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Tutakhail, Abdulkarim. "Potential muscular doping effects of anti-depressants." Thesis, Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLS513.
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Bien que l’effet psychotrope des antidépresseurs soit bien connu, afin de corriger les conséquences du stress et de renforcer la confiance en soi, de nombreux autres effets pharmacologiques, notamment périphériques, doivent encore être approfondis. Les antidépresseurs inhibiteurs de la recapture de la sérotonine (ISRS) peuvent avoir un effet bénéfique sur la performance physique en participant à une réparation et à une croissance plus rapides des muscles. Il a récemment été démontré que la sérotonine était impliquée dans la récupération de la force musculaire chez un modèle murin de myopathie de Duchenne (Gurel et al., 2015). Les antidépresseurs tels que les inhibiteurs sélectifs de la recapture de la sérotonine (ISRS) sont largement utilisés pour traiter divers troubles de la santé mentale, tels que la dépression modérée à sévère et l’anxiété. Les deux symptômes contribuent à l’insomnie, à la perte d’appétit, au manque de motivation et à une fatigue physique accrue. Ces symptômes peuvent nuire aux performances physiques des athlètes, en particulier de ceux qui développent des habiletés et des techniques spécifiques à un sport, reçoivent des volumes d’entraînement plus importants à différentes intensités et participent à des compétitions plus fréquentes. Par conséquent, les athlètes peuvent utiliser des médicaments qui renforcent la motivation et / ou améliorent la condition physique générale en réduisant les symptômes dépressifs. L'utilisation d'antidépresseurs n'est pas encore interdite dans les sports d'élite. Des rapports récents sur le dopage associé aux ISRS montrent une tendance croissante de son utilisation chez les athlètes en bonne santé. La consommation d'antidépresseurs chez les athlètes a augmenté dans différents sports au cours de la dernière décennie, notamment les sports d'endurance.. Notre projet doit donc permettre de caractériser les conséquences d'un traitement chronique par ISRS sur les performances physiques chez la souris et de mettre en évidence le ou les mécanismes impliqués, en particulier la variation du shunt métabolique sérotonine / kynurénine, ainsi que les modifications de biomarqueurs, variations potentiellement utilisables chez l'homme dans la lutte contre le dopage.Nous aimerions élucider notre travail de recherche dans les articles suivants:Article 1: Nous avons étudié les effets de l'exercice et de la fluoxétine seuls ou en association avec un traitement prolongé à la fluoxétine (18 mg / kg / jour) et un exercice physique d'endurance (six semaines) chez la souris mâle BalbC / j, sur tapis roulant. Nous avons ensuite évalué l'activité neurocomportementale, les marqueurs musculaires du stress oxydatif et les modifications du métabolisme du tryptophane dans les tissus plasmatiques, musculaires et cérébraux des souris BalbC / J. En général, nous nous sommes concentrés sur la vitesse aérobie la plus élevée, le temps d’endurance jusqu’à l’épuisement, la force musculaire des membres antérieurs en saisissant un mesureur de force, des tests neurocomportementaux tels que le test en champ ouvert et élevé et le labyrinthe, l’activité enzymatique mitochondriale (activité du citrate synthase et du cytochrome C oxydase) dans le muscle gastrocnémien. , marqueur de stress oxydant tel que le test DHE (Dihydroéthidium) et DCF-DA (Dichlorofluorscine diacétate).Article 2: Nous avons étudié les effets de l’exercice et de la fluoxétine seule ou les effets combinés d’un traitement prolongé à la fluoxétine (18 mg / kg / jour) et d’un exercice d’endurance physique (six semaines) chez la souris mâle BalbC / j, sur tapis roulantAs much as the psychotropic effect of antidepressants is well known, correcting the consequences of stress and boosting self-confidence, so many other pharmacological effects, peripheral in particular, remain to be deepened. Serotonin reuptake inhibitor antidepressants (SSRIs) may have a beneficial effect on physical performance by participating in faster muscle repair and growth. It has recently been shown that serotonin was involved in the recovery of muscle strength in a mouse model of Duchenne myopathy (Gurel et al., 2015).Antidepressants such as selective serotonin reuptake inhibitors (SSRIs) are widely used to treat various mental health disorders, such as moderate-to-severe depression and anxiety. Both symptoms contribute to insomnia, loss of appetite, lack of motivation and increased physical fatigue. These symptoms can impair physical performances for athletes, more specifically for those who develop sport-specific skills and techniques, receive higher training volumes at various intensities, and participate in more frequent competitions. Therefore athletes may use drugs that enhance motivation and/or improve overall fitness by reducing depressive symptoms. The use of antidepressants is not yet forbidden in elite sports. Recent reports on doping associated with SSRIs show an increasing trend of its usage among healthy athletes. The antidepressants intake among athletes has increased in different sports over the last decade, especially endurance sports. The antidepressants Bupropion and Amineptine were removed from the list of banned substances.Our project must therefore make it possible to characterize the consequences of chronic treatment with SSRIs on the physical performance in mice and to highlight the mechanism (s) involved, in particular the variation of the serotonin / kynurenine metabolic shunt, as well as the modifications of biomarkers, potentially usable variations in humans in the fight against doping.We would like to elucidate our research work in the following articles:Article 1: We studied the effects of exercise and fluoxetine alone or in combination of long-term fluoxetine treatment (18mg/kg/day) and endurance physical exercise (six weeks) in male balbC/j mice, on animal treadmill. Subsequently we evaluated neurobehavioral activity, muscle markers of oxidative stress, and changes in tryptophan metabolism in plasma, muscle and brain tissues in the BalbC/J mice. Generally we focused on the highest aerobic velocity, endurance time until exhaustion, forelimb muscle strength by gripping strength meter, neurobehavioral tests such as open field and elevated plus maze test, mitochondrial enzyme activity (Citrate synthase and cytochrome-C oxidase activity) in gastrocnemius muscle, oxidative stress marker such as DHE (Dihydroethidium) and DCF-DA (Dichlorofluorscine di-acetate)test.Article 2: We studied the effects of exercise and fluoxetine alone or combinative effects of long-term fluoxetine treatment (18mg/kg/day) and endurance physical exercise (six weeks) in male balbC/j mice, on animal treadmill. After the mentioned exercise protocol we focused on changes in tryptophan (TRP) metabolism in plasma, muscle and brain tissues in the BalbC/J mice. To confirm the metabolomic, we also studied the KP related enzyme related genes and proteins by the modern required materials and methods. We correlated the result of article1 with the metabolites level of kynurenine pathway of tryptophan metabolism. We studied the expression of transcriptor factor PGC1α level in muscle which is induced by physical exercise(Agudelo et al., 2014). PGC1α subsequently induce the expression of kynurenine aminotransferase 1 and 2 (KAT1 and KAT2) in skeletal muscles, which convert kynurenine (KYN) to kynurenic acid (KYNA). Conversion of kynurenine to kynurenic acid decrease the level of kynurenine and quinolinic acid an NMDA receptor agonist and a neurotoxic compound
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Thompson, Robin Forster. "Doping effects in hydrogenated amorphous silicon solar cells." Thesis, Heriot-Watt University, 1985. http://hdl.handle.net/10399/1624.
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Rodriguez-Nieva, Joaquin F. (Joaquin Francisco). "Effects of isotope doping on the phonon modes in graphene." Thesis, Massachusetts Institute of Technology, 2012. http://hdl.handle.net/1721.1/79563.
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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2012.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 41-46).
Carbon related systems have attracted a large amount of attention of the science and technology community during the last few decades. In particular, graphene and carbon nanotubes have remarkable properties that have inspired applications in several fields of science and engineering. Despite these properties, creating structurally perfect samples is a difficult objective to achieve. Defects are usually seen as imperfections that degrade the properties of materials. However, defects can also be exploited to create novel materials and devices. The main topic of this thesis is studying the effect of isotope doping on the phonon properties of graphene. The advantage of the isotope enrichment technique is that only phonon frequencies or thermal properties can be modified without changing the electrical or chemical properties. We calculated the values of the phonon lifetimes due to isotope impurity scattering for all values of isotopic fractions, isotopic masses and for all wave-vectors using second order perturbation theory. We found that for natural concentrations of 13C, the contribution of isotopic scattering of optical modes is negligible when compared to the contribution from the electron-phonon interaction. Nevertheless, for atomic concentrations of 13C as high as [rho] = 0.5 both the isotopic and electron-phonon contributions become comparable. Our results are compared with recent experimental results and we find good agreement both in the 13C atomic density dependence of the lifetime as well as in the calculated spectral width of the G-band. Due to phonon scattering by 13C isotopes, some graphene phonon wave-functions become localized in real space. Numerical calculations show that phonon localized states exist in the high-energy optical phonon modes and in regions of flat phonon dispersion. In particular, for the case of in-plane optical phonon modes, a typical localization length is on the order of 3 nm for 13C atomic concentrations of [rho] ~~ 0.5. Optical excitation of phonon modes may provide a way to experimentally observe localization effects for phonons in graphene.
by Joaquin F. Rodriguez-Nieva.
