tenen per fórmula [Ru(trpy)(Ph-box-R)X] on (X = Cl, H2O, py, MeCN, 2-OH-py). Caracterització estructural exhaustiva en estat sòlid (Raig-X) en solució (RMN) i en fase gas (càlculs DFT). Avaluació de la seva activitat catalítica en reaccions asimmetriques d'epoxidació de substrats proquirals.
Síntesi de nous lligands polipiridílics quirals amb simetria C3. Estudi de la seva química de coordinació i avaluació de la seva activitat catalítica en reaccions asimmetriques d'oxidació i reducció.
Synthesis, spectroscopic characterization and redox properties of a new Ru-H2O complex containing 1,10-phenantroline and the soft [9]aneS3 ligand. Substitution pathways of a new Ru-py complex [Ru(phen)(py)([9]aneS3)]2+ to form the corresponding Ru-MeCN complex through kinetic analysis. Kinetic establishment of a reaction intermediate. Synthesis of new Ru(II) complexes containing the chiral 1,2-bis(oxazolinyl) benzene ligand. Rotationally restricted isomers were produced upon coordination to a ruthenium metal centre. Atropisomeric discrimination was observed due to steric effects between the oxazolinic and the auxiliary ligands. Evaluacion of the catalytic activity of the family of complexes in C=C double bond epoxidations.
Development of new synthetic routes toward chiral "pineno-fused" N-donor ligands. Synthesis of Ru(II) complexes containing different combinations of these new ligands with other non-chiral N-N or p-P compounds. Evaluacion of the catalytic activity of these complexes in catalytic oxidation (epoxidations) and reductions (hydrogenation and transfer hydrogenation) of C=C double bonds.
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Sneddon, Scott. "Characterisation of inorganic materials using solid-state NMR spectroscopy." Thesis, University of St Andrews, 2016. http://hdl.handle.net/10023/8239.
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This thesis uses solid-state nuclear magnetic resonance (NMR) spectroscopy and density functional theory (DFT) calculations to study local structure and disorder in inorganic materials. Initial work concerns microporous aluminophosphate frameworks, where the importance of semi-empirical dispersion correction (SEDC) schemes in structural optimisation using DFT is evaluated. These schemes provide structures in better agreement with experimental diffraction measurements, but very similar NMR parameters are obtained for any structures where the atomic coordinates are optimised, owing to the similarity of the local geometry. The ³¹P anisotropic shielding parameters (Ω and κ) are then measured using amplified PASS experiments, but there appears to be no strong correlation of these with any single geometrical parameter. In subsequent work, a range of zeolitic imidazolate frameworks (ZIFs) are investigated. Assignment of ¹³C and ¹⁵N NMR spectra, and measurement of the anisotropic NMR parameters, enabled the number and type of linkers present to be determined. For ¹⁵N, differences in Ω may provide information on the framework topology. While ⁶⁷Zn measurements are experimentally challenging and periodic DFT calculations are currently unreliable, calculations on small model clusters provide good agreement with experiment and indicate that ⁶⁷Zn NMR spectra are sensitive to the local structure. Finally, a series of pyrochlore-based ceramics (Y₂Hf₂₋ₓSnₓO₇) is investigated. A phase transformation from pyrochlore to a disordered defect fluorite phase is predicted, but ⁸⁹Y and ¹¹⁹Sn NMR reveal that rather than a solid solution, a significant two-phase region is present, with a maximum of ~12% Hf incorporated into the pyrochlore phase. The use of ¹⁷O NMR to provide insight into the local structure and disorder in these materials is also investigated. Once the different T₁ relaxation and nutation behaviour is considered it is shown that quantitative ¹⁷O enrichment of Y₂Sn₂O₇ is possible, and that ¹⁷O does offer a promising future tool for study.
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Smith, Christopher. "p-block hydrogen storage materials." Thesis, University of Oxford, 2010. http://ora.ox.ac.uk/objects/uuid:6dd710a5-baf2-4fd2-918c-d1df97c229bf.
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The development of a clean hydrogen economy will aid a smooth transition from fossil fuels which is required to stem the environmental impact and economic instability caused by oil dependency. For vehicular application, in addition to being cheap and safe, a commercial hydrogen store must contain a certain weight percentage of hydrogen to provide a reasonable range (~300 miles). It must also be able to release hydrogen under near-ambient conditions (80-120°C) and have a reasonable cycling capacity (~1000 cycles). The primary motivation of this thesis is to gain a fundamental understanding into the sorption processes of hydrogen on carbon- and aluminium-based materials to improve their hydrogen storage capacity. The sorption processes of hydrogen on mechanically milled graphite have been investigated, primarily using Electron Spin Resonance Spectroscopy and Inelastic Neutron Scattering. An investigation into the storage properties of tetrahydroaluminates, primarily NaAlH4 and LiAlH4, is performed in the presence and absence of a catalyst, and a new phase of NaAlH4 is observed prior to its decomposition. Variable temperature neutron and synchrotron diffraction, in conjunction with gravimetric and mass spectroscopy data were obtained for several mixtures of tetrahydroaluminates and alkali amides and the hydrogen desorption processes are shown to be quite different from the constituent materials. The structure of Ca(AlH4)2 has been experimentally determined for the first time and a complete set of equations describing its decomposition pathway is given.
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Gawlitza, Kornelia [Verfasser], and Regine von [Akademischer Betreuer] Klitzing. "P-NIPAM microgels as stimuli responsive matrix for embedding functional inorganic and organic particles / Kornelia Gawlitza. Betreuer: Regine von Klitzing." Berlin : Universitätsbibliothek der Technischen Universität Berlin, 2012. http://d-nb.info/1029355584/34.
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Palmer, Erick J. "Synthesis, characterization and density functional theory investigations of tris-cyclopentadienyl compounds of zirconium and hafnium." The Ohio State University, 2005. http://rave.ohiolink.edu/etdc/view?acc_num=osu1109969235.
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He, Mingfu. "Towards Efficient Solar Energy Conversion and Storage Devices—the p-type Dye-sensitized Solar Cell and Sodium-Oxygen Battery." The Ohio State University, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=osu1480521221820685.
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Fournier, Olivier Jaques Henri. "Effects of the interfaces in planar hybrid lead trihalide perovskite solar cells with n-type and p-type inorganic charge transport layers." Thesis, KTH, Energiteknik, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-246122.
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Perovskite-solceller är en framväxande och lovande tunnfilmsteknik, som uppnådde hög effektivitet på en ofantlig kort tid. Den nuvarande arkitekturen i cellen, som innefattar titanoxid och Spiro-OMeTAD (en organisk förening) som laddningstransportlager (CTL), saknar stabilitet och visar hysteretiskt beteende. För att bedöma dessa stora problem utvecklas oorganiska CTL i PV-samhället. I detta arbete utförs en grundlig översyn av litteraturen om dessa oorganiska CTL. Fyra av dem identifieras som bra kandidater på grund av de höga prestanda de uppnådde och deras kemiska stabilitet: SnO2, ZnO, CuSCN och NiO. Betydelsen av gränssnitten i denna typ av cell visas också. Numerisk simulering av CTLs utförs också med ett dedikerat 1D-modelleringsverktyg (SCAPS), vilket gör att vi kan föreslå viktiga parametrar för att optimera i en CTL. Slutligen studeras effekterna av gränssnittet på prestanda hos en perovskit-solcell med hyperspektral avbildning av cellens fotoluminescensrespons. Med hjälp av en korrekt passningsalgoritm ger denna icke-destruktiva metod insikt om de opto-elektroniska egenskaperna hos perovskiten som odlas på olika substrat.Perovskite solar cells are an emerging and promising thin film technology, which reached high efficiencies in an unprecedented short time. However, the current architecture of the cell, which includes titanium oxide and Spiro-OMeTAD (an organic compound) as charge transport layers (CTLs), lacks stability and shows hysteretic behavior. In order to assess these major issues, inorganic CTLs are developed in the PV community. This work performs a thorough review of the literature regarding these inorganic CTLs. Four of them are identified as good candidates because of the high performances they reached, and of their chemical stability: SnO2, ZnO, CuSCN and NiO. The significance of the interfaces in this kind of cell is also demonstrated. Numerical simulation of CTLs is also performed using a dedicated 1D modelisation tool (SCAPS), which allows us to propose key parameters to optimize in a CTL. Finally, the effects of the interface on the performances of a perovskite solar cell are studied with hyperspectral imaging of photoluminescence response of the cell. Using a proper fit algorithm, this non-destructive method gives insight into the opto-electronic properties of the perovskite grown on different substrates.
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Condron, Leo M. "Chemical nature and plant availability of phosphorus present in soils under long-term fertilised irrigated pastures in Canterbury, New Zealand." Lincoln College, University of Canterbury, 1986. http://hdl.handle.net/10182/1875.
