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Scholefield, Roger. "Luminescence of quartz /." Title page, contents and summary only, 1994. http://web4.library.adelaide.edu.au/theses/09SM/09sms3678.pdf.
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Guerra, Christiano Pereira 1966. "Desenvolvimento de sílica vítrea por fusão em chama a partir de lascas de quartzo brasileiro visando aplicações de alta transmitância no médio UV." [s.n.], 2013. http://repositorio.unicamp.br/jspui/handle/REPOSIP/264827.
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Orientador: Carlos Kenichi SuzukiTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica
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Resumo: A sílica vítrea é um material fundamental para a indústria de alta tecnologia devido as suas propriedades únicas. Dentre estas podemos destacar a sua alta pureza aliada ao elevado ponto de fusão e alta transmitância no ultravioleta. É um material muito usado na indústria de semicondutores e em fotônica. Para aplicações na indústria óptica e de lâmpadas especiais, é necessário que a sílica vítrea tenha alta transmitância na região do ultravioleta médio (200 nm - 300 nm) e do visível e contenha um reduzido teor de bolhas. Tarugos de sílica vítrea foram produzidas pelo método de Verneuil a partir da fusão em chama com gás GLP e O2. Foram utilizados pós de quartzo natural brasileiro de diferentes regiões com variados teores de impurezas e pós de quartzo comerciais nacionais e importados. Foi introduzida uma etapa de lixiviação ácida em um dos pós de quartzo comercial brasileiro com o objetivo de diminuir o teor de bolhas na sílica vítrea. As impurezas nos pós de quartzo foram determinadas através da técnica de ICP-MS. A transmitância óptica entre 190-3200 nm foi determinada por espectroscopia óptica. O teor de OH presente nas amostras de sílica foi determinado através da banda de absorção em 2730 nm na região do infravermelho do espectro. O teor de bolhas foi determinado através de microscopia óptica, considerando bolhas maiores que 0,01 mm. Foi avaliada a relação entre a transmitância das amostras de sílica vítrea e os teores de impurezas presentes nos pós de quartzo. Os resultados de transmitância na região do médio UV das amostras de sílica vítrea produzida com pós de quartzo feitos a partir das lascas de quartzo brasileiro foram comparados com a sílica vítrea produzida com pó de quartzo comercial importado. Os teores de bolhas foram avaliados em relação às condições de processo de fusão e temperatura de fusão do tarugo. Os resultados mostram a excelente viabilidade do quartzo brasileiro para a fabricação de sílica vítrea de elevado valor agregado
Abstract: Due to their unique thermal and optical properties, silica glasses are highly demanded for use in the high technology industry. They are widely used in the semiconductor and optics industries. For most of the applications in optical industry it is necessary to present high optical transmittance in the medium ultraviolet region (200 nm - 300 nm) and visible and low content of bubbles. Silica glass rods were produced by the Verneuil method from flame fusion with LPG and O2 gases by using Brazilian natural quartz from various regions of the country and also imported and national commercial quartz powders. An acid leaching procedure in a commercial Brazilian powder quartz was tested with the purpose of reducing the bubbles content in silica glass. The measurements of impurities concentration in the quartz powders were determined by ICP-MS technique. The optical transmittance from 190-3200 nm was determined by optical spectroscopy. The OH content was determined by the absorption band at 2730 nm in the infrared region of the spectrum. The content of bubbles larger than 0.01 mm was determined by optical microscopy. The relationship between the optical transmittance of the silica glass samples and the level of impurities in the quartz powders was evaluated. The results of the average transmittance in the UV region of the silica glass samples produced from Brazilian quartz lascas were correlated with the silica glass produced using imported commercial quartz powders. The concentration of bubbles was evaluated with respect to the process conditions of fusion and ingot melting temperature. The results show an excellent feasibility of application of Brazilian natural quartz to produce high value added silica glass
Doutorado
Materiais e Processos de Fabricação
Doutor em Engenharia Mecânica
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Ga̧siorek, Stanisława. "Solid phase epitaxial regrowth of alkali ion irradiated [alpha]-quartz [alpha-quartz]." [S.l.] : [s.n.], 2004. http://deposit.ddb.de/cgi-bin/dokserv?idn=970906064.
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Ozkan, Berrin. "Growth Of Gold Films On Quartz Surfaces For Quartz Crystal Microbalance Application." Master's thesis, METU, 2010. http://etd.lib.metu.edu.tr/upload/12612198/index.pdf.
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In this study, we have investigated the effect of substrate temperature, use of adhesive layer, deposition rate, annealing and substrate prebaking on the morphology of gold films deposited onto quartz surfaces. For the film growth, physical vapor deposition methods namely electron beam and thermal depositions have been used. Surface morphology of the films have been characterized with atomic force microscopy. Our aim was to confirm the general trends observed for these parameters in our evaporator system for a limited working range in order to produce gold films which are suitable to be used simultaneously for quartz crystal microbalance and helium atom diffraction measurements.
At the end of this study, we confirmed the general trends regarding the effect of these parameters stated in literature except annealing process. We obtained a minimum 170 nm2 atomically flat surface with a roughness value smaller than 0.200 nm by thermal deposition method.
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Lontsi, Sob Aaron Joel. "Thermoluminescence of natural quartz." Thesis, Rhodes University, 2014. http://hdl.handle.net/10962/d1013358.
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The kinetic and dosimetric features of the main thermoluminescence peak of quartz have been investigated in unannealed as well in quartz annealed at 500˚C for 10 minutes. The main peak is found at 92 and 86˚C respectively for aliquots of unannealed and annealed samples irradiated to 10 Gy and heated at 5.0˚C/s. For each sample, the intensity of the main peak is enhanced with repetitive measurement whereas its maximum temperature is unaffected. The peak position of the main peak in each sample is independent of the irradiation dose and this, together with its fading characteristics are consistent with first-order kinetics. For low doses, typically between 2 and 10 Gy, the dose response of the main peak in each sample is linear. In the intermediate dose range from 10 to 60 Gy, the growth of the main peak in each sample is sub-linear and for greater doses, in the range from 60 Gy to 151 Gy, it is linear again. The half-life of the main peak of the unannealed sample is about 1.3 h whereas that of the annealed sample is about 1.2 h. The main peak in each sample can be approximated to a first-order glow peak. As the heating rate increases, the intensity of the main peak in each sample decreases. This is evidence of thermal quenching. The main peak in each sample is the only peak regenerated by phototransfer. The resulting phototransferred peak occurs at the same temperature as the original peak and has similar kinetic and dosimetric features. For a preheat temperature of 120˚C, the intensity of the phototransferred peak in each sample increases with illumination time up to a maximum and decreases afterwards. At longer illumination times (such as 30 min up to 1 h), no further decrease in the intensity of the phototransferred peak is observed. The traps associated with the 325˚C peak are the main source of the electrons responsible for the regenerated peak. Radioluminescence emission spectra were also measured for quartz annealed at various temperatures. Emission bands in quartz are affected by annealing and irradiation. A strong enhancement of the 3.4 eV (~366 nm) emission band is observed in quartz annealed at 500˚C. A new emission band which grows with annealing up to 1000˚C is observed at 3.7 eV (~330 nm) for quartz annealed at 600˚C. An attempt has been made to correlate the changes in radioluminescence emission spectra due to annealing with the influence of annealing on luminescence lifetimes in quartz.
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Shamshurov, A. V., V. M. Beresnev, and N. A. Volovicheva. "Nano-reinforced Quartz Composites." Thesis, Sumy State University, 2013. http://essuir.sumdu.edu.ua/handle/123456789/35246.
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We have studied the process of interaction between the components in the system «β-SiO2–Fe3O4–Na2O» in the temperature range from 20 to 1100 °C. Nano-reinforced composite building materials were developed on the base of quartz raw material. Developed materials are produced by low-temperature cal-cining technology.
When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/35246
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Brooks-Dalton, Lily. "Quartz and Other Stories." PDXScholar, 2016. http://pdxscholar.library.pdx.edu/open_access_etds/3027.
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The following is a collection of six short stories written between 2014 and 2016. While the short stories are not connected, they tend to grapple with issues of grief and belonging. Characters who struggle to name their feelings, to inhabit them, and yet feel them nonetheless, populate these pages.
There is also a theme of fantastical bodies in some of the stories--women who levitate and little boys who suffer heart problems when they feel too much joy. The interplay between emotion and physical ailment is exaggerated and dramatized in these instances.