S.M.
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Walkup, Daniel. "Doping and strain effects in strongly spin-orbit coupled systems." Thesis, Boston College, 2016. http://hdl.handle.net/2345/bc-ir:106810.
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Thesis advisor: Vidya MadhavanWe present Scanning Tunneling Microscopy (STM) studies on several systems in which spin-orbit coupling leads to new and interesting physics, and where tuning by doping and/or strain can significantly modify the electronic properties, either inducing a phase transition or by sharply influencing the electronic structure locally. In the perovskite Iridate insulator Sr3Ir2O7, we investigate the parent compound, determining the band gap and its evolution in response to point defects which we identify as apical oxygen vacancies. We investigate the effects of doping the parent compound with La (in place of Sr) and Ru (in place of Ir). In both cases a metal-insulator transition (MIT) results: at x ~ 38% with Ru, and x ~ 5% with La. In the La-doped samples we find nanoscale phase separation at dopings just below the MIT, with metallic spectra associated with clusters of La atoms. Further, we find resonances near the Fermi energy associated with individual La atoms, suggesting an uneven distribution of dopants among the layers of the parent compound. Bi2Se3 is a topological insulator which hosts linearly dispersing Dirac surface states. Doping with In (in place of Bismuth) brings about topological phase transition, achieving a trivial insulator at x ~ 4%. We use high-magnetic field Landau level spectroscopy to study the surface state’s properties approaching the phase transition and find, by a careful analysis of the peak positions find behavior consistent with strong surface-state Zeeman effects: g~50. This interpretation implies, however, a relabeling of the Landau levels previously observed in pristine Bi2Se3, which we justify through ab initio calculations. The overall picture is of a g-factor which steadily decreases as In is added up to the topological phase transition. Finally, we examine the effects of strain on the surface states of (001) thin films of the topological crystalline insulator SnTe. When these films are grown on closely-related substrates—in this case PbSe(001)—a rich pattern of surface strain emerges. We use phase-sensitive analysis of atomic-resolution STM topographs to measure the strain locally, and spatially-resolved quasiparticle interference imaging to compare the Dirac point positions in regions with different types of strain, quantifying for the first time the effect of anisotropic strain on the surface states of a topological crystalline insulator
Thesis (PhD) — Boston College, 2016
Submitted to: Boston College. Graduate School of Arts and Sciences
Discipline: Physics
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Khromov, Sergey. "Doping effects on the structural and optical properties of GaN." Doctoral thesis, Linköpings universitet, Tunnfilmsfysik, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-100760.
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Today there is a strong drive towards higher efficiency light emitters and devices for power electronics based on GaN and its ternary compounds. Device performance can be improved in several ways on the material level. Development of bulk GaN to substitute sapphire and SiC as substrate materials can allow lower defect density epitaxial GaN layers to be grown. Using nonpolar homoepitaxial layers alleviates the problem of polarization fields present in polar GaN epilayers. This thesis advances the field by attacking outstanding problems related to doping and its influence on structural and optical properties of GaN. Optical and structural investigations were performed on bulk GaN grown by halide vapor phase epitaxy (HVPE) and on polar and nonpolar epitaxial GaN grown by metal organic chemical vapor deposition (MOCVD), doped with different impurities: Mg, Si, O or C. Optical characterization was done using photoluminescence (PL), time-resolved photoluminescence (TRPL), and cathodoluminescence (CL) in-situ scanning electron microscope, whereas structural properties were studied by means of transmission electron microscopy (TEM) and atom probe tomography (APT). A correlation between Mg doping levels and stacking fault (SF) concentration in highly Mg-doped c-plane homoepitaxial GaN layers is found. Increasing Mg concentrations, from 2×1018 cm-3 to 5×1019 cm-3, coincides with increasing density of small, 3-10 nm-sized, SFs. Emission lines ascribed to SFs are observed in CL in all the studied samples. The observed SF-related luminescence can be explained by a model where Mg atoms interacting with the nearby SF changes the confinement for holes and leads to a pronounced defectrelated luminescence. Non-polar m-plane homoepitaxial GaN layers with Mg concentration of 2×1018 cm-3 and 3×1019 cm-3 exhibits high density of basal SFs as well as a number of prismatic SFs. Instead of normally observed in nonpolar GaN SF-related broad lines several sharp lines are detected in the 3.36-3.42 eV region. Their relation to donor-acceptor pair recombination (DAP) was dismissed by calculating the DAP energies and fitting with the measured spectra. The sharp lines are tentatively explained by some impurities bound to point defects or SFs. The origin of two Mg related acceptor bound exciton (ABE) peaks in the emission spectra is also proposed: narrower ABE1 peak at 3.466 eV is identified as coming from a substitutional Mg atom. Broader emission at 3.454 eV is deemed to be coming from a Mg acceptor atom perturbed by a nearby SF. Additionally, Mg cluster formation in the highest doped sample ([Mg] = 1×1020 cm-3) was revealed by APT. Simultaneous doping by Si and O was studied for HVPE grown bulk GaN. Doping with O concentration from 1017 cm-3 leads to a decrease in the Si concentration to less than 1016 cm-3. Si incorporation is believed to be suppressed by the competing Ga-vacancy-O incorporation process. Bandgap narrowing by 6 meV due to high doping was observed. Donor bound exciton (DBE) lifetime was obtained from TPRL experimental data and it is found to decrease with increasing doping. In non-polar m-plane homoepitaxial GaN Si doping influences the SF-related luminescence. At moderate Si concentrations excitons are bound to the impurity atoms or impurity-SF complex. Proximity of impurity atoms changes the potential for SF creating localization for charge carriers resulting in SF-related emission. At dopant concentrations higher than the Mott limit screening destroys the carrier interaction and, thus, the exciton localization at impurity-SF complex. Finally, C-doped HVPE grown bulk GaN layers were studied by TEM, CL, and TRPL. Enhanced yellow line (YL) luminescence was observed with increasing C doping. Stability of YL in a wide temperature range (5-300 K) confirms that YL is due to a deep defect, likely CN-ON complex. Low-temperature CL mapping reveals a pit-like structure with different luminescence properties in different areas. DBE emission dominates in CL spectra within the pits while in pit-free areas, in contrast, two ABE lines typical for Mg-doped GaN are observed.
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Harrison, Mark J. "The effects of using aliovalent doping in cerium bromide scintillation crystals." Diss., Manhattan, Kan. : Kansas State University, 2009. http://hdl.handle.net/2097/1322.
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Bradley, I. V. "Interdiffusion of III-V semiconductors heterostructures : effects of ion implantation and doping." Thesis, University of Surrey, 1993. http://epubs.surrey.ac.uk/842950/.
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Photoluminescence coupled with repetitive thermal annealing has been used to determine diffusion coefficients for intermixing in In0.2Ga0.8As/GaAs and GaAs/Al0.2Ga0.8As 100A single quantum wells and to study the effects of doping with silicon and beryllium and of ion implantation on the interdiffusion. It has been shown that the diffusion obeys Pick's law and that doping concentrations of beryllium up to 2.5 x 1019 cm-3 and silicon up to 10 18 cm-3 have no effect on the interdiffusion coefficients in either material system. For the In0.2Ga0.8As/GaAs system it was shown that following implantation and annealing there was a fast interdiffusion process which is independent of implant ion species and anneal temperature. This is thought to be due to recovery of the crystals from implant damage. After this rapid process, it was found that neither gallium nor krypton ions had any further effects on the interdiffusion. However, following arsenic implantation an additional enhanced region of interdiffusion coefficient was observed, with diffusion coefficients an order of magnitude greater than that of a control unimplanted sample. This enhancement is thought to be due to the creation of group in vacancies by the implanted arsenic atoms moving onto group V sites. This fast process was transient in nature returning to that of the unimplanted samples after the well has broadened by about 85A. An activation energy for the diffusion process of 3.7 +/- 0.1 eV was measured over a temperature range of 750-1050°C. This was found to be independent of implanted ion or dopant incorporated in the samples, indicating that the same process controls the interdiffusion in all cases. Similar results were found for the GaAs/Al0.2Ga0.8As system.
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Gu, Hang. "Magnetoresistance and doping effects in conjugated polymer-based organic light emitting diodes." Thesis, Queen Mary, University of London, 2015. http://qmro.qmul.ac.uk/xmlui/handle/123456789/8940.
