Дисертації з теми "Mesoporous structures"
Оформте джерело за APA, MLA, Chicago, Harvard та іншими стилями
Ознайомтеся з топ-50 дисертацій для дослідження на тему "Mesoporous structures".
Біля кожної праці в переліку літератури доступна кнопка «Додати до бібліографії». Скористайтеся нею – і ми автоматично оформимо бібліографічне посилання на обрану працю в потрібному вам стилі цитування: APA, MLA, «Гарвард», «Чикаго», «Ванкувер» тощо.
Також ви можете завантажити повний текст наукової публікації у форматі «.pdf» та прочитати онлайн анотацію до роботи, якщо відповідні параметри наявні в метаданих.
Переглядайте дисертації для різних дисциплін та оформлюйте правильно вашу бібліографію.
Atluri, Rambabu. "Novel Syntheses, Structures and Functions of Mesoporous Silica Materials." Doctoral thesis, Uppsala universitet, Nanoteknologi och funktionella material, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-122289.
Повний текст джерелаSun, Zhen Kun. "Rational design of mesoporous materials with Core/shell structures with applications for sustainability." Doctoral thesis, Université Laval, 2015. http://hdl.handle.net/20.500.11794/26106.
Повний текст джерелаMesoporous materials, especially ordered ones have become ones of great importance nanomaterials, which possess regular, uniform and interpenetrating mesopores in nanoscale. Morphology and texture controls towards mesoporous materials are critical for a variety of practical applications, the ultimate goal of which are the realization of their functional design. Core/shell composite materials are a type of functional hybrid materials which not only possess the properties of the individual components, but also exhibit some new or synergistic effects between the core and the shell. The design of mesoporous materials with unique core/shell configuration and multifunctions to make them successfully applied in practice, should be an important driving force for the continuous development of current material science. This thesis mainly focuses on two aspects: (1) careful design of core/shell structured mesoporous materials in order to solve the problem and difficulty in synthesis, which hinders their further applications and (2) application of mesoporous materials in cyclic CO2 capture to enhance the durability of CO2 sorbents by taking advantage of the core/shell concept. Aiming at the calcium looping cycle, an attractive technology for large-scale CO2 capture, we have prepared novel mesoporous core/shell structured CaO-based sorbents which exhibit highly stable cyclability and excellent attrition-resistance performances, attributed to advantages of both mesoporous materials and unique core/shell configuration. Our fabrication method could easily be realized in large-scale and meet the requirements of circulating fluidized bed reactors. Owing to their high surface energies, metallic nanoparticles normally tend to aggregate together during catalytic reactions, and their separation from a complex heterogeneous system is another obstacle. In this regards, we have demonstrated a facile and versatile synthesis of multicomponent and multifunctional microspheres Fe3O4@C-Pd@mSiO2 with well-defined core/shell structures, confined catalytic Pd nanoparticles and accessible ordered mesopore channels. Recently, various methods have been proposed for coating mesoporous shells on cores by soft-templating process. However, the generated mesopores are usually very small (< 3 nm), which may limit their further applications. In this work, we have accomplished the synthesis of superparamagnetic core/shell structured microspheres possessing an outer shell of ordered mesoporous silica with large pores (4.5 nm) by adopting triblock-copolymer Pluronic P123 as soft-template.
Schmidt, Sonja. "Tuning Mesoporous Silica Structures via RAFT Polymers: From Multiblock Copolymers as new Templates to Surface Modification." Doctoral thesis, Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2018. http://hdl.handle.net/11858/00-1735-0000-002E-E379-C.
Повний текст джерелаCastro, Alichandra Maria Gonçalves. "Design of multifunctional mesoporous thin films for electronic applications." Doctoral thesis, Universidade de Aveiro, 2016. http://hdl.handle.net/10773/18658.
Повний текст джерелаOs materiais multiferróicos possuem simultaneamente pelo menos duas das três propriedades ferróicas: i) ferroelectricidade; ii) ferromagnetismo; e / ou iii) ferroelasticidade. Estes materiais têm despertado considerável interesse na indústria microeletrónica devido ao seu potencial para serem usados em dispositivos de armazenamento de informação com elevada capacidade e eficiência energética. A constante procura pela redução do tamanho e aumento da funcionalidade dos dispositivos, imposta pela Lei de Moore, exige materiais ferróicos, na forma de filmes finos e multifuncionalidade. Contudo, à medida que a espessura dos filmes diminui, as propriedades ferróicas ficam comprometidas em virtude de constrangimentos provocados pelo substrato ou outros efeitos. Neste contexto, esta tese estuda a possibilidade de utilizar a porosidade em filmes funcionais para criar sistemas compósitos multifuncionais. Assim, desenvolveram-se estratégias para a preparação de filmes de ferroeléctricos, ferromagnéticos e multiferroícos com porosidade uniforme e ordenada. O efeito dessa porosidade foi avaliado nas propriedades físicas locais e macroscópicas. Foram estudados óxidos multimetálicos com estrutura de perovisquite ou de espinela por serem promissores para aplicação em sensores; atuadores; condensadores; memórias; etc. Escolheu-se uma metodologia química em que os filmes são depositados por técnica de mergulho em soluções sol-gel contendo um copolímero em bloco que se organiza espontaneamente conjuntamente com os precursores durante o processo de evaporação. PbTiO3 foi a composição inicialmente escolhida para entender o efeito da nanoporosidade nas propriedades eléctricas locais por ser o material piezoeléctrico protótipo que possui o mais alto coeficiente piezoeléctrico conhecido. Assim, foram preparados filmes nanoporosos e densos de PbTiO3 com espessura de cerca de 100 nm e diâmetro de poro na ordem dos 50 nm. A presença da nanoporosidade contribui para a cristalização precoce da fase cristalina por aumento local da temperatura durante a decomposição do copolímero e / ou por funcionarem como núcleos de cristalização. Consequentemente, os fimes porosos exibem melhores coeficientes piezoeléctricos e baixo campo coercivo, sendo mais fácil inverter a direção da polarização por efeito do campo elétrico. Sendo a porosidade um meio para atingir propriedades melhoradas, esta pode funcionar como uma ferramenta para ajustar as propriedades ferroeléctricas à aplicação desejada. Todos os resultados de PFM foram previstos através de modelação teórica usando o modelo de elementos finitos. Foi também investigada a preparação de filmes porosos de titanado de bário enquanto protótipo de um ferroeléctrico sem chumbo. Neste contexto, foi avaliado o efeito de vários parâmetros, tais como: i) o