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Yu, George Yang. "Magnetic quartz crystal microbalance." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2008. http://hdl.handle.net/1853/24615.
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Thesis (Ph.D.)--Electrical and Computer Engineering, Georgia Institute of Technology, 2009.Committee Chair: Janata, Jiri; Committee Co-Chair: Hunt, William; Committee Member: Allen, Mark; Committee Member: Brand, Oliver; Committee Member: Ferguson, Ian; Committee Member: Lyon, Andrew
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Laschitsch, Alexander Thomas. "Dynamical measurements with quartz resonators." [S.l.] : [s.n.], 2000. http://ArchiMeD.uni-mainz.de/pub/2000/0021/diss.pdf.
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Lider, Mustafa Cem. "Alpha-beta Transition In Quartz." Master's thesis, METU, 2011. http://etd.lib.metu.edu.tr/upload/12613650/index.pdf.
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Alpha-Beta transition in quartz is studied using the Raman scattering. The Raman frequencies
of some lattice modes are analyzed at various temperatures close to the alpha beta transition
in quartz. For this analysis, the experimental data from the literature is used and the soft mode
behavior of those Raman phonons is investigated . On the basis of the predictions of some
models, the temperature dependencies for the Raman frequencies of the lattice modes which
move towards zero (soft mode) and their bandwidths close to the transition temperature Tc are
explained for the alpha-beta transition in quartz. In addition, by using the experimental volume
data from literature, calculation of the temperature dependence of the Raman frequencies
through the Grüneisen parameter have been studied near the phase transition.
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Sartbaeva, Asel. "Ionic mobility in quartz structures." Thesis, University of Cambridge, 2005. https://www.repository.cam.ac.uk/handle/1810/251980.
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Niyonzima, Pontien. "Thermoluminescence characteristics of synthetic quartz." Thesis, Rhodes University, 2014. http://hdl.handle.net/10962/d1013190.
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Quartz is one of the most abundant natural minerals in the crust of the earth. Due to its dosimetric luminescence properties, it is employed in retrospective dosimetry, archaeological and geological dating. The intensity and the structure of the TL glow curves of quartz are strongly dependent upon the origin, impurity content, formation condition and pre-irradiation heat treatment. The aim of this project is to study the mechanisms of thermoluminescence (TL), Phototranssferred thermoluminescence (PTTL) and radioluminescence (RL) in synthetic quartz and to discuss the results in terms of physical characteristics of point defects involved. Thermoluminescence measurements were made on a sample of synthetic quartz in its as-received state (unannealed) synthetic quartz annealed at 500˚C for 10 minutes. The unannealed sample shows six TL glow peaks located at 94, 116, 176, 212, 280 and 348˚C at a heating rate of 5˚Cs⁻¹. The annealed sample shows seven TL peaks at 115, 148, 214, 246, 300, 348 and 412˚C at a heating rate of 5˚Cs⁻¹. The intensity of peak I, at 94 and 115˚C for the unannealed and annealed samples respectively, increases with irradiation. Peak I has an activation energy of approximately 0.90 eV and a frequency factor of the order of 10¹¹ s⁻¹. The order of kinetics is between 0.9 and 1.2. The unannealed synthetic quartz shows phototransferred thermoluminescence (PTTL) at the position of peak I after removal of the first three peaks followed by illumination. The PTTL intensities show peak shaped behaviour when plotted against illumination time. The PTTL showed a quadratic increase with dose. The material exhibits fading of PTTL intensity with delay time. Radioluminescence was measured on synthetic quartz unannealed and annealed annealed at 500, 600, 700, 800, 900 and 1000˚C for 10 to 60 min. The emission spectra of synthetic quartz show seven emission bands. The effect of irradiation on the RL spectra is to increase the intensity of all emission bands for samples annealed at temperatures less than or equal to 700˚C. The effect of annealing time is to increase the RL amplitude for the samples annealed at temperatures greater than 700˚C. The annealing temperature increases the RL amplitude of all emission bands of the spectrum for all samples.
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韓志勇 and Zhiyong Han. "Thermoluminescence dating of granitic quartz." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1999. http://hub.hku.hk/bib/B31238555.
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Han, Zhiyong. "Thermoluminescence dating of granitic quartz /." Hong Kong : University of Hong Kong, 1999. http://sunzi.lib.hku.hk/hkuto/record.jsp?B21583766.
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Atang, Elizabeth Fende Midiki. "Thermoluminescence of annealed synthetic quartz." Thesis, Rhodes University, 2016. http://hdl.handle.net/10962/420.
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The kinetic and dosimetric features of the main thermoluminescent peak of synthetic quartz have been investigated in quartz ordinarily annealed at 500_C as well as quartz annealed at 500_C for 10 minutes. The main peak is found at 78 _C for the samples annealed at 500_C for 10 minutes irradiated to 10 Gy and heated at 1.0 _C/s. For the samples ordinarily annealed at 500_C the main peak is found at 106 _C after the sample has been irradiated to 30 Gy and heated at 5.0 _C/s. In these samples, the intensity of the main peak is enhanced with repetitive measurement whereas its maximum temperature is unaffected. The peak position of the main peak in the sample is independent of the irradiation dose and this, together with its fading characteristics, are consistent with first-order kinetics. For doses between 5 and 25 Gy, the dose response of the main peak of the annealed sample is superlinear. The half-life of the main TL peak of the annealed sample is about 1 h. The activation energy E of the main peak is around 0.90 eV. For a heating rate of 0.4 _C/s, its order of kinetics b derived from the whole curve method of analysis is 1.0. Following irradiation, preheating and illumination with 470 nm blue light, the main peak in the annealed sample is regenerated during heating. The resulting phototransferred peak occurs at the same temperature as the original peak and has similar kinetic and dosimetric features, with a half-life of about 1 h. For a preheat temperature of 200 _C, the intensity of the phototransferred peak in the sample increases with illumination time up to a maximum and decreases thereafter. At longer illumination times, no further decrease in the intensity of the phototransferred peak is observed. The traps associated with the 325 _C peak are the main source of the electrons responsible for the regenerated peak.
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Hubert, Pascal. "Textures et inclusions fluides des quartz aurifères : application au gîte de Cros-Gallet, Haute-Vienne, France et au prospect de Sanoukou, district de Kenieba, Mali /." Orléans : Ed. du Bureau de recherches géologiques et minières, 1987. http://catalogue.bnf.fr/ark:/12148/cb36147675f.
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Payette, Christine. "The melt inclusions in quartz phenocrysts of the quartz-feldspar porphyry, Harvey Station, New Brunswick /." Thesis, McGill University, 1985. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=63383.
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Enokihara, Cyro Teiti. "Estudo do quartzo verde de origem hidrotermal tratado com radiação Gama." Universidade de São Paulo, 2013. http://www.teses.usp.br/teses/disponiveis/85/85131/tde-18022014-133514/.