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Magnetoresistance (MR) and doping effects have been investigated in a poly(3-hexylthiophene-2,5-diyl) (P3HT) based organic light emitting diodes. In single device of fixed composition (Au/P3HT/Al as spun and processed in air), the measured MR strongly depends on the drive conditions. The magnetoconductance (MC) varies from negative to positive (-0.4% ≤ MC ≤ 0.4%) with increasing current density, depending on which microscopic mechanism dominates. The negative MC is due to bipolaron based interactions and the positive MC to triplet-polaron based interactions (as confirmed by light emission). Oxygen doping is prevalent in P3HT devices processed in air and the effect of de-doping (by annealing above the glass transition temperature) is investigated on the MC of an Au/P3HT/Al diode. De-doping reduces the current through the device under forward bias by ~3 orders of magnitude, but increases the negative (low current) MC from a maximum of -0.5% pre-annealing to -3% post-annealing. This increased negative MC is consistent with bipolaron theory predictions based on Fermi level shifts and density of states (DoS) changes due to de-doping. The decrease in current density is explained by increased injection barriers at both electrodes also resulting from de-doping. Deliberate chemical doping of P3HT is carried out using pentacene as a hole trap centre. The trapping effect of pentacene is confirmed by reproducible and significant hole mobility-pentacene concentration behaviour, as measured by dark injection (DI) transient measurements. The enhanced carrier injection resulting from the pentacene doping also leads to increased electroluminescence (EL). The resultant MC in pentacene doped devices is strongly dependent on carrier injection and can be significantly enhanced by doping, for example from -0.2% to -0.6% depending on device and drive conditions. Throughout this thesis Lorentzian and non-Lorentzian function fitting is carried out on the measured MC, although the underlying microscopic mechanisms cannot always be discerned.
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Crowley, Kyle McKinley. "Electrical Characterization, Transport, and Doping Effects in Two-Dimensional Transition Metal Oxides." Case Western Reserve University School of Graduate Studies / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=case1597327584506971.
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Modarresi, M., M. R. Roknabadi, N. Shahtahmasbi, and M. Mirhabibi. "Many body effects on the transport properties of a doped nano device." Thesis, Sumy State University, 2011. http://essuir.sumdu.edu.ua/handle/123456789/20568.
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In this article, we study the effect of electron-electron interaction in a doped nano
cluster sandwich between two electrodes. The Hamiltonian of the cluster is written in
the tight-binding model and electrodes are described in the wide-band approximation.
The GW approximation has been used for the calculation of the exchange-correlation
term in the cluster region. Our results showed that in the presence of the electronelectron
interaction the transmittance gap increases and current decreases. Also, in a
doped nano structure the transmission decreases and many body effect becomes more
important. By considering the exchange-correlation in a doped nano cluster in the GW
approximation the transmission and current decrease drastically.
When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/20568
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OLBRIGHT, GREGORY RICHARD. "FEMTOSECOND DYNAMICS AND NONLINEAR EFFECTS OF ELECTRON-HOLE PLASMA IN SEMICONDUCTOR DOPED GLASSES." Diss., The University of Arizona, 1987. http://hdl.handle.net/10150/184091.
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The following is a comprehensive study of transient and steady-state nonlinear optical properties of semiconductor microcrystals embedded in a glass matrix (semiconductor doped glass). Transient thermal effects which give rise to longitudinal excitation discontinuities (i.e., kinks) that arise from partial sample switching in increasing absorption optical bistability are observed in a doped glass. The transient thermal effects occur on time scales of a few hundred milliseconds. Femtosecond and nanosecond laser pulses are employed to measure time-resolved and steady-state transmission and differential transmission spectra. The measured spectra reveal several beautiful effects which are attributed to the many-particle effects of electron-hole plasma. The spectra reveal: bandgap renormalization, broadening of the tail states and screening of the continuum states, state filling (spectral hole burning), thermalization of nonthermal carrier population distributions, band filling due to carrier relaxation of the thermal and nonthermal distributions, direct electron-hole recombination and long lived (>>100 ps) tail states which are attributed to electron trapping. Absorption edge dynamics discussed in this dissertation span 15 orders of magnitude.
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Monteiro, Pedro Manuel da Silva. "A close study of a ferromagnetic semiconductor : doping effects in EuO thin films." Thesis, University of Cambridge, 2015. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.709424.
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Villalpando, Paéz Federico. "Effects of doping single and double walled carbon nanotubes with nitrogen and boron." Thesis, Massachusetts Institute of Technology, 2006. http://hdl.handle.net/1721.1/36215.
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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2006.Includes bibliographical references (p. 135-143).
Controlling the diameter and chirality of carbon nanotubes to fine tune their electronic band gap will no longer be enough to satisfy the growing list of characteristics that future carbon nanotube applications are starting to require. Controlling their band gap, wall reactivity and mechanical properties is imperative to make them functional. The solution to these challenges is likely to lie in smart defect engineering. Defects of every kind can induce significant changes on the intrinsic properties of carbon nanotubes. In this context, this thesis analyzes the effects of doping single and double walled carbon nanotubes with nitrogen and boron. We describe the synthesis of N-doped single-walled carbon nanotubes (N-SWNTs), that agglomerate in bundles and form long strands (<10cm), via the thermal decomposition of ferrocene/ethanol/benzylamine (FEB) solutions in an Ar atmosphere at 950°C. Using Raman spectroscopy, we noted that as the N content is increased in the starting FEB solution, the growth of large diameter tubes is inhibited. We observed that the relative electrical conductivity of the strands increases with increasing nitrogen concentration. Thermogravimetric analysis (TGA) showed novel features for highly doped tubes, that are related to chemical reactions on N sites.
(cont.) We also carried out resonance Raman studies of the coalescence process of double walled carbon nanotubes in conjunction with high resolution transmission electron microscope (HRTEM) experiments on the same samples, heat treated to a variety of temperatures and either undoped or Boron doped. As the heat treatment temperatures are increased (to 1300°C) a Raman mode related to carbon-carbon chains (w = 1855cm-1) is observed before DWNT coalescence occurs. These chains are expected to be 3-5 atoms long and they are established covalently between adjacent DWNTs. The sp carbon chains trigger nanotube coalescence via a zipper mechanism and the chains disappear once the tubes merge. Other features of the Raman spectra were analyzed as a function of heat treatment with special emphasis on the metallic or semiconducting nature of the layers constituting the DWNTs. DWNTs whose outer wall is metallic tend to interact more with the dopant and their outer tubes are the predominant contributors to the line shape of the G and G' bands.
(cont.) The metallic or semiconducting nature of the layers of the DWNTs does not affect their coalescence temperature. All the experiments and analysis presented in this thesis are the result of a collaborative effort between Professor Dresselhaus' group at MIT and its international collaborators, including Professor Endo's group at Shinshu University, Nagano, Japan, Professors Pimenta's and Jorio's group at the Federal University of Minas Gerais, Belo Horizonte, Brazil, and Professors M. and H. Terrones' group at IPICYT, San Luis Potosi, Mexico.
by Federico Villalpando Paéz.
S.M.
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Dynkin, Alexey. "Effects of strontium doping on oxygen reduction kinetics in thin-film LSCF cathodes." Thesis, Boston University, 2013. https://hdl.handle.net/2144/12092.
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Thesis (M.S.)--Boston UniversityDense films of the mixed ionic-electronic conductor lanthanum strontium cobalt fenite (La1-xSrxCo0.2Fe0.8O3-δ) with x= 0.4, 0.3 and 0.2 (thereafter refened to as LSCF-6428, LSCF-7328 and LSCF-8228) were deposited in fixed patterns on yttria-stabilized zirconia (YSZ) substrates on top of a gadolinium-doped ceria (GDC) barrier layer by pulsed laser deposition (PLD) at the Pacific Northwest National Laboratory (PNNL) in Richland, WA. A counter electrode of porous 50-50 wt %/48.3-51.7 vol.% LCMIYSZ was screen-printed on the opposite side of the substrates. Electrochemical impedance spectroscopy (EIS) data were gathered for each of the compositions in air, but at varying temperatures (600, 700 and 800 °C). The total electrode polarization resistance, Rpob was plotted as a function of composition and temperature. Results show that, for all temperatures, the total polarization resistance drops considerably when the Sr composition is reduced from 0.4 to 0.3, and then increases slightly as the Sr composition is further reduced from 0.3 to 0.2 The relatively high polarization resistance for LSCF-6428 may be explained by recent evidence found by other members of our research group of surface strontium migration in LSCF-6428 films, which results in the formation of phases that could potentially affect electrochemical performance.
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Pei, Min. "Effects of Lanthanum doping on the microstructure and mechanical behavior of a SnAg alloy." Diss., Available online, Georgia Institute of Technology, 2007, 2007. http://etd.gatech.edu/theses/available/etd-03272007-120709/.
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Thesis (Ph. D.)--Mechanical Engineering, Georgia Institute of Technology, 2007.Neu, Richard W., Committee Member ; Sanders, Thomas H. Jr., Committee Member ; Wong, C.P., Committee Member ; McDowell, David L., Committee Member ; Qu, Jianmin, Committee Chair.
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趙裕隆 and Yu-lung Chiu. "Effects of boron doping on the microstructure and mechanical properties of [gamma/gamma'] superalloys." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1999. http://hub.hku.hk/bib/B31238336.
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Chiu, Yu-lung. "Effects of boron doping on the microstructure and mechanical properties of [gamma/gamma'] superalloys /." Hong Kong : University of Hong Kong, 1999. http://sunzi.lib.hku.hk/hkuto/record.jsp?B20933356.
