Dissertations / Theses: 'Silicone compounds'

1

Parr, J. A. "Antimicrobial properties of silicone quaternary ammonium compounds." Thesis, Bucks New University, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.375600.

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2

Weigenand, Oliver. "Wood modification with different types of silicon compounds /." Göttingen : Sierke, 2006. http://d-nb.info/98270948X/04.

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3

Al-Juhni, Abdulhadi A. "INCORPORATION OF LESS TOXIC ANTIFOULING COMPOUNDS INTO SILICONE COATINGS TO STUDY THEIR RELEASE BEHAVIORS." University of Akron / OhioLINK, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=akron1154974014.

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4

Boissezon, Rémi. "Amélioration du comportement au feu des élastomères silicones pour des applications en câblerie." Thesis, Montpellier 2, 2014. http://www.theses.fr/2014MON20186.

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Les silicones possèdent naturellement d'excellentes propriétés au feu. Ils dégagent peu de chaleur et ne produisent pas de composés toxiques en brulant. Cependant, pour leur utilisation en câblerie de sécurité, il est nécessaire d'améliorer la cohésion des cendres et diminuer l'opacité des fumées produites par leur combustion. Aussi, dans le cadre de ce travail, plusieurs additifs phosphorés ont été incorporés dans une formulation silicone modèle pour générer du charbonnement. Quel que soit le composé phosphoré introduit, le comportement au feu a été dégradé du fait d'une diminution de la stabilité thermique du silicone. De plus, la cohésion des résidus n'a pas été améliorée par ces composés. C'est pourquoi des verres de bas point de ramollissement et des borates ont été testés dans un second temps. Sur l'ensemble de ces nouveaux essais, seul un verre en particulier a permis d'augmenter la cohésion des cendres mais celui-ci a également dégradé le comportement au feu en déstabilisant thermiquement le silicone. L'objectif de la réduction de la quantité de fumées dégagée a été atteint en générant un effet barrière grâce à la dispersion d'un talc de haut facteur de forme. Cet effet barrière a également permis de diminuer le débit calorifique et d'augmenter la quantité de résidus finaux sans cependant augmenter la cohésion des cendres. La combinaison de ce même talc avec le cyanurate de mélamine nous a permis d'obtenir la classification V-0 au test UL-94. L'effet barrière du talc a été conservé mais est légèrement perturbé par le dégagement gazeux de l'additif azoté. Une optimisation de la formulation serait intéressante à mener pour conserver la classification V-0 et un effet barrière optimum
Silicones exhibit excellent fire properties. They do not release toxic products and release a low rate of heat when they burn. However, to be used as wires for safety devices, they need greater ashes cohesion and they have to release less smoke during combustion. To that end, many phosphorus compounds have been introduced in a model silicone formulation to generate a charring layer. Whatever the phosphorous compound introduced in formulations, the fire behavior was deteriorated and the silicone thermal stability decreased. Moreover, the residue cohesion was not improved by these compounds. Hence, glass frits with low melting points and borates based compounds were tested in a second step. Just one particular glass frit was able to improve the ashes cohesion but the fire behavior was impaired by a decrease of the silicone thermal stability.The objective in term of decrease of smoke release was achieved by the dispersion of a high aspect ratio talc able to generate a barrier effect. This barrier effect also permitted to decrease the total heat release and mass loss. Unfortunately, ashes cohesion was not improved by this talc. In combination with melamine cyanurate, this talc succeeded to reach the V-0 classification according to the UL-94 test. The talc still imparts a barrier effect but it was slightly disturbed by the gaseous release of nitrogen compound. An optimization of the formula could be interesting to preserve the V-0 classification and an optimum barrier effect

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5

Bratton, G. J. "Silicate/silicon hybrid materials." Thesis, University of Greenwich, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.234283.

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6

Batra, Ashish. "Stress relieving technique for plastic packages in a high volume manufacturing environment." Diss., Online access via UMI:, 2009.

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Thesis (Ph. D.)--State University of New York at Binghamton, Thomas J. Watson School of Engineering and Applied Science, Department of Systems Science and Industrial Engineering, 2009.
Includes bibliographical references.

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7

Rozell, James M. (James Morris). "Silenes and Silenoids in the Chemistry of Cyclopentadienylsilanes." Thesis, North Texas State University, 1986. https://digital.library.unt.edu/ark:/67531/metadc331302/.

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Evidence is presented that apparent silene products obtained from the metalation of cyclopentadienyldimethyl - chlorosilane either with tert-butyl1ithium or with methylenetriphenylphosphorane actually arise from the metalated starting material, a silenoid, rather than from a silafulvene intermediate. Trimethylmethoxysi1ane is shown to be an effective trap for dimethylsilafulvene. A new dimethylsilafulvene precursor, bis(dimethylmethoxysi1yl) cyclopentadiene, which gives high yields of dimethyldimethoxysi1ane and the silafulvene at temperatures as low as 240°C is reported.