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Soil P fractionation was used to examine changes in soil inorganic and organic P under grazed irrigated pasture in a long-term field trial at Winchmore in Mid-Canterbury. The soil P fractionation scheme used involved sequential extractions of soil with O.5M NaHCO₃ @ pH 8.5 (NaHCO₃ P), 0.1M NaOH (NaOH I P), 1M HCl (HCl P) and 0.1M NaOH (NaOH II P). The Winchmore trial comprised 5 treatments: control (no P since 1952), 376R (376 kg superphosphate ha⁻¹ yr⁻¹ 1952-1957, none since), 564R (564 kg superphosphate ha⁻¹ yr⁻¹ 1952-1957, none since) 188PA (188 kg superphosphate ha⁻¹ yr⁻¹ since 1952) and 376PA (376 kg superphosphate ha⁻¹ yr⁻¹ since 1952: Topsoil (0-7.5cm) samples taken from the different treatments in 1958, 1961, 1965, 1968, 1971, 1974 and 1977 were used in this study. Changes in soil P with time showed that significant increases in soil inorganic P occurred in the annually fertilised treatments (l88PA, 376PA). As expected, the overall increase in total soil inorganic P between 1958 and 1977 was greater in the 376PA treatment (159 µg P g⁻¹) than that in the 188PA treatment (37 µg P g⁻¹). However, the chemical forms of inorganic P which accumulated in the annually fertilised treatments changed with time. Between 1958 and 1971 most of the increases in soil inorganic P in these treatments occurred in the NaHCO₃ and NaOH I P fractions. On the other hand, increases in soil inorganic P in the annually fertilised treatments between 1971 and 1977 were found mainly in the HCl and NaOH II P fractions. These changes in soil P forms were attributed to the combined effects of lime addition in 1972 and increased amounts of sparingly soluble apatite P and iron-aluminium P in the single superphosphate applied during the 1970's. In the residual fertiliser treatments (376R, 564R) significant decreases in all of the soil inorganic P fractions (i.e. NaHCO₃ P, NaOH I P, HCl P, NaOH II p) occurred between 1958 and 1977 following the cessation of P fertiliser inputs in 1957. This was attributed to continued plant uptake of P accumulated in the soil from earlier P fertiliser additions. However, levels of inorganic P in the different soil P fractions in the residual fertiliser treatments did not decline to those in the control which indicated that some of the inorganic P accumulated in the soil from P fertiliser applied between 1952 and 1957 was present in very stable forms. In all treatments, significant increases in soil organic P occurred between 1958 and 1971. The overall increases in total soil organic P were greater in the annually fertilised treatments (70-86 µg P g⁻¹) than those in the residual fertiliser (55-64 µg P g⁻¹) and control (34 µg P g⁻¹) treatments which reflected the respective levels of pasture production in the different treatments. These increases in soil organic P were attributed to the biological conversion of native and fertiliser inorganic P to organic P in the soil via plant, animal and microbial residues. The results also showed that annual rates of soil organic P accumulation between 1958 and 1971 decreased with time which indicated that steady-state conditions with regard to net 'organic P accumulation were being reached. In the residual fertiliser treatments, soil organic P continued to increase between 1958 and 1971 while levels of soil inorganic P and pasture production declined. This indicated that organic P which accumulated in soil from P fertiliser additions was more stable and less available to plants than inorganic forms of soil P. Between 1971 and 1974 small (10-38 µg P g⁻¹) but significant decreases in total soil organic P occurred in all treatments. This was attributed to increased mineralisation of soil organic P as a result of lime (4 t ha⁻¹) applied to the trial in 1972 and also to the observed cessation of further net soil organic P accumulation after 1971. Liming also appeared to affect the chemical nature of soil organic P as shown by the large decreases in NaOH I organic P(78-88 µg P g⁻¹) and concomitant smaller increases in NaOH II organic P (53-65 µg P g⁻¹) which occurred in all treatments between 1971 and 1974. The chemical nature of soil organic P in the Winchmore long-term trial was also investigated using 31p nuclear magnetic resonance (NMR) spectroscopy and gel filtration chromatography. This involved quantitative extraction of organic P from the soil by sequential extraction with 0.1M NaOH, 0.2M aqueous acetylacetone (pH 8.3) and 0.5M NaOH following which the extracts were concentrated by ultrafiltration. Soils (0-7.5cm) taken from the control and 376PA annually fertilised treatments in 1958, 1971 and 1983 were used in this study. 31p NMR analysis showed that most (88-94%) of the organic P in the Winchmore soils was present as orthophosphate monoester P while the remainder was found as orthophosphate diester and pyrophosphate P. Orthophosphate monoester P also made up almost all of the soil organic P which accumulated in the 376PA treatment between 1958 and 1971. This indicated that soil organic P in the 376PA and control treatments was very stable. The gel filtration studies using Sephadex G-100 showed that most (61-83%) of the soil organic P in the control and 376PA treatments was present in the low molecular weight forms (<100,000 MW), although the proportion of soil organic P in high molecular weight forms (>100,000 MW) increased from 17-19% in 1958 to 38-39% in 1983. The latter was attributed to the microbial humification of organic P and indicated a shift toward more complex and possibly more stable forms of organic P in the soil with time. Assuming that the difference in soil organic P between the control and 376PA soils sampled in 1971 and 1983 represented the organic P derived from P fertiliser additions, results showed that this soil organic P was evenly distributed between the high and low molecular weight fractions. An exhaustive pot trial was used to examine the relative availability to plants of different forms of soil inorganic and organic P in long-term fertilised pasture soils. This involved growing 3 successive crops of perennial ryegrass (Lolium perenne) in 3 Lismore silt loam (Udic Ustochrept) soils which had received different amounts of P fertiliser for many years. Two of the soils were taken from the annually fertilised treatments in the Winchmore long term trial (188PA, 376PA) and the third (Fairton) was taken from a pasture which had been irrigated with meatworks effluent for over 80 years (65 kg P ha⁻¹ yr⁻¹). Each soil was subjected to 3 treatments, namely control (no nutrients added), N100 and N200. The latter treatments involved adding complete nutrient solutions with different quantities of N at rates of 100kg N ha⁻¹ (N100) and 200kg N ha⁻¹ (N200) on an area basis. The soil P fractionation scheme used was the same as that used in the Winchmore long-term trial study (i.e. NaHCO₃ P, NaOH I P, HCl P, NaOH II p). Results obtained showed that the availability to plants of different extracted inorganic P fractions, as measured by decreases in P fractions before and after 3 successive crops, followed the order: NaHCO₃ P > NaOH I P > HCl P = NaOH II P. Overall decreases in the NaHCO₃ and NaOH I inorganic P fractions were 34% and 16% respectively, while corresponding decreases in the HCl and NaOH II inorganic P fractions were small «10%) and not significant. However, a significant decrease in HCl P (16%) was observed in one soil (Fairton-N200 treatment) which was attributed to the significant decrease in soil pH (from 6.2 to 5.1) which occurred after successive cropping. Successive cropping had little or no effect on the levels of P in the different soil organic P fractions. This indicated that net soil organic P mineralisation did not contribute significantly to plant P uptake over the short-term. A short-term field experiment was also conducted to examine the effects of different soil management practices on the availability of different forms of P to plants in the long-term fertilised pasture soils. The trial was sited on selected plots of the existing annually fertilised treatments in the Winchmore long-term trial (188PA, 376PA) and comprised 5 treatments: control, 2 rates of lime (2 and 4 t ha⁻¹ ) , urea fertiliser (400kg N ha⁻¹ ) and mechanical cultivation. The above ground herbage in the uncultivated treatments was harvested on 11 occasions over a 2 year period and at each harvest topsoil (0-7.5 cm) samples were taken from all of the treatments for P analysis. The soil P fractionation scheme used in this particular trial involved sequential extractions with 0.5M NaHCO₃ @ pH 8.5 (NaHCO₃ P), 0.1M NaOH (NaOH P), ultrasonification with 0.1M NaOH (sonicate-NaOH p) and 1M HCl (HCl P). In addition, amounts of microbial P in the soils were determined. The results showed that liming resulted in small (10-21 µg P g⁻¹) though significant decreases in the NaOH soil organic P fraction in the 188PA and 376PA plots. Levels of soil microbial P were also found to be greater in the limed treatments compared with those in the controls. These results indicated that liming increased the microbial mineralisation of soil organic P in the Winchmore soils. However, pasture dry matter yields and P uptake were not significantly affected. Although urea significantly increased dry matter yields and P uptake, it did not appear to significantly affect amounts of P in the different soil P fractions. Mechanical cultivation and the subsequent fallow period (18 months) resulted in significant increases in amounts of P in the NaHCO₃ and NaOH inorganic P fractions. This was attributed to P released from the microbial decomposition of plant residues, although the absence of plants significantly reduced levels of microbial P in the cultivated soils. Practical implications of the results obtained in the present study were presented and discussed.
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Vu, Hai Minh. "Binding study of inorganic phosphate to chicken erythrocyte histone H4 by ³²PO₄ micropartition and by ³¹P-NMR. ¹H-NMR assignment of akrhrkv and its binding to PO₄." Scholarly Commons, 1993. https://scholarlycommons.pacific.edu/uop_etds/2958.
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New methods were developed to purify histone H4 from chicken erythrocyte nuclei. Hydroxylapatite gel sedimentation required approximately one hour to isolate whole histones from chromatin as opposed to days when the traditional HTP chromatography was employed. In addition, a selective membrane ultrafiltration technique was proven to be as effective as the HTP gel in separating histones from DNA. A reversed-phase high performance liquid chromatography elution profile was developed to isolate histone H4 from other histones. A linear gradient from 95% H2O : 5% CH3CN (both solvents contained 0.1% v/v trifluoroacetic acid) to 42% H2O : 58% CH3CN through a C18 column (Axxiom, 3μm, spherical particles, 60 Å pore size, 4.6 mm x 100 mm) at a flow of 1 ml/min for 1 hour yielded electrophoretically pure histone H4.
The binding of 32PO4 to purified histone H4 was studied by equilibrium partitioning across a 5 kD MWCO semipermeable membrane in an Amicon micro-partition system. A linear Scatchard plot was obtained indicating a stoichiometric ratio of 5 molecules of ligand to every molecule of histone H4 (n = 5.4) and a dissociation constant in the millimolar range (Kd = 2.8 x 10-3 M). The 31P-NMR linewidths increased markedly and progressively as a function of histone H4 concentration. However, the 31P peak became narrower, although never back to the original value for PO4 alone, when the [PO4] : [H4] ratio was greater than 5. At ratios higher than 5 : 1, free phosphate contributes significantly to the observed relaxation rate. Hence, both types of studies suggest the same 5 to 1 stoichiometry for the inorganic phosphate-histone H4 interaction.
Two-dimensional high-resolution NMR was used to assign all resolvable peaks from a 500 MHz 1H-NMR spectrum of N-acetyl-AKRHRKV, an oligopeptide that resembles an important part of the N-terminal end of histone H4. Binding of this peptide segment with inorganic phosphate was studied by 31P- and 1H-NMR. Analysis of 31P-NMR linewidths with added peptide revealed a dissociation constant of 7.04 x 10-2 M. The apparent spin-spin relaxation times for free, TF2,and histone-bound phosphate, TB2. were calculated to be 28.7 mseconds and 6.3 mseconds respectively. 1H-NMR TOCSY and NOESY spectra indicated that this peptide adopts a loop conformation with the C-terminal valine H-bonded to the histidine carbonyl. The involvement of the histidine imidazole ring in phosphate binding is also indicated by the shifts of the H2 and H4 protons in the presence of PO4.
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Olaiya, Babatunde Samuel. "Stabilized Photocatalytic Hydrogen Generation using a Molecular Ru(II) Sensitizer, a Molecular Cobalt Catalyst and an Amine Derivative as an Electron Donor." Bowling Green State University / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1371066177.
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Castanho, Gisela Muassab. "Estudo comparativo in vitro das estruturas orgânicas e inorgânicas da dentina saudável e esclerosada humana e bovina: nanodureza, concentração de Ca e P e análise morfológica." Universidade de São Paulo, 2010. http://www.teses.usp.br/teses/disponiveis/23/23134/tde-22122010-112739/.
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A dentina esclerosada é um substrato comumente encontrado em pacientes idosos. No entanto, existem poucos estudos comparativos entre dentina humana e bovina esclerosadas. O objetivo deste estudo foi comparar os componentes inorgânicos e orgânicos da dentina saudável e esclerosada humana e bovina, através de cinco parâmetros: nanodureza, módulo de elasticidade, análise quantitativa da concentração de Cálcio (Ca) e Fósforo (P), densidade tubular e morfologia do colágeno. Trinta dentes humanos e 30 bovinos foram distribuídos em 4 grupos experimentais (n=15 por grupo): dentina humana saudável (DHS), esclerosada humana (DEH), bovina saudável (DBS), e bovina esclerosada (DBE). Os dentes saudáveis foram preparados na mesma altura e inclinação dos dentes esclerosados expondo níveis similares da dentina e obtendo fragmentos com 2mm de espessura. Foram realizadas 3 medições por espécime em 3 áreas pré determinadas de dentina intertubular com a utilização do Nanoindentador (carga de 500N por 5 s). Cinco espécimes de cada grupo foram preparados para Microscopia Eletrônica de Varredura (MEV). Com o auxílio da Energia Dispersiva por Raios-X EDX foram obtidos os valores (em percentagem) das concentrações de Ca e P e calculada a relação Ca:P. A contagem dos túbulos por área foi realizada em todas as eletromicrografias. Após descalcificação e preparo, o restante dos espécimes foi analisado em Microscopia Eletrônica de Transmissão (MET). DBS obteve maiores valores de nanodureza comparada à DBE e DHS. DHE sem diferenças com DHS e DBE (p=0,0008). DBS exibiu maiores valores de módulo de elasticidade somente comparada à DHS (p=0,000). A análise estatística não demonstrou diferenças estatisticamente significantes (p=0,71) entre as concentrações de Ca e P. Quanto à densidade tubular (número de túbulos/mm²), os grupos saudáveis foram maiores que os esclerosados e os humanos maiores que os bovinos. As fibras colágenas da DBS mostraram-se mais compactadas e mais desorganizadas que as demais. Pôde se concluir que apenas as concentrações de Ca e P foram similares e que as dentinas esclerosadas humana e bovina mostraram similaridade. Esta pesquisa teve suporte da Fapesp sob o número 2008/10290-8.The sclerotic dentin has been commonly found in elderly patients. However, there are scarce reports in the literature comparing on the use of human and bovine sclerotic dentins. The objective of this study was to compare inorganic and organic components of healthy and sclerotic dentins from human and bovine. Five parameters were analyzed: nanohardness, elastic modulus, quantitative analysis of Calcium (Ca) and Phosphorous (P) concentrations, tubular density and ultrastructural morphology. Thirty human teeth plus 30 bovine teeth were distributed in 4 experimental groups (n=15 per group): human healthy dentin (HHD), human sclerotic dentin (HSD), bovine healthy dentin (BHD) and bovine sclerotic dentin (BSD). Healthy teeth were cut in the same level and inclination of the sclerotic superficial dentins. The nanohardness and elastic modulus (GPa) of three pre determined areas of each exposed dentin was measured using a nanoindenter (500N for 5s). Five samples of each group were prepared for scanning electron microscopy (SEM) examination. Energy Dispersive X-ray (EDX) was used for obtaining the Ca/P ratio. The tubular density was obtained by counting the tubules in scanning electron micrographs taken in the same magnification and work distance. Data were statistically analyzed by ANOVA complemented by the Tukeys test (p0.05). The ultrastructure of the dentins was observed in specimens processed for transmission electron microscopy (TEM). BHD exhibited significant higher nanohardness than BSD and HHD. HSD nanohardness was similar to those of HHD and BSD (p=0,0008). BHD exhibited significant higher elastic modulus than HHD (p=0,000). The Ca:P ratios were similar amongst all groups (p=0.71). The tubular densities were higher in the healthy dentins than in the sclerotic for both human and bovine. The human dentins presented higher tubular densities than bovine dentins (p=0.000). The intertubular dentin of BHD showed short collagen fibers distributed in a condensed fashion; whereas the other dentins exhibited well-organized long bundles of collagen fibers. It was concluded that sclerotic dentins of human and bovine share most morphological and structural characteristics. This research was supported by Fapesp grants number 2008/10290-8.