aquecimento da solução de precursores; ii) adição de precursores inorgânicos / solventes orgânicos; e iii) envelhecimento da solução inicial, na estrutura final dos filmes.Verificou-se que o uso de uma solução fresca de precursores sem qualquer ciclo de aquecimento contribuía para uma melhor organização dos filmes porosos de BaTiO3. Verificou-se também que o tamanho dos blocos num copolímero à base de poliestireno e poli(óxido de etileno) era preponderante para a ordem e microestrutura cristalina dos filmes finais. Copolímeros em bloco com cadeias de bloco mais longas são preferíveis para obter uma estrutura ordenada e aparentemente desempenham um papel na cristalização precoce da fase ferroeléctrica tetragonal, contribuindo para uma melhoria da resposta piezoeléctrica. Em analogia com o PbTiO3, os resultados indicam que nos filmes nanoporosos de BaTiO3, a cristalização ocorre a temperaturas mais baixas do que nos filmes densos. Utilizou-se a deposição electroquímica para inserir nanopartículas metálicas de cobalto dentro dos poros dos filmes de BaTiO3. O carácter multiferróico dos filmes foi constatado através da avaliação nanoscópica das propriedades elétricas e pela medida das propriedades magnéticas macroscópicas à temperatura ambiente. Verificaram-se as dificuldades de conseguir um preenchimento uniforme dos poros e de otimizar a interface entre as duas fases ferróicas. Assim com vista a tentar ultrapassar estas dificuldades, prepararam-se filmes mais finos e em que a porosidade estivesse devidamente organizada, com poros perpendiculares à superfície. Conceberam-se filmes nanotexturados ordenados de óxidos multimetálicos com propriedades ferroelétricas, ferromagnéticas e multiferróicas com espessuras e texturas de dimensão inferior a 100 nm. As composições escolhidas foram PbTiO3, CoFe2O4 e BiFeO3. Os filmes finos porosos nanotexturados PbTiO3 apresentaram a fase cristalográfica tetragonal mesmo em espessuras de filme de 22 nm. Os filmes finos de CoFe2O4 apresentaram uma orientação preferencial no plano e elevadas magnetizações de saturação. Deduziu-se que os filmes teriam uma impureza ferromagnética compatível com uma liga metálica rica em platina. A presença desta impureza não só melhora o desempenho magnético dos filmes mas também fornece uma forte evidência para a potencial aplicabilidade dos filmes de CoFe2O4 como catalisadores para a oxidação de hidrocarbonetos através do mecanismo de Mars-Van-Krevelen. Foram também preparados filmes finos porosos nanotexturados de BiFeO3, com 66 nm de espessura e tamanho médio de diâmetro de 100 nm. Verificou-se o caráter multiferróico destes filmes e mais uma vez a melhoria clara das propriedades eléctricas locais induzida pela porosidade. A estrutura porosa também tem um efeito positivo nas propriedades magnéticas no plano, mostrando uma componente ferromagnética 50% maior que a medida em filmes densos. Verificou-se também que porosidade dos filmes de BiFeO3 pode ter interesse para aplicações fotocatalíticas, conjugando reduzido valor do hiato óptico direto (2.58 eV) com relativamente elevada área porosa (ca. 57 %). Para testar a aplicabilidade dos filmes nanotexturados na construção de um filme multiferróico compósito, uma matriz porosas ferroelétricos (BaTiO3) foi funcionalizada por preenchimento dos poros com nanopartículas ferromagnéticas de níquel. A estratégia de funcionalização dos poros foi a deposição por arrastamento com CO2 supercrítico, seguida de redução da espécie metálica a 250 ºC ativada por etanol. Pequenas nanopartículas de níquel com cerca de 21 nm foram depositadas dentro dos poros da matriz porosa, tendo-se verificado as propriedades estruturais e magnéticas do compósito. Esta tese, provou a adequação desta metodologia química de baixo custo na concepção de materiais multifuncionais, criando novas perspectivas para a indústria da microeletrónica na sua abordagem contínua de redução de tamanho e custo, enquanto aumenta a complexidade de funcionamento.
Multiferroic materials, exhibiting simultaneously at least two of the three ferroic properties: i) ferroelectricity; ii) ferromagnetism; and iii) ferroelasticity, have attracted considerable interest from the microelectronics industry. Due to their potential, these materials can be used in information storage applications with significantly high energetic efficiencies and elevated capacities. During the last decades and owing the increasing need for miniaturization of electronic devices, the ferroic materials, mainly in the format of thin films, have been extensively studied both theoretically and experimentally. However, as the film thickness decreases the ferroics properties progressively decreases due to the in-plane strain relaxation constrained by the substrate or others intrinsic and extrinsic effects. Within this context, here we exploit the role of nanoporosity on local and macroscopic properties of ferroelectrics, ferromagnetic and multiferroics thin films. Although, porosity is normally considered as a defect (or secondary phase) having usually a detrimental effect on the electrical macroscopic response; it can also be regarded as an asset, in terms of: i) density (light weight) and ii) capacity to host other functionality/ies. Oxides with perovskite and spinel structures are promising materials because they possess extraordinarily useful properties namely to be used as piezoelectrics sensors, as ferroelectric actuators, capacitors and memories, in high-strength dielectrics, for ferromagnetics or even multiferroics. Among the bottom-up approaches, the sol-gel method and evaporation-induced self-assembly methodology are the most suitable, low-cost and easy preparation method to prepare nanoporous and nanopatterned thin films of different compositions. PbTiO3 is the chosen composition to understand the role of the nanoporosity on the local electric properties. Thus, nanoporous and dense ferroelectric PbTiO3 thin films with 100 nm and ~ 50 nm pore size formed using a block polymer as a structure-directing agent are prepared. The presence of nanoporosity markedly affects the microstructure, crystallization and ferroelectric film properties. The crystallization of tetragonal phase is enhanced in nanoporous films. It seems that the decomposition of the block-copolymer in porous films triggers the crystallization of the perovskite phase at low temperatures via the local increase of temperature. Moreover, pores may work as initiators of the crystallization. Consequently, nanoporous films with improved tetragonality exhibit enhanced piezoelectric coefficients, switchable polarization and low local coercivity. In fact, the porosity induces instability in the dipole-dipole interactions and consequently the reverse polarization can be favoured for low bias values. By providing a means of achieving enhanced properties, nanoporosity may work as a tool to tune electric properties to the desired ferroelectric application. All the PFM results were supported by theoretical modelling using Finite Element Model. To have a more complete picture