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8

Nieder, Anian. "Energetic organo-silicon compounds." Diss., Ludwig-Maximilians-Universität München, 2013. http://nbn-resolving.de/urn:nbn:de:bvb:19-162183.

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9

Grant, Guy Hamilton. "Molecular modelling of silicon compounds." Thesis, University of Liverpool, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.329403.

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10

Maiti, Pranab. "1,5-stereocontrol using silicon-containing compounds." Thesis, University of Cambridge, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.619545.

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11

Gruhn, Nadine Ellen. "Electronic structures of unsaturated silicon compounds and transition metal-silicon interactions." Diss., The University of Arizona, 1994. http://hdl.handle.net/10150/187562.

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The electronic structures of disilenes and tungstenocene complexes of disilenes, silenes, and alkenes are studied by gas phase valence photoelectron spectroscopy (PES). PES is reported for three stable disilenes: Mes2Si=SiMes2' (Mes)(ᵗBu)Si=Si(ᵗBu)(Mes), and [(Me₃Si)₂CH]Si=Si[CH(SiMe₃)₂] [Mes = 2,4,6- C₆H₃(CH₃)₃, Me = CH₃]. The PES of tetramesityldisilene is compared to that of tetraphenylethylene. Fenske-Hall calculations are also reported. This comparison shows that the primary difference between the interaction of a C=C bond and a Si=Si bond with aryl substituents is the direction of the "push" of the filled-filled interaction with the π orbitals of the aryl. While for an olefin, interaction with aryl groups stabilizes the C=C π ionization, for a disilene this interaction destabilizes the Si=Si π ionization. This is the direct influence of the difference in energy between the C=C π bond and Si=Si π bond. The PES of the two alkyl substituted disilenes indicates that some type of decomposition is occurring in the gas phase, possibly forming silylene. More study is needed to confirm the gas phase process that is occurring. The PES of the complexes CP₂W(η ²-H₂C=CH2), CP₂W(η²-Me₂Si=CH₂), and CP₂W(η²-Me₂Si=SiMe₂) are also reported (Cp = η⁵-C₅H₅). The overall amount of electron donation by the alkene, silene, and disilene ligands appears to be approximately the same. For the alkene and silene complexes, the highest occupied molecular orbital (HOMO) is the a₁, metal based orbital associated with the d² metal center, and contains little to no contribution from the olefinic ligand. The HOMO of the disilene complex is the same molecular orbital, but contains a significant amount of silicon character due to increased interaction with the disilene π orbital. This additional interaction is due to greater overlap and better energy matching of the ligand P and metal fragment a₁ orbitals. The relationship between these differences in bonding and differences between the reactivity of the disilene complex and the reactivity of the alkene and silene complexes is also discussed.

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12

Chinchani, Rameshwari. "Strained silicon/silicon-germanium heterostructure complimentary metal oxide semiconductor devices a simulation study of linearity /." Ohio : Ohio University, 2004. http://www.ohiolink.edu/etd/view.cgi?ohiou1176143999.

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13

Yeh, Jen-Yu. "Electron-beam biased reactive evaporation of silicon, silicon oxides, and silicon nitrides /." Online version of thesis, 1991. http://hdl.handle.net/1850/11106.

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Meng, Shuang. "Heteroepitaxial growth of gallium selenium compounds on silicon /." Thesis, Connect to this title online; UW restricted, 2000. http://hdl.handle.net/1773/9749.

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15

Habtemariam, Abraha. "Sterically hindered organozinc compounds containing functional silicon centres." Thesis, University of Sussex, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.304970.

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16

Madsen, Lynnette D. Carleton University Dissertation Engineering Electrical. "Rapid densification of Borophosphosilicate glass." Ottawa, 1988.

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17

Rowlandson, Michael Barry Carleton University Dissertation Engineering Electrical. "A true polysilicon emitter transistor." Ottawa, 1988.

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18

McDonald, Andrew Michael Carleton University Dissertation Geology. "The crystal structures of three minerals: phosinaite-(Ce), abenakiite-(Ce) and yoshimuraite, with remarks on the crystal chemistry of silicophosphates." Ottawa, 1992.

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19

Chigondo, Fidelis. "Continuous flow synthesis of silicon compounds as feedstock for solar-grade silicon production." Thesis, Nelson Mandela Metropolitan University, 2016. http://hdl.handle.net/10948/4529.