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Esmaeili, Mostafa. "The Effects of Nitrogen doping on Chemical, Optical and Electronic properties of Carbon Dots." Thesis, Griffith University, 2022. http://hdl.handle.net/10072/414280.
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Photoluminescent carbon dots have received significant research interest in recent years owing to their extraordinary optical properties, biocompatibility, and versatile functionalities. Nitrogen-doping is a widely used strategy for enhancing the photoelectronic functionalities of carbon dots. However, there is a lack of systematic study on the composition and concentration-dependency emission behaviour of N-doped carbon dots in the literature. In this study, multicolour carbon dots (CDs) having different degree of nitrogen doping were synthesized by varying the molar ratio of citric acid to urea in the precursor via hydrothermal treatment. The effects of nitrogen doping on chemical, optical, and electronic properties of CDs were characterized using various techniques including transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), Fourier-transform infrared (FTIR); fluorescence and absorption spectroscopy; fluorescence lifetime and Hall effect measurements. Three main emissive centres were recognized in concentration-dependent fluorescence study of N-CDs which can be ascribed to molecular type of fluorescence, core emission, and mid-gap nitrogen states on the edge/surface of CDs. A plausible mechanism in relation to the obtained results is proposed. This work provides insights on the opto-electro-tunability of CDs via N-doping.Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
School of Eng & Built Env
Science, Environment, Engineering and Technology
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Kayhan, Mehmet. "Effects Of Synthesis And Doping Methods On Thermoluminescence Glow Curves Of Manganese Doped Lithium Tetraborate." Master's thesis, METU, 2009. http://etd.lib.metu.edu.tr/upload/3/12610667/index.pdf.
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In this study, differences in glow curves of Mn doped LTB powder samples synthesized with solid and wet synthesis methods and doped by using solid and wet doping techniques were investigated. Firstly, LTB was synthesized by using wet synthesis method which mainly comprises dissolution of reactants in water as solvent. Second way to produce LTB which was used in this study was solid synthesis method. In solid synthesis method, reactants were mixed in powder form.
In the second part of the study, LTB produced by two different methods were doped with Mn and additionally Ag, Mg or P by using two different doping techniques.
In order to see structural differences between differently synthesized and differently doped LTB samples which contained different amount of dopant powder X-Ray Diffraction (XRD) method was employed. Besides, FTIR (Fourier Transform Infrared) spectroscopy analyses were performed in order to detect differences in the bond structure caused by doping. Additionally, Inductively Coupled Plasma Optical Emission Spectrometer (ICP-OES) was used to determine the actual amount of dopant in LTB. Also morphological structures of samples were compared by using Scanning Electron Microscopy (SEM). Thermoluminescence measurements were performed with (TLD) Thermoluminescence Dosimeter equipment.
XRD and FTIR analysis showed that syntheses of products were done in well success. Addition of dopants did not cause any changes in structural or bonding properties of LTB. It was possible to observe that, synthesis and doping methods and dopant concentration effect the thermoluminescence glow curves of doped LTB.
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Mirzakuchaki, Sattar. "Growth and characterization of diamond thin films : effects of substrate pretreatment, doping, and selective deposition /." free to MU campus, to others for purchase, 1996. http://wwwlib.umi.com/cr/mo/fullcit?p9737867.
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Macpherson, Ross Fraser. "Monte Carlo modelling of Gunn devices incorporating thermal heating effects : investigations of broad frequency devices, heating effects in GaN devices and doping nucleation." Thesis, University of Aberdeen, 2009. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=203872.
Full textAbstract:
Monte Carlo modelling is a common technique in numerous fields, and is widely used in semiconductor device simulation. This thesis describes the application of Monte Carlo modelling to the simulation of Gunn diode devices, focusing on devices composed of Gallium Arsenide (GaAs) and Gallium Nitride (GaN). Gunn diodes are simple structures that take advantage of negative differential resistance to act as a source of high frequency radiation, from 10 GHz to over 100 GHz in GaAs devices. It has been theorised that GaN should exhibit negative differential resistance and a GaN Gunn diode could produce radiation of even higher frequency, within the terahertz band. Gunn diodes have the advantage of being cheap and portable, and so are worth exploring as such a source. Unfortunately, GaN devices have a high electron density and so they tend to generate heat quickly. It therefore becomes important to include modelling of heat generation and flow in simulations of these devices. This is uncommon in Monte Carlo models of Gunn diodes, as in less highly doped devices thermal effects can usually be assumed to result in the device reaching an equilibrium temperature of about 100 K above the ambient. This thesis describes the creation of a model to track the generation and distribution of heat during operation of a GaN device. Simulations found that thermal effects within the device were significant. Heat generation occurred to the extent that the device could only be operated in pulsed mode, with on pulses of 2 ns requiring 50 ns of cooling for sustainable operation. The increased temperature within the device also lead to deleterious changes in the Gunn diode's operating frequency. In the simulated device, a 150 K change in temperature lead to a decrease in operating frequency of 40 GHz, from an initial frequency of 280 GHz. At the end of 2 ns of operation, the mean temperature within the device had increased by 120 K. The high accidental doping level in GaN also means the use of a doping notch to act as a nucleation point for dipoles within a Gunn diode, a common technique in other materials, becomes less feasible. As an alternative to a notch, a device was simulated incorporating a doping spike to nucleate the dipole. The use of a doping spike is not novel, however its use in GaN has not been previously explored. Simulations found that a fully-depleted p-type doping notch of length 2.1 nm, doped at 1x1024 m-3 would act as a nucleation point for dipole operation. The device was compared to a simulated device incorporating a doping notch of width 0.25 µm doped at 0.5x1023 m-3 and found to operate at a similar frequency and RF efficiency, making it a viable substitute. One limitation of Gunn diodes is that when operated in transit-time mode, the operating frequency is determined by the length of the diode's transit region and so is well-defined and fixed. This means that traditional Gunn diodes are not as useful a source of radiation for spectroscopic applications as might be desirable. Recent experimental results for planar devices have shown a broadening in operation frequency and even multiple frequencies. This thesis explores the hypothesis that such a broadening might be achieved in a vertical structure via the incorporation of an additional notch into the Gunn diode's transit region, effectively incorporating two transit regions into the device. Results showed that this novel device structure did show multiple modes of operation. Under a DC applied voltage, the device showed spontaneous switching behaviour, oscillating between dipole and accumulation layer operation from the second notch. Changes in the frequency of an applied RF voltage would shift the device from operating from the first or second notch, in dipole and accumulation layer mode respectively.
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張富欽. "Characterizations of Doping Effects in Nitride Films." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/67030038710784166379.
Full textAbstract:
博士國立交通大學
電子物理系所
93
We have carried out systematic studies on epitaxial growth of d In isoelectronic doping p-GaN using metalorganic vapor phase epitaxy technique (MOVPE). For the isoelectronic In-doping effects on Mg-doped GaN films, The preliminary results indicate that when In atoms are added, the surface morphology is greatly improved, and a virtually featureless structure can be obtained. properties, The Hall resulting optimum hole concentration and resistivity are 9× 10e17 cm-3 and 1 Ω-cm, respectively. Perhaps the most striking result is the observance of a linear I-V characteristic on the as-deposited sample, which indicates the good Hall properties associated with such types of film. The Photoluminescence (PL) studies of In-doped GaN:Mg films revealed that the Mg-related emission at 3.1 eV is enhanced by more than one order of magnitude on the shoulder of the broad band centered at 2.8 eV for GaN:Mg after an optimal In concentration was added into the films. This enhancement of the 3.1 eV band is believed to be associated with the reduction in the number of self-compensation centers. A slow decay in PL intensity evolution was also observed, which may be ascribed to a local energy barrier that impedes carriers that relax into the valence band. The temperature dependences of the decay time constants were measured and a barrier energy as high as ~ 103±7 meV was obtained for In-doped GaN:Mg as compared with 69±8 meV for GaN:Mg.
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Chen, Han-Ping, and 陳漢平. "Doping effects in GaAs studies by photoreflectance spectroscopy." Thesis, 1993. http://ndltd.ncl.edu.tw/handle/85407795568837111731.
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Hsu, Miao-Chih, and 徐妙枝. "Isoelectronic Indium Doping Effects On P-type GaN Films." Thesis, 2002. http://ndltd.ncl.edu.tw/handle/22909728328174972455.
Full textAbstract:
碩士國立交通大學
電子物理系
90
We have investigated the isoelecetronic indium doping effects of Indium on p-type GaN films. Two sets of samples were prepared：one is pure Mg-doped GaN film, the other is Mg-In codoped GaN film. Whether Indium is doped or not, the photoluminescence spectra of as-grown p-type GaN films all show one broad emission peak around 2.78eV, which indicating Mg-rich in all of our p-type GaN samples. Besides, it is interesting to note that the hole concentration of Mg-In codoped GaN is higher than that of Mg-doped one based on room-temperature Hall measurement data. The optimum hole concentration is 7.32´1017cm-3. We believe the increase of the hole concentration in these indium doped p-GaN films can be attributed primarily to the reduction of the acceptor activation energy, the decrease of compensation effects as well as effective incorporation of Mg atom as shallow acceptor, rather than deep impurity, not directly related to the Mg solid concentration in the film.