of the role of the nanoporosity on the crystallization and electric properties, the procedure is applied to prepare a nanoporous lead-free material, BaTiO3. However, this expantion was not trivial whereas the crystallization temperature of the tetragonal phase necessary for the ferroelectric properties is much higher than the decomposition temperature of the block-copolymer used as template. From this, several parameters such as: heating the solution, addition of inorganic precursors / organic solvent and aging time of solution are studied in order to understand the effect of these on the micellization process and consequently in the final porous BaTiO3 films. Based on the results of this study, for this specific multimetallic oxide system it is preferable to use a very fresh solution, without any heating cycles. In addition, block-copolymers based on polystyrene and poly(ethylene oxide) with different block sizes are used to investigate their influence on the order and crystalline microstructure of the final films. Blocks-copolymers with longer block chains are preferable to get an ordered structure and apparently play a role on the earliest crystallization of the tetragonal ferroelectric perovskite phase, contributing to an enhancement of the piezoelectric response. Similarly to PbTiO3, our results indicate that in nanoporous BaTiO3 films the crystallization occurs as well before in dense films. Moreover, besides providing a means of achieving enhanced properties, nanoporosity may work as a tool to tune electric properties to the desired ferroelectric application. BaTiO3 nanoporous films are tested as a kind of “golf course” full of holes to accommodate ferromagnetic particles. In this way, electrochemical deposition is used to insert the cobalt metal nanoparticles into the pores of BaTiO3 films. Films containing cobalt particles within the pores are obtained and piezoelectric and ferromagnetic properties are evaluated. For many applications would be a challenge to prepare ferroelectric thin films with lateral sizes well below 100 nm. Furthermore, the design of nanofeatures, uniformed in size and shape at a reasonable large-range order, i.e. “nanopatterning”, would extend their utility for electronic devices and integrated circuits, which require that each pixel feature can be individually addressable. Additionally, nanopatterned porous ferroelectric thin films may be interesting to develop vertical composite structures with perfect strain coupling at the interface. Thus, and using the chemical self-assembly method, different functional nanopatterned porous thin films: PbTiO3, BiFeO3 and CoFe2O4 are designed. Nanopatterned PbTiO3 thin films display the tetragonal ferroelectric crystallographic phase even when the films are as thin as 22 nm. CoFe2O4 thin films present a preferential in-plane orientation. High saturation magnetizations (close or even higher than in bulk CoFe2O4) are determined in all films, pointing to the presence of a ferromagnetic impurity compatible with a platinum-rich metal alloy. The presence of this impurity not only enhances the magnetic performance but also provides evidence for the catalytic activity of these CoFe2O4 films for hydrocarbon oxidation through a Mars-Van-Krevelen mechanism. For the BiFeO3 composition, crystalline nanopatterned BiFeO3 layers with 66 nm of thickness and average pore diameter of 100 nm at 600 ºC are obtained. The large vertical porosity markedly enhances the local electric and macroscopic magnetic properties when compared with the dense counterparts. The porous structure also has a positive effect on the parallel magnetic characteristics of the system, displaying a 50% larger ferromagnetic component and enhanced remanent magnetization when compared to the dense thin films counterpart. The porosity is also important for the photocatalytic applications conjugating the smallest direct band gap (2.58 eV) and extended porous area (ca. 57 %). The nanopatterned thin films allow the exploitation of a new concept to prepare multiferroic nanocomposite thin films. The multiferroic films based on in two chemical-based bottom-up steps, including: i) the formation of a porous ferroic matrix and ii) the accomodation of nanoparticles from another ferroic phase within the pores. Hexagonal-arranged pores with diameter of ca. 95 nm, running perpendicularly to the substrate are filled with nickel nanoparticles using the supercritical fluid deposition technique from reduction of hydrated nickel nitrate in a supercritical CO2-ethanol mixture at 250 ºC. Small nickel nanoparticles with ca. 20 nm are deposited inside the pores of the porous matrix. Structural and magnetic properties proved the coexistence of both phases. The chemical based methodology offers thus an excellent control of the physical and chemical properties of nanostructured materials such as: stoichiometry, thickness, size, array and porous distribution. Moreover the self-assembly of block-copolymers provides a versatile platform to prepare functional nanostructured materials, namely mesostructured oxide thin films, due to their capability to form large pores and thick walls, apart from being industrially available and hazard-free. Additionally, the chemical-assembly method can allow the direct nanopatterning of large substrate areas with a functional oxide at a cost-effective price, in the absence of expensive equipment or etching processes (which typically affect negatively the ferroic properties).Besides, the functional properties of the porous films by themselves, the porous films are extremely promising to achieve multiferroic composites.
Moushey, Douglas Lee. "Formation of Mesoporosity in Zeolite and Mesoporous Molecular Sieve Structures through use of Carbon as a Secondary Templating Agent." University of Cincinnati / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1218657179.
Повний текст джерелаGrudzien, Rafal M. "Synthesis and characterization of ordered cage-like siliceous mesostructures with organic pendant and bridging groups." [Kent, Ohio] : Kent State University, 2008. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=kent1226507948.
Повний текст джерелаTitle from PDF t.p. (viewed Dec. 17, 2009). Advisor: Mietek Jaroniec. Keywords: mesoporous, FDU-1, SBA-16, organosilicas, pendant groups, bridging groups, adsorption, isocyanurate, template removal, cage-like structures. Includes bibliographical references (p. 219-238).
Muroyama, Norihiro. "Studies of inorganic crystal structures and gas adsorption process in mesoporous crystals : new approach through analysis of electron charge distribution by synchrotron powder X-ray diffraction /." Stockholm : Department of Physical, Inorganic and Structural Chemistry, Stockholm university, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-7367.
Повний текст джерелаFREIRE, Vitória de Andrade. "Desenvolvimento de material micro-mesoporoso do tipo MCM-22/MCM-41: sítese e caracterização." Universidade Federal de Campina Grande, 2016. http://dspace.sti.ufcg.edu.br:8080/jspui/handle/riufcg/297.