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This thesis describes the key steps in the production of high purity (solar-grade) silicon from metallurgical-grade silicon for use in the production of photovoltaic cells as alternative renewable, environmentally benign and cheap energy source. The initial part of the project involves the development and optimization of a small chemical production platform system capable of producing alkoxysilanes from metallurgical-grade silicon as green precursors to solar-grade silicon production. Specifically, the main aim of the study was to synthesize trialkoxysilanes in continuous flow mode, although the synthesis on monosilane was also done in batch mode. The alkoxylation reaction was carried out in a traditional slurry phase batch reactor, packed bed flow tubular reactor and also attempted in a continuous flow falling film tubular reactor. The effect of key parameters which affect the silicon conversion and selectivity for the desired trialkoxysilane were investigated and optimized using ethanol as a reagent model. The synthesis was then extended to the other alcohols namely methanol, n-propanol and n-butanol. Copper catalysts which were tested in the alkoxylation reaction included: CuCl, Cu(OH)2, CuO and CuSO4. CuCl and Cu(OH)2 showed comparable activity in the batch mode but the former was more efficient in the packed bed flow tubular reactor. Cu(OH)2 could be used as a non-halide catalyst but its activity is limited to short reaction cycles (<10 h). The uncatalysed reaction resulted in negligible reaction rates in both types of reactors. High temperature catalyst pre-heating (>500 oC) resulted in a lower rate of reaction and selectivity than when slightly lower temperatures are used (<350 oC) in both reactors, although much difference was noticed in the packed bed flow tubular reactor. Synthesis in the batch reactor needed longer silicon-catalyst activation time, higher pre-heating temperature and higher catalyst amounts as compare to the packed bed flow tubular reactor. Reaction temperature and alcohol flow rate influenced the reaction in both methods. The optimum reaction temperature range and alcohol flow rate was comparable in both reactors (230 to 240 oC) and 0.1mL/min respectively. The effect of alcohol R-group (C1 to C4) on the reaction revealed that conversion and selectivity generally decrease with an increase in carbon chain length in both methods. Ethanol showed highest selectivity (>95% in batch and >97% in flow) and conversion (about 88% in batch and about 64% in flow) as compared to all other alcohols studied showing that it could be the most efficient alkoxylation alcohol for this reaction. Overally, the packed bed flow tubular reactor resulted in higher selectivity to trialkoxysilanes than the batch system. Performing the reaction under pressure resulted in increased conversion but selectivity to the desire trialkoxysilane diminished. Synthesis in a continuous flow falling film tubular reactor was not successful as it resulted in very poor conversion and selectivity. Monosilane was successfully synthesized from the disproportionation of triethoxysilane using homogeneous and heterogeneous catalysts in batch mode. The results obtained from homogeneous catalysis showed that the reaction can be conducted at room temperature. The heterogeneous catalysis method resulted in slow conversion at room temperature but mild heating up to 55 oC greatly improved the reaction. Conducting the reaction under neat conditions produced comparable results to reactions which were carried out using solvents. The disproportionation reaction was best described by the first order kinetic model. The results obtained in this research indicate that the packed bed flow tubular reactor can be utilized with future modifications for continuous flow synthesis of alkoxysilanes as feedstock for the solar-grade silicon production.

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20

Borbaruah, Moheswar. "Models for coordination and reactivity at silicon." Thesis, Open University, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.293111.

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21

Bocharov, Semyon. "Properties of organic and metalorganic molecules on silicon(100)-2 x 1 and at silicon/titanium carbon nitride interface." Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file 10.09 Mb., 175 p, 2006. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pqdiss&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&rft_dat=xri:pqdiss:3205440.

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22

Nieder, Anian [Verfasser], and Thomas Matthias [Akademischer Betreuer] Klapötke. "Energetic organo-silicon compounds : silicon makes the difference / Anian Nieder. Betreuer: Thomas Matthias Klapötke." München : Universitätsbibliothek der Ludwig-Maximilians-Universität, 2013. http://d-nb.info/1044532181/34.

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23

Nieder, Anian Verfasser], and Thomas M. [Akademischer Betreuer] [Klapötke. "Energetic organo-silicon compounds : silicon makes the difference / Anian Nieder. Betreuer: Thomas Matthias Klapötke." München : Universitätsbibliothek der Ludwig-Maximilians-Universität, 2013. http://nbn-resolving.de/urn:nbn:de:bvb:19-162183.

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24

Crump, Roger Adrian Neil Callow. "Enantio- and diastereocontrol with silicon compounds in organic synthesis." Thesis, University of Cambridge, 1993. https://www.repository.cam.ac.uk/handle/1810/272577.

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25

Soomro, Fateh Muhammad T. M. "Effect of silicon compounds on microbial transformations in soil." Thesis, University of Sheffield, 2000. http://etheses.whiterose.ac.uk/10235/.