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Sandström, Malin. "Structural and solid state EMF studies of phases in the CaO–K2O–P2O5 system with relevance for biomass combustion." Doctoral thesis, Umeå University, Applied Physics and Electronics, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-858.
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Fosfaters reaktioner i energiomvandlingsprocesser är kritisk för den generella processen som helhet, för askrelaterade problem, emissioner liksom för en effektiv och hållbar användning av askan.
Denna avhandling är en sammanställning och diskussion med utgångspunkt i åtta artiklar som behandlar strukturella och termodynamiska studier på faser i CaO-K2O-P2O5-systemet, vilka är av relevans inom förbränning av biomassa. Målsättningen med denna avhandling var: i) att sammanställa och granska tillgängliga strukturella och termodynamiska data i CaO-K2O-P2O5-systemet samt att identifiera avsaknad av data, ii) att fylla i dessa luckor med grundläggande termodynamiska, strukturella och fasstabilitets studier samt iii) att visa på användning samt fördelarna med dessa nya data vid praktisk tillämpning.
En initial litteraturundersökning i CaO-K2O-P2O5-systemet visade att det saknades både strukturella och termodynamiska data. När det gällde tillgängliga termodynamiska data var situationen särskilt otillfredsställande. Det fanns endast data för några kalcium– och kaliumfosfater med varierande tillförlitlighet. Situationen beträffande pulverröntgen för fasidentifiering var bättre, fast fördunklad av det faktum att strukturellt liknande fasövergångar ofta förekommer i det undersökta systemet. Däremot fattades det tillfredställande enkristallstrukturdata för ternära faser i det undersökta systemet.
Enkristallröntgendiffraktion användes för att bestämma strukturerna för CaK2P2O7, CaKP3O9, Ca10K(PO4)7 och CaKPO4. Faserna CaK2P2O7 and CaKPO4 tillsammans med Ca3(PO4)2, KPO3 och K4P2O7 studerades med pulverröntgendiffraktion och termiska analysmetoder för att klargöra fasmodifikationer och övergångstemperaturer. Gibbs bildningsenergi bestämdes för Ca(PO3)2, Ca2P2O7, Ca3(PO4)2, Ca10K(PO4)7, CaK2P2O7, CaKPO4 och CaK4(PO4)2 med ems-metodik och yttriastabiliserad zirkonia som fast elektrolyt och Ni/Ni3P som hjälpsystem. Både de strukturella och termodynamiska data användes sedan vid analyser i ett förbrännningexperiment av olika sädesslag. Framtagna data användes både vid identifiering och även vid kvantifiering av bildade faser i biomassaresterna.
The behaviour of phosphates in thermochemical biomass conversion processes are critical for the general process chemistry, for ash related problems, for emissions as well as for an efficient, sustainable and beneficial use of the ash residues.
This thesis is a summary and a discussion of eight papers dealing with structural and thermodynamical studies of phases in the CaO-K2O-P2O5 system, with relevance for biomass combustion. The objectives were: i) to compile and review the available structural and thermodynamical data of phases in the CaO-K2O-P2O5 system as well as to identify existing gaps in the field of these data, ii) to fill in as many as possible of the gaps by fundamental thermodynamic, structural and phase stability studies and iii) to demonstrate the uses and the benefits of the new data in practical applications.
An initial review of the CaO-K2O-P2O5 system showed that both structural information and thermodynamic data were lacking. The situation regarding the available thermodynamic data was especially unsatisfactory, data could only be found for some few calcium phosphates and a few potassium phosphates with varying reliability. Concerning powder X-ray diffraction patterns for phase identification the situation was better, though obscured by the fact that structurally close related phase transitions often occur in the studied system. However, adequate single crystal structural data of ternary phases in the system was completely missing.
Crystal structures of CaK2P2O7, CaKP3O9, Ca10K(PO4)7 and CaKPO4 were determined by single-crystal X-ray diffraction. The phases CaK2P2O7 and CaKPO4 were together with Ca3(PO4)2, KPO3 and K4P2O7, investigated by powder X-ray diffraction and thermal analysis to elucidate phase modifications and transitions temperatures. Gibbs standard energy of formation was determined for Ca(PO3)2, Ca2P2O7, Ca3(PO4)2, Ca10K(PO4)7, CaK2P2O7, CaKPO4 and CaK4(PO4)2 by solid state emf measurements with yttria stabilised zirconia as solid electrolyte and Ni/Ni3P as auxiliary solid couple. Both the structural and thermodynamical data were subsequently utilised in analysis of a combustion experiment of cereal grains. The data were also used to both identify and quantify the phases formed in biomass combustion residues.
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Kavuru, Padmini. "Hierarchy of Supramolecular Synthons in the of Design Multi-Component Crystals." Scholar Commons, 2012. http://scholarcommons.usf.edu/etd/4096.
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Most of the biological systems in nature are sustained by molecular self-assemblies which are the finest examples of supramolecular architectures. Non-covalent interactions are key concepts which govern these molecular assemblies. Inspired by these examples crystal engineering emerged as an important tool in supramolecular chemistry which aids in the invention of new molecular structures with desired properties. Understanding of how the molecules interact at the molecular levels enables one to rationally design novel solid forms with modulated physicochemical properties. This feature of crystal engineering has heightened its position in materials chemistry and is currently one of the most well studied fields for generating novel compounds with pre-defined composition and supramolecular architectures.
One such class of compounds that has immensely attracted the scientific community and is under continuous study for wider applications is cocrystals. The applications include various interdisciplinary fields such as pharmaceutics, catalysis, organic conductors, explosives etc. Distinctly on the other side, cocrystals also provide a means to discover new supramolecular synthons which is the ultimate key to molecular assembly. Many robust supramolecular synthons have been discovered and hierarchies are also being developed which can serves as a design tool for cocrystal synthesis. The Cambridge Structural Database (CSD) is an important accessory in determining the robustness of a supramolecular synthon but, this does not preclude us from discovering new synthons.
The work presented here explores new persistent supramolecular synthons in polyphenols utilizing the basic concepts of crystal engineering and the CSD statistical analysis. This contribution also includes the implementation of cocrystallization for various categories of compounds which includes nutraceuticals, pharmaceuticals and ionic salts for the design and synthesis of molecular and ionic cocrystals.
Chapter 1 highlights how supramolecular synthon approach can be used to design and synthesize multi-component crystals, namely, cocrystals. The role of the CSD and its importance in crystal engineering has also been discussed. Chapters 2 and 3 focus on new persistent supramolecular synthons in the context of nutraceuticals. The cocrystals isolated in the study are also compared with the existing cocrystals in the CSD supramolecularly in terms of synthon formation. These persistent supramolecular synthons are helpful in developing hierarchies which could be utilized and applied to similar and analogous compounds. The main feature of Chapter 4 is expanding the field of cocrystallization by studying the properties of cocrystals. Some of the properties which have been examined here include effects of cocrystallization on solubility and correlations between the solubility of cocrystal with cocrystal former (CCF) and melting point of the cocrystal. The extension of cocrystals to the active pharmaceutical ingredients (APIs) has been explored in the context of pharmaceutical cocrystals by selecting a BCS class IV drug, hydrochlorothiazide in Chapter 5. Chapter 6 highlights the hybridization of organic and inorganic components for the synthesis of ionic cocrystals and is exemplified by considering lithium salts with achiral and homochiral amino acids for the generation of 1:1 and 1:2 cocrystals.
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梁景雄 and King-hung Daniel Leung. "Investigation of metal-metal bonding interactions of initially excitedstate associated with d * p transitions in Pt2(P2O5H2)44-, M2(dcpm)2(M=Au,Ag,Cu) and M2(dmpm)3 (M=Au,Cu) (dcpm=bis(dicyclohexylphosphine)methane) inorganic complexes." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2000. http://hub.hku.hk/bib/B31240525.
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Leung, King-hung Daniel. "Investigation of metal-metal bonding interactions of initially excited state associated with d * p transitions in Pt2(P2O5H2)44-, M2(dcpm)2 (M=Au, Ag, Cu) and M2(dmpm)3 (M=Au, Cu) (dcpm= bis(dicyclohexylphosphine)methane) inorganic complexes /." Hong Kong : University of Hong Kong, 2000. http://sunzi.lib.hku.hk/hkuto/record.jsp?B21490272.
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Tallapally, Venkatesham. "Colloidal Synthesis and Photophysical Characterization of Group IV Alloy and Group IV-V Semiconductors: Ge1-xSnx and Sn-P Quantum Dots." VCU Scholars Compass, 2018. https://scholarscompass.vcu.edu/etd/5568.
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Nanomaterials, typically less than 100 nm size in any direction have gained noteworthy interest from scientific community owing to their significantly different and often improved physical properties compared to their bulk counterparts. Semiconductor nanoparticles (NPs) are of great interest to study their tunable optical properties, primarily as a function of size and shape. Accordingly, there has been a lot of attention paid to synthesize discrete semiconducting nanoparticles, of where Group III-V and II-VI materials have been studied extensively. In contrast, Group IV and Group IV-V based nanocrystals as earth abundant and less-non-toxic semiconductors have not been studied thoroughly. From the class of Group IV, Ge1-xSnx alloys are prime candidates for the fabrication of Si-compatible applications in the field of electronic and photonic devices, transistors, and charge storage devices. In addition, Ge1-xSnx alloys are potentials candidates for bio-sensing applications as alternative to toxic materials. Tin phosphides, a class of Group IV-V materials with their promising applications in thermoelectric, photocatalytic, and charge storage devices. However, both aforementioned semiconductors have not been studied thoroughly for their full potential in visible (Vis) to near infrared (NIR) optoelectronic applications. In this dissertation research, we have successfully developed unique synthetic strategies to produce Ge1-xSnx alloy quantum dots (QDs) and tin phosphide (Sn3P4, SnP, and Sn4P3) nanoparticles with tunable physical properties and crystal structures for potential applications in IR technologies.