Повний текст джерелаMade available in DSpace on 2018-03-19T16:09:58Z (GMT). No. of bitstreams: 1 VITÓRIA DE ANDRADE FREIRE - DISSERTAÇÃO PPGEQ 2016..pdf: 2687690 bytes, checksum: 093bc81d91144a15964f2333d08a5c8f (MD5) Previous issue date: 2016-04-29
Capes
A pesquisa no desenvolvimento de estruturas do tipo micro-mesoporosas tem por intuito a obtenção de materiais porosos com características superiores, uma vez que busca unir a ácidez elevada da zeólita MCM-22, com o sistema de mesoporos, da peneira molecular MCM-41, consequentemente melhorar a difusão de moléculas volumosas. Nesta pesquisa foram sintetizadas as seguintes estruturas porosas: Inicialmente foi obtido o percussor lamelar MCM22-(P) com razão molar SiO2\Al2O3 = 30 e ativada para obter sua forma zeólítica MCM-22 a 550 0C por 5 horas. Em seguida, foi realizada a síntese do material micro-mesoporoso do tipo MCM-22/MCM-41, tratando 2 g da zeólita MCM-22, com uma solução de 25 mL de brometo de cetiltrimetilamônio (CTABr) a 10 % em massa, onde o material permaneceu em estufa a 1100C por 7 dias. Com o intuito de obter um novo material com melhor organização estrutural, utilizou-se a MCM-22 nas seguintes proporções (5%, 10% e 15%), permanecendo em estufa a 300C por 24 horas, sendo ativado em corrente de ar por 5500C por 5 horas. Os resultados das caracterizações de difratometria de raios-X, evidenciaram a formação do precursor MCM-22 (P) e sua forma zeólítica MCM22, com os picos da topologia MWW. A curvas obtidas por meio da análise termogravimétrica (TG/DrTG), demostraram as perdas de massa da água e demais adsorvatos. As micrografias (MEV), apresentou formato toroidal com depreciamento na região central para a MCM-22. Por meio dos resultados de adsorção física de N2, verifica-se que as zeólitas MCM-22, com isotermas do tipo I e loop de histerese do tipo H4. A partir dos difratogramas de raios - X para os materiais micro-mesoporosos foi possível observar a formação das estruturas porosas, com a identificação dos picos de reflexão pertinentes a fase microporosa da MCM-22 e da peneira molecular MCM-41, coexistindo em uma única fase estrutural. As imagens obtidas por MEV, detectam a formação de aglomerados de partículas da fase mesoporosa sendo constituída em torno da fase microporosa. A análise textural mostraram uma diminuição do volume de microporos e um aumento do volume de mesoporos, com isotermas do tipo IV e histereses 2. Demonstrando assim que as caracterizações foram eficazes na elucidação das estruturas porosas. Foi possível obter os materiais micromesoporosos para ambas as metodologias adotadas, sendo o teor de 5% de zeólita MCM-22 a melhor condição de síntese para obtenção desse novo material.
The research on the development of micro-mesoporous structures has the purpose of obtaining porous materials with superior characteristics, once it seeks to join the high acidity of MCM-22 zeolite with the mesoporous system of MCM41 molecular sieve, consequently improving the diffusion of bulky molecules. In this research, the following porous structures were synthesized: Initially, the MCM-22-(P) lamellar precursor was obtained with molar ratio of SiO2\Al2O3 = 30 and was activated to obtain its MCM-22 zeolite form at 550 °C for 5 hours. Then, MCM-22/MCM-41 micro-mesoporous material was synthesized by treating 2 g of MCM-22 zeolite with a solution of 25 mL of 10% wt cetyltrimethylammonium bromide (CTABr), where the material remained in an incubator at 110 °C for 7 days. In order to obtain a new material with better structural organization, the MCM-22 was used in the following proportions (5%, 10% and 15%), remaining in an incubator at 30 °C for 24 hours, being activated in air stream at 550 °C for 5 hours. The results of the X-ray diffraction characterization demonstrated the MCM-22 (P) precursor formation and its MCM-22 zeolite form, with MWW topology peaks. The curves obtained by means of the thermogravimetric analysis (TG/DrTG), showed the losses of water mass and other adsorbates. The micrographs (SEM) presented toroidal format with depreciation in the central region for MCM-22. By means of the results of physical adsorption of N2, it was verified for MCM-22 zeolites: type I isotherms and hysteresis loops of type-IV. From the X-ray diffractograms for the micro-mesoporous materials, it was possible to observe the formation of the porous structures, with the identification of the reflection peaks pertinent to the microporous phase of MCM-22 and the MCM-41 molecular sieve, coexisting in a single structural phase. The SEM images detected the formation of particle agglomerates of the mesoporous phase being constituted around the microporous phase. The textural analysis showed a decrease in the volume of micropores and an increase in the volume of mesopores, with type IV isotherms and hysteresis loops of type-II. Thus demonstrating that the characterizations were effective in elucidating the porous structures. It was possible to obtain the micro-mesoporous materials for both methodologies, being the 5% content of MCM-22 zeolite the best synthesis condition to obtain this new material.
Schmidt, Sonja Verfasser], Philipp [Akademischer Betreuer] Vana, Philipp [Gutachter] Vana, Marcus [Gutachter] Müller, Burkhard [Gutachter] Geil, Michael [Gutachter] [Buback, Ricardo [Gutachter] Mata, and Florian [Gutachter] Ehlers. "Tuning Mesoporous Silica Structures via RAFT Polymers: From Multiblock Copolymers as new Templates to Surface Modification / Sonja Schmidt ; Gutachter: Philipp Vana, Marcus Müller, Burkhard Geil, Michael Buback, Ricardo Mata, Florian Ehlers ; Betreuer: Philipp Vana." Göttingen : Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2018. http://nbn-resolving.de/urn:nbn:de:gbv:7-11858/00-1735-0000-002E-E379-C-7.
Повний текст джерелаSchmidt, Sonja [Verfasser], Philipp [Akademischer Betreuer] Vana, Philipp [Gutachter] Vana, Marcus [Gutachter] Müller, Burkhard [Gutachter] Geil, Michael [Gutachter] Buback, Ricardo [Gutachter] Mata, and Florian [Gutachter] Ehlers. "Tuning Mesoporous Silica Structures via RAFT Polymers: From Multiblock Copolymers as new Templates to Surface Modification / Sonja Schmidt ; Gutachter: Philipp Vana, Marcus Müller, Burkhard Geil, Michael Buback, Ricardo Mata, Florian Ehlers ; Betreuer: Philipp Vana." Göttingen : Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2018. http://d-nb.info/1154307611/34.
Повний текст джерелаFan, Junpeng. "Synthesis and advanced structural and magnetic characterization of mesoporous transition metal–doped sno2 powders and films." Doctoral thesis, Universitat Autònoma de Barcelona, 2017. http://hdl.handle.net/10803/457982.