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A study was made of the effects of adding a range of silicon compounds (of potential use as fertilizers) to a variety of different soils. In addition the solubilization of insoluble silicon compounds by bacteria and a species of Penicillium isolated from ferns growing in walls (as a likely silicon-rich environment) was determined. The results of the present study show that: 1) Bacteria solubilize rock potash, releasing free silicon into the medium. 2) Growth of a Penicillium Sp. in vitro increases the solubilization of sodium silicate, but concentrations of free silicon decrease when the fungus is grown in the presence of silicic acid and rock potash presumably duet o Si-immobilization by the fungus. 3) Water-extractable silicon increased when either silicic acid or rock potash was added to all soils, under both aerobic and anaerobic (waterlogged) conditions. 4) Liming increased the release of soluble silicon from sodium silicate, silicic acid and rock potash the effect being seen in all soil types. 5) Silicic acid generally decreased bacterial numbers in all soils, at least over the first 14 days of the incubation period. 6) Silicic acid and rock potash had no effect on nitrification, while the addition of sodium silicate stimulated nitrate production, this effect is assumed to be largely due to the resultant marked increase in soil pH. 7) Addition of silicic acid and rock potash led to increased sulphur oxidation. 8) The addition of silicic acid to the agricultural loam soil led to a decrease in arylsulphatase and ehydrogenase activity, as well as respiration and soil biomass.

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26

Collicott, Roland. "Investigation of chiral silicon compounds for the determination of enantiomeric purity." Thesis, n.p, 2001. http://ethos.bl.uk/.

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27

Namavari, Mohammad 1950. "Thermal Reactions of Four-Membered Rings Containing Silicon or Germanium." Thesis, University of North Texas, 1988. https://digital.library.unt.edu/ark:/67531/metadc330607/.

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The synthesis of E- and Z-1,1,2,3-tetramethylsilacyclobutanes is described. Pyrolysis of either isomer at 398.2 °C provides the same products but in different amounts: propene, E- and Z-2-butene, allylethyldimethylsilane, dimethylpropylsilane, the respective geometric isomers, 1,1,2,3,3-pentamethyl-1,3-disilacyclobutane, 1,1, l-ethyldimethyl-2,2,2-vinyldimethyl-disilane and E- and Z-1,1,2,3,3,4-hexamethyl-1,3-disilacyclobutane. Mechanisms involving di- and trimethylsilenes are described for disilane formation and rate constants of the elementary steps for the fragmentation reactions are reported. Photochemically generated dimethylsilylene in the hydrocarbon solution inserts into the cyclic Ge-C or Si-C bonds of 1,1-dimethylgerma- or silacyclobutane to produce 1-germa-2-sila- or 1,2-disilacyclopentane. The relative reactivities of 1,1-dimethylgerma- and silacyclobutanes toward the dimethylsilylene have been determined. The carbenoid resulting from the cuprous chloride catalyzed decomposition of diazomethane at 25 °C in cyclohexane reacts with 1,1-dimethylgermacyclobutane to give, surprisingly 1,1,5,5-tetramethyl-1,5-digermacyclooctane as the major product. The reactions of the carbenoid with 1,1-dimethylsilacyclobutane are described. The kinetics of gas phase thermal decomposition of 1,1-dimethylgermacyclobutane has been studied over the temperature range, 684 - 751 K at pressures near 14 Torr. The Arrhenius parameters for the formation of ethylene are k_1 (s^-1) = 10^(14.6 ± 0.3) exp (62.7 ± 2.9 kcal mol^-1/RT) and those for the formation of propene and cyclopropane are k_2 (s^-1) = 10^(14.0 ± 0.1 ) exp (60.4 ± 2.8 kcal mol^-1/RT). Static gas phase pyrolyses of 1,1-dimethyl-lsilacyclobutene, DMSCB, in the presence of a variety of alkenes and alkynes at 260 - 365 °C have been studied. Our experimental results suggest that under these conditions the DMSCB ring opens to 1,1-dimethyl-l-silabutadiene, which either recyclizes to DMSCB or reacts with alkenes or alkynes in competing 4 + 2 and 2 + 2 cycloadditions.

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28

Yang, Li Ph D. Massachusetts Institute of Technology. "Lattice mismatched compound semiconductors and devices on silicon." Thesis, Massachusetts Institute of Technology, 2011. http://hdl.handle.net/1721.1/77491.