Low-cost, less-non-toxic, and abundantly-produced Ge1-xSnx alloys are an interesting class of narrow energy-gap semiconductors that received noteworthy interest in optical technologies. Admixing of α-Sn into Ge results in an indirect-to-direct bandgap crossover significantly improving light absorption and emission relative to indirect-gap Ge. However, the narrow energy-gaps reported for bulk Ge1-xSnx alloys have become a major impediment for their widespread application in optoelectronics. Herein, we report the first colloidal synthesis of Ge1-xSnx alloy quantum dots (QDs) with narrow size dispersity (3.3±0.5 – 5.9±0.8 nm), wide range of Sn compositions (0–20.6%), and composition-tunable energy-gaps and near infrared (IR) photoluminescence (PL). The structural analysis of alloy QDs indicates linear expansion of cubic Ge lattice with increasing Sn, suggesting the formation of strain-free nanoalloys. The successful incorporation of α-Sn into crystalline Ge has been confirmed by electron microscopy, which suggests the homogeneous solid solution behavior of QDs. The quantum confinement effects have resulted in energy gaps that are significantly blue-shifted from bulk Ge for Ge1-xSnx alloy QDs with composition-tunable absorption onsets (1.72–0.84 eV for x=1.5–20.6%) and PL peaks (1.62–1.31 eV for x=1.5–5.6%). Time-resolved PL (TRPL) spectroscopy revealed microsecond and nanosecond timescale decays at 15 K and 295 K, respectively owing to radiative recombination of dark and bright excitons as well as the interplay of surface traps and core electronic states. Realization of low-to-non-toxic and silicon-compatible Ge1-xSnx QDs with composition-tunable near IR PL allows the unprecedented expansion of direct-gap Group IV semiconductors to a wide range of biomedical and advanced technological studies.
Tin phosphides are a class of materials that received noteworthy interest in photocatalysis, charge storage and thermoelectric devices. Dual stable oxidation states of tin (Sn2+ and Sn4+) enable tin phosphides to exhibit different stoichiometries and crystal phases. However, the synthesis of such nanostructures with control over morphology and crystal structure has proven a challenging task. Herein, we report the first colloidal synthesis of size, shape, and phase controlled, narrowly disperse rhombohedral Sn4P3, hexagonal SnP, and amorphous tin phosphide nanoparticles (NPs) displaying tunable morphologies and size dependent physical properties. The control over NP morphology and crystal phase was achieved by tuning the nucleation/growth temperature, molar ratio of Sn/P, and incorporation of additional coordinating solvents (alkylphosphines). The absorption spectra of smaller NPs exhibit size-dependent blue shifts in energy gaps (0.88–1.38 eV) compared to the theoretical value of bulk Sn3P4 (0.83 eV), consistent with quantum confinement effects. The amorphous NPs adopt rhombohedral Sn4P3 and hexagonal SnP crystal structures at 180 and 250 °C, respectively. Structural and surface analysis indicates consistent bond energies for phosphorus across different crystal phases, whereas the rhombohedral Sn4P3 NPs demonstrate Sn oxidation states distinctive from those of the hexagonal and amorphous NPs owing to complex chemical structure. All phases exhibit N(1s) and ʋ(N-H) energies suggestive of alkylamine surface functionalization and are devoid of tetragonal Sn impurities.
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Lachgar, Abdessadek. "Etude cristallographique et spectroscopique de quelques phases nouvelles du systeme k : :(2)o-sb::(2)o::(5)-p::(2)o::(5)." Nantes, 1987. http://www.theses.fr/1987NANT2015.
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Identification de cinq phases nouvelles. Determination de la structure pour chacune d'entre elles par diffraction rx sur monocristal. Les edifices covalents sont construits a partir d'octaedres sbo::(6) partageant des sommets ou des aretes, et de tetraedre po::(4) lies aux octaedres par deux, trois ou leurs quatre sommets. Caracterisation par absorption ir, diffusion raman et spectrometre rmn du **(31)p
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Oyetola, Samuel. "Synthese et etude des composes a**(i)m**(v)p::(2)o::(8) (a = k, rb, cs; m = sb, nb, mo, ta) et des acides echangeurs ioniques hm**(v)(po::(4))::(2),xh::(2)o (m = sb, ta), nouveaux types de luminophores potentiels : les phases (m'**(iii)::(1/2)m**(v)::(1/2))p::(2)o::(7) (m'=sb, bi, ln; m=sb, nb, ta)." Nantes, 1988. http://www.theses.fr/1988NANT2008.
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Premilere partie: la plupart des phases du titre ont une structure en couches voisine de celle de zrp-alpha. Le traitement en milieu acide des phases en couches km**(i)(po::(4))::(2), m=sb, ta permet d'obtenir les acides correspondant hm**(v)(po::(4))::(2)xh::(2)o. Un autre acide, hta(po::(4))::(2) 3d, peut etre obtenu directement par voie seche, description de sa structure tridimensionnelle. Determination de la teneur en eau, de la structure et du comportement thermique de ces differents acides dont la thermolyse conduit a des phases originales qui sont etudiees. Seconde partie: dans la premiere famille, les phases (m'**(iii)::(1/2)m**(v)::(3/2)) (po::(4))::(3) sont de type nasicon ou sc::(2)(no::(4))::(3) ou d'un nouveau type structural, dans la seconde, les phases m'**(iii)::(1/2)m**(v)::(1/2))p::(2)o::(7) presentent des structures voisines de celle de zrp::(2)o::(7)
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GOIS, Elba Pereira de. "Aspectos estruturais e potencialidade leishmanicida de compostos de paládio(II) ciclometalados ou não, com o ligante imínico H3C-O-p-C6H4-(E)HC=N-C6H4-p-N=CH(E)-C6H4-p-O-CH3." Universidade Federal de Alfenas, 2011. https://bdtd.unifal-mg.edu.br:8443/handle/tede/379.
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Nos últimos anos verificou-se um aumento significativo no número de trabalhos de pesquisa que relatam a utilização de compostos de metais de transição com fins terapêuticos. Muitos estudos tomaram como base as possíveis interações dos íons metálicos com as biomoléculas presentes no organismo vivo. Sabe-se que a geometria quadrado-planar presentes nos íons metálicos paládio(II), platina(II), ouro(III), níquel(II) - campo forte e irídio(I) - campo forte, favorece a interação íon-DNA e atuam principalmente como drogas intercaladoras de modo inter ou intra-fita. O presente trabalho foi norteado pela síntese e caracterização de novos complexos de paládio(II) com possíveis aplicações farmacológicas. Foi obtido um composto ciclometalado de Pd(II) mediante reação de ciclometalação do ligante nitrogenado H2ani2p-fen com tetracloropaladato(II) de lítio, nas proporções estequiométricas (1:1 e 1:2). O complexo da estequiometria (1:1) [Pd2(Hani2p-fen)2Cl2] C2 foi utilizado como precursor na síntese de outros cincos complexos, por substituição do cloro por haletos bromo e iodo e pseudohaletos azida, cianato e tiocianato: [Pd(H2L)X2], [Pd2(HL)2X2], [Pd4(H2L)2X4] e [Pd4L2X4] sendo X = N3, NCO, SCN, Br e I. Já o complexo da estequiometria (1:2) [Pd4(Hani2p-fen)2(ani2p-fen)Cl4] C8 foi utilizado como precursor na síntese de mais outros cincos complexos. As substituições também foram do cloro por haletos (Br, I) e pseudohaletos (N3, NCO e SCN), obtendo os complexos: [Pd4(HL)2(L)X4] e [Pd4(L)2X4] sendo X = N3, NCO, SCN, Br e I. Além das técnicas espectroscópicas (IV, UV-Vis, RMN de 1H), foram realizados testes de solubilidade, ponto de fusão, análise elementar (CHNS) e estudos termogravimétricos (TG-DTA), tanto para o ligante imínico, como para os complexos metálicos. No tocante, a espectroscopia vibracional na região do ultravioleta – visível, foi observado o deslocamento das bandas de absorção dos complexos indicando a coordenação do ligante, bem como a substituição regioespecífica dos grupos coordenados em ponte. A técnica de espectroscopia vibracional na região do infravermelho permitiu inferir sobre o modo de coordenação dos pseudohaletos e confirmar a presença do ligante coordenado ao centro metálico. Esta técnica confirmou que os grupos azida, cianato e tiocianato estão coordenados preferencialmente de modo end-on, end-to-end e terminal. A análise dos espectros de RMN de 1H ligante nitrogenado e dos complexos ciclopaladados mostrou a presença de sinais compatíveis com as estruturas propostas. Em relação às curvas termogravimétricas foi possível propor um mecanismo de termodecomposição para os novos complexos, pois como único resíduo encontrou-se paládio metálico, identificado por difração de raios-X pelo método de pó. Visando empregar estes compostos em ensaios biológicos frente à Leishmania, foram realizados experimentos in vitro de células promastigotas e amastigotas da L. (L.) brazilienses. Determinou-se a viabilidade celular destas culturas, expressa pelo Índice de Citotoxicidade (IC50), que indica a concentração de substância que induz à morte 50% da população celular. Os complexos que apresentaram melhor atividade leishmanicida foram os derivados que contêm cloro (C8) e tiocianato (C11).In recent years there has been a significant increase in the number of research papers that report the use of transition metal compounds for therapeutic purposes. Many studies were based on the possible interactions of metal ions with bimolecular present in living organisms. It is known that the geometry of square-planar metal ions present in the palladium(II), platinum(II), gold(III), nickel(II) - strong field and iridium(I) - strong field, favors the ion-DNA interaction and drugs act mainly as intercalation inter-or intra-tape. This work was guided by the synthesis and characterization of new complexes of palladium(II) with potential pharmacological applications. We obtained a compound cyclometallated Pd(II) by reacting the ligand nitrogen cyclometallated H2ani2p-fen with tetracloropalad(II) of lithium in molar ratio (1:1 or 1:2). The complex stoichiometry (1:1) [Pd2(Hani2p-fen)2Cl2] C2 was used as precursor in the synthesis of five complexes, of halide substitution by chlorine and bromine and iodine pseudohalide azide, cyanate and thiocyanate: [Pd(H2L)X2], [Pd2(HL)2X2], [Pd4(H2L)2X4] and [Pd4L2X4] where X = N3, NCO, SCN, Br and I. Since the complex stoichiometry (1:2) [Pd4(Hani2p-fen)2(ani2p-fen)Cl4] C8 was used as precursor in the synthesis of more complex five others. Substitutions were also chlorine by halides (Br, I) and pseudohalide (N3, SCN and NCO), yielding the complexes: [Pd4(HL)2(L)X4] and [Pd4(L)2X4] where X = N3, NCO, SCN, Br and I. In addition to the spectroscopic techniques (UV-Vis, IR e NMR of 1H), Tests of solubility, melting point, elemental analysis (CHNS) and thermogravimetric studies (TG-DTA) for both the imine ligand, as for the complexes metal. Regarding the vibrational spectroscopy in the ultraviolet - visible, there was the shift of the absorption bands of the complexes indicating coordination of the ligand and the substitution of groups coordinated regiospecífies bridge. The technique of vibrational spectroscopy in the infrared region allowed inferring the mode of coordination of pseudohalide and confirms the presence of the ligand coordinated to the metal center. This technique confirmed that the azide, cyanate and thiocyanate groups are preferably coordinated so end-on, end-to-end and terminal. The analysis of NMR 1H spectra of ligand and complexes cyclopalladated nitrogen showed the presence of signs consistent with the proposed structures. Regarding the thermograms was possible to propose a mechanism for new thermodecomposition complex, because as the only waste met Pd identified by X-ray diffraction by the powder method. Aiming to employ these compounds in biological assays front of Leishmania, experiments were performed in vitro cell promastigotes and amastigotes of L. (L.) braziliensis. Determined the viability of these cultures, expressed by the Index of Cytotoxicity (IC50), which indicates the concentration of substance that induces death 50% of the cell population. The compounds that showed better leishmanicidal activity were those containing chlorine (C8) and thiocyanate (C11).
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BENDRAOUI, ABDELLATIF. "Traitements chimiques et thermiques de composes semi-conducteurs iii-v a base de in, ga, as, p en vue d'une reprise d'epitaxie." Clermont-Ferrand 2, 1989. http://www.theses.fr/1989CLF21151.