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Chuang, Alvin, and 莊志平. "Multi-layer growth CuAlO2 and effects of doping Fe2O3." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/99423827754407353441.
Full textAbstract:
碩士國立成功大學
奈米科技暨微系統工程研究所
96
In this study,we deposited CuAlO2 thin films on Al2O3(0001) substrate by ion beam sputter. The first work we deposited [CuO(10Å)/Al2O3(10Å)] multi-layers ,and 1100℃ annealed samples under argon ambience in order to get CuAlO2 thin films. The second work we deposited [CuO(10 Å)/Fe2O3(1Å、3 Å)/Al2O3(10 Å)] multi-layers ,and 1100℃ annealed samples under argon ambience .The structural ,electrical ,and magnetic properties of annealed samples have been investigated. The ferromagnetism of [CuO(10 Å)/Fe2O3(1 Å、3 Å)/Al2O3(10 Å)] increased after 400℃ annealing under oxygen ambience but decreased under argon ambience. The results suggest that ferromagnetism in [CuO(10 Å)/Fe2O3(1 Å、3 Å)/Al2O3(10Å)] comes from an intrinsic factor highly correlated to defects. We will go on studying to find the origin of ferromagnetism exactly.
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Lin, Dian-Wei, and 林典偉. "Doping effects on optoelectronic materials: First-principles band unfolding study." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/83187688553384420393.
Full textAbstract:
碩士淡江大學
物理學系碩士班
104
In modern materials science, introducing the impurities (such as, vacancies, dopants, lattice dislocations, etc.) inside a periodic lattice structure is the most effective approach to manipulate the fundamental characteristics of materials, including electronic , magnetic and optical properties. Corresponding to the progress of modern experiments by means of novel techniques and sample preparation of doping crystals, theoretical atomic-level simulation of doping structures can be performed within a supercell scheme. However, the connection between the corresponding structures of doped and undoped compounds will be obscured by zone-folding induced reduction of Brillouin zone in a supercell calculation.. Thus, it is our task to unfold the supercell band structure by combining the basis transformation and momentum space unfolding methods. The unfolded band structure enables us to observe directly the impacts of doping on the band structure such as symmetry breaking and band width modification. A direct comparison between the first-principles unfolded band structure calculations and ARPES measurements can be achieved.. In this thesis, we will study the following three systems: group IV semiconductor doping, group III-V defects and 2D graphene structures.
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Lin, Yii-Chung, and 林以中. "The Primary and Secondary Doping Effects of Poly-3- alkylthiophene." Thesis, 1997. http://ndltd.ncl.edu.tw/handle/14986205238200326475.
Full textAbstract:
碩士國立中央大學
化學系
85
We synthesize poly-3-alkylthiophene with different side chain length by applying chemical and electrochemical polymerization of the corresponding monomer. The regioregularity and solubility of the polymer prepared from chemical polymerization are better than those from electrochemical polymerization. After primary doping (partial oxidation) of the neutral polymer (chemically prepared), the conductivity increases 105~108 times. The longer the side chain, the lower the conductivity of doped polymer. For the polymer film at ca. 5000 A, regardless the side chain length, the maximum conductivity was obtained after doping for 20 to 30 minutes. We also demostrate that the primary doping reaction produces polarons and bipolarons by cyclic voltammetry experiment. The oxidation potentials of the polymers depend on the structure regioregularity but not on the side chain length. The secondary doping (rearrangement of polymer chain) of the doped poly-3- alkylthiophene is performed with the vapor-transfer method. It was found that most solvents have the tendency to increase the dedoping rate of doped poly-3-alkylthiophene. The higher the polarity of the solvent, the faster the dedoping rate. Interestingly, when toluene is used as a secondary dopant, although slightly dedoping phenomenon also occurs, the conductivity increases. It implied that the secondary doping effect of FeCl3 doped poly-3-alkylthiophene may occur when toluene is used as a secondary dopant.
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WANG, YU-SHENG, and 王裕勝. "Doping Effects of Li-rich Mn-based Oxides Battery Materials." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/8j52e9.
Full textAbstract:
碩士國立暨南國際大學
應用化學系
108
Sn-doped Li-rich Mn-based oxides of Li1.083Ni0.333Co0.083Mn0.5-xSnxO2 was synthesized via a sol-gel method, and the electrochemical performance of the battery can be improved by doping the appropriate tin ions. While doping with x=0.005 tin, the degree of reduction of the initial voltage of the battery is improved. After 50 cycles of charge and discharge, the degree of battery power degradation decreased from 8% to 4%, comparing to the original undoped sample. The battery still maintains a discharge capacity of 180 mAh/g. In this experiment, the change of lattice constant and volume before and after doping was analyzed by XRD, and the change of discharge initial voltage of the battery before and after doping was compared by the differential graph of charge and discharge curves of the battery.
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"Doping effects on the colossal magnetoresistance of lanthanum-calcium- manganese-oxygen." 1998. http://library.cuhk.edu.hk/record=b6073130.
Full textAbstract:
"January 1998."Thesis (Ph.D.)--Chinese University of Hong Kong, 1998.
Includes bibliographical references.
Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web.
Mode of access: World Wide Web.
Abstract in Chinese.
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Yeo, Sunmog Fisk Zachary. "Doping effects on the Kondo lattice materials FeSi, CeCoIn5, and YbInCu4 /." 2003. http://etd.lib.fsu.edu/theses/available/etd-11112003-065129/.
Full textAbstract:
Thesis (Ph. D.)--Florida State University, 2003.Advisor: Dr. Zachary Fisk, Florida State University, College of Art and Sciences, Dept. of Physics. Title and description from dissertation home page (viewed Mar. 2,2004). Includes bibliographical references.
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Matias, José Pedro Teixeira. "Testosterona no Desporto: reposição hormonal ou doping?" Master's thesis, 2020. http://hdl.handle.net/10400.6/10738.
Full textAbstract:
Introdução: A competição faz parte da história da humanidade desde os seus
primórdios e, como tal, a procura de formas para aumentar a performance desportiva são
cada vez mais variadas. Este facto, aliado à crescente influência das redes-sociais e dos
media na conceção da imagem das pessoas, leva a uma busca de métodos ditos mais rápidos
de obtenção de resultados a nível físico. Posto isto, surge uma problemática interessante,
que já não se prende com a prática desportiva de forma leal, mas sim quais serão as
consequências para a saúde dos atletas que usam estes compostos numa tentativa de
melhorar a sua performance desportiva.
Objetivos: Despertar o interesse da comunidade científica para as práticas atuais de
abuso de esteroides anabolizantes androgénicos; Elucidar os atletas envolvidos nestes
hábitos das consequências nefastas que estas práticas podem ter para a sua saúde;
Sensibilizar as entidades reguladoras do desporto para esta problemática, motivando-as
para a criação de mecanismos de prevenção e identificação destas situações; Ajudar a
melhor identificar situações em que existe necessidade de suplementação hormonal em
casos de Hipogonadismo secundário ao exercício físico.
Metodologia: A pesquisa bibliográfica foi realizada através do motor de busca
PubMed. As publicações foram selecionadas de acordo com a sua relevância em relação ao
tema, tendo sido dada preferência aos artigos mais recentes. Através da bibliografia
analisada foram ainda utilizados outros trabalhos presentes nas suas bibliografias,
mediante o interesse para o tema.
Conclusão: O abuso destes compostos, quer com o objetivo de melhorar o
desempenho desportivo quer com a finalidade de obter uma imagem corporal mais
desejada, começa a ser um problema grave de saúde pública. As limitações éticas e morais
acabam por ser um entrave à realização de estudos que figurem as dosagens e práticas
realmente utilizadas, quer por atletas de alta competição quer por competidores recreativos,
o que nos leva a tirar conclusões muito superficiais, mas ainda assim esclarecedoras. Por
tudo isto, torna-se notório que a questão principal para a elaboração de um plano que tenha
em vista combater este problema passa pela premissa “educar para a saúde”. Dado que estes
atletas seguem esquemas de administração e dosagens que encontram na internet, muitas
delas sem base científica e completamente desreguladas, sem estarem elucidados para os
potenciais efeitos nefastos para a sua saúde.Introduction: Competition is part of the history of mankind since its beginning. Likewise, the search for ways of enhancing sports performance grows every day. This fact, linked to the growing influence of social media on body image perception, is leading people to search for faster methods to obtain good results at the physical level. With that being said, an important issue arises, one that is not about practicing sports at an unfair level, but about the consequences for the health of these athletes that use these compounds as an attempt to improve their athletic performance. Objectives: Peak the scientific community interest in the current practices of anabolic androgenic steroids abuse; Raise awareness for the consequences of these habits to the health of athletes; Sensitize the regulatory agencies towards this issue, motivating them to create mechanisms to prevent and identify these situations; Aiding in the identification of situations where there is a need for hormonal supplementation in athletes with hypogonadism. Methodology: The literature was researched using PubMed’s search engine. The articles were selected according to their relevance, had been given preference to the most recent ones. After analysis of the essays, other articles that were in their bibliography were used. Webpages from some agencies dedicated to this issue, were also consulted. Conclusion: The abuse of these compounds, with the purpose of enhancing athletic performance or to get a better body image, is turning out to be a public health problem. The ethical and moral limitations prove to be an obstacle to the performance of clinical trials that mimic the actual doses and practices used by athletes and recreational users, what takes us to draw superficial conclusions. Nevertheless, they are very enlightening. With that being said, it is paramount to elaborate a plan of action to oppose this problem, one with the goal to advise athletes. The main reason for it is the fact that these practices are searched and used on the internet by athletes, a lot of them with no scientific background and completely unregulated, without being aware of the damage they may be causing to their health.