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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Physics, 2011.
Cataloged from PDF version of thesis.
Includes bibliographical references (p. 121-125).
III-V compound semiconductors, due to their superior electron mobility, are promising candidates for n-type metal-oxide-semiconductor field effect transistors (MOSFETs). However, the limited size of III-V substrates and the degradation of IIIV MOSFET channel mobility remain two major challenges for III-V MOSFETs. The purpose of this thesis is to solve or partially solve these challenges. To create large diameter III-V materials, the synthesis of high quality III-V compound semiconductors (lattice-matched to InP) on Si substrates by metal-organic chemical vapor deposition (MOCVD) was studied. Epitaxy of III-V/Si (or Ge) may give rise to antiphase disorders due to the inequivalence of the two face-centered-cubic sublattices of III-V zinc-blende structures. By using a 60 offcut substrate (Ge on insulator) which favors a double-step surface reconstruction upon annealing, antiphase disorders were suppressed and single-domain GaAs on Si was demonstrated. The lattice was then graded from GaAs to InP by compositionally graded InxGa1-xAs-InyGa1-yP alloys and GaAsi-zSbz alloys, which introduce the strain gradually to promote dislocation propagation while suppressing nucleation. It was demonstrated that the phase separation in these pseudobinary alloys could be kinetically suppressed by the low surface diffusivity of adatoms during the non-equilibrium MOCVD process. This allowed us to achieve high quality InP on offcut GaAs. In addition, the dislocation kinetics of GaAs1-zSbz alloys was studied. The dislocation glide velocity of GaAs1-zSbz alloys was estimated to be 1 im/s at 575°C by fitting the experimental data with the dislocation propagation theory. The channel electron mobility of InP-based Ino.53GaO.47As quantum-well MOSFETs was studied by Hall measurements and the dominant scattering mechanisms were discussed. Although invariant for different gate dielectric (Al203) thicknesses, the mobility turns out to be strongly dependent on the barrier thickness, gate dielectric/barrier interfacial defect states and carrier density. To understand and quantify this dependence, a theoretical model based on internal phonon scattering and interfacial defect coulomb scattering was developed. The Born approximation, random-phase approximation, and two-dimensional limit for carriers were assumed for the coulomb scattering. The results of this model are in good agreement with the experimental data, and the predictions from this model shed light on future MOSFET design and synthesis.
by Li Yang.
Ph.D.

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29

Hissink, Catharina Everdina. "Silicon-Bridged donor-acceptor compounds: synthesis and nonlinear optical properties." [S.l. : [Groningen] : s.n.] ; [University Library Groningen] [Host], 1996. http://irs.ub.rug.nl/ppn/148933343.

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30

Sohail, Mohammad. "Synthesis, structures and stereodynamic study of 5-coordinate silicon compounds." Thesis, Open University, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.525840.

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31

Paukstis, Sarah Joan. "The spectroscopy of small silicon clusters Si₂X(X = N,O)." Diss., Georgia Institute of Technology, 2000. http://hdl.handle.net/1853/30309.

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32

Kang, Song-yun. "Theoretical Study on the Reactivity of Organosilicon Compounds and Silicon Surface." 京都大学 (Kyoto University), 2002. http://hdl.handle.net/2433/149786.

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McLachlan, Lorna J. "Steric and electronic effects on the structures of substituted silicon compounds." Thesis, University of Edinburgh, 2004. http://hdl.handle.net/1842/15345.

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This thesis is concerned with the application of the SARACEN method to a range of molecules with interesting structural properties and applications in industry. The gas-phase structures of a series of compounds have been obtained, combining gas-phase electron diffraction and ab initio molecular orbital theory. For each compound a series of the potential energy surface was carried out to investigate the number of conformational minima and to locate the global energy minimum. The gas-phase structures of trans-1,2-dichloro-1,2-disilylethene (1), 1,1-bromosilylethene (2) and 1,1,1,4,4,4-hexachloro-1,4-disilabutane (3) were studied and ab initio calculations on analogous compounds were carried out. This study revealed extreme asymmetry in coordination at carbon, and trends in bond lengths and angles were interpreted in terms of cumulative electronic and steric contributions. The structure of bistrichlorosilyldimethylgermane [(Me₂Ge(SiCl₃)₂] (4) was determined ab initio and by gas-phase electron diffraction and compared to that of a previously determined trimethyl analogue. An important difference between experimental and theoretical results was revealed. Three silylhydrazines, F₃SiN(Me)NMe₂ (5) and F₃SiN(SiMe₃)NMe₂ (6) ClH₂SiN(Me)NMe₂ (7), have been studied ab initio and by gas-phase electron diffraction. Previous solid- and gas-phase investigations of other substituted silylhydrazines revealed unusually narrow Si-N-N bond angles. Structural investigations were initiated for the halogen and bulky alkyl-substituted compounds to gauge the effects of these different substitutions on the Si-N-N bonds angles. Further calculations were carried out on similar compounds upon removing the “donor” and “acceptor” atoms, to verify the presence of suspected Si β-N interactions.

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34

Frontzek, Matthias Dietrich. "Magnetic properties of R2PdSi3 (R = heavy rare earth) compounds." Göttingen Cuvillier, 2009. http://d-nb.info/997364173/04.

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35

Savchyn, Oleksandr. "Silicon-sensitized erbium excitation in silicon-rich silica for integrated photonics." Doctoral diss., University of Central Florida, 2010. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/4642.