Повний текст джерелаThis Thesis dissertation covers the synthesis by means of nanocasting and evaporation–induced self–assembly (EISA) methods as well as the advanced characterization of Ni, Cu–doped mesoporous SnO2 powders and films. The origin of the magnetic properties in these materials is also discussed in detail. Firstly, ordered mesoporous SnO2 powders doped with different Ni amounts were synthesized by nanocasting from mesoporous KIT–6 silica. Successful replication of the silica template was verified by scanning electron microscopy. No extra phases attributed to Ni or NiO were detected in the corresponding X–ray diffractograms except for the sample with the highest doping amount (e.g., 9 at.% Ni), for which NiO as secondary phase was observed. The oxidation state and spatial distribution of Ni in the powders was investigated by X–ray photoelectron spectroscopy and electron energy loss spectroscopy, respectively. Ni–containing powders exhibit ferromagnetic response at low and room temperatures, due to uncompensated spins at the surface of NiO nanoparticles and the occurrence of oxygen vacancies. Secondly, continuous mesoporous Ni–doped SnO2 thin films were synthesized from variable [Ni(II)]/[Sn(IV)] molar ratios through a sol–gel based self–assembly process, using P–123 triblock copolymer as a structure directing agent. A deep structural characterization revealed a truly 3–D nanoporous structure with thickness in the range of 100–150 nm, and average pore size about 10 nm. Grazing incidence X–ray diffraction experiments indicated that Ni had successfully substituted Sn in the rutile–type lattice, although energy–dispersive X–ray analyses also revealed the occurrence of small NiO clusters in the films produced from high [Ni(II)]/[Sn(IV)] molar ratios. Interestingly, the magnetic properties of these mesoporous films significantly vary as a function of the doping percentage. The undoped SnO2 films exhibit a diamagnetic behaviour, whereas a clear paramagnetic signal with small ferromagnetic contribution dominates the magnetic response of the Ni–doped mesoporous films. Thirdly, the magnetic properties of ordered mesoporous Cu–doped SnO2 powders, prepared by hard–templating from KIT–6 silica, were also studied. While Fe contamination or the presence of oxygen vacancies might be a plausible explanation of the room temperature ferromagnetism, the low–temperature ferromagnetism was mainly and uniquely assigned to the nanoscale nature of the formed antiferromagnetic CuO nanoparticles (uncompensated spins and shape–mediated spin canting). The reduced blocking temperature, which resided between 30 and 5 K, and small vertical shifts in the hysteresis loops confirmed size effects in the CuO nanoparticles.
Grecco, Saulo de Tarso Figueiredo. "Preparação de zeólitas mordenita com estrutura hierárquica de poros." Instituto de Química, 2013. http://repositorio.ufba.br/ri/handle/ri/16481.
Повний текст джерелаApproved for entry into archive by Ana Hilda Fonseca (anahilda@ufba.br) on 2014-10-30T02:15:21Z (GMT) No. of bitstreams: 1 Tese_Doutorado_Saulo.pdf: 12043320 bytes, checksum: 9e747c238576b9219840bfcd38f02a2e (MD5)
Made available in DSpace on 2014-10-30T02:15:21Z (GMT). No. of bitstreams: 1 Tese_Doutorado_Saulo.pdf: 12043320 bytes, checksum: 9e747c238576b9219840bfcd38f02a2e (MD5)
FINEP, CNPq
As restrições difusionais aos reagentes, causadas pelos microporos, limitam o uso das zeólitas no processamento de moléculas pesadas. Isto demanda o desenvolvimento de materiais que combinem as propriedades de zeólitas com as de materiais mesoporosos. Um número significativo de procedimentos experimentais, pré ou pós síntese, vem sendo sugerido para a obtenção de zeólitas hierarquicamente estruturadas. As metodologias de síntese mais bem sucedidas envolvem o uso de agentes geradores de mesoporosidade (agentes orgânicos e nanopartículas) ou nanomoldes (moldagem em nanoespaços), que geram sólidos com mesoporosidade intracristalina com uma estreita distribuição de tamanho de poros; isto resulta em sólidos contendo mesoporos, além dos microporos intrínsecos das zeólitas. Entretanto, ainda não existem estudos sistemáticos, que permitam estabelecer o efeito das variáveis de preparação sobre as características dos sólidos finais. A fim de superar essa dificuldade, neste trabalho foi estudado o efeito do tempo e da temperatura de cristalização do gel de síntese sobre as características de materiais baseados em mordenita com estrutura hierárquica de poros. Na preparação das amostras, adicionou-se um organossilano gerador de mesoporosidade (TPOAC, cloreto de [3- (trimetoxissilil)propil]octadecildimetilamônio), ao gel de síntese da mordenita, que foi cristalizado por diferentes períodos e em distintas temperaturas. Os sólidos obtidos foram submetidos à troca iônica com cloreto de amônio e posterior calcinação, de modo a obter a forma ácida do material. As amostras foram caracterizadas por termogravimetria, espectroscopia no infravermelho com transformada de Fourier, difração de raios X, análise textural por adsorção de nitrogênio, ressonância magnética nuclear de 29Si e de 27Al, microscopia eletrônica de varredura e medidas de acidez por dessorção de amônia à temperatura programada. Observou-se que a formação da mordenita contendo mesoporos é influenciada pelo tempo e temperatura de cristalização do gel da zeólita. O emprego de tempos relativamente curtos ou baixas temperaturas favorece a formação de um sólido amorfo, enquanto longos tempos ou elevadas temperaturas favorecem a formação de mesoporos intracristalinos na mordenita. Por outro lado, tempos e temperaturas intermediárias favoreceram a formação da mordenita com uma estrutura hierárquica de poros e mesoporos desordenados. O aumento da cristalinidade da mordenita acarreta uma diminuição na área e no volume de mesoporos, mas promove um acréscimo na área e no volume de microporos. A área externa também tende a diminuir devido ao aumento do tamanho do cristal da mordenita em função da cristalinidade. Os sólidos obtidos foram susceptíveis à desaluminação durante a etapa de calcinação. A extensão da desaluminação diminuiu com o aumento do tempo ou da temperatura de cristalização, devido à inserção dos átomos de alumínio na rede da zeólita em formação. Porém, em tempos de cristalização longos e temperaturas altas, pode ocorrer a redispersão dos átomos de alumínio. Todos os sólidos apresentaram elevada acidez que aumentou com a cristalinidade. Entretanto, nas amostras preparadas em tempos curtos e temperaturas baixas, a maioria dos sítios apresentou força ácida moderada, enquanto aquelas obtidas em tempos longos e temperaturas altas apresentaram maior quantidade de sítios ácidos fortes.