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L'etat de surface des semiconducteurs iii-v avant la reprise d'epitaxie conditionne les proprietes electroniques et la stabilite des composants realises. Mise en evidence de l'aspect dynamique de stabilisation des composes iii-v a base de in, ga, p et as sous hydrures. Developpement d'une methode originale de stabilisation statique de ces composes a base de chlorures d'in. Analyse des resultats experimentaux et interpretation en utilisant des modeles theoriques bases sur la thermodynamique statistique
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Hamdoune, Salaheddine. "Relations entre les structures et les propriétés de transport des solutions solides Li(1+x)Ti(2-x)In(x)P(3)O(12)." Grenoble 1, 1986. http://www.theses.fr/1986GRE10088.
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Etude cristallographique par diffraction rx d'electrons de li::(1+x) ti::(2-x) in::(x) p::(3) o::(7) et de li in p::(2) o::(7) afin de permettre une meilleure comprehension des mecanismes de transport de li**(+) dans ces composes. Suivant la concentration en in, les etudes structurales mettent en evidence trois phases differentes dans la solution solide. Les mesures de la conductivite ont montre que la modification des proprietes electriques est associee a l'etablissement d'une structure favorable a une conductivite elevee. C'est pourquoi cinq cristaux de compositions differentes ont ete etudies. Comme application, essai de realisation d'une pile a partir de la phase la plus conductrice : resultats prometteurs
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Aversa, Pierfrancesco. "Primary Defects in Halide Perovskites : Effect on Stability and Performance for Photovoltaic Applications Effect of organic PCBM Electron transport Layers on natural and post-irradiation ageing of optical absorption and emission in methyl ammonium lead triiodide spin –coated on p-i-n Solar Sell Substrates Effect of organic PCBM Electron transport Layers on natural and post-irradiation ageing of optical absorption and emission in triple cation lead mixed halide perovskite spin –coated on p-i-n Solar Sell Substrates Electron Irradiation Induced Ageing Effects on Radiative Recombination Properties of methylammonium lead triiodide layers on p-i-n solar cell substrates Electron Irradiation Induced Ageing Effects on Methylammonium Lead Triiodide Based p-i-n Solar Cells Electron Irradiation Induced Ageing Effects on Radiative Recombination Properties of Quadruple Cation Organic-Inorganic Perovskite Layers." Thesis, Institut polytechnique de Paris, 2020. http://www.theses.fr/2020IPPAX050.
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Ces onze dernières années ont vu apparaitre les pérovskites organiques inorganiques hybrides (HOIPs) comme un passionnant domaine de recherche pour leur application potentielle dans les technologies du photovoltaïque (PV) en raison de leurs exceptionnelles propriétés optoélectroniques et de leur facilité de mise en oeuvre. Cependant, les matériaux HOIPs ont plusieurs inconvénients dont leur manque de stabilité en conditions opérationnelles. Améliorer celle-ci est l'un des plus grands défis à relever avant commercialisation. La formule générale est (A1,A2,A3,A4)Pb(X1,X2)3, où les sites A occupés par une distribution de 1 à 4 cations métalliques/organiques et les sites X par celle d’anions halogénures. Les défauts lacunaires natifs sont considérés comme une cause possible de dégradation des cellules solaires HOIPs. L'objectif de ce travail est de comprendre le rôle des défauts dans la stabilité à long terme des matériaux PV HOIPs. A cette fin, des défauts primaires ont été introduits de manière contrôlée par irradiation avec des électrons de haute énergie (1MeV) dans des lots de couches et cellules solaires (SCs) à base de divers composés HOIPs. Il s'agit notamment du prototype PV HOIPs, MAPbI3 (A1PbX13), et de nouveaux composés mixtes d’halogénures à triple ou quadruple cations, (CsMAFA)Pb(I1-xBrx)3 (A3PbX23) ou (GACsMAFA)Pb(I1-yBry)3 (A4PbX23). Les couches sont fabriquées selon la même procédure que les couches actives SCs et, ensuite, traitées dans des conditions similaires. Pour A1PbX13/A3PbX23, la structure SC est de type p-i-n avec des couches organiques pour le transport des trous et des électrons (HTL/ETL). Les couches sont déposées sur le substrat verre/ITO/HTL (PEDOT:PSS) sans ou avec couche supérieure ETL (PCBM). Pour A4PbX23, la structure SC est de type n-i-p avec des couches ETL inorganiques (TiO2) et HTL organiques (Spiro-OMeTAD). Les couches sont directement déposées sur du verre.La spectroscopie d'annihilation de positons donne une évidence directe de l'existence de défauts lacunaires natifs et induits par irradiation dans chaque composé. Les spectres d’absorbance en fonction de l’énergie montrent que le vieillissement naturel et après irradiation génère différentes populations de défauts dans chaque composé. De plus, celles-ci pour A1PbX13 et A3PbX23 diffèrent selon l'absence ou la présence de la couche supérieure ETL. Les populations de défauts évoluent pendant au moins 3 mois. Le vieillissement modifie (i) la bande interdite, (ii) les queues de bande de conduction/valence et (iii) l'absorption optique via des niveaux électroniques profonds. Les effets d’illumination sous laser varient aussi en fonction du vieillissement. L’asymétrie des pics de photoluminescence (PL) dans chaque composé sous illumination laser continue reflète une superposition de raies d’émission gaussiennes à énergie, FWHM et hauteur évoluant avec le temps d'illumination. Les transitions d'émission impliquent des niveaux électroniques localisés peu profonds dans A3PbX23/A4PbX23 et résonnants dans A1PbX13. De tels effets durent au moins 3 mois dans A4PbX23. Ces niveaux électroniques sont attribués à des populations de défauts spécifiquement induits par illumination. Le vieillissement naturel et après irradiation donne des spectres PL à décroissance temporelle résolue en une ou deux exponentielles. Le nombre et la durée de vie sont fortement influencés par l’irradiation initiale et la composition. Une amélioration frappante du fonctionnement PV pour le type SC p-i-n est induite par le vieillissement dû à l'irradiation. Le rendement quantique externe et les performances PVs ont des valeurs plus élevées pour l’état irradié que de référence durant 6 à 12 mois de vieillissement. Cela prouve que l'ingénierie des défauts par irradiation d'électrons à haute énergie a le potentiel de fournir des voies de traitement innovantes pour améliorer la stabilité à long terme des performances photovoltaïques HOIPsDuring the last eleven years, Hybrid Organic Inorganic Perovskites (HOIPs) materials have emerged as an exciting topic of research for potential application in solar cell technologies due to their outstanding optoelectronic properties and processing advantages. However, HOIPs materials suffer from several drawbacks with, in peculiar, their lack of stability under operational conditions (light, bias, environment…). To improve this stability is one of the biggest challenges to be addressed before commercialization. The general formula for HOIPs is (A1,A2,A3,A4)Pb(X1,X2)3, where the A sites can be occupied by a distribution of 1 to 4 metallic/organic cations and X sites with halide anions. The role of native vacancy defects has been questioned as a possible cause for HOIPs solar cells degradation. The aim of this work is to understand the defect role in long term stability of HOIPs materials for photovoltaics. For this reason, primary defects were introduced in a controlled way via high energy electron irradiation (1MeV) in sets of layers and solar cells (SCs) fabricated using various HOIPs compounds. Those include the photovoltaic HOIPs prototype, MAPbI3 (A1PbX13), and emergent triple or quadruple cation mixed halide HOIPs, (CsMAFA)Pb(I1-xBrx)3 (A3PbX23) or (GACsMAFA)Pb(I1-yBry)3 (A4PbX23). The HOIPs layers are fabricated according to the same procedure as the HOIPs active SC layers and, subsequently, treated in similar conditions. For A1PbX13 and A3PbX23, the solar cells are of the p-i-n structure with organic hole and electron transport layer (HTL/ETL). The HOIPs layers are deposited on the glass/ITO/HTL (PEDOT:PSS) substrate without or with the top ETL layer (PCBM). For A4PbX23, the solar cells are of the n-i-p type with inorganic ETL (TiO2) and organic HTL (Spiro-OMeTAD) layers. The layers are directly deposited on glass without the ETL layer.Positron Annihilation Spectroscopy (PAS) gives direct evidence for native vacancy-type defects and irradiation induced ones in layers of each HOIP compound. The energy dependence of absorbance shows that natural and after irradiation ageing generates different defect populations in each HOIP compound. These populations strikingly also differ depending on the absence or presence of the top ETL layer for the A1PbX13 and A3PbX23 compounds. The defect populations evolve over ageing duration as long as 3 months. The prominent effects of ageing include (i) band gap modification, (ii) tailing of conduction/valence band extrema and (iii) optical absorption via deep subgap electronic levels. Illumination effects under laser also vary with ageing for each HOIP compound. Asymmetric photoluminescence (PL) peaks in each compound under continuous laser illumination reflect that radiative emission involves Gaussian emission rays with energy, FWHM and height evolving with illumination time. The emission transitions involve shallow localized electronic levels in A3PbX23 and A4PbX23 and resonant ones in A1PbX13. These electronic levels are attributed to specifically illumination-induced defect populations. Natural and after irradiation ageing result in PL decay lifetime spectra resolved into one or two exponential decay components. The decay components number and lifetime are strongly affected by the initial production of irradiation defects and HOIPs composition. Such effects last over 3 months at least in A4PbX23. The p-i-n solar cells exhibit most striking irradiation ageing induced photovoltaics performance. The External Quantum Efficiency (EQE versus photon energy) and the photovoltaic performance (I-V under illumination) of the irradiated solar cells have higher values than those in the reference SCs after 6 to 12 months of ageing. This gives evidence that defect engineering via high energy electron irradiation has a potential for providing innovative processing pathways to enhance the long-term stability of HOIPs photovoltaic performance
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Maurel, Philippe. "Contribution a l'etude des proprietes physiques des composes ga : :(x)in::(1-x)as::(y)p::(1-y) obtenus par croissance en phase vapeur par la methode des organometalliques." Paris 6, 1987. http://www.theses.fr/1987PA066517.
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Etude des proprietes electriques et optiques a basse temperature dans inp de haute purete. Observation de l'effet hall quantique par etude detaillee de proprietes de transport des porteurs bidimensionnels a l'heterojoncion, a dopage module de type p ou n dans inp/ga::(0,47) in::(0,53) as et inp/ga::(0,25) in::(0,75) as::(0,5) p::(0,5). Etude des proprietes structurelles et optiques des puits quantiques multiples inp/ga::(0,47) in::(0,53) as
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Jouanneaux, Alain. "Etude par r. P. E. De diffraction de neutrons des composes mixtes rb : :(x)(nh::(4))::(1-x)alf::(4), desordre chimique, transition de phase, ordre local, verre de spin structural." Nantes, 1987. http://www.theses.fr/1987NANT2044.
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Mise en evidence, a temperature ambiante, de la substitution de rb**(+) a toute concentration. Determination par diffraction de neutrons sur poudre de la structure moyenne des cristaux mixtes : resultats en accord avec les resultats rpe. Puis, etude a basse temperature de l'ordre du sous-reseau des ions nh::(4)**(+) pour 0
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Rodrigues, Claudia. "Estudo sobre o mecanismo de reações de hidrogenação em complexos do tipo [RuCl2(P)2(N)2][(P)2= mono ou bifosfina; N= piridina ou derivados]." Universidade Federal de São Carlos, 2010. https://repositorio.ufscar.br/handle/ufscar/6472.