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Uma variedade específica de quartzo de cor verde, seja natural ou induzida pela radiação é muito rara. Trata-se de um mecanismo de formação de cor completamente diferente daqueles conhecidos e amplamente discutidos na literatura, que são responsáveis pela formação do quartzo fumê, do citrino e da ametista, incluindo a prasiolita produzida pelo aquecimento da ametista de Montezuma (MG). Somente duas ocorrências, conhecidas até o momento, tem o quartzo incolor, uma no pequeno distrito em Thunder Bay Amethist Mine, no Canadá e a outra na Bacia do Paraná ( Brasil) , ao longo de uma faixa de 600 km, com ocorrências dispersas de geodos, que se estende da região de Quaraí (RS) até a localidade de Uberlândia (MG). Estas duas ocorrências foram formadas sob fortes atividades hidrotermais, a de Thunder Bay é devido ao tectonismo e a da Bacia do Paraná está relacionada às atividades da água meteórica e hidrotermal do Aquífero Guarani. Estes cristais de quartzo hidrotermal apresentam um histórico de crescimento muito rápido, permitindo a formação dos defeitos de crescimento como as geminações, o crescimento em mosaico, as formações com pequenos ângulos inclinados e as estrias que facilitam a absorção da água na forma de água molecular, silanol (Si-OH), hidroxila (OH) e como micro inclusões. Este tipo de quartzo pode ser considerado como quartzo hidratado (wet quartz) semelhante ao quartzo sintético. O teor em água, com até 3200 ppm em massa, é superior à concentração das impurezas estruturais como o Fe, Al e Li. Não existe uma correlação entre o conteúdo da água e a quantidade de impurezas, como ocorre em outras variedades de cor do quartzo. No quartzo hidrotermal de geodos são formados complexos de silanol que quando são irradiados geram os centros de cor NBOHC (Centro de cor do oxigênio com elétron desemparelhado que não participa da ligação) que apresenta absorção no intervalo de 590 nm a 620 nm e formando uma janela de transmissão a 550 nm aproximadamente, responsável pela cor verde. Várias técnicas de análises químicas e de espectroscopia foram empregadas para caracterizar estas amostras de quartzo verde. A determinação do teor de água por meio dos espectros de infravermelho FTIR mostraram menos água (até 2300 ppm em massa), em comparação com os resultados das análises de aquecimento (3200 ppm) decorrente provavelmente, ao complexo silanol remanescente. Para documentar a influência da água na formação da cor verde foram realizadas análises por espectroscopia de infravermelho FTIR em amostras de quartzo de 3 diferentes grupos de ambientes geológicos, o quartzo pegmatítico com Al e Li formado à alta temperatura da região de Santana do Araguaia, o quartzo de veios hidrotermais com Al, mas sem água originado à média temperatura, da região de Curvelo e a ametista com muito Fe, pouco Al e pouco silanol da região de Brejinho e o quartzo de geodos hidrotermais formado a baixa temperatura com alto conteúdo de água molecular e silanol, e com muito Fe e pouco Al. As análises e as comparações permitiram diferenciar e determinar a formação do centro de cor NBOHC (Centro de cor do oxigênio com elétrons desemparelhados que não participam da ligação) para o quartzo hidrotermal de geodos da Bacia do Paraná. Assim, somente cristais de quartzo com alta concentração de água molecular e silanol são apropriados para desenvolver a cor verde por meio da radiação gama. Pode-se mencionar que no mesmo geodo podem coexistir cristais de quartzo com diferentes teores de água. Cabe ressaltar também que o quartzo verde tratado com radiação gama é sensível à radiação ultravioleta e ao aquecimento, levando à perda parcial ou total da cor verde.A specific variety of quartz showing a green color in nature or induced artificially by radiation is quite rare. This can be explained by the fact that the mechanism of formation of this color is very different from the ones widely discussed in the literature and responsible for the formation of the fumée, citrine and amethyst types of quartz, including the prasiolite (leak green quartz) formed by heating amethyst from Montezuma, Brazil. Only two occurrences are known today, where this type of quartz can be found: Canada, at the Thunder Bay Amethyst Mine, Ontario, a small district, and Brazil, at widely scattered geode occurrences along a 600 km stretch from Quaraí at Brazils southernmost tip to Uberlandia in Minas Gerais. These two occurrences have been formed by strong hydrothermal activities, at Thunder Bay due to tectonics and in Brazil by meteoric and hydrothermal waters of the Guarani aquifer. That way much quartz crystals showed a very fast growth history facilitating the formation of growth defects (twinning, small angle tilting, mosaic growth, striations) and the uptake of water in form of micro inclusions, molecular water, silanol (Si-OH) and OH. This type of quartz can be considered ¨wet quartz¨, similar to synthetic quartz. The water content with up to 3200 ppm by weight exceeds the amount of charge balancing cations (Fe, Al, Li). There is no correlation between water content and cations as in other color varieties. Instead, silanol complexes are formed, which by radiation due to gamma rays form the color center NBOHC (non-bonding oxygen hole defect), showing absorption between 590 to 620 nm and leaving a transmission window at about 550nm, responsible for the green color. To characterize samples which will be colored green by gamma rays analyses by ICP, NAA, Electron microscopy, water loss techniques and UV-VIS and NIR-FTIR spectroscopic have been made. The spectroscopic water determination showed less water (up to 2300 ppm by weight) compared with heating techniques (3200 ppm), probably due to remaining silanol complexes.To trace the influence of water on color formation, samples from 3 different geological settings (high temperature pegmatitic quartz with Al and Li, from Santana de Araguaia; intermediate temperature vein quartz with Al but without water from Curvelo; amethyst with more Fe, less Al and small silanol content from Brejinho, and low temperature regimes from geodes, high silanol and high molecular water, cations similar to the above mentioned) have been analised by NIR spectroscopy.The former will not show green color, only the latter one. It may be mentioned that even in geodes one has crystals with high and intermediate water content coexisting. The crystals with high silanol and molecular water are the ones to treat by radiation. The radiation induced color is heat and UV sensible with bleaching by longer exposure to these factors.
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Mineli, Thays Desirèe 1985. "Avaliação do quartzo como dosímetro pessoal baseado na luminescência opticamente estimulada." [s.n.], 2015. http://repositorio.unicamp.br/jspui/handle/REPOSIP/258958.
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Orientadores: Eduardo Tavares Costa, André Oliveira SawakuchiDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Elétrica e de Computação
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Resumo: O uso de radiação ionizante é cada vez mais intenso, seja na indústria seja na área médica. Os efeitos nocivos da radiação ionizante exigem medidas de segurança na sua utilização e um dos meios mais comuns para proteção da saúde do operador de equipamentos que usam esta radiação é o controle da dose que este pode receber em determinado período de tempo. Para tal controle, são normalmente utilizados dosímetros pessoais. Estudos sobre datação de sedimentos costeiros e fluviais do Brasil têm encontrado tipos específicos de quartzo com excelentes características dosimétricas. Com o objetivo de analisar as propriedades dosimétricas de amostras de quartzo de elevada sensibilidade de luminescência e avaliar a sua possível utilização na dosimetria pessoal, foram feitos testes comparativos com amostra do principal e mais utilizado dosímetro pessoal do tipo OSL (Optically Stimulated Luminescence), o Al2O3:C. Este trabalho apresenta as características de luminescência de amostras de quartzo. Essas características foram determinadas por testes de recuperação de dose conhecida (dose recovery) por meio de protocolo de alíquota única (Single-Aliquot Regenerative ¿ SAR) em amostras irradiadas por fonte de radiação beta. Foram realizados testes de sensibilidade e de estabilidade do sinal OSL e testes com radiação gama. Os resultados mostraram que as amostras de quartzo estudadas foram capazes de recuperar com exatidão doses de 50 mGy a 50Gy. Estimou-se que as amostras de quartzo saturam em doses (114-175 Gy) superiores à dose de saturação da amostra de Al2O3:C (35 Gy). A dose mínima capaz de ser medida pelas amostras de quartzo variou de 0,2 mGy (para radiação gama) a aproximadamente 20 mGy (para radiação beta). As amostras de quartzo não apresentaram fading do sinal OSL. O sinal OSL ultravioleta da amostra de Al2O3:C cresceu com o tempo. A amostra de Al2O3:C apresentou maior sensibilidade em comparação às amostras de quartzo no teste com radiação beta. A sensibilidade da amostra de quartzo TE65B no teste com radiação gama foi superior à sensibilidade da amostra Al2O3:C. Estes resultados indicam que as amostras de quartzo estudadas têm potencial como material para dosímetros e incentivam estudos mais aprofundados para avaliar o uso destes tipos de quartzo como elementos sensores em dosímetros pessoais
Abstract: The use of ionizing radiation is becoming more intense, whether in industry or in the medical field. The harmful effects of ionizing radiation require safety measures in its use. One of the most common ways to protect the health of the operator of ionizing radiation equipment is the dose control that he/she can receive in a given time period. Personal dosimeters are used for this purpose. Studies on dating of coastal and fluvial sediments in Brazil have found quartz types with very high luminescence signal and excellent dosimetric characteristics. In order to analyze the dosimetric properties of very bright Brazilian quartz samples and evaluate their use in personal dosimetry, comparative tests with the most used personal OSL (Optically Stimulated Luminescence) dosimeter, Al2O3:C, were made. This work presents the luminescence characteristics of quartz samples. These characteristics were determined by dose recovery tests using a Single-Aliquot Regenerative dose protocol (SAR) in samples irradiated by beta radiation. Sensitivity and stability tests and gamma radiation tests were made. The results have shown that the studied quartz samples were able to recover at least a dose range from 50 mGy to 50 Gy. It was estimated that the quartz samples saturate in doses (114-175 Gy) above the saturation dose of Al2O3:C sample (35 Gy). The minimum dose capable of being measured by the quartz samples ranged from 0.2 mGy (for gamma rays) to about 20 mGy (for beta radiation). The quartz samples showed no fading of the OSL signal. The ultraviolet OSL signal of Al2O3:C sample increased with time. The Al2O3:C sample showed higher sensitivity compared to quartz samples in beta radiation test. However, the sensitivity of TE65B quartz sample for the gamma radiation test was higher than the sensitivity of the Al2O3:C sample. These results indicate that the studied quartz samples have potential as dosimeter material and encourage further studies to evaluate the use of this type of quartz as sensor element in personal dosimeters
Mestrado
Engenharia Biomedica
Mestra em Engenharia Elétrica
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Barbosa, Cassandra Terra. "A origem do quartzo green gold: tratamento e ambiente geológico." Universidade de São Paulo, 2012. http://www.teses.usp.br/teses/disponiveis/44/44144/tde-13022014-150426/.