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It is widely accepted that the continued increase of processor performance requires at least partial replacement of electronic interconnects with their photonic counterparts. The implementation of optical interconnects requires the realization of a silicon-based light source, which is challenging task due to the low emission efficiency of silicon. One of the main approaches to address this challenge is the use of doping of silicon based matrices with optical centers, including erbium ions. Erbium ions incorporated in various hosts assume the trivalent state (Er[super]3+) and demonstrate a transition at 1.54 micrometer], coinciding with optical transmission windows in both silicon and silica. Due to the low absorption cross-section and discrete energy levels of the Er[super]3+ ion, indirect excitation is necessary. In late 90s it was demonstrated that the incorporation of excess silicon in erbium-doped silica results in strong erbium sensitization, leading to an increase of the effective absorption cross-section by orders of magnitude. The sensitization was considered to occur via silicon nanocrystals that formed at high annealing temperatures. While a large increase of the absorption cross-section was demonstrated, the incorporation of Si nanocrystals was found to result in a low concentration of excited erbium, as well as silicon related free-carrier absorption. The focus of this dissertation is the investigation of the nature of the sensitization mechanism of erbium in silicon-rich silica. The results presented in the dissertation demonstrate that erbium in silicon-rich silica is predominantly excited by silicon-excess-related luminescence centers, as opposed to the commonly considered silicon nanocrystals. This is a remarkable conclusion that changes the view on the exact origin of erbium sensitization, and that resolves several technical challenges that exist for nanocrystal-based sensitization.; The work shows that in order to sensitize erbium ions in silicon-rich silica there is no need for the presence of silicon nanocrystals, and consequently lower fabrication temperatures can be used. More importantly, the results strongly suggest that higher gain values can be acquired in samples annealed at lower temperature (without silicon nanocrystals) as compared to samples annealed at high temperatures (with silicon nanocrystals). In addition, the maximum gain is predicted to be relatively independent of excitation wavelength, significantly relaxing the requirements on the pump source. Based on the experimental results it is predicted that relatively stable performance of erbium-doped silicon-rich silica is possible up to typical processor operating temperatures of ~ 80 - 90[degrees]C making it a viable material for on-chip devices. The results suggest that low temperature annealed erbium-doped silicon-rich silica is a preferable material for on-chip photonic devices as compared with its high temperature annealed counterpart.; The work shows that the density of indirectly excited erbium ions is significantly larger in samples without silicon nanocrystals (annealed at T[less than]1000[degrees]C) as opposed to samples with silicon nanocrystals (annealed at T[greater than]1000[degrees]C). The density of indirectly excited erbium ions, defining the maximum achievable gain, was demonstrated to be approximately excitation wavelength independent, while the effective erbium absorption cross-section was shown to significantly depend on the excitation wavelength. The excitation mechanism of erbium by luminescence centers was shown to be fast (less than] 30 ns) and capable of erbium sensitization to different energy levels. This multilevel nature of erbium excitation was demonstrated to result in two different mechanisms of the excitation of the first excited state of erbium: fast (less than]30 ns) direct excitation by the luminescence centers, and slow (greater than]2.3 microseconds]) excitation due to the relaxation of erbium ions excited into higher energy levels to the first excited state. Based on photoluminescence studies conducted in the temperature range 15-300K it was shown that the relaxation efficiency of erbium from the second excited state to the first excited state (responsible for the slow excitation mechanism) is temperature independent and approaches unity. The relative stability of the optical properties demonstrated in the temperature range 20-200[degrees]C, implies that relatively stable optical gain can be achieved under realistic on-chip operating conditions. The optimum Si excess concentration corresponding to the highest density of sensitized Er[super]3+ ions is shown to be relatively insensitive to the presence of Si nanocrystals and is ~ 14.5 at.% and ~ 11.5 at.% for samples without and with Si nanocrystals respectively. The presented results and conclusions have significant implications for silicon photonics and the industrial application of Er-doped SiO[sub]2. The work shows that in order to sensitize erbium ions in silicon-rich silica there is no need for the presence of silicon nanocrystals, and consequently lower fabrication temperatures can be used. More importantly, the results strongly suggest that higher gain values can be acquired in samples annealed at lower temperature (without silicon nanocrystals) as compared to samples annealed at high temperatures (with silicon nanocrystals). In addition, the maximum gain is predicted to be relatively independent of excitation wavelength, significantly relaxing the requirements on the pump source. Based on the experimental results it is predicted that relatively stable performance of erbium-doped silicon rich silica is possible up to typical processor operating temperatures of ~ 80 - 90[degrees]C making it a viable material for on-chip devices. The results suggest that low temperature annealed erbium doped silicon-rich silica is a preferable material for on-chip photonic devices as compared with its high temperature annealed counterpart.
ID: 029094291; System requirements: World Wide Web browser and PDF reader.; Mode of access: World Wide Web.; Thesis (Ph.D.)--University of Central Florida, 2010.; Includes bibliographical references.
Ph.D.
Doctorate
Optics and Photonics

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36

Manesh, Saeed Heshmati. "Phase transformation and thermomechanical treatment of TiAl based alloys containing silicon." Thesis, Imperial College London, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.307035.