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WU, YI-LIN, and 吳一霖. "Polypyrrole/Reduced Graphene Oxide Nanocomposite as Supercapacitor Electrode-Effects of Preparation Procedures and Doping Effect." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/7cd8qn.
Full textAbstract:
碩士國立雲林科技大學
化學工程與材料工程系
106
The ain of this study is to investigate the effects of dopants and different preparation procedures for the preparation of polypyrrole(PPy)/reduced graphene oxide(RGO) nanocomposite electrode materials applied on the impact of supercapacitor electrode. Firstly, different groups of PPy are prepared by different (dopant types), and PPy-Dopant with better performance is selected, and then PPy-Dopant with different concentration ratios is synthesizes by different (oxidant concentration, dopant concentration). The best electrochemical performance of PPy-Dopant was selected. Finally, two groups of different dopants and different material concentration ratios of PPy were synthesized, which were PPy-DBSA and PPy-CTAB. During the experiment, it was found that the chemical in-situ polymerization of PPy and PPy/GO composite materials, the order of addition of dopants and pyrrole monomers, had a significant effect on the integrity after polymerization, by cyclic voltammetry ( CV) shows that the electrochemical active areas of PPy (CTAB), PPy (DBSA) and PPy (CTAB) 7GO3, PPy (DBSA) 7GO3 in two different processes are significantly different, and the electrochemical area is compared with each other. The order of adding the pyrrole after the dopant is greater than the order of adding the pyrrole and then adding the dopant. Because GO has poor conductivity and the electrochemical active area of RGO is larger than GO, PPy/GO is further prepared into PPy/RGO. There are three ways to process respectively: two-step synthesis (polymerization of PPy/GO, then reduction to PPy/RGO), two-step synthesis(reduction of RGO, then polymerization to PPy/RGO), one-step synthesis (simultaneous polymerization and PPy(DBSA)7RGO3 prepared by the preparation methods showd that the electrochemical activity area of PPy(DBSA)7RGO3 was larger than that of PPy(CTAB)7RGO3 prepared by three processes. The result proves that DBSA is The best dopant is used to prepare PPy7RGO3. It is known that DBSA is the best dopant for the preparation of PPy7RGO3, and PPy(DBSA)7RGO3 prepared by one-step synthesis (simultaneous polymerization and reduction) has the highest specific capacitance value 574 F/g at a scan rate of 5 mV/s, and PPy(DBSA)7RGO3 prepared by two-step synthesis (first polymerization) has the second highest specific capacitance value 538 F/g. Because of the different process methods, the electrochemical active area is also different, so two processes of PPy (DBSA) 7RGO3 were tested for a series of electrochemical activities. The results show that PPy(DBSA)7RGO3 prepared by two-step synthesis (first polymerization) has an optimum retention rate of 73% and a long charge and discharge time at 0.5 A/g constant current charge and discharge, and a one-step synthesis method. PPy(DBSA)7RGO3 prepared by simultaneous polymerization and reduction has the largest electrochemical active area and specific capacitance value under cyclic voltammetry (CV) of 5 mV/s.
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LeBlanc, James Patrick Francis. "The Effects of Electronic Doping on Quantum Materials: Cuprates and Graphene." Thesis, 2012. http://hdl.handle.net/10214/3562.
Full textAbstract:
In recent years there has been significant work aimed at understanding what effect the variation of electronic doping has on material properties.
In the high transition-temperature (high-T$_c$) cuprate superconductors hole doping has an impact on the superconducting transition temperature. In the underdoped regime, the cuprates exhibit anomalous properties due to a pseudogap which forms and is thought to be related to Mott insulating physics.
While there is no general consensus as to the mechanism underlying high temperature superconductivity, the resonating valence bond (RVB) theory proposed by Anderson in 1987 with a Gutzwiller projected d-wave BCS wave function could give a first picture of the high-T$_c$ cuprates.
We have calculated properties of the cuprates using the assumption that the pseudogap state acts as a normal state to an otherwise standard BCS mean field theory. We find that the phenomenological RVB spin liquid model proposed by Yang, Rice and Zhang (YRZ) is highly successful at describing the doping dependent features of the cuprates. Through application of the YRZ model and the tools of many-body theory we present results on anomalous properties observed in: electronic specific heat; Raman and angle-resolved photoemission spectroscopy (ARPES) data; effective mass renormalization; and thermal broadening seen in ARPES.
We verify that the YRZ ansatz qualitatively describes these anomalies along with their doping dependent variations. We conclude from this work that the physics underlying the pseudogap, while distinct in origin from superconductivity, is likely to arise from an RVB wavefunction that is closely related to the BCS state.
In graphene, variation in doping modifies the polarization function which describes a screened electron-electron interaction. This leads to additional features in the spectral function which are due to electron-plasmon coupling. In this work, we calculated the electronic density of states including this interaction along with its doping dependence with and without an electron-phonon interaction. We find clear features of electron-electron interactions in the density of states. These features are related to the energies of plasmaron bands in the spectral function and can be modified through doping so as to be distinct from the phonon energy scales.
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Lin, Chih-Pin, and 林智斌. "Transition Metal Dichalcogenides Thin Film Transistor: Grain Size and Doping Effects." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/zbhpwh.
Full textAbstract:
碩士國立交通大學
電子工程學系 電子研究所
104
The successful synthesis of graphene demonstrates the stability of two-dimensional (2D) materials with an atomic thickness, and inspires strong interests on the research of 2D materials. Several commercial products, such as touch screen and battery, have taken advantages of the attractive properties of graphene. However, the unique gapless band structure of graphene makes it unsuitable for logic circuit applications. Among various 2D materials, transition metal dichalcogenides (TMDs) with finite bandgap values are promising as the next-generation channel materials of the transistor for nanoelectronic and photoelectronic applications. The property of the TMD films and their device characteristics are the key point to evaluate the potentials of 2D TMDs. We used the chemical vapor deposition system at the Prof. Lain-Jong Li’s group to synthesize large-scale TMD films and analyzed their quality and property by using various optical techniques at the Prof. Wen-Hao Chang’s group. Final, the TMD thin film transistors (TFTs) were fabricated at Nano Facility Center, National Chiao Tung University and National Nano Device Laboratories. The objective of this study is to evaluate the grain size and doping effect on transistor characteristics, and provides a general guideline to improve device performance. In this thesis, we analyzed the grain size effect of the monolayer MoS2 TFT, and used the nondestructive second harmonic generation (SHG) measurement to characterize the grain size. The statistics of device performance correlate well with the grain size, suggesting that the device performance can be further improved by enlarging the grain size. However, we also observed that the poor device electrical characteristics, which are depended strongly on the contact resistance and the doping of TMDs. We examined the doping effect before and after transferring MoS2 and WSe2, and used the defect generation (by plasma treatment) and different hosting substrates of transferred films to improve the device performance and reduce the contact resistance. Although the different hosting substrate effect on film synthesis and device performance are still under investigation, this thesis points out useful directions and provides effectives analysis techniques and methodology.
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YohanYuwana and 蔡金榮. "Effects of Nitrogen Doping on the Capacitive Performance of Porous Carbons." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/41155447262457372624.
Full textAbstract:
碩士國立成功大學
化學工程學系
103
Effect of nitrogen doping on the capacitive performance of porous carbons were observed by ammonia doping during heat treatment at high temperature. The activated mesophase pitch and phenol formaldehyde carbons were mixed with carbon nanotube then were doped ammonia doping at 700 C for 30 min, 1 and 2 hours. The cell equipped with each nitrogen doping on porous carbons in 1 M Na2SO4 solution can reach a high capacitance value of 250 F g-1 at 0.05 A g-1 and retention 51 % at 100 A g-1. Nitrogen content on carbon surface can increase the polarity and hydrophobicity of carbon and facilitates the wettability between electrode and electrolyte. Wettability of inner-pore carbon surface, will make the electrolyte ions penetrate into inner pores easily and promote the utilization of charge storage. Moreover, because of nitrogen doping function as non-faradaic process or electrostatics as EDLC then N-Q and N-X which positively charges affect electron transfer through the carbon frameworks. As the result, the symmetric cells can deliver high energy of 22 kW kg-1 at low discharge rate with superior stability of 92% capacitance retention after 10,000 cycles of galvanostatic charge-discharge. Keywords: ammonia doping, activated porous carbons, nitrogen doping, EDLC, Na2SO4
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Tsai, Ping-Chun, and 蔡秉均. "Effects of Indium doping on the Topological Crystalline Insulator (Pb0.5Sn0.5)Te." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/53s294.