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O quartzo hialino quando tratado com irradiação gama, seguida ou não de tratamento térmico, pode desenvolver diversos matizes de verde, amarelo e marrom. Estas cores causam um acréscimo no seu valor comercial e as variedades coloridas são frequentemente lapidadas e usadas como gemas, porém, o resultado dependerá de sua composição química e do seu ambiente de formação. Alguns matizes obtidos através desse tratamento não são encontrados na natureza, como é o caso da tonalidade amarelo-esverdeada, e quando o quartzo hialino desenvolve esta cor é conhecido como green gold. Este estudo tem como principal objetivo analisar a formação do matiz amarelo-esverdeado desenvolvido por cristais de quartzo hialinos após irradiação e tratamento térmico, assim como correlacionaras cores obtidas com o ambiente de formação e prováveis elementos químicos responsáveis pela cor. Para isto foram utilizadas 97 amostras de quartzo, sendo 93 de quartzo green golde 4 de quartzo morion natural, provenientes de pegmatitos de Santana do Araguaia (PA) e de veios hidrotermais próximos a Joaquim Felício (MG), respectivamente. Os cristais de quartzo green gold foram divididos em 17 grupos e as amostrasde quartzo morion constituíram somente 1 grupo, sendo o critério de separação as diferentes tonalidades. Uma amostra de cada lote foi mantida original para ser utilizada como padrão e posteriormente comparada às cores obtidas. Todos os grupos de Santana do Araguaia - PAforam aquecidos a 330°C para perderem a cor e serem novamente tratados. A partir desta etapa, estes lotes foram irradiados com 330kGy utilizando uma fonte de \'Co POT.60\' e depois aquecidos a uma temperatura que variou de 217°C à 330°C. O grupo de quartzo morion de Joaquim Felício - MG foi apenas aquecido nas mesmas condições de temperatura. As cores desenvolvidas após o tratamento foram classificadas visualmente pelo método CMYK e analisadas através da espectroscopia no visível, assim, estes dados foram comparados às cores das amostras padrão. Todos osgrupos provenientes dos pegmatitos de Santana do Araguaia - PA não desenvolveram a coloração inicial, tendo se tornados amarelados e amarronzados. Somente uma amostra deste lote de quartzo desenvolveu uma peculiar coloração verde após o re-tratamento. Os cristais de Joaquim Felício - MG, quando aquecidos, tornaram-se marrom-acinzentados. Os resultados deste estudo sugerem que a tonalidade de cor obtida no processo de produção do quartzo green gold está intimamente relacionada ao número de vezes que as amostras de quartzo são tratadas, à dose de irradiação gama e temperaturas utilizadas, à origem do mineral e a sua composição química.The hyaline quartz when treated with gamma irradiation, whether followed by heat treatment or not, can develop various hues of green, yellow and brown. These colors cause an increase in the commercial value of the quartz and colored varieties are often cut and used as gems, however, the result depends on its chemical composition and its geological environment. Some hues obtained through this treatment are not found in nature, as is the case of greenish-yellow hue; when the hyaline quartz develops this color itis known as \"green gold\". This study has as its mainobjective to analyze the formation of yellow-greenish hues developed by hyaline quartz crystals after irradiation and heattreatment, as well as to correlate the colors obtained from the geological environment and the chemical elements responsible for color. For this, 97 quartz samples were used, 93 of which were \"green gold\" quartz and 4 natural morion quartz, from pegmatites of Santana do Araguaia (PA) and hydrothermal veins near the Joaquim Felício (MG), respectively. The \"green gold\" quartz crystals were divided into 17 groups and the morion quartz samples were only 1 group, the criteria for separating the groups being the different hues. A sample from each group was kept original to be used as a standard, and later compared to the colors obtained. All groups of Santana do Araguaia - PA were heated to 330° C to lose color and be re-treated. After that, these lots were irradiated with 330kGy using a source of Co-60 and then heated to a temperature that ranged from 217° C to 330° C.The morion quartz group of Joaquim Felício - MG was only heated under the same conditions oftemperature. The colors developed after the treatment were visually classified by CMYK method and analyzed through visible spectroscopy. The data obtained have been compared to the colors of the standard samples. None of the groups from the pegmatites of Santana do Araguaia - PA developed the original color, only yellowish and brownish hues. Onlyone sample developed a peculiar green color after the re-treatment. The crystals of Joaquim Felício-MG, when heated, became grayish-brown. The results of this study suggest that the colors obtained in the process of production of the \"green gold\" quartz are related to the number of times that the quartz samples are treated, the dose of gamma irradiation and temperatures used, the origin of the mineral, and its chemical composition.
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Teinturier, Stéphane. "Diagenèse expérimentale du quartz en présence d'hydrocarbures." Nancy 1, 2002. http://www.theses.fr/2002NAN10272.
Full textAbstract:
La cimentation du quartz est un processus diagénétique important puisqu'elle influence directement la qualité d'un réservoir pétrolier, notamment en régulant la porosité et donc son potentiel en huile ou en gaz. Les expériences réalisées en système silice±eau±sels±huile±gaz ont permis de simuler et d'approcher les conditions de la diagenèse siliceuse d'un réservoir pétrolier naturel et d'améliorer la compréhension des mécanismes de formation des inclusions fluides et de croissance de quartz en milieu aqueux et/ou hydrocarbonéQuartz cementation has a great impact on petroleum reservoir quality by controlling the porosity and thus the gas or oil storage. Experiments were carried out in a silica±water±salts±oil±gas system with the objective to simulate the siliceous diagenesis of natural petroleum reservoirs and to better understand the mechanisms of fluid inclusions formation and quartz cementation in a water and/or petroleum system
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Waterman, Alfred James. "Laser-driven shock waves in quartz." Thesis, University of British Columbia, 1990. http://hdl.handle.net/2429/28728.
Full textAbstract:
The formation and propagation of laser-driven shock waves has been observed by optical
shadowgraphy in fused quartz, α-quartz and sodium chloride. Target materials were irradiated with a 0.53 µm , ~ 2.5 ns FWHM laser pulse at intensities ranging between
0.2 — 2 x 10¹³ W/cm², producing peak pressures varying from 0.3 — 3 Mbar at the shock front. Observations in both varieties of quartz reveal transient, high-speed shock propagation followed by deceleration towards a steady asymptotic shock speed. Similar high-speed transients were not seen in sodium chloride. The results in quartz were found to be in significant disagreement with both one-dimensional and two-dimensional hydrodynamic
calculations based on equilibrium equations of state. The non-steady shock propagation is interpreted as being due to a relaxation process in the phase transformation
of quartz into the high-pressure stishovite phase which occurs at the shock front. The effects of such a relaxation process on the shock dynamics and shock compression process are considered for the case of a direct relaxation from quartz into stishovite, as well as for an indirect relaxation process in which the -transformation of quartz into stishovite is preceded by shock-induced amorphization of the quartz. It is shown that either scenario would result in higher shock speeds and less compressible shock states than those obtained under equilibrium conditions.Science, Faculty of
Physics and Astronomy, Department of
Graduate
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Rhodes, Edward John. "Optical dating of quartz from sediments." Thesis, University of Oxford, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.258027.
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Masurkar, Amrita V. "Extensions of quartz-enhanced photoacoustic spectroscopy." Thesis, Massachusetts Institute of Technology, 2009. http://hdl.handle.net/1721.1/51579.
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Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Physics, 2009.Includes bibliographical references (p. 57-58).