The diffusion restrictions of the reactants caused by the micropores limit the use of zeolites for processing heavy molecules. This demands for the development of materials that can combine the properties of zeolites and of mesoporous materials. A significant number of experimental procedures, pre or post synthesis, has been suggested for obtaining hierarchically structured zeolites. The most successful synthesis involve the use of mesoporosity generating agents (nanoparticles and organic agents) or nanotemplates (templating in nanospaces), which generate solids with intracristaline mesoporosity with a narrow pore size distribution. This results in solids containing mesoporous besides the intrinsic zeolite micropores. However, there is not any systematic study which allows to state the effect of crystallization time and temperature of the synthesis gel on the properties of the final solid. In order to overcome this difficulty, the effect of time and temperature of the synthesis gel on the properties of mordenite-based materials with hierarchical pore structure was studied in this work. In the samples preparation a mesoporosity generating organosilane (TPOAC, [3-(trimethoxysilyl) propyl] octadecyldimethylammonium chloride) was added to the synthesis gel of mordenite, which was crystallized for different times and temperatures. The solids were then submitted to ion exchange with ammonium chloride and further calcination to obtain the acidic form of the zeolite. The samples were characterized by thermogravimetry, Fourier transformed infrared spectroscopy, X-ray diffraction, textural analysis by nitrogen adsorption, 29Si and 27Al NMR, scanning electron microscopy and acidity measurements by ammonia desorption. It was observed that the formation of mordenite containing mesoporous is affected by the time and temperature of crystallization of the zeolite gel. The use of relatively short times and low temperatures favors the formation of an amorphous solid, while long times or high temperatures favor the formation of intracristaline mesoporosity in the mordenite. On the other hand, intermediate times and temperatures favor the formation of mordenite with hierarchical pore structure and disordered mesopores. The increase in mordenite crystallinity leads to a decrease in mesopore area and volume but promotes an increase in micropore area and volume. The external area also tends to decrease due to the increased crystal size as a function of mordenite crystallinity. The solids obtained were susceptible to dealumination during the calcination step. The degree of dealumination decreased with the increasing crystallization time or temperature due to the insertion of aluminum atoms in the zeolite lattice. However, at long crystallization times and high crystallization temperatures the redispersion of aluminum atoms can occur. All solids showed high acidity which increased as a function of crystallinity. However, the samples prepared at short times and low temperatures showed the majority of moderate acid sites of medium strength, whereas those obtained at long times and high temperatures have more strong acid sites. Thus, intermediate times and temperatures favor the formation of solids having zeolitic characteristics and high mesoporosity.
Warnant, Jérôme. "Synthèse et caractérisation de nanomatériaux fonctionnels siliciques structurés à l'aide de micelles complexes de copolymères séquencés doublement hydrophiles." Thesis, Montpellier, Ecole nationale supérieure de chimie, 2010. http://www.theses.fr/2010ENCM0005/document.
Повний текст джерелаThis study focused on the design and development of new structuring agents of silica constituted of induced and reversible assemblies of original copolymers, the double hydrophilic block copolymers (DHBC). The first system studied consists of a neutral-anionic DHBC PAPEO-b-PAA ou poly(acrylate methoxy poly (ethylene oxide))-b-poly (acrylic acid). The PAA block is a weak polyacid with a degree of ionization depending on the pH. In aqueous solution and in a right pH range, the association of this copolymer with a weak polybase, an oppositely charged polyamine, such as an oligochitosan, leads to the formation of polyion complex micelles (PIC) with a core/corona structure. These micelles can direct the structure of highly organized inorganic materials with different types of mesostructures. In a second step, by adjusting the conditions of pH, ionic strength, it is possible to "control" the extraction of organic species to get functional porous materials able to trap species of charge opposite to the functionality. Organized materials are obtained because of a favourable balance of the interactions between organic and inorganic species. If a polyamine/silica interaction occurs at the expense of the interaction polyamine/DHBC, the mesostructuring process by the micelles is limited. A neutral-cationic DHBC PEO-b-PDMAEMA poly(ethylene oxide)-b-poly(2-(dimethylamine)ethyl) associated with an anionic PVS poly(vinyl sulfonic acid) polymer can play a dual role in the synthesis of silica materials: firstly managing the growth of silica particles by interacting with the silicates and secondly acting as a structuring agent in association with PVS, confering a mesostructuration to the material. Finally, a very promising approach allowed to encapsulate water-soluble and charged drugs in a material by using as silica complexing agent a complex between the drug and a DHBC
Lund, Kristina. "Structural and morphological studies of mesoporous crystals /." Stockholm : Department of Physical, Inorganic and Structural Chemistry, Stockholm university, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-7110.
Повний текст джерелаEsterle, Thomas Frederic. "Investigation into the internal structure of mesoporous metals." Thesis, University of Southampton, 2012. https://eprints.soton.ac.uk/341751/.
Повний текст джерелаSaravanapavan, Priyadharshini. "Mesoporous calcium silicate gel-glasses : synthesis, structure and bioactivity." Thesis, Imperial College London, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.271675.
Повний текст джерелаDixon, Jacqueline Mary. "Structure, bonding and catalytic activity of modified mesoporous silicates." Thesis, Nottingham Trent University, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.403081.
Повний текст джерелаKnowles, John Philip. "The preparation, characterisation and application of nano-structured mesoporous materials." Thesis, University of Reading, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.437124.
Повний текст джерелаKeene, Matthew T. J. "The structure of kanemite and some related compounds." Thesis, University of Reading, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.339455.
Повний текст джерелаGierszal, Kamil. "Synthesis, adsorption and structural properties of carbons with uniform and ordered mesopores." [Kent, Ohio] : Kent State University, 2008. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=kent1207762469.
Повний текст джерелаTitle from PDF t.p. (viewed May 28, 2009). Advisor: Mietek Jaroniec. Keywords: mesoporous carbons, inverse replication, hard templating, OMC, CMK-3, CMK-5, mesoporous silicas, OMS, SBA-15, MCM-48, KIT-6, colloids, colloidal crystal, nanomaterials, gas adsorption. Includes bibliographical references (p. 184-194).
Wang, Sen-Ming, Rohit Kanungo, Bendaoud Nohair, Sergey Vasenkov, and Serge Kaliaguine. "Self-Diffusion of methyl oleate in mesoporous materials with SBA-16 structure." Universitätsbibliothek Leipzig, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-185463.
Повний текст джерелаWang, Sen-Ming, Rohit Kanungo, Bendaoud Nohair, Sergey Vasenkov, and Serge Kaliaguine. "Self-Diffusion of methyl oleate in mesoporous materials with SBA-16 structure." Diffusion fundamentals 16 (2011) 59, S. 1-2, 2011. https://ul.qucosa.de/id/qucosa%3A13802.