Full textAbstract:
碩士國立交通大學
電子物理系所
106
Recent discovery of the topological insulators, owning unique physical properties and behaving entirely different from the trivial band insulators, has drawn considerable attentions due to their potentials in replacing current semiconductors and in realizing quantum computers. This thesis reports the study of the topological crystalline insulators (Pb0.5Sn0.5)1-xInxTe, for x=0, 0.1, 0.2, 0.3, by nuclear magnetic resonance (NMR) techniques and magnetic susceptibility measurement. Analyses of the 125Te, 117Sn, and 207Pb NMR spectra and the nuclear spin-lattice relaxation time T1 provide the information of the local electron orbitals and band structures which allow us to understand the variation of the electrical transport behavior with different In concentrations. The superconductivity in the x=0.3 sample is investigated by the T1 experiment as a function of temperature, where a Hebel-Slichter coherence peak is observed near the critical temperature. This suggests that the superconducting gap in the bulk is fully opened and this feature favors that (Pb0.5Sn0.5)0.7In0.3Te is a conventional superconductor rather than a chirality p-wave superconductor predicted by the theories.
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Lin, Tzu-yi, and 林子翼. "Effects of Doping on the Performance of InAs/GaAs Quantum Dots Lasers." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/7w66hu.
Full textAbstract:
碩士國立中央大學
電機工程研究所
96
In this study, the effects of doping on the temperature characteristics of InAs quantum dot lasers are investigated. The p-doped quantum dot laser shows the highest saturation power and characteristic temperature among these lasers. However, the threshold current density of the p-doped is higher than that of the n-doped device. Besides, SiO2/TiO2 anti-reflection film with a very high transmission (~ 99.976%) is designed and realized. A bandwidth of 90 nm for transmission over 99.9% is measured on this film. With this coating, temperature-dependent spontaneous emission spectra are investigated to study the behavior of carrier in these devices. Based on the correlation between the negative characteristic temperature and the reduced spectral linewidth, the observed behavior of these devices can be attributed to the carrier redistribution between quantum dots.
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Ye, Wei-Lin, and 葉瑋琳. "The Effects of Cu Doping on Microstructure and Properties of Cu2O Target." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/yppr52.
Full textAbstract:
碩士義守大學
材料科學與工程學系
103
Because of easy reaction with oxygen at ambient atmosphere, Cu2O is formed under vacuum or in a protected atmosphere. In this study, we fabricated dense Cu2O ceramics by mixing Cu2O and Cu powder. The purpose of adding copper powder is to assist the densification of Cu2O by providing viscous flow during sintering processing. The concentration of copper powder is ranged from 1 to 20wt%. The effect of copper concentration on the densification behavior, microstructure and electrical property is investigated. The results showed that no any CuO phases were formed. The Cu2O ceramic has a lowest electrical resistivity about 5.4×104Ω．cm at 10wt% of copper addition. In addition, the relative density can reach to 99.99% at sintering temperature 1000℃ and 1050℃. The apparent porosity also decreased to 0.41%. Whereas the same performance can be also achieved by hot-pressing process.
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Chien, Wei-Chueh, and 簡緯玨. "The Effects of Doping Glass Powder on Sintering and Properties of ZnO." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/3t2p2t.
Full textAbstract:
碩士義守大學
材料科學與工程學系
103
This research is studied the effect of glass doping on the densification behavior and electrical properties of ZnO ceramics. The adding glass powder is ranged from 1 to 10 wt%. The glass doped ZnO ceramics is hot-pressed at sintering temperature of 1000°C to 1200°C under 150 kN pressure in a N2 atmosphere. The resultant data showed that addition of glass increased the densification rate and grain size of ZnO ceramics. The liquid phase of glass dopant assisted the densification of ZnO ceramics at lower sintering temperature. In addition, hot-pressing also promoted the densification of ZnO ceramics. As a result, the ZnO ceramics can reach to a 99.8% of theoretical density at 1000°C.
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Sun, Cheng-Kai, and 孫宸楷. "The Effects of Doping Glass Powder on Sintering and Properties of SnO2." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/mkr6ct.
Full textAbstract:
碩士義守大學
材料科學與工程學系
103
A unique glass composition based on GeO2, MoO3 and V2O5 was designed to act as sintering aid to enhance the densification and to adjust the electrical properties of SnO2. This allows the low temperature processing of approximately 950 ◦C to be feasible with a desirable electrical property. The effect of metal oxide glass concentration on the densification behavior and electrical properties of SnO2 was investigated by Archimedes'' principle, x-ray diffractometer (XRD), scanning electron microscopy (SEM) techniques. The addition of glass was found not to affect the crystal structure of SnO2, but it increased the densification rate and the grain size of SnO2. The glass additive formed a thin continuous liquid phase and rearranged SnO2 particles into a dense microstructure at much low temperature. Applying the external press during hot pressing also assisted the densification rate of SnO2 and resulted in a relatively small grain size and denser microstructure. The electrical properties of were found to affect by the microstructure of glass doped SnO2 ceramics. At higher glass concentration doping, the possible formation amorphous phase around at grain boundary played a key role on the electrical properties of SnO2 ceramics. Further work on the identification of grain boundary phase is needed to perform as well as chemical composition of SnO2 grains.
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Chen, Te-Yi, and 陳德一. "Doping Effects on the Characteristics of PbTiO3-based Ceramics and Their Applications." Thesis, 2001. http://ndltd.ncl.edu.tw/handle/82573183439492365652.
Full textAbstract:
碩士國立成功大學
電機工程學系
89
It is essential for piezoelectric materials with large electromechanical coupling factor kt and small planar electromechanical coupling factor kp for the applications of piezoelectric transformers with thickness extension vibration mode. In general, lead zirconate-titanate (PZT) solid solution family ceramics not only have a large coupling factor kt for piezoelectric stiffened mode, but also have a large electromechanical coupling factor k31 and kp for piezoelectric unstiffened effect. However Lead titanate (PbTiO3) family ceramics have large piezoelectric anisotropy, where kt is larger than 50﹪and kp is less than 5﹪, which can be utilized for the piezoelectric transformer applications. In this research, effects of calcium, strontium and cadmium dopants on the piezoelectric and dielectric properties of Sm-modified PbTiO3 ceramics have been investigated. Sm-modified PbTiO3 ceramics were prepared by conventional mixed-oxide methods. We successfully showed that Ca, Sr and Cd additives are helpful to obtain much higher thickness electromechanical coupling coefficient, kt, than that of conventional PbTiO3 based ceramics and still keep small planar electromechanical coupling coefficient, kp. Microstructural and compositional analyses of these doped ceramics have been carried out using XRD and SEM.
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Shiau, victor, and 蕭正曄. "Effects of Ni doping on the transport and magnetic behavior in La0.7Ca0.3MnO3." Thesis, 2001. http://ndltd.ncl.edu.tw/handle/58830691187916050075.
Full textAbstract:
碩士國立高雄師範大學
物理學系
89
The ceramic samples (La0.7Ca0.3Mn1-xNixO3，x=0、0.03、0.06、0.09) used in our study were prepared by the standard ceramic route, employing sintering at a temperature of 1450℃.X-ray powder diffraction shows single phase. Magnetic and transport properties have been measured by Quantum Design physics properties measurement system (PPMS). The resistivity data at high temperature fits better to variable range hopping model than nearest-neighbor hopping model .The localization length decreases with Ni contents , it indicates that Ni doesn’t participate in the double exchange interaction , therefore, Tp and Tc decrease .The magnetoresistance data shows negative property and the maximum of MR ratio appears at Tp. MR ratio increases with Ni contents at applied field. Near Tc we also find spin glass behavior in all samples.
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Yan, Wei-De, and 顏維德. "Cobalt-Doping Effects on Photovoltaic and Structural Properties in BiFeO3 Multiferroic Ceramics." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/86161909726900075810.