The goal of this thesis was to perform quartz-enhanced photoacoustic spectroscopy (QEPAS) on trace concentrations of NH3 in the 1.53 pm region with a DFB laser without the use of a resonating cavity. I analyzed the process of QEPAS both analytically and experimentally. First, absorption spectroscopy was performed with a 1.55 pm DFB laser on the 1558.033 nm absorption line of H13C12N. The wavelength of the laser radiation was then modulated, and the spectral components of the absorbance were analyzed. In addition, low concentrations of NH3 were generated through the use of a vacuum system, and absorption spectroscopy was performed on these samples. A tuning fork was also characterized. Photoacoustic signals were ultimately not realized, however, plans for future work are mentioned.
by Amrita V. Masurkar.
S.B.
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Barr, A. D. "Strain-rate effects in quartz sand." Thesis, University of Sheffield, 2016. http://etheses.whiterose.ac.uk/15989/.
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Soil-filled wire and geotextile gabions are commonly used to construct defensive infrastructure in military bases, where the attenuating properties of soil are used to protect personnel and key assets from the effects of blast and fragmentation. The behaviour of soils in these extreme loading regimes is not well understood, and so designers require data at these high pressures and strain rates in order to develop robust soil constitutive models and adapt to new threats. The one-dimensional compression of three sandy soils was compared under quasi-static loading to axial stresses of 800 MPa. Trends in behaviour were identified with respect to the particle size distributions of the soils, and were found to correspond to the relationships observed at lower stresses. Split Hopkinson pressure bar (SHPB) experiments were used to investigate the strain rate dependence of this behaviour. Measurements of radial stress indicated that an increase in the axial stiffness of the soils between strain rates of 10^-3 s^-1 and 10^3 s^-1 was likely due to radial inertial effects. Potential sources of error were identified in the SHPB experiments, leading to the implementation of a dispersion-correction algorithm, which improved the measurement of axial stresses. Analysis of the electromagnetic activity around the specimen isolated the cause of erroneous radial stress measurements. Quasi-static experiments were used to investigate the effect of moisture content on soil stiffness at high pressures, and SHPB experiments at the same moisture contents were used to consider the effect of strain rate on the quasi-static behaviour. Recovery SHPB experiments were designed to enable reliable post-test particle size analyses to be performed, and the range of moisture contents was expanded to investigate the change in soil behaviour on reaching full saturation. Reduced triaxial compression experiments were used to define the yield surface of a sand to a mean stress of 400 MPa. The high-pressure compression and yield strength data was used to calibrate LS-DYNA soil models, and the performance of the models was assessed through modelling of the SHPB experiments.
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Tessier, Loïc. "Immunodétection par un résonateur à quartz." Tours, 1993. http://www.theses.fr/1993TOUR3302.
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French, Marsha. "Quartz growth : understanding porosity-preserving microcrystalline quartz through EBSD, TEM, and NanoSIMS examination of low temperature silica." Thesis, University of Liverpool, 2012. http://livrepository.liverpool.ac.uk/7157/.
Full textAbstract:
Deeply buried sandstones in sedimentary basins typically have low porosity due to cementation and compaction. Formation of microcrystalline quartz has proven to be effective at preserving porosity in deeply buried sandstone petroleum reservoirs, typically cemented by syntaxial quartz cement. There remains much uncertainty about what controls the growth of microcrystalline quartz and how it prevents syntaxial quartz overgrowths. Here, the Cretaceous Heidelberg Formation, Germany, and the Oligocene Fontainebleau Formation, Paris Basin, France, provide a natural laboratory to study silica polymorphs and develop an understanding of their crystallography, paragenetic relationships, and growth mechanisms, leading to a new understanding of the growth mechanisms of porosity-preserving microcrystalline quartz. Data from scanning electron microscopy (SEM), electron backscatter diffraction (EBSD), and transmission electron microscopy (TEM) data illustrate that porosity-preserving microcrystalline quartz cement is misoriented with respect to the host grain upon which it grows. In contrast, ordinary quartz cement grows in the same orientation (epitaxially) as the host quartz sand grain, and typically fills pore spaces. EBSD and TEM observations reveal nanofilms of amorphous silica (~ 50-100 nm in thickness) between the microcrystalline quartz and the host grain. The microcrystalline quartz is interpreted to be misoriented relative to the host grain, because the amorphous silica nanofilm prevents growth of epitaxial quartz cement. Instead, the microcrystalline quartz is similar to chalcedony with [11-20] perpendicular to the growth surface and c axes parallel with, but randomly distributed (rotated) on, the host quartz grain surface. Development of pore-filling quartz growing into the pore (in the fast-growing c-axis direction) is thus inhibited due to the amorphous silica nanofilm initially and, subsequently, the misoriented microcrystalline quartz that grew on the amorphous silica. High precision, in situ oxygen isotope analyses of Cretaceous Heidelberg Formation detrital grains and quartz cements show three varieties of authigenic silica growing on detrital quartz grains. Interpretation of these data show that quartz overgrowths grew from meteoric water at about 80°C followed by concentric bands of silica cements. A thin layer of chalcedony was first deposited on both detrital quartz grains and quartz overgrowth cements followed by microcrystalline quartz; this cycle was then repeated. If it is assumed that the closely-related chalcedony and microcrystalline quartz grew from the same water, then isotope data suggest that chalcedony grew at approximately 34°C while microcrystalline quartz grew at approximately 60°C from meteoric water. To further understand the role of chalcedony in microcrystalline quartz growth, chalcedony in two agates from the Citronelle Formation in Louisiana and Lake Superior in Michigan, were studied This study concludes that the bands formed as a result of discrete influxes of siliceous fluid. Within these individual bands there is a sequence of minerals; chalcedony-A (with amorphous silica and nanocrystalline quartz) à chalcedony-MQ (with microcrystalline quartz) à quartz. This paragenetic sequence suggests a viable model for the growth of chalcedony in agates, which helps explain the growth of chalcedony and microcrystalline growth in sandstones. Now that we know what controls microcrystalline quartz growth and why it preserves porosity, it can be used to help identify, rank and appraise deeply buried petroleum accumulations.
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Farias, Thiago Michel de Brito. "Estudo das propriedades termoluminescentes e de absorção óptica de oito variedades de quartzo." Universidade de São Paulo, 2009. http://www.teses.usp.br/teses/disponiveis/43/43134/tde-15042009-165630/.