Повний текст джерелаGorka, Joanna. "Polymer-based mesoporous carbons: soft-templating synthesis, adsorption and structural properties." Kent State University / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=kent1290460109.
Повний текст джерелаGao, Chuanbo. "Formation mechanism of anionic-surfactant-templated mesoporous silica (AMS)." Doctoral thesis, Stockholm : Department of Physical, Inorganic and Structural Chemistry, Stockholm University, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-29628.
Повний текст джерелаGu, Shihai. "ADSORPTION AND STRUCTURAL PROPERTIES OF POLYMER-TEMPLATED ORDERED MESOPOROUS ORGANOSILICAS SYNTHESIZED BY USING REACTIVE ORGANOSILANES." Kent State University / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=kent1320082453.
Повний текст джерелаOrman, Sultan. "Zr And Silicotungstic Acid Incorporated Silicate Structured Mesoporous Catalysts For Dimethyl Ether Synthesis." Master's thesis, METU, 2011. http://etd.lib.metu.edu.tr/upload/12613499/index.pdf.
Повний текст джерелаmethanol dehydration on acidic catalysis and syn-gas conversion on bifunctional catalysis. In this study, the aim is to synthesize acidic catalysts using direct hydrothermal synthesis method for DME synthesis as using methanol as feed stock via dehydration and to characterize these materials. The support of the synthesized materials comprises of MCM-41 structure and silicotungstic acid (STA) and metals (Zr / Ni / Cu) were incorporated into the MCM-41 structure during synthesis. Two different techniques were used to extract the surfactant (CTMABr) from catalyst matrix. First one is the conventional calcination technique (at 350°
C) and the second is supercritical fluid extraction (at various operating conditions) with methanol modified CO2. The effect of metal loading on extraction performance is analyzed through characterizations of Ni and Cu incorporated materials. In addition, The effect of operation parameters on catalyst properties are also investigated with performing extraction at different pressures for different durations. By changing the type of metal incorporated into the catalyst, the extraction performance is also monitored. The characterization results indicated that, SFE process is also a promising method for surfactant removal. The activities of zirconium added catalysts are tested in methanol dehydration reaction towards DME. It is concluded that the conversion of methanol and selectivity of DME in presence of extracted samples are lower (maximum yield -0.54- obtained at 450°
C with sceSZ1) compared to the calcined materials (maximum yield -0.80- obtained at 300°
C with cSZ6). This result can also be foreseen by DRIFTS analysis of pyridine adsorbed samples. The acid sites of extracted materials are not as strong as in the calcined catalysts.
Wang, Siyang. "Structure Control of Functional Mesoporous Materials and Synthesis of Polydimethylsiloxane-Containing Block Copolymer." University of Akron / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=akron1463958304.
Повний текст джерелаSaraci, Erisa, Robert Arndt, Jens Kullmann, Dirk Enke, Tim-Arne Meier, Detlev Belder, Marc-Olivier Coppens, and Roger Gläser. "Diffusion limitations and effectiveness factor of mesoporous and hierarchically structured catalysts for SCR-DeNOx." Universitätsbibliothek Leipzig, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-198608.
Повний текст джерелаSaraci, Erisa, Robert Arndt, Jens Kullmann, Dirk Enke, Tim-Arne Meier, Detlev Belder, Marc-Olivier Coppens, and Roger Gläser. "Diffusion limitations and effectiveness factor of mesoporous and hierarchically structured catalysts for SCR-DeNOx." Diffusion fundamentals 24 (2015) 44, S. 1, 2015. https://ul.qucosa.de/id/qucosa%3A14564.
Повний текст джерелаMauder, Daniel. "Investigation of structure and surface properties of mesoporous silica materials by solid state NMR." Berlin mbv, Mensch-und-Buch-Verl, 2009. http://d-nb.info/998069116/04.
Повний текст джерелаGrant, Stacy M. "Polymer Templating Synthesis, Adsorption and Structural Properties of Alumina-Based Ordered Mesoporous Materials." Kent State University / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=kent1317593306.
Повний текст джерелаNell, Kara. "Functionalized Nano-structured Silicas for Trace Collection from Natural Waters." Thesis, University of Oregon, 2016. http://hdl.handle.net/1794/20681.
Повний текст джерела10000-01-01
Sinlapadech, Sunsanee. "Photoionization of organic molecules in MCM-41, AlMCM-41 and metal containing AlMCM-41 mesoporous materials." online access from Digital Dissertation Consortium, 2003. http://libweb.cityu.edu.hk/cgi-bin/er/db/ddcdiss.pl?3085619.
Повний текст джерелаMascotto, Simone, Bernd M. Smarsly, Dirk Wallacher, and Andreas Brandt. "In-situ-SANS investigations of C5F12 condensation in mesoporous silicas with a hierarchical pore structure." Universitätsbibliothek Leipzig, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-191435.
Повний текст джерелаMascotto, Simone, Bernd M. Smarsly, Dirk Wallacher, and Andreas Brandt. "In-situ-SANS investigations of C5F12 condensation in mesoporous silicas with a hierarchical pore structure." Diffusion fundamentals 11 (2009) 94, S. 1-2, 2009. https://ul.qucosa.de/id/qucosa%3A14067.
Повний текст джерелаHong-Qi, Xia. "Improvement of the Performance of Direct Electron Transfer-Type Bioelectrocatalysis Based on the Understanding of the Interaction between Redox Enzymes and Electrodes." Kyoto University, 2017. http://hdl.handle.net/2433/227638.
Повний текст джерелаXiao, Changhong. "A structural investigation into the complexity of mesoporous silica crystals : From a view of curvature and micellar interaction to quasicrystallinity." Doctoral thesis, Stockholms universitet, Institutionen för material- och miljökemi (MMK), 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-82382.
Повний текст джерелаAt the time of the doctoral defense, the following paper was unpublished and had a status as follows: Paper 7: Manuscript.
Han, Lu. "Synthesis and Characterization of Functionalized Silica Mesoporous Crystals Cationic Surfactant and Co-structure Directing Agent System /." Doctoral thesis, Stockholm : Department of Materials and Environmental Chemistry (MMK), Stockholm University, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-38398.
Повний текст джерелаAlsyouri, Hatem M. "Synthesis of Ordered Mesoporous Silica and Alumina with Controlled Macroscopic Morphologies." University of Cincinnati / OhioLINK, 2004. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1100816267.