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Previous issue date: 2010-03-26Universidade Federal de Sao Carlos
In this study, it was performed synthesis and characterization of the complexes of general formula cis-[RuCl2(PPh3)2(N)2], cis-[RuCl2(PPh3)2(N-N)], trans- [RuCl2(dppb)(N)2], cis-[RuCl2(dppb)(N-N)] and cis-[RuCl2(P-P)(N-N)] [PPh3 = triphenylphosphine, dppb = 1,4-bis(diphenylphosphino)butane, (P-P) = bis(diphenylphosphino)methane, 1,2-bis(diphenylphosphino)ethane and 1,3- bis(diphenylphosphino)propane, N = pyridine (py), 4-picoline (4-pic), 4-tertbutilpyridine (4t-Bupy ), 4-vinylpyridine (4-vpy) and 4-phenylpyridine (4-Phpy), N-N = 2,2'-bipyridine (bipy), 1,10-phenanthroline (phen), 4,4'-dimethyl-2,2'-bipyridine (4- Mebipy), di-2-piridilcetona (dpk) and 4,4'-dimethoxy-2,2'-bipyridine (MeO-bipy)]. The characterizations were performed using elemental analysis, conductivity, Infrared spectrometry (IR), NMR 31P {1H}, cyclic voltammetry and differential pulse voltammetry as well as X-ray diffraction, when suitable crystals were obtained. Kinetic studies of substitution of one chloride ligand from the coordination sphere of the complex by a monodentate L ligand (pyridine (py) or 4-picoline (4-pic)) were performed for the complex series of cis-[RuCl2(P-P)(N-N)] in terms of pseudo-first order conditions. The catalytic studies of some of the complex obtained in this work in hydrogenation reactions of cyclohexene were carried out. For the catalytic reactions were used a stainless steel reactor purging with H2 pressure, temperature and agitation were controlled and the analysis of results were performed in a gas chromatograph with detector flame ionization detector (GC-FID) with a capillary column DB5. The catalytic reactions performed with the complex series of [RuCl2(PPh3)2(N)2] showed a high conversion of reactant (cyclohexene - CXE) to product (cyclohexane - CXA) and a high value of TOF (turnover frequency) above 1000 h-1, during 24 hours of reaction. For complex series of [RuCl2(dppb)(N)2] the values of conversion (%) and TOF (h-1) were not as high, but still significant. For the other tested complexes, the values were low and the conversions were not significant.
Neste trabalho, realizaram-se as sínteses e caracterizações dos complexos de fórmula geral cis-[RuCl2(PPh3)2(N)2], cis- [RuCl2(PPh3)2(N-N)], trans-[RuCl2(dppb)(N)2], cis-[RuCl2(dppb)(N-N)], cis-[RuCl2(PP)( N-N)] [PPh3 = trifenilfosfina, dppb = 1,4-bis(difenilfosfina)butano, (P-P) = bis(difenilfosfina)metano, 1,2-bis(difenilfosfina)etano e 1,3-bis(difenilfosfina)propano; N = piridina (py), 4-picolina (4-pic), 4-terc-butilpiridina (4t-Bupy), 4-vinilpiridina (4-Vpy) e 4-fenilpiridina (4-Phpy); N-N = 2,2 -bipiridina (bipy), 1,10-fenantrolina (fen), 4,4 - dimetil-2,2 -bipiridina (4-Mebipy), di-2-piridilcetona (dpk) e 4,4 -dimetoxi-2,2 -bipiridina (MeO-bipy)]. As caracterizações foram realizadas por meio de análise elementar, condutividade, espectroscopia de absorção na região do infravermelho (IV), RMN de 31P{1H}, voltametria cíclica e voltametria de pulso diferencial e difração de raios X, quando se obteve cristais. Os estudos cinéticos de substituição de um ligante cloreto da esfera de coordenação do complexo por um ligante L monodentado (piridina (py) ou 4-picolina (4-pic)) foram realizados para os complexos da série cis-[RuCl2(P-P)(NN)] em condições de pseudo primeira ordem. Os estudos catalíticos de alguns dos complexos obtidos durante este trabalho em reações de hidrogenação do cicloexeno foram realizados. Para as reações catalíticas foi utilizado um reator de aço inox com pressão de H2, temperatura e agitação controladas e as análises dos resultados foram realizadas em um cromatógrafo a gás com detector de ionização por chama (GC-FID) com coluna capilar DB5. As reações catalíticas realizadas com os complexos da série [RuCl2(PPh3)2(N)2] apresentaram uma alta conversão de reagente (cicloexeno - CXE) em produto (cicloexano - CXA) e um alto valor de TOF (turnover frequency) acima de 1000 h-1, em 24 horas de reação. Para os complexos da série [RuCl2(dppb)(N)2] os valores de conversão (%) e TOF (h-1) não foram tão altos, mas ainda são significativos. Para os demais complexos testados, os valores encontrados foram baixos e as conversões não foram significativas.
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Melo, RÃgis Lopes. "EletrodeposiÃÃo, CaracterizaÃÃo e Estudos de CorrosÃo de Camadas de Ni-Mo-P." Universidade Federal do CearÃ, 2009. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=3492.
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Conselho Nacional de Desenvolvimento CientÃfico e TecnolÃgicoO presente trabalho descreve a sÃntese, a caracterizaÃÃo e o estudo de corrosÃo em meio de NaCl 0,1 mol L-1 das ligas de Ni-Mo-P. Todas as ligas foram obtidas por eletrodeposiÃÃo sobre uma superfÃcie de cobre a temperatura ambiente, a 50ÂC e a 70ÂC, essas camadas foram caracterizadas em termos de microestrtura, composiÃÃo quÃmica, estrutura cristalogrÃfica, microdureza e resistÃncia à corrosÃo. O eletrÃlito utilizado, para eletrodeposiÃÃo dos revestimentos de Ni-Mo-P, foi uma soluÃÃo de Na2MoO4.2H2O 0,02 mol L-1; NiSO4Â6H2O 0,20 mol L-1; NaPH2O2 0,02 mol L-1 e 0,04 mol L-1; Na3C6H5O7.2H2O 0,10 mol L-1 e o pH ajustado para 9,0 com hidrÃxido de amÃnia. A caracterizaÃÃo fÃsica e quÃmica das camadas foram feitas por MEV, EDX, DRX e medidas de microdureza. Os testes eletroquÃmicos de corrosÃo foram feitos por polarizaÃÃo potenciodinÃmica linear (PPL) e pela espectroscopia de impedÃncia eletroquÃmica (EIE). As medidas de microdureza foram feitas em amostras nÃo tratadas e tratadas termicamente nas temperaturas de 100, 200, 400 e 600ÂC. Os resultados de DRX mostram uma mudanÃa de estrutura cristalina para amorfa com o aumento do teor de fÃsforo na camada. Observa-se o aumento da microdureza dos revestimentos de Ni-Mo-P com o aumento da temperatura de tratamento tÃrmico, as anÃlises de DRX feitas nas amostras tratadas termicamente mostraram que com o aumento da temperatura de tratamento hà a precipitaÃÃo de fases duras Ni3P, Ni e Ni-Mo. Na avaliaÃÃo do estudo de corrosÃo observa-se uma tendÃncia de deslocamento dos potenciais de corrosÃo para valores mais positivos, com o aumento do teor de fÃsforo na camada. Analisando os resultados de ensaios de corrosÃo pode-se determinar que o revestimento de Ni78Mo10P12 apresentou-se como o mais resistivo dentre as camadas de Ni-Mo-P.
The present work describes the electrodeposition and characterization of the Ni-Mo-P coatings as well their corrosion behavior in 0.1 mol L-1 NaCl solution. The coatings were obtained by under galvanostatic control in the range of 25 mA cm-2 to 100 mA cm-2 and at the following plating solutions temperatures: room temperature (@ 27 ÂC), 50 ÂC and 70 ÂC. As-electrodeposited and as-annealed Ni-Mo-P coatings were characterized using Scaning Electron Microscopy (SEM), X-ray diffraction (XRD), Energy Dispersive X-ray (EDX) techniques and by microhardness measurements. The Ni-Mo-P coatings were electrodeposited on a copper surface using a plating solution contain 0.02 mol L-1 Na2MoO4.2H2O; 0.20 mol L-1 NiSO4Â6H2O; 0.02 mol L-1, 0.04 mol L-1 NaPH2O2 and 0.10 mol L-1 Na3C6H5O7.2H2O, with the pH adjusted to 9.0 with ammonia solution. The corrosion tests were carried out by Potentiodynamic Linear Polarization (PLP) and by Electrochemical Impedance Spectroscopy (EIS) techniques. The microhardness measurements were made in samples as-electrodeposited and asannealed at 100, 200, 400 and 600ÂC. XRD diffractograms showed a change from crystalline structure for amorphous with the increase of P content in the coating. The increase of the microhardness of the coatings is observed with the increase of the annealing temperature which was related to the precipitation of Ni3P, Ni and Ni-Mo phases. The corrosion study shows a tendency of shift of the corrosion potentials for more positive values with the increase of P in the layer. Analyzing the corrosion results it can determine that Ni78Mo10P12 is the more resistive coating among the layers of studied.
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Santos, Edjane Rocha dos. "Síntese e caracterização de complexos de fórmula geral [Ru(AA)(P-P)(N-N)]PF6, onde (AA= aminoácidos; PP=bifosfinas; N-N= 2,2 -bipiridina e derivados e 1,10-fenantrolina): avaliação de suas potencialidades citotóxicas." Universidade Federal de São Carlos, 2011. https://repositorio.ufscar.br/handle/ufscar/6213.
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The present work describes the syntheses and characterization of complexes of general formula [Ru(AA)(P-P)(N-N)]PF6 where AA = aminoacids (Gly, Ala, Val, Met, Tyr, Trp, Leu, Arg, Ser, Lys, His); P-P = 1,4- bis(diphenylphosphino)butane and 1,3-bis(diphenylphosphino)propane; N-N= 1,10- phenanthroline, 4,4 -dimethyl-2,2 -bipyridine, 5,5 -dimethyl-2,2 -bipyridine e 4,4 - methoxy-2-2'-bipy. The complexes were evaluated against cell lines MDA-MB-231, MCF-7 (breast tumor cells), DU-145 (prostate tumor cells) and in FGH and V79 (fibroblasts, normal cells), HeLa (colon tumor cells), as well as antimicrobial tests (tuberculosis) and antiparasite (malaria (CW-2 chloroquine resistant) and Chagas disease (Y-form) ). By analytical techniques such as elemental analysis, UV-vis and infrared spectroscopies and nuclear magnetic resonance (31P{1H}, 13C{1H} and 1H), it was possible to confirm the proposed structures for the synthesized compounds. By the 31P{1H}, 13C and 1H NMR spectra, it was suggested the presence of isomers, these data combined with the X-ray structure analysis of the [Ru(LLeu)( dppb)(bipy)]PF6, allowed us to conclude that those isomers are diastereoisomers. The cyclic voltammograms of all the complexes are similar with the first anodic wave around 1.1 V being attributed to the oxidation RuII→RuIII, and the second anodic wave, in 1.2 V, is attributed to the oxidation of the COO- group of the aminoacid ligands. In the IR spectra of the complexes, characteristic stretching bands of the group NH2 and COO- were observed, which are found shifted to higher frequencies when compared to the free aminoacid. The complexes here studied presented promising results against diseases evaluated. The values of the IC50 for some of the compounds showed 31,5-fold lower than the cisplatin. The antimycobacterial tests were satisfactory, since the complexes showed lower MIC values than some drugs actually used in the tuberculosis treatment. Considering the antiparasitic tests, low IC50 values were also observed.