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No presente trabalho, foram investigadas propriedades de absorção óptica e termoluminescência para sete variedades de quartzo natural brasileiro (Azul, com enxofre, leitoso, rosa, verde, vermelho e preto). Para efeitos comparativos, empregou-se o quartzo hialino e o sintético, ambos na fase alfa. Ametista e citrino não foram estudados devido ao número grande de relatos na literatura destes materiais. A difração de raios-X mostrou que todas as variedades de quartzo estudadas possuem a mesma estrutura padrão de quartzo. A composição das amostras obtidas por Fluorescência de Raios-X e Espectroscopia de Massas com Plasma (ICP-MS), revelam a presença de Al2O3 e Na2O em todas as variedades além de concentrações de Ca, Zn, Zr e Ba. Os picos TL nas curvas de emissão são discrepantes das curvas usualmente encontradas na literatura, com picos em 1100C, 2200C e 3250C. Apenas o pico em 1100C é comum a todas as amostras. Em relação à forma das curvas de emissão também existe discrepância. O comportamento da intensidade TL em função da dose, para picos em 2200C e 3250C é singular para cada amostra, de forma que o comportamento linear-supralinear-sublinear é observado apenas nos picos em 2200C para amostras de quartzo azul e hialino. O pico em 3250C, apresenta em praticamente todas as amostras, um terceiro estágio de crescimento com a dose. Admiti-se que o segundo estágio, que é da supralinearidade, é causado pela criação de novas vacâncias de oxigênio pela radiação, o segundo estágio é seguido de outro não-linear. Aqui se propõe um modelo em que a radiação cria novas vacâncias, dentro do grupo de tetraedros SiO4, do qual se formou a vacância de oxigênio. O germânio, no presente trabalho, possui concentrações baixíssimas em amostras como o quartzo leitoso e quartzo com enxofre, de maneira que não apresenta correlação com o pico de 110°C, conforme descrito na literatura, pois ambas amostras apresentam intensos picos nesta região de temperatura. Estudos de absorção óptica revelam a existência de bandas de absorção em 620, 450 e 350nm. Conforme a literatura, estas bandas são causadas pela presença do alumínio, pois crescem rapidamente com a radiação, causando a transição do quartzo hialino para quartzo fumê. Ao se comparar com amostra de quartzo artificial, com concentrações de alumínio, próximas as do hialino, a amostra não apresentou as três bandas mencionadas anteriormente, de maneira que se pode concluir que o alumínio não é o responsável por elas. Conclui-se que, as sete variedades de quartzo do presente trabalho, apresentam propriedades TL e de AO muito singulares para cada variedade, ao contrário do que se espera ao analisar os difratogramas das amostras.Thermoluminescence and optical absorption properties of seven varieties of natural Brazilian quartz, namely, blue, sulphurous, milky, pink, green, red and black quartzs, have been investigated. For comparasion measurements were carried out also on natural alpha and synthetic quartz. Since gemological amethyst and citrine have been studied by several authors, they were not included in this work. The X Ray diffraction analysis has shown that all seven varieties of quartz have a same crystal structure of a standard sample. X Ray fluorescence and Plasma Mass Spectrometry (ICP-MS) analysis reveal Al2O3 and Na2O in all the quartz in fairly large amount, wich are essential in TL emission. Ca, Zn, Ba and Zr are also found in all the quartz samples, however several previous studies of silicate minerals indicated that they do not participate in the physical properties investigated. It is commonly known that a natural alpha quartz presents in its glow curve, 110, 220 and 325°C (sometimes replaced by 375°C) peaks. Except for 110°C peak, the two others are found is some variety but not in others. No explanation was found yet. The shape of glow curves also vary considerably from one variety to others. A striking result was obtained concerning TL response as function of radiation dose of 220°C (245°C in black quartz) and 325°C peaks. The linearsupralinear- sublinear, commonly observed in alkali halides, oxides, sulphates, etc. crystals are not observed in quartz samples except for 220°C peak in blue quartz and hyaline quartz. If linear and supralinear behavior are called first and second stage, the third stage in many of them is not sublinear, rather it keeps growing. In some cases, the first and second stages are strongly supralinear, sulphurous such as in quartz and pink quartz . In alkali halide crystal, for instance, the second stage is due to anion vacancy generated by radiation. In quartz it is due to generation of oxygen vacancy. For the third stage it is proposed that the radiation creates new oxygen vacancy in the group of SiO4 tetrahedron generating oxygen vacancy for the second stage. In the literature, one finds Ge being responsible for production of 110°C peak. The ICP-MS measurements has shown that Ge is found in all the varieties seven quartz, except in sulphurous one, but in less that 2 ppm concentration. Furthermore it was found that the 110°C peak intensity, in these quartz, has no correlation to Ge concentration, the 110°C peak has a huge intensity. Therefore, it is proposed that the oxygen removed from its normal site ends up in an intersticial position as neutral oxygen. The irradiation liberating e-h pairs enable intersticial oxygen to capture electron and became O- centre. This is the source of 110°C peak. The optical absorption spectra of alpha quartz, particularly of heavily irradiated one, show bands at 620, 450 and 350nm. They were attributed to aluminum. Similar result was found in alpha quartz, but the synthetic one with a comparable concentration of aluminum as in the natural alpha quartz did not present such bands, even after irradiation to 20 to 25kGy gamma rays. It was concluded that 620, 450 and 350nm bands are not due to aluminum. It was not found the impurities responsible for there bands. In conclusion, the seven varieties investigated, present quite different behaviour. Compared to that of the usual nature alpha quartz.
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Milner, Simon Charles, and Simon Charles Milner. "The geology and geochemistry of the Etendeka Formation quartz latites, Namibia." Doctoral thesis, University of Cape Town, 1988. http://hdl.handle.net/11427/23306.
Full textAbstract:
The Etendeka Formation volcanics of north-western Namibia form part of the Karoo Igneous Province of southern Africa and consist of a series of basalts interbedded with quartz latites and minor volumes of latite. This thesis examines various aspects of the geology and geochemistry of the quartz latites, in particular the volcanological and petrogenetic origin of these rocks . This study has involved the geological mapping of ca. 5000 km² of the southern Etendeka region and the documentation of the field and petrographic characteristics of the quartz latites. 183 whole rock quartz latite samples have been analysed for 32 elements by x-ray fluorescence spectrometry and 17 of these samples were selected for detailed mineral analyses by electron microprobe.
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Anthony, Matthew B. "Introduction to quartz resonator based electronic oscillators and development of electronic oscillators using inverted-mesa etched quartz resonators." abstract and full text PDF (UNR users only), 2009. http://0-gateway.proquest.com.innopac.library.unr.edu/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:1467740.
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Zhang, Qianzhe. "Microstructural control of epitaxial α-quartz films." Doctoral thesis, Universitat Autònoma de Barcelona, 2019. http://hdl.handle.net/10803/670104.
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Las capas epitaxiales de α-cuarzo, gracias a sus propiedades piezoeléctricas, pueden permitir fabricar sensores de masa de una sensibilidad jamás alcanzada que podrían dar lugar a aplicaciones novedosas en electrónica, biología y medicina. Sin embargo, para ello se debe poder controlar perfectamente su cristalización y la microestructura resultante para que sea posible nanoestructurarlas. En esta Tesis se adopta un nuevo enfoque sistemático para comprender la cristalización de capas epitaxiales de α-cuarzo sobre Silicio(100) a partir de la desvitrificación de capas de sílice mesoporosa mediante tratamientos térmicos. Se ha podido mostrar que aumentando la cantidad de agente devitrificante (Sr) se puede pasar de tener capas porosas y de muy baja rugosidad a otras cuya microestructura está caracterizada por la presencia de cristales de α-cuarzo densos. Asimismo estos estudios han permitido comprender con más detalle el mecanismo por el cual el Sr facilita la cristalización de la sílice.
Además, se han podido estudiar los efectos que tienen parámetros cómo el espesor de las capas, la temperatura de tratamiento térmico, la humedad relativa o el tipo de surfactante sobre la microestructura y la homogeneidad de las capas. Aumentando el espesor es posible pasar de tener capas parcialmente cristalinas y porosas a que éstas sean completamente cristalinas y caracterizadas por la presencia de cristales densos. La temperatura del tratamiento térmico puede tener una enorme influencia en el proceso de cristalización ya que incide fuertemente en la dinámica y la reactividad del Sr contenido en las capas de sílice. Una humedad relativa suficientemente elevada da lugar a perforaciones circulares en las capas por un mecanismo de separación de fases inducido per la presencia de agua en el ambiento, siendo este fenómeno muy dependiente del tipo de surfactante utilizado en la síntesis. Las perforaciones tienen influencia en cristalización del cuarzo ya que afectan a la distribución del Sr en las capas. Todos estos estudios han permitido entender mejor el mecanismo de divitrificación asistida por el Sr y por otra parte se han obtenido claves para poder controlar la microestructura de las capas de cuarzo mediante estos diferentes parámetros.
Asimismo se ha desarrollado un método de multideposición para poder aumentar el espesor de las capas desde los pocos centenares de nanómetros hasta el rango de las micras. Esto, junto con la posibilidad de controlar la microestructura ha permitido acometer con éxito la formación de nanoestructuras en capas epitaxiales de α-cuarzo sobre Silicio(100) sobre grandes áreas . Esto se ha conseguido gracias al uso combinado de las siguientes técnicas litográficas de bajo coste: (i) Litografia por transferencia laser, (ii) soft nanoimprint lithography aplicadas sobre capas de sílice dopadas con Sr obtenidas por sol-gel y (iii) el uso de máscaras nanométricas de nanopartículas de SrCO3 ensambladas. Así se han conseguido por primera vez pilares nanométricos de diferentes diámetros, que pueden llegar a ser de sólo 50 nm, y alturas de hasta 2 micras. Esta parte de la tesis demuestra que se puede conseguir controlar la forma y la micro o nano estructuración de capas delgadas epitaxiales de cuarzo preservando su cristalinidad y sus propiedades piezoeléctricas. Ello abre la puerta a la fabricación de resonadores de alta frecuencia que podrían dar lugar a sensores ultrasensibles con aplicaciones potenciales en diferentes campos.Epitaxial films of piezoelectric α-quartz could enable the fabrication of sensors with unprecedented sensitivity for prospective applications in electronics, biology and medicine. However, a prerequisite is harnessing the crystallization of epitaxial α-quartz, tailoring suitable film microstructures for nanostructuration. In my PhD work, we bring new insights into the crystallization of epitaxial α-quartz films on Silicon(100) from the thermal devitrification of nanoporous silica and the control the film microstructures: We show that by increasing the quantity of devitrifying agent (Sr) it is possible to switch from an α-quartz microstructure consisting of porous flat film to one dominated by larger and fully dense α-quartz crystals. The mechanism of Sr-assisted devitrification was also investigated simultaneously. Then, we found that film thickness, annealing temperature, relative humidity and the nature of surfactant also play an important role in the control of the microstructure and homogeneity of the films. By increasing its, thickness it is possible to switch from a partly crystalline and porous film to fully a crystalline and dominated by dense crystals one. Annealing temperature can impact the crystallization process very deeply for it can change the dynamics and reactivity of Sr within the silica film. High relative humidity cooperates with a suitable surfactant to create perforations on the films via a water-induced phase separation phenomenon. This perforation can also influence the film crystallinity by altering the distribution of Sr inside film. All these studies on the one hand give us a better understanding of the mechanism of Sr-assisted devitrification and on the other hand can show us a versatile microstructural control of the epitaxial α-quartz film. Besides, via a multilayer deposition method, we have extended the maximum thickness of the α-quartz films from a few hundreds of nm into the µm range. Moreover, in my thesis, we report unprecedented large-scale fabrications of ordered arrays of piezoelectric epitaxial α-quartz nanostructures on silicon(100) substrates by the combination of three cost-effective lithographic techniques: (i) laser transfer lithography, (ii) soft nanoimprint lithography on Sr-doped SiO2 sol-gel thin films and (iii) self-assembled SrCO3 nanoparticles reactive nanomasks. Epitaxial α-quartz nanopillars with different diameters (down to 50 nm) and heights (up to 2000 nm) were obtained for the first time. This part of my PhD work demonstrates the control over the shape, micro- and nano-patterning of α-quartz thin films while preserving its crystallinity, texture and piezoelectricity, which opens the opportunity to fabricate new high frequency resonators and high sensitivity sensors relevant in different fields of application.