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37

Schow, Clint Lee. "Development of a high-speed, monolithically integrated silicon optical receiver /." Digital version accessible at:, 1999. http://wwwlib.umi.com/cr/utexas/main.

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38

Nakajima, Keizo. "A Theoretical Study on the Electronic Structures of Silicon and Related Compounds." Kyoto University, 2000. http://hdl.handle.net/2433/181012.

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39

Behray, Mehrnaz. "Synthesis, characterisation and biological activity of silicon nanoparticles functionalised by anticancer compounds." Thesis, University of East Anglia, 2016. https://ueaeprints.uea.ac.uk/59420/.

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Silicon Nanoparticles (SiNPs) are non-toxic materials particularly suitable for various biomedical applications. They exhibit unique optical properties for use in bioimaging and diagnostic applications. To exploit these aspects, this thesis explores the synthesis, characterisation and biological activity of SiNPs functionalised by anticancer compounds. Thiourea-based compounds have been shown to represent one of the most promising classes of anticancer agents due to their strong inhibitory activity against Epidermal Growth Factor Receptor (EGFR), overexpression of which is observed in common types of cancer cells. Conjugation of thiourea compounds in nanosystems presents one potential approach to target such cells. In this thesis, successful synthesis of novel thiourea-functionalised SiNPs was undertaken and their physiochemical properties were investigated by photoluminescence emission and elemental analysis. In vitro cytotoxicity assay was employed to evaluate the effect of SiNPs. Confocal microscopy images demonstrate SiNP internalisation and flow cytometry data confirms receptor-mediated targeting in cancer cells. Isothiocyanates (ITCs) can prevent the onset of carcinogenesis and act as chemopreventive compounds. ITC-functionalised SiNPs were synthesised using two different methods, initiated from two different types of SiNPs. The surface chemistry of these particles were characterised and their optical properties examined to assess both synthesis approaches. The samples produced from the precursor Br SiNPs exhibit strong photoluminescence and therefore are suitable for uptake studies. The cytotoxicity of ITC SiNPs was evaluated by MTT and their internalisation confirmed using confocal microscopy and flow cytometry assay. Synchrotron-based FTIR microspectroscopy was used as a novel approach to investigate ITC SiNP cell internalisation. Spectral comparison between treated and control cells shows the effect of ITCs, leading to an increase both in protein level in the nuclei, and also in the chance of apoptosis, which increases phospholipid contents. Considering the obtained results, such multifunctional nanosystems have the potential to be applied for further diagnostic and therapeutic applications.

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40

Thibodeaux, Kristin. "Alkali-silica reaction in oilwell cement slurries using hollow glass spheres." Thesis, Georgia Institute of Technology, 2003. http://hdl.handle.net/1853/19288.

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41

Collins, Courtney Lloyd. "Examination of the mechanism by which lithium additives inhibit alkali-silica reaction gel expansion." Thesis, Georgia Institute of Technology, 2002. http://hdl.handle.net/1853/21295.

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42

Kan, Xin, and 阚欣. "Growth of Bi2Se3 on Si substrate by molecular beam epitaxy." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2011. http://hub.hku.hk/bib/B46474687.

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43

Hardy, Julie. "Novel materials based on functionalised silsesquioxanes." n.p, 2000. http://library7.open.ac.uk/abstracts/page.php?thesisid=43.

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44

Bates, Tim Frank. "The Stereochemistry of Silenes and Alpha-Lithio Silanes." Thesis, North Texas State University, 1987. https://digital.library.unt.edu/ark:/67531/metadc332323/.

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When E- or Z-l-methyl-l-phenyl-2-neopentylsilene was generated by the retro-Diels-Alder vacuum-sealed tube thermolysis of its corresponding anthracene adduct, in the presence of various alkoxysilanes, only one diastereomeric adduct was formed in each case, showing that the reactions are stereospecific. An x-ray crystal structure of the methoxytriphenylsilane adduct of the E-silene confirmed its relative configuration as (R,S) or (S,R). This demonstrated that the addition of alkoxysilanes to silenes is stereospecific and syn. The relative configurations of similar alkoxysilane and alkoxystannane adducts to E- and Z-l-methyl-l-phenyl-2-neopentylsilene were assigned based on a combination of xray structures and *3C NMR data. A strong, nonbonded oxygen-metal interaction is apparent in all of those compounds studied. Treatment of the alkoxystannane adducts with alkyl lithium reagents results in tin-lithium exchange in some cases. The results indicate that the resulting

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45

Witchlow, G. P. "Electronic structure of transition metal silicides and related compounds and interfaces." Thesis, University of Bath, 1988. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.379594.