Neste trabalho obtiveram-se complexos de fórmula geral [Ru(AA)(PP)( N-N)]PF6 onde AA = aminoácidos (Gly, Ala, Val, Met, Tyr, Trp, Leu, Arg, Ser, Lys, His); P-P = 1,4-bis(difenilfosfina)butano e 1,3-bis(difenilfosfina)propano; N-N= 1,10- fenantrolina, 4,4 -dimetil-2,2 -bipiridina, 5,5 -dimetil-2,2 -bipiridina e 4,4 -metoxi-2-2'- bipy, os quais foram avaliados frente as linhagens de células do tipo MDA-MB-231, MCF-7 (células tumorais de mama), DU-145 (células tumorais de próstata), HeLa (células tumorais de câncer de colo de útero) e em FGH e V79 ((linhagem celular não tumoral, fibroblastos), além de testes para avaliação antimicrobacteriana (tuberculose) e antiparasitária (malária (CW-2 resistente a cloroquina) e doença de Chagas (Cepas-Y) ). Através das técnicas de análise elementar, espectroscopia de absorção na região do ultravioleta visível e infravermelho e ressonância magnética nuclear de 31P{1H}, 13C{1H}, 1H foi possível confirmar as estruturas propostas para os compostos sintetizados. Através dos espectros de RMN de 31P{1H}, 13C{1H}, 1H sugeriu-se a presença de isômeros, estes dados, junto à determinação da estrutura de raios X do [Ru(Leu)(dppb)(bipy)]PF6 permitiram concluir que esses isômeros são diastereoisômeros. Nos voltamogramas cíclicos dos complexos, a primeira onda anódica, em torno de 1,1 V é atribuída ao RuII→RuIII, e a segunda onda anódica, em 1,2 V, é atribuída à oxidação do grupo COO- do aminoácido. No espectro de IV dos complexos, existem estiramentos das bandas do grupo NH2 e do COO-, característicos dos aminoácidos. Esses estiramentos deslocaram-se para frequências mais altas quando comparados com os mesmos estiramentos dos ligantes livres. Os complexos aqui estudados apresentaram resultados promissores frente às doenças avaliadas. Os valores de IC50 para alguns dos compostos obtidos foram 31,5 vezes menores que do cisplatina. Os testes de atividade antimicobactericida foram satisfatórios, pois os complexos apresentaram valores de MIC mais baixos que alguns fármacos usados atualmente no tratamento da tuberculose. Quanto aos testes antiparasitários baixos valores IC50 foram observados.
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Teixeira, José Augusto. "Síntese, caracterização e estudo termoanalítico dos p-aminobenzoatos de lantanídeos (III) e ítrio (III), exceto promécio, no estado sólido /." Araraquara, 2018. http://hdl.handle.net/11449/157461.
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Orientador: Massao IonashiroCoorientador: Flávio Junior Caires
Banca: Rodrigo Fernando Costa Marques
Banca: Gilbert Bannach
Banca: Salvador Claro Neto
Banca: Adriano Buzutti de Siqueira
Resumo: O estudo da interação de compostos orgânicos e íons metálicos se apresenta como ferramenta importante para a confecção de novos compostos. Uma vez preparados, as propriedades físico-químicas desses compostos são diversas e devem ser conhecidas, portanto, é importante que se realize uma pesquisa básica destes complexos. Neste contexto, foram realizadas as sínteses, caracterizações e estudos termoanalíticos dos compostos sólidos obtidos através da coordenação do ácido p-aminobenzoico com os íons lantanídeos trivalentes e ítrio (III), exceto promécio. Tal estudo teve o intuito de adquirir conhecimento das propriedades físico-químicas e estruturais dos produtos obtidos. Os compostos sólidos foram preparados por meio de duas vias de síntese diferentes. Do La ao Gd os compostos foram obtidos reagindo os respectivos cloretos ou nitratos destes metais com uma solução de p-aminobenzoato de sódio previamente preparada pela neutralização do ácido p-aminobenzoico com NaOH. Enquanto que, os compostos do Tb ao Lu e Y foram obtidos reagindo o ácido p-aminobenzoico com os respectivos carbonatos desses metais. Após serem filtrados, lavados e secos os compostos foram caracterizados por espectroscopia de absorção na região do infravermelho com transformada de Fourier (FTIR), termogravimetria-análise térmica diferencial simultânea (TG-DTA), análise dos gases liberados (EGA por TG-FTIR), calorimetria exploratória diferencial (DSC), calorimetria exploratória diferencial acoplada a sistema foto-vis... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: The study of the interaction of organic compounds and metallic ions is an important tool for making new compounds. Once the prepared, the physicochemical properties of these compounds are diverse and must be known should be known, therefore is important to carry out a basic research of these complexes. In this context, the syntheses, characterizations and thermoanalytical studies of the solid compounds obtained by the coordination of p - aminobenzoic acid with trivale nt lanthanides and yttrium (III), except promethium, was performed. This study aimed to acquire knowledge of the physical - chemical and structural properties of the products obtained. Solid compounds were prepared by two different synthetic routes. From La to Gd the compounds were obtained by reacting the respective chlorides or nitrates of these metals with a solution of sodium p - aminobenzoate previously prepared for the neutralization of p - aminobenzoic acid with NaOH. While the compounds of Tb to Lu and Y were obtained by reacting p - aminobenzoic acid with the respective carbonates of these metals. After being filtered, washed and dried the compounds were characterized by Infrared absorption spectroscopy (FTIR), simultaneous thermogravimetry and differential thermal analysis (TG - DTA), evolved gas analysis (EGA) by TG/DSC - FTIR, differential scanning calorimetry (DSC), DSC - photovisual system (DSC - Photo v is ual ), X - ray powder diffractometry ( X R P D) and complexometry with EDTA . From the resul... (Complete abstract click electronic access below)
Doutor
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Colin, Thierry. "Etude et réalisation d'hétérojonctions CdxHg(1-x)Te/CdyHg(1-y)Te en épitaxie par jets moléculaires." Grenoble 1, 1991. http://www.theses.fr/1991GRE10120.
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La realisation en ejm d'heterojonctions a base de cmt a necessite la reprise d'une etude detaillee de la croissance de ce materiau suivant l'orientation (111). La presence d'une couche adsorbee de tellure a la surface du materiau en croissance semble jouer un role majeur dans le controle de la qualite cristalline. Les efforts entrepris pour controler la croissance et mettre en place une modelisation quantitative nous ont permis d'etudier les principaux effets parasites rencontres en ejm de cmt. La mise en place d'innovations technologiques importantes a permis d'en reduire certains effets. Le dopage in de cmt par croissance sous flux de dopant a ete etudie. Des dopages de quelques 10#1#8 cm##3 avec une activite de pres de 100% ont ete obtenus. Les dispersions constatees sur l'incorporation et l'activite de l'indium proviendraient d'un effet de segregation dependant du taux de couverture en tellure lors de l'epitaxie. Le phenomene d'activation apres recuit sous mercure a ete observe. L'interpretation de cet effet a partir de la formation d'in2te3 semble valide. Pour la realisation du dopage p dans les heterojonctions, le dopage intrinseque du aux lacunes de hg a ete utilise. Afin d'obtenir des dopages assez importants, nous avons mis en place une procedure de recuit in-situ apres epitaxie en mettant a profit la connaissance des phenomenes rencontres en croissance de cmt. Sur le plan des dispositifs la connaissance du materiau et les efforts de modelisation ont permis l'obtention de structures aux caracteristiques electro-optiques performantes
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Medrano, Sanchez Carlos. "Étude par tomographie au rayonnement synchrotron de domaines et coexistences de phase dans des matériaux magnétiques (MnP, Fe3O4, (alpha)-Fe2O3)." Université Joseph Fourier (Grenoble ; 1971-2015), 1997. http://www.theses.fr/1997GRE10293.
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Nous avons profite des possibilites nouvelles de la topographie aux rayons x associees a l'usage d'un synchrotron de troisieme generation pour etudier des domaines et coexistences de phases dans des materiaux magnetiques (mnp, fe#3o#4, -fe#2o#3). Dans mnp, nous avons observe en temps reel la nucleation de la phase eventail a l'interface entre les deux autres phases, heli et ferromagnetique. Une interface inhabituelle, de largeur observable par topographie, se produit entre les phases ferromagnetique et eventail. Ceci pourrait suggerer l'existence de nouvelles phases intermediaires, qui ne se forment que pendant la coexistence ferromagnetique-eventail. Les domaines magnetiques a temperature ambiante ont ete observes dans fe#3o#4 dans le cas a trois ondes en faisceau blanc. Ils presentent un contraste similaire a celui que l'on obtient en l'onde plane monochromatique ; nous donnons une explication de ce fait. Par ailleurs, nous avons tire, a partir de nos resultats par topographie en section et faisceau blanc, la structure des macles monocliniques dans la phase basse temperature. Cette structure est energetiquement favorable (energies elastique, magnetostatique et electrostatique). Des distorsions additionnelles sont observees et indiquent que la vraie symetrie est triclinique. Un echantillon epais (1. 2 mm) d'hematite, -fe#2o#3, a ete etudie par topographie en section en utilisant des photons de haute energie. Les images revelent une structure de domaines paralleles a la surface (111) de l'echantillon. Le developpement avec le champ montre un processus d'aimantation inhabituel qui se fait surtout par rotation des moments a l'interieur des domaines. Ceci est associe au piegeage des parois et a la faible anisotropie dans le plan de base.
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Kvitek, Zdenek. "Etude de la transition ferroélectrique-ferroélastique du KD2PO4 : forme du front de phase en fonction du gradient thermique." Université Joseph Fourier (Grenoble), 1995. http://www.theses.fr/1995GRE10046.
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La coexistence de phase paraelectrique-ferroelectrique (et ferroelastique) du kd#2po#4 a ete etudiee en fonction du gradient thermique. Dans cette transition tetragonale-orthorhombique, la forme du front de phase varie en fonction de l'orientation et de l'intensite du gradient thermique. Les fronts quasiplans ou en forme de toits (sections en zigzag) sont etudies experimentalement et expliques a l'aide d'un bilan energetique ou l'energie mecanique est calculee par la theorie de khachaturyan
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Oliveira, Francyelle Moura de. "Síntese de nanopartículas anisotrópicas de ouro e sua avaliação como catalisadores na redução química do p-nitrofenol." Universidade Federal de Alagoas, 2017. http://www.repositorio.ufal.br/handle/riufal/1866.