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Vallin, Örjan. "Silicon and Quartz Microengineering : Processing and Characterisation." Doctoral thesis, Uppsala University, Solid State Electronics, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-5852.
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Microengineering has developed a broad range of production techniques to reduce size, increase throughput, and reduce cost of electrical and mechanical devices. The miniaturisation has also entailed entirely new opportunities.
In this work, a piezoresistive silicon sensor measuring mechanical deformation has been designed and fabricated with the help of microengineering. Due to the large variety of used processes, this device can serve as a survey of techniques in this field. Four basic process categories are recognised: additive, subtractive, modifying, and joining methods.
The last category, joining methods, has previously been the least investigated, especially when it comes to compatibility with the other categories. The adaptability of wet chemical etching to established silicon wafer bonding technique has been investigated. Further, phenomena related to oxygen plasma pre-treatment for direct bonding has been investigated by blister bond adhesion tests, X-ray photoelectron spectroscopy, and atomic force microscopy.
Wafer bonding has been adapted to monocrystalline quartz. For wet chemical pre-treatment, characteristics specific for quartz raise obstacles. Problems with limited allowable annealing temperature, low permeability of water released in the bond at annealing, and electrostatic bonding of particles to the quartz surface, have been studied and overcome. The influence of internal bond interfaces on resonators has been investigated.
Chemical polishing of quartz by ammonium bifluoride has been experimentally investigated at high temperatures and concentrations. Chemometrical methods were used to search for optimum conditions giving the lowest surface roughness. These extreme conditions showed no extra advantages.
Adhesion quantification methods for wafer bonding have been comprehensively reviewed, and augmentations have been suggested. The improved techniques’ usefulness for three areas of use has been forecasted: general understanding, bonding scheme optimisation, and quality control. It was shown that the quality of measurements of all commonly used methods could be dramatically improved by small means.
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Vallin, Örjan. "Silicon and quartz microengineering : processing and characterisation /." Uppsala : Acta Universitatis Upsaliensis : Univ.-bibl. [distributör], 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-5852.
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Pavey, Karl David. "Piezoelectric quartz crystal monitoring of surface interactions." Thesis, University of Brighton, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.299222.
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Quartz crystal microbalances, (QCM), are high frequency oscillators, capable of nanogram mass resolution in both air and liquid environments. ~ work has produced data showing the feasibility of using the QCM for monitoring interactions in liquids for several types of systems and has allowed comparison with surface plasmon resonance (SPR) where appropriate. Bulk phase changes in viscosity and density have been used in the development of a QCM agglutination assay for the Staphylococcus epidermidis infection which has reduced diagnosis periods by a factor of twelve. Direct interactions at the crystal electrode have been employed when studying bacterial adhesion to protein treated gold surfaces. It was shown that suspensions containing as little as I x 10-2 cellsml-1 could be recognised using the QCM system. A novel boronic acid - vicinal diol interaction mechanism has been employed as a model for receptor-ligand binding. New boronic acid disulphide and short chain thiol derivatives have been synthesised and the formation of self assembled monolayers of the~e compounds monitored, both on the gold QCM electrodes and on the gold films of SPR slides, the assembly mechanism being shown to fit a two stage model shown by other workers for straight chain thiols. Monolayer orientation was confirmed using SPR, by the binding of a range of saccharides and the diol containing enzyme cofactor nicotinamide adenine dinucleotide. The enzymes lactate dehydrogenase and glucose-6-phosphate dehydrogenase have been shown to interact with bound NAD using both a novel flow injection system with QCM detection and SPR. The low molecular weight saccharide, glucose, was shown to bind reversibly to GDH on the surface of a QCM and the potential for kinetic stu4ies recognised. This was taken one step further with a preliminary investigation into sensing within real fluids, using diluted and spiked human seruin samples.
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Chithambo, M. L. "Pulsed optical stimulation of luminescence from quartz." Thesis, University of Edinburgh, 2000. http://hdl.handle.net/1842/16963.
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A light emitting diode based pulsing system capable of producing luminescence time-resolved spectra was developed for study of optically stimulated luminescence from quartz and feldspar. The aim of the pulsed optical stimulation method is to separate in time stimulation and detection of luminescence so that luminescence can be measured in the absence of scatter from stimulating light unlike in conventional continuous stimulation where luminescence monitored includes such scatter. Pulsed optical stimulation not only offers the possibility of improvements in signal to background ratio but also the ability to investigate the time dependence of luminescence emission relative to the time of stimulation. Although study of pulsed luminescence has been dominated by laser-based systems, a pulsing system based on light emitting diodes offers, in comparison, advantages of simplicity and economy. The present system has been used over a wide range of pulse widths (25 ns (FWHM) - 30 ms) and dynamic ranges (40 ns - 64 ms). The system can be adapted for use with a wide range of wavelengths with pulse widths from 25 ns (FWHM) to as long as desired. Luminescence time-resolved spectra have been recorded from feldspar and quartz. Half lives measured from feldspar range from 25 ns and from quartz, 20 - 28 ms. Properties of luminescence half lives from quartz were studied in detail as a function of experimental parameters such as stimulation time, temperature, radiation dose, and preheating method. The influence of temperature on luminescence intensity was studied for time-resolved spectra recorded at long stimulation times. Explanations are proposed to account for experimental results.
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Bel, Olivier. "Gyromètre à quartz 2-D micro-usine." Besançon, 2001. http://www.theses.fr/2001BESA2010.
Full textAbstract:
Indispensables pour la navigation inertielle, les gyroscopes et les gyromètres font l'objet de nombreuses recherches, particulièrement dans le domaine microtechnique. Le travail de recherche proposé par SFIM industries (puis SAGEM à partir de 1999) consistait à démontrer le principe d'une mesure sur deux axes de la vitesse angulaire, principe dont le brevet est détenu par SFIM. Le principe d'usinabilité du quartz par attaque chimique de dispositifs de ce type ayant été démontré dans un avant-projet, il restait à valider le principe de fonctionnement par la réalisation du capteur et de l'électronique permettant de mesurer la vitesse angulaire. . .
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SMAALI, MOHAMMED. "Heterodiffusion et irradiation gamma du quartz alpha." Besançon, 1998. http://www.theses.fr/1998BESA2051.