Full textAbstract:
碩士輔仁大學
物理學系碩士班
102
In this research, 5% and 10% Co-doped BFO multiferroic ceramics have been synthesized by solid state reaction (SSR) method with various sintering temperature and present single phase in XRD measurements. The average grain size of Co-doped BFO observed by SEM grows significantly as increasing sintering temperature. The ferromagnetic behavior at room temperature is enhanced as cobalt doped in BFO and grains demonstrate more rectangle shape with increasing Co content. The temperature- and frequency- dependent dielectric permittivity of Co-doped BFO show strong frequency dispersion and high electric conductivity around 250 oC. For photovoltaic (PV) effects measurement, the ITO and Au films were deposited on both sides of Co-doped BFO and the thickness of BFO is 0.2 mm. The diode laser of λ = 405 nm was used as an excitation source to measure open circuit voltage and short circuit current density. The photovoltaic phenomena can be explained by the developed model which is based on p-n junction concepts. On the other hand, the photovoltaic responses also depend on the average grain size and an application of magnetic field~3000 Oe. The relation between photovoltaic response and light intensity can be described by exponential equations Voc = Vb[1-exp(I/α)] and Jsc = Jb [1-exp(I/β)], where Voc, Jsc, Vb, and Jb are open-circuit voltage, short- circuit current density , saturated open-circuit voltage, and saturated short-circuit current density, respectively.
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JiaDing-Pan and 潘家鼎. "Effects of doping Fe3O4 in buffer layer of P3HT:PCBM organic solar cells." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/17832606324771988672.
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Lin, Sun-Wen, and 林舜文. "Approaches and Effects of Doping in Polymer for Organic Light Emitting Diodes." Thesis, 2001. http://ndltd.ncl.edu.tw/handle/34107513702673551682.
Full textAbstract:
碩士國立臺灣大學
光電工程學研究所
89
Research in the use of molecular organic materials or polymer materials as active layer in light emitting diodes (OLEDs) has advanced rapidly, due to its applications on flat panel displays or light sources. To achieve the practical applications, the efficiency, driving voltage and power consumption should be continuously improved. It is known that by means of various doping methods, quantum efficiency or electric properties of the OLEDs can be improved effectively. First, we investigated the solvent-assisted dye-diffusion thermal transfer (FS-D2T2). We show that in an atmosphere of organic solvent vapor, effective dye-diffusion thermal transfer may be carried out at temperatures much below the glass transition temperatures of host polymers. The solvent vapor penetrates into the polymer throughout the process and causes the plasticization effect of polymers. As a consequence, the effective glass transition temperature of the system is lowered and the diffusion of dyes in the host polymer is enhanced. In addition, we also propose a doping method called rechargeable thermal transfer stamping to allow repeated use of the dye-dispersed donor films. Furthermore, we studied the conductive doping in polymer. We investigated the electroluminescence performance of OLEDs having a doped hole transport layer. The dopant and the host material used here are SbCl5 and poly (N-vinylcarbazole) (PVK), respectively. We experiment on various device structures with and without the conductively doped polymer and examine the characteristics of these device structures.
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Jou, G.-J., and 周國正. "Effects of Ga-doping on the magnetic ordering of Pr in PrBa2Cu3O7." Thesis, 1994. http://ndltd.ncl.edu.tw/handle/82285537316523758309.
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Zhuang, Shu-Han, and 莊舒涵. "Doping Effects on Na3V2(PO4)2F3 Cathode Materials for Sodium-Ion Batteries." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/564zsz.
Full textAbstract:
碩士中原大學
化學工程研究所
107
The demand of green energy has rapidly increased in these years, particularly for the on-going massive demand for electric and plug-in hybrid vehicles. The main limiting factor of lithium-ion battery arises from the limited resource of lithium metal availability in the world. During recent decades, sodium-ion batteries (SIBs) have been regarded as a promising alternative to lithium-ion batteries as a result of their advantages, such as abundancy, low cost, safety and high-power energy storage. In this regard, present investigation focused on the synthesis and development of Na3V2(PO4)2F3 as a cathode material for sodium-ion battery application. Na3V2(PO4)3 (NVP) and Na3V2(PO4)2F3 (NVPF) are known as two appealing NASICON-type materials capable of motivating intercalation chemistry for sodium ions. This research provides a step-by-step improvement for NASICON-type Na3V2(PO4)2F3 sodium-ion battery cathode materials. It involves finding the optimal concentration suitable for the sol-gel method and evaluating the best dopant for NVPF. The electrochemical tests revealed that C-rate performance was enhanced when an excess of sodium fluoride (NaF) was used. The batteries obtained capacities of 72.8 and 98.7 mAh/g for standard and excess NaF content, respectively when cycled back to 0.1C. In addition, ionic conductivity and diffusion of NVPF was improved by doing it with chromium and aluminum. X-ray diffraction and transmission electron microscopy confirm that high purity doped NVPF samples were obtained. Furthermore, electronic conductivity was augmented through amorphous carbon coating. The results indicate that NVCrPF-0.03 and NVAlPF-0.07 provided.
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Ni, Wei-Shih, and 倪維仕. "Impurity doping effects on the structural, photoluminescent and magnetic properties of ZnS films." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/52965194317122186527.
Full textAbstract:
博士國立彰化師範大學
光電科技研究所
104
This study investigates the effect of Co, Mn, and Cu content on the structural, luminescence, and magnetic properties of sol-gel ZnCoS, ZnMnS, and ZnCuS films by x-ray diffraction (XRD), photoluminescence (PL), energy dispersive spectrometer (EDS), atomic force microscopy (AFM), and alternating gradient magnetometer (AGM) measurements. Dependences of optical properties and crystal structure upon Co, Mn, and Cu content were found. In addition, combining with PL, XRD and AGM results, a direct link between the magnetization and defects of sol-gel ZnCoS, ZnMnS, and ZnCuS films was established. Currents through Cu-doped ZnS (ZnCuS)/n-type Si structures were studied. The electrical conduction investigations suggest that the carrier transport behavior is governed by the Poole–Frenkel emission for ZnCuS/n-type Si devices having the low Cu concentration. However, the carrier transport behavior is governed by the thermionic emission for ZnCuS/n-type Si devices having the high Cu concentration. The photoluminescence result revealed that sulfur vacancy (VS) is the origin of conduction behavior conversion. The dependence of VS on the film composition was identified for providing a guide to control the current transport behavior of ZnCuS/n-type Si devices.
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Park, Keeseong 1972. "Magnetic phase diagram of Ca₂₊xY₂₋xCu₅O₁₀₋[delta]: oxygen hole-doping effects." Thesis, 2007. http://hdl.handle.net/2152/3242.
Full textAbstract:
Oxygen hole-doping effects on a spin-chain system, Ca[subscript 2+chi]Y[2-chi]Cu₅O[subscript 10-delta](CaYCuO) are reported. CaYCuO is a good specimen to study the magnetic properties of the CuO₂ chain at the ground state because it has no complex structure other than the chain and it has hole dopability up to the formal copper valence number of +2.4. Specifically, we can dope holes into the CuO₂ chain by substituting Ca²⁺ for Y³⁺ or by utilizing oxygen deficiency. After a systematic study of the two methods to dope holes, we found that oxygen doping makes a more critical change in magnetic ordering in the chain than the replacement of Ca²⁺. Oxygen deficiency effects of the chain on the magnetic properties were explained using a mean field theory. A new relation for the effective hole doping was found as p = x - [alpha delta], where a = 3/2(x - [delta]) - 1/4. We study the anisotropy of magnetic properties of single crystal Li-cathode material (LiFePO₄) for g-factor, Curie-Weiss temperature, and effective moment. Magnetic properties Au/SiO₂ coated [gamma]-Fe₂O₃ are compared with pure [gamma]-Fe₂O₃ finding a decrease in the blocking temperature and the irreversible temperature for the coated nanoparticles.text
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Chen, Chia-Hsin, and 陳嘉鑫. "Doping Effects on the High-Anisotropy Materials and Their Applications on Piezoelectric Transformers." Thesis, 2000. http://ndltd.ncl.edu.tw/handle/58282262684726497016.
Full textAbstract:
碩士國立成功大學
電機工程學系
88
It is essential for piezoelectric materials with large electromechanical coupling factor kt and small planar electromechanical coupling factor kp for the applications of piezoelectric transformers with thickness extension vibration mode. In general, lead zirconate-titanate (PZT) solid-solution-family ceramics not only have a large coupling factor kt for piezoelectric stiffened mode, but also have a large electromechanical coupling factor k31 and kp for piezoelectric unstiffened effect. However, Lead titanate (PbTiO3) family ceramics have large piezoelectric anisotropy, where kt is larger than 50﹪and kp is less than 5﹪, which can be utilized for the piezoelectric transformer applications. In this research, effects of calcium and cadmium dopants on the piezoelectric and dielectric properties of Sm-modified PbTiO3 ceramics have been investigated. Sm-modified PbTiO3 ceramics were prepared by conventional mixed-oxide methods. We successfully showed that Ca and Cd additives are helpful to obtain much higher thickness electromechanical coupling coefficient, kt, than that of conventional PbTiO3 based ceramics and still keep small planar electromechanical coupling coefficient, kp. Microstructural and compositional analyses of these doped ceramics have been carried out using XRD and SEM. Sm-modified PbTiO3 ceramics, doped with BiFeO3 (BF) and Ba(Cu0.5W0.5)O3(BCW), prepared by conventional mixed-oxide methods with sintering temperature at 1000℃-1200℃ have also been investigated. We found that these additives were helpful in lowing the sintering temperature.