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Gold nanoparticles (AuNPs) have constantly attracted the attention of the scientific and industrial community due to the variety of physicochemical properties presented which are different and considered new properties from those that are evidenced in their mass form. Those new properties are strongly related to their morphology, providing a wide range of possible applications in several areas such as optics, medicine and catalysis. As well known, nanoparticles are thermodynamically unstable and consequently they have an easy tendency to agglomarate. In this context, the synthesis of nanoparticles in a general procedure, in particular the metallic ones, and more particularly the gold ones, need synthesis strategies with adequate growth control in the dynamics formation. Therefore, it becomes a constant challenge to obtain nanostructured materials with high yields and degree of selectivity. Among the various preparation methodologies, the seed-mediated method, seeding, is most commonly used, classically in the presence of Cetyltrimethylammonium bromide (CTABr) as a growth-driving agent. The obtained AuNPs were characterized by Visible Ultraviolet Absorption Spectroscopy (UV-vis) and Electron Transmission Microscopy (MET). These nanoparticles were evaluated in catalytic tests in chemical reduction reactions of p-Nitrophenol, where we investigated the influence of different reaction conditions such as the concentration of the catalyst, the reducing agent, and the optimum concentration and temperature variation. Surfactants were characterized by Ultraviolet Absorption Spectroscopy (UV-vis). Among the catalytic tests, the concentration of the reductant (NaBH4) was decreased from 0.1 mol L-1 to 0.05 mol L-1, 0.025 mol L-1 and 0.0025 mol L-1, between these concentrations, the molar ratio of the substrate/reductant was decreased from 500 to 12.5. The lowest borohydride concentration, 0.0025 mol L-1, gives a longer time to 100% conversion of p-nitrophenol, thus conducting studies varying the temperature of the system, in order to optimize the conversion time. herefore, the reaction was evaluated at temperatures of 25, 35, 45 and 55 °C, observing that with the increase of temperature, the reaction time of the reaction decreased. The reactions had a kinetic profile of pseudo-first order, so the apparent velocity constant was calculated for each reaction and it was observed that the reactions catalyzed by gold nanobastones (AuNRs) had a higher rate constant when compared to gold nanospheres (AuNSs). Finally, the activation energy (Ea) of the system was calculated, where Ea for reactions catalyzed by AuNRs was 70.5 kJ mol-1 and AuNSs obtained 105 kJ mol-1.Coordenação de Aperfeiçoamento de Pessoal de Nível Superior
As nanopartículas de ouro (AuNPs) tem atraído constantemente a atenção da comunidade científica e industrial devido à variedade de propriedades físico-químicas apresentadas que são diferentes e consideradas novas das que são evidenciadas em sua forma mássica. Tais novas propriedades estão fortemente relacionadas à sua morfologia, proporcionando um grande leque de possíveis aplicações em diversas áreas como em óptica, medicina e catálise. Como se sabe, as nanopartículas são termodinamicamente instáveis e por isso possuem uma fácil tendência de se aglomerarem. Dentro desse contexto, a síntese de nanopartículas de um modo em geral, em particular as metálicas e mais particularmente as de ouro, precisam de estratégias de síntese com controle adequado de crescimento na dinâmica de formação. Portanto, torna-se um constante desafio a obtenção de materiais nanoestruturados com elevados rendimentos e grau de seletividade, .Entre as diversas metodologias de preparação, o método mediado por semente, ou semeadura, é o mais comumente utilizado, classicamente na presença de brometo de cetiltrimetilamônio (CTABr) como um agente direcionador de crescimento. As AuNPs obtidas foram caracterizadas por Espectroscopia de Absorção no Ultravioleta Visível (UV-vis) e por Microscopia Eletrônica de Transmissão (MET). Posteriormente, estas mesmas nanopartículas foram avaliadas em testes catalíticos em reações de redução química do p-Nitrofenol, onde investigamos a influência de diferentes condições reacionais como a variação da concentração do catalisador, do agente redutor buscando uma concentração otimizada e variação de temperatura.As reações de reduçãoforam caracterizadas por UV-vis. Dentre os testes catalíticos, a concentração do redutor (NaBH4) foi diminuída, de 0,1 mol L-1 para 0,05 mol L-1, 0,025 mol L-1 e 0,0025 mol L-1, entre essas concentrações, a razão molar do substrato/redutor foi diminuída de 500 vezes para 12,5 vezes. A menor concentração de borohidreto, 0,0025 mol L-1, aprensenta maior tempo para 100% de conversão do p-nitrofenol, assim realizou-se estudos variando a temperatura do sistema, com o objetivo de otimizar o tempo de conversão. Portanto a reação foi avaliada nas temperaturas de 25, 35, 45 e 55 °C, observando que com o aumento da temperatura, o tempo de conversão da reação diminuiu. As reações apresentaram perfil cinético de pseudo-primeira ordem, portanto foi calculado a constante de velocidade aparente para cada reação e observou-se que as reações catalisadas por nanobastões de ouro (AuNRs) apresentavam maior constante de velocidade quando comparadas as nanoesferas de ouro (AuNSs). Por fim, calculou-se a energia de ativação (Ea) do sistema, onde a Ea para as reações catalisadas por AuNRs obteve valor de 70,5 kJ mol-1 e por AuNSs obteve 105 kJ mol-1.
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Costa, Maria Jos? Fonseca. "S?ntese de catalisadores nanoporosos na aus?ncia total e parcial de direcionadores org?nicos para pir?lise catal?tica de ?leos pesados e intermedi?rios." Universidade Federal do Rio Grande do Norte, 2013. http://repositorio.ufrn.br:8080/jspui/handle/123456789/17786.
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Previous issue date: 2013-06-03Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior
The processing of heavy oil produced in Brazil is an emergency action and a strategic plan to obtain self-sufficiency and economic surpluses. Seen in these terms, it is indispensable to invest in research to obtain new catalysts for obtaining light fraction of hydrocarbons from heavy fractions of petroleum. This dissertation for the degree of Doctor of Philosophy reports the materials preparation that combine the high catalytic activity of zeolites with the greater accessibility of the mesoporosity, more particularly the HZSM-5/MCM-41 hybrid, done by synthesis processes with less environmental impact than conventional ones. Innovative methodologies were developed for the synthesis of micro-mesoporous hybrid material by dual templating mechanism and from crystalline zeolitic aluminosilicate in the absence of organic template. The synthesis of hybrid with pore bimodal distribution took place from one-single organic directing agent aimed to eliminate the use of organic templates, acids of any kind or organic solvents like templating agent of crystalline zeolitic aluminosilicate together with temperature-programmed microwave-assisted, making the experimental procedures of preparation most practical and easy, with good reproducibility and low cost. The study about crystalline zeolitic aluminosilicate in the absence of organic template, especially MFI type, is based on use of H2O and Na+ cation playing a structural directing role in place of an organic template. Advanced characterization techniques such as X-Ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM), Highresolution Transmission Electron Microscopy (HRTEM), Adsorption of N2 and CO2, kinetic studies by Thermogravimetric Analysis (TGA) and Pyrolysis coupled to Gas Chromatography/Mass Spectrometry (Pyrolysis-GC/MS) were employed in order to evaluate the synthesized materials. Achieve the proposed objectives, has made available a set of new methodologies for the synthesis of zeolite and hybrid micro-mesoporous material, these suitable for catalytic pyrolysis of heavy oils aimed at producing light fraction
O processamento do petr?leo pesado produzido no Pa?s ? uma a??o emergencial e estrat?gica para obter a auto-sufici?ncia e super?vits econ?micos. Neste sentido, ? indispens?vel o investimento em pesquisas de novos catalisadores para obten??o de derivados leves a partir de fra??es pesadas do petr?leo. O trabalho de doutorado aqui reportado dedicouse ? prepara??o de materiais que combinem, numa ?nica estrutura, a elevada atividade catal?tica de ze?litas, com melhor acessibilidade de materiais mesoporosos, como a estrutura h?brida HZSM-5/MCM-41, utilizando processos de s?ntese com menor impacto ambiental que os convencionais. Metodologias inovadoras foram desenvolvidas para a s?ntese do catalisador h?brido micro-mesoporoso ou ze?lito-mesoporoso por mecanismo de direcionamento estrutural via duplo agente diretor org?nico e tamb?m a partir de estrutura zeol?tica sintetizada na aus?ncia total de direcionador org?nico. Esse ?ltimo, tamb?m chamado de s?ntese do h?brido com distribui??o bimodal de poros a partir de um ?nico agente diretor org?nico, visou eliminar o uso dos direcionadores org?nicos, ?cidos de qualquer natureza ou solventes org?nicos como molde estrutural da estrutura zeol?tica em conjunto com o m?todo hidrot?rmico assistido por irradia??o via micro-ondas, tornando o procedimento experimental de prepara??o pr?tico e simples, com boa reprodutibilidade e menor custo. A metodologia de prepara??o da ze?lita MFI do tipo ZSM-5 utiliza H2O e c?tions Na+ no papel de direcionamento estrutural e compensa??o de cargas na estrutura. T?cnicas relevantes de caracteriza??o, como Difra??o de Raios-X (XRD), Espectroscopia no Infravermelho com Transformada de Fourier (FTIR), Microscopia Eletr?nica de Varredura (SEM), Microscopia Eletr?nica de Transmiss?o de Alta Resolu??o (HRTEM), Adsor??o de N2 e CO2, estudos cin?ticos via An?lises Termogravim?tricas (TGA) e Pir?lise acoplada ? Cromatografia Gasosa/Espectrometria de Massas (Pyrolysis-GC/MS), foram empregadas no intuito de avaliar os materiais sintetizados. Alcan?ados os objetivos propostos, disponibilizou-se um conjunto de novas metodologias para s?ntese de catalisadores zeol?ticos e h?bridos micromesoporosos, estes adequados para pir?lise catal?tica de ?leos pesados visando ? produ??o de derivados leves
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Chitnis, Saurabh Sunil. "P-P and P-Sb coordination chemistry." Thesis, 2015. http://hdl.handle.net/1828/5981.
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The coordination chemistry of compounds featuring P-P and P—Sb bonds has been investigated to define the fundamental features of bonding in these systems. New reaction methodologies to form P—P bonds have been evolved based on careful consideration of bond strengths in the gas and condensed phase. Insights revealed from systematic studies of molecular structures have been used to augment and expand the scope of existing models for structural prediction (e.g. VSEPR theory). Unique classes of catena-antimony compounds have been discovered, illustrating a remarkable structural and electronic diversity for this heavy p-block metal. Detailed mechanistic examinations have revealed a previously unrecognized mode of ligand activation for phosphine complexes of very electrophilic acceptors. Stable sources of the hitherto unisolated and highly reactive tris-triflate reagents, E(OTf)3 (E = P, As, Sb, Bi), have been prepared and their coordination chemistry as Lewis acids and oxidizing agents has been mapped. Collectively, the findings described here span a range of coordination chemistry paradigms for p-block elements that may be broadly applicable across the periodic table. A robust plan has been proposed for applying these insights towards the preparation of fundamentally interesting molecular frameworks and towards new strategies for small molecule activation.Graduate
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Le, Thi Huong Xuan. "Nitrogen and phosphorus removal from wastewater added to sand by wheat straw addition and wheat plants." Thesis, 2019. http://hdl.handle.net/2440/124604.
Full textAbstract:
Wastewater irrigation can add nutrients to soils, but also increase nutrient leaching, particularly in sandy soils. For sustainable use of wastewater, nutrient leaching should be minimized. It is unclear how wheat straw amendment to sand or wheat growth on sandy soil influences removal of N and P from wastewater. This thesis aimed to investigate (1) the ability of wheat straw to remove inorganic N and P from wastewater collected from a sewage treatment plant when mixed into sand at different rates (Experiment 1) and decomposition stages of the straw (Experiment 2), and (2) the effect of wastewater irrigation at different early growth stages of wheat plants on nutrient uptake (Experiment 3). In the first experiment, wheat straw was mixed with sand at 2.5, 5, 7.5, 10, 12.5 g kg-1 in leaching columns before adding wastewater. The control was unamended sand. Leaching was conducted on 4, 8 and 16 days after wastewater addition. With straw amendment, nitrate in the sand-straw mixes was lower than in sand alone while ammonium was higher at 12.5 g straw kg- 1. Over 95 % of inorganic N from added wastewater was removed irrespective of straw rate. Straw amendment had no consistent effect on P leaching. In the second leaching column experiment, sand was mixed with wheat straw at 12.5 g straw kg-1 and incubated moist for 7 or 14 days or added just before adding wastewater (fresh straw). The control was unamended sand. Leaching was conducted 4, 8 or 16 days after wastewater addition. With straw amendment, available N in the sand-straw mixes was highest in fresh straw on day 16. Leachate inorganic N was much lower than in sand alone irrespective of straw decomposition stage. In both leaching column experiments, very little N2O was released, suggesting that denitrification was not an important process. Likely mechanisms for nutrient removal by straw are dissimilatory nitrate reduction to ammonium and nutrient binding to straw. It was concluded that mixing wheat straw into sandy soil prior to wastewater application can substantially reduce inorganic N leaching. In a pot experiment, sandy soil was left unplanted (control) or planted with wheat, which was grown for 7, 14 or 21 days before wastewater addition. All pots received reverse osmosis (RO) water for 20 days. Half of the planted pots and unplanted pots were irrigated with wastewater from day 21 to 35, the other pots still received RO until day 35. Wastewater irrigation increased N uptake compared to RO irrigation only in plants that were 21 days old before wastewater addition but had little effect on plant growth and on inorganic N and P in soil. However, presence of wheat reduced available N and P in soil compared to unplanted soils which would reduce potential of nutrient leaching after wastewater irrigation. It can be concluded that inclusion of organic amendments and/ or suitable crops are the potential options for wastewater reuse on sandy soils. Field experiments should be carried out to confirm the applicability of these effects.Thesis (Ph.D.) -- University of Adelaide, School of Agriculture, Food and Wine, 2019