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46

Cottier, Ryan James Littler Christopher Leslie. "Growth and characterization of ß-iron disilicide , ß-iron silicon germanide, and osmium silicides." [Denton, Tex.] : University of North Texas, 2009. http://digital.library.unt.edu/ark:/67531/metadc12107.

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47

Fenwick, William Edward. "Metalorganic chemical vapor deposition of gallium nitride on sacrificial substrates." Diss., Georgia Institute of Technology, 2009. http://hdl.handle.net/1853/34687.

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GaN-based light emitting diodes (LEDs) face several challenges if the technology is to make a significant impact on the solid state lighting market. The two most pressing of these challenges are cost and efficiency. The development of alternative substrate technologies shows promise toward addressing both of these challenges, as both GaN-based device technology and the associated metalorganic chemical vapor deposition (MOCVD) technology are already relatively mature. Zinc oxide (ZnO) and silicon (Si) are among the most promising alternative substrates for GaN epitaxy. This work focuses on the development of MOCVD growth processes to yield high quality GaN-based materials and devices on ZnO and Si. ZnO, because of its similar lattice constant and thermal expansion coefficient, is a promising substrate for growth of low defect-density GaN. The major hurdles for GaN growth on ZnO are the instability of ZnO in a hydrogen atmosphere and out-diffusion of zinc and oxygen from the substrate. A process was developed for the MOCVD growth of wurtzite GaN and InxGa1-xN on ZnO, and the structural and optical properties of these films were studied. High zinc and oxygen concentrations remained an issue, however, and the diffusion of zinc and oxygen into the subsequent GaN layer was studied more closely. Silicon is the most promising material for the development of an inexpensive, large-area substrate technology. The challenge in GaN growth on Si is the tensile strain induced by the lattice and thermal mismatch between GaN and Si. A thin atomic layer deposition (ALD)-grown Al2O3 interlayer was employed to relieve strain while also simplifying the growth process. While some strain was still observed, the oxide interlayer leads to an improvement in thin film quality and a reduction in both crack density and screw dislocation density in the GaN films. A comparison of GaN-based LEDs grown on sapphire and Al2O3/Si shows similar performance characteristics for both devices. IQE of the devices on silicon is ~32%, compared to ~37% on sapphire. These results show great promise toward an inexpensive, large-area, silicon-based substrate technology for MOCVD growth of GaN-based optoelectronic devices.

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48

Hayes, Roger Nicholas. "A study of some gas phase nucleophilic substitution reactions of carbon, silicon and boron by ion cyclotron resonance mass spectrometry /." Title page, table of contents and summary only, 1985. http://web4.library.adelaide.edu.au/theses/09PH/09phH418.pdf.

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49

Hong, Pengda, and 洪鹏达. "Synthesis and characterization of LiNi0.6Mn0.35Co0.05O2 and Li2FeSiO4/C as electrodes for rechargeable lithium ion battery." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2011. http://hub.hku.hk/bib/B47150294.

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The rechargeable lithium ion batteries (LIB) are playing increasingly important roles in powering portal commercial electronic devices. They are also the potential power sources of electric mobile vehicles. The first kind of the cathode materials, LiXCoO2, was commercialized by Sony Company in 1980s, and it is still widely used today in LIB. However, the high cost of cobalt source, its environmental unfriendliness and the safety issue of LiXCoO2 have hindered its widespread usage today. Searching for alternative cathode materials with low cost of the precursors, being environmentally benign and more stable in usage has become a hot topic in LIB research and development. In the first part of this study, lithium nickel manganese cobalt oxide (LiNi0.6Mn0.35Co0.05O2) is studied as the electrode. The materials are synthesized at high temperatures by solid state reaction method. The effect of synthesis temperature on the electrochemical performance is investigated, where characterizations by, for example, X-ray diffraction (XRD) and scanning electron microscopy (SEM), for particle size distribution, specific surface area, and charge-discharge property, are done over samples prepared at different conditions for comparison. The electrochemical tests of the rechargeable Li ion batteries using LiNi0.6Mn0.35Co0.05 cathode prepared at optimum conditions are carried out in various voltage ranges, at different discharge rates and at high temperature. In another set of experiments, the material is adopted as anode with lithium foil as the cathode, and its capacitance is tested. In the second part of this study, the iron based cathode material is investigated. Lithium iron orthosilicate with carbon coating is synthesized at 700℃ by solid state reaction, which is assisted by high energy ball milling. Characterizations are done for discharge capacities of the samples with different carbon weight ratio coatings.
published_or_final_version
Physics
Master
Master of Philosophy

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50

Lawson, Llewellyn Rhys. "Hybrid silicon-organic ring resonator photonic devices /." Thesis, Connect to this title online; UW restricted, 2006. http://hdl.handle.net/1773/11542.

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Dissertations / Theses on the topic 'Silicone compounds'

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