Повний текст джерелаDong, Bin. "Controllable synthesis for fabrication of micro/nano-structured mesoporous precursor particles for high performance lithium-ion batteries." Thesis, University of Nottingham, 2018. http://eprints.nottingham.ac.uk/52091/.
Повний текст джерелаHuang, Baiyu. "Facile Synthesis and Improved Pore Structure Characterization of Mesoporous γ-Alumina Catalyst Supports with Tunable Pore Size". BYU ScholarsArchive, 2013. https://scholarsarchive.byu.edu/etd/3553.
Повний текст джерелаZhang, Ying. "Synthesis and Determination of the Local Structure and Phase Evolution of Unique Boehmite-Derived Mesoporous Doped Aluminas." BYU ScholarsArchive, 2018. https://scholarsarchive.byu.edu/etd/7105.
Повний текст джерелаGierszal, Kamil Piotr. "Synthesis, adsorption and structural properties of carbons with uniform and ordered mesopores." Kent State University / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=kent1207762469.
Повний текст джерелаMiyasaka, Keiichi. "A structural study into the boundary surface and associated curvature of three-dimensional mesoporous silica crystals /." Stockholm : Department of Physical, Inorganic and Structural Chemistry, Stockholm University, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-7651.
Повний текст джерелаZahed, Nizar Bassam. "Formation of Meso-Structured Multi-Scale Porous Titanium Dioxide by Combined Soft-Templating, Freeze-Casting and Hard-Templating Using Cellulose Nanocrystals." Thesis, Virginia Tech, 2019. http://hdl.handle.net/10919/99386.
Повний текст джерелаMS
Chao, Bing. "The Effects of Ordered Mesoporous Carbon (OMC) Structure on the Adsorption Capacity for Resorcinol Removal| Laboratory and Simulation Approaches." Thesis, University of Louisiana at Lafayette, 2016. http://pqdtopen.proquest.com/#viewpdf?dispub=10163281.
Повний текст джерелаOrdered Mesoporous Carbons (OMCs) with well-controlled pore structure and narrow pore size distribution demonstrated great potential as highly functional adsorbents. The pore size and surface chemistry of OMCs were considered two of the most important factors that affect the adsorption capacity of organic compounds. The objective of this study is to optimize the structure of OMCs for resorcinol adsorption by changing the pore size and oxygen content using computational approach. New rhombic OMC models with varied pore size and oxygen content were constructed using Materials Visualizer module. The specific surface area, total pore volume, small angle X-ray diffraction patterns, and resorcinol adsorption capacity results were calculated by Forcite and sorption module in Materials Studio package. The simulation results were validated by the experimental data. Experimentally, the OMCs were synthesized using sucrose as carbon precursor by hard-template method. The tunable pore size (4nm to 15nm) and oxygen content of the OMCs are obtained by adjusting the amount of boric acid as a pore-expanding reagent. The experimental results, such as BET surface area, X-ray power diffraction patterns, and adsorption capacity of resorcinol, were compared with the simulation results. The optimal pore size of OMC for resorcinol removal was found to be 6 nm. The simulation results confirmed that oxygen containing functional group was an important factor for adsorption on OMCs. The improvement of adsorption capacity was not so significant comparing with the influence of specific surface area, since the adsorption process was a more of a physical process rather than a process with chemical interaction.
Mueller, Andre. "Designer 3D magnetic mesostructures." Thesis, University of Bath, 2012. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.558883.
Повний текст джерелаTaft, Jenna R. "VO(dtpa) Complexes Immobilized on Mesoporous Silica: Structural Characterization and Mechanistic Investigation of Sulfide and Alkene Oxidation Reactions." ScholarWorks @ UVM, 2019. https://scholarworks.uvm.edu/graddis/976.
Повний текст джерелаRuan, Juanfang. "Development of electron microscopy towards nano-structured porous materials : focus on novel zeolites from layered silicates and chiral mesoporous nanotubes /." Stockholm : Department of Physical, Inorganic and Structural Chemistry, Stockholm university, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-7439.
Повний текст джерелаLin, Jun. "Radiation-induced alterations in mesoporous silicas : The effect of electronic processes involving ions and electrons." Thesis, Montpellier, Ecole nationale supérieure de chimie, 2022. http://theses.enscm.fr/ENSCM_2022_LIN.pdf.
Повний текст джерелаMaterials used in nuclear energy (fuel, packaging matrix, structural materials...) are subject to significant stresses due to the creation of defects that modify their properties. Several studies have shown that interfaces can act as a sink for defects caused by irradiation, which suggests that nanomaterials could have a higher resistance to irradiation than materials with a "micrometric" structure. Simultaneously, mesoporous silica materials have grown in popularity in recent years and are becoming more involved in the domain related to radiation conditioning, such as the prospective use of conditioning for nuclear waste. While research has begun to focus on the behavior of non-porous silica materials when exposed to radiation, no extensive investigations have been conducted on the behavior of mesoporous silica when exposed to radiation, particularly at electronic irradiation regime.This thesis aims to comprehend and explain the radiation-induced changes in mesoporous silicas under electronic regimes. This work quantified the evolution of physical (pore volume, pore diameter and distribution...) and structural (polymerization of the network, creation of defects...) properties of mesoporous silica irradiated with high-energy ion beams with stopping powers ranging from 1 keV/nm to 12 keV/nm, and with electron beams (10 - 300 keV and 0.6 - 2.4 MeV). Post-irradiation characterization methods (X-ray reflectivity, gas adsorption, SAXS, FTIR, etc.) have been used, as well as in-situ pore structure monitoring using electron microscopes. The experimental findings indicated that pore structures were susceptible to a certain degree of irradiation-induced shrinking. In contrast, evidence shows that the silica network itself does not alter much in porous silica compared to non-porous silica. Meanwhile, a 3DTS (3D thermal spike) model has been successfully applied to describe and explain the observed pore contraction behavior in response to ionic irradiation. Additionally, the mechanism of pore contraction under electron irradiation has been delineated according to the domain of incident electron energies. When compared to non-porous silica, this research has demonstrated that the existence of nanoscale pores reduces the accumulation of damage induced by irradiation. In conjunction with this effect, the pore contracts until it completely disappears under the impact of irradiation. This characteristic could, from an applicative point of view, be of interest to practitioners in the context of new methods of treating radioactive effluents, such as through the use of a "separation/conditioning" strategy, or in the context of the self-healing of porous gel layers formed on the surface of vitrified waste packages whose final destination is deep geological disposal