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L'objet de ce travail etait l'etude par spectrometrie du comportement des defauts dans le quartz, soumis a deux traitements : - le premier consiste a eliminer, sous l'effet d'un champ electrique et a temperature elevee, les impuretes interstitielles presentes dans le cristal : c'est le balayage ou sweeping out. - le second consiste a introduire, dans le cristal un heteroatome sous l'effet d'un champ electrique et a temperature elevee. Nous avons applique ceci, soit a des quartz non traites, soit aux quartz sweepes sous air ou sous atmosphere d'azote en utilisant differents cations alcalins comme heteroatome : c'est le dopage ou sweeping in. Les effets des irradiations se sont montres plus importants dans le cas des quartz non traites (synthetiques ou naturels), et les quartz naturels dopes. Le recuit des quartz de synthese non traites permet la restauration d'une partie des defauts initiaux. Le recuit n'a pas modifie les spectres ir des quartz de synthese traites. Le recuit des quartz naturels, traites ou non, permet a une certaine partie des defauts de retrouver leur etat initial. Lors de l'operation de recuit, nous avons enregistre les courbes de thermoluminescence. Les traitements tels que le sweeping, le dopage et l'irradiation, appliques a differents types de cristaux, nous ont permis de distinguer plusieurs maxima et de les attribuer a un ou plusieurs types de defauts. L'etude des quartz colores par spectroscopie infrarouge permet de determiner leur mode de cristallisation, naturelle ou de synthese. Nous avons montre que chaque espece coloree, possede ses propres criteres pour l'identification de son origine.
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Duffin, Roger. "Molecular toxicology studies on the quartz hazard." Thesis, Edinburgh Napier University, 2003. http://researchrepository.napier.ac.uk/Output/2777.
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Silicon makes up almost 28% of the Earth's crust and within that crust, quartz (crystalline silica) is one of the most abundant minerals. Exposure to quartz can occur in a number of occupations, including the mining and construction industries in which respirable quartz particles are generated and become airborne. Inhalation of quartz can lead to the fibrosing lung disease silicosis and cancer. Silicosis has been recognised for many decades as one of the most prevalent occupational lung diseases. In 1997, an IARC working Group classified quartz as a class 1 lung carcinogen, but only in some industries, suggesting that the quartz hazard is a variable entity. The reactivity of the quartz surface may underlie its ability to cause inflammation and treatments that ameliorate this reactivity would then reduce the quartz hazard. In the present study the effect of treating quartz with aluminium lactate, a procedure reported to decrease the quartz hazard, on the highly reactive quartz surface and on proinflammatory events in the rat lung were explored. Aluminium lactate-treated quartz showed a reduced surface reactivity as measured by electron spin resonance. Eighteen hours post-instillation of quartz into the rat lung, there was massive inflammation as indicated by the number of neutrophils in the bronchoalveolar lavage (BAL) and an increase in BAL macrophage inflammatory protein-2 (MIP-2). However, aluminium lactate-treated quartz had no significant effect when compared to control. Epithelial damage as indicated by BAL protein and gamma glutamyl transpeptidasea lso increased with quartz instillation but not with aluminium lactate-treated quartz and furthermore, quartz induced an increase in MIP-2 mRNA content of BAL cells while aluminium lactate-treated quartz had no effect compared to controls. There was an increase in nuclear binding of the transcription factor nuclear factor-kappa B (NF-xB) in the quartz exposed BAL cells and again, no effect on nuclear NF-xB binding in BAL cells from aluminium lactate-treated quartz instilled rats. In addition, the effect of aluminium lactate and PVNO quartz treatment on DNA damage, cell cytotoxicity and particle uptake by A549 cells was assessed. DNA strand breakage, as produced by quartz at non-toxic concentrations, could be completely prevented by both coating materials. Particle uptake by A549 cells appeared to be significantly inhibited by the PVNO coating, and to a lesser extent by the aluminium lactate coating, demonstrating that respirable quartz particles induce oxidative DNA damage in human lung epithelial cells and indicating that the surface properties of the quartz as well as particle uptake by these target cells are important in the cytotoxic and genotoxic effects of quartz in vitro. Finally, the role played by surface area and specific reactivity in the acute inflammatory response to particles was investigated. Acute inflammatory response following instillation of particles has been used to evaluate hazard but has been criticised because of the non-physiological delivery and the problems of local overload. Here, a number of low toxicity dusts of various particle sizes were instilled and the neutrophil influx into the lung 18-24 hours post-instillation assessed. The extent of inflammation was shown to be a function of the surface area instilled and ultrafine particles, which present a case of high surface area per unit mass, were inflammogenic pro rata with their surface area. There is no evidence that ultrafine particles of carbon black, titanium dioxide or polystyrene have any special reactivity in addition to their large surface area. We further tested whether this approach could be used to model the reactivity of highly toxic dusts. Rats were instilled with either quartz or aluminium lactate-treated quartz and, as anticipated, the high specific surface reactivity of quartz meant that it was much more inflammogenic than was predicted using the relationship described for `low toxicity' dusts. This approach represents the possibility of modelling potential toxicity for nuisance dusts based on the inflammatory response of a given instilled surface area dose.
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Argonz, Raquel. "Purificação de rejeitos de lascas de quartzo das industrias de silicio." [s.n.], 2001. http://repositorio.unicamp.br/jspui/handle/REPOSIP/264918.
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Orientador: Carlos K. SuzukiTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica
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Resumo: O Brasil é na atualidade um dos principais produtores de silício para o mundo, sendo que a quantidade de quartzo extraído para a sua produção incluindo o ferro-silício, é da ordem de 2 milhões de toneladas/ano. Para a obtenção do quartzo destinado à redução carbotérmica em silício, nos diversos estágios de extração, britagem, seleção, transporte, e lavagem, cerca de 300.000 toneladas/ano de lascas de quartzo tomam-se rejeitos. Neste trabalho foi desenvolvida uma metodologia ambientalmente correta, denominada "quench-Ieaching" e "crush-leaching", que se utiliza da lixiviação aquosa para a purificação deste material. Os resultados mostram que ocorre uma remoção efetiva de impurezas majoritárias nas lascas de quartzo, tais como, AI, Fe, Na, K, Ca, Mn, ..., dando-lhe uma pureza de 99,9% de SI 'O IND 2'. Uma comparação com diversos insumos de quartzo produzidos no exterior para uso em tecnologia avançada, como para produção de sílica vítrea translucente e "fillers" de "micro-chips", revela que este material purificado com esta tecnologia toma-se de qualidade equivalente ao pó de quartzo internacional
Abstract: Nowadays, Brazil is one of the main silicon metal and iron-silicon producer in the world. But on the other hand, the amount of natural quartz that has been extracted for this purpose is up to 2 milliontons/year. The key-point is the large quantity of rejected quartz lascas, approximately 300,000 tons/year, generated during the various stages of extraction, crushing, selection, transportation, and washing. A new environrnentally mendly purification methodology denominated "quench-Ieaching" and "crush-leaching, that only uses aqueous leaching, has been developed. The result shows an effective elimination of major quartz impurities, such as Al, Fe, Na, K, Ca, Mn, ... , that transforms this rejected material into a 99.9% purity SI 'O IND 2'. The quality of this material is as high as the quartz powder commercially available in the intemational market for use as "fillers" and translucent silica glass raw material for semiconductor industries
Doutorado
Materiais e Processos de Fabricação
Doutor em Engenharia Mecânica
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Santos, Murilo Ferreira Marques dos 1989. "Avaliação de jazidas brasileiras de quartzo mais adequadas para uso em sílica vítrea." [s.n.], 2014. http://repositorio.unicamp.br/jspui/handle/REPOSIP/265927.
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Orientadores: Carlos Kenichi Suzuki, Jacinta EnzweilerDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica
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Resumo: Este trabalho foi conduzido com base em avaliar o potencial de jazidas de quartzo localizadas no Brasil para a utilização na fabricação de sílica vítrea para as indústrias de alta tecnologia (principalmente focando a manufatura de utensílios para a purificação e processamento de silício e de vidro óptico transparente no UV). As jazidas foram escolhidas conforme sua importância econômica no passado, seus níveis de produção, sua pureza química e a disponibilidade de minério. Elas foram avaliadas quanto à sua geologia, composição química (pela técnica de ICP-MS) e comportamento quando submetidas à fusão em sílica vítrea. Para esta fusão duas técnicas foram utilizadas, a técnica de Verneuil e a fusão em plasma pulsado (Spark Plasma Sintering). Os vidros fundidos com o material de cada jazida foram caracterizados quanto à transmitância óptica no visível e no UV. O trabalho também buscou identificar qual seria a melhor maneira de processar industrialmente o mineral proveniente de cada jazida. Os resultados obtidos mostram que várias jazidas são capazes de produzir vidros de alta qualidade, em especial aqueles provenientes de amostras da formação Serra de Santa Helena, localizada no norte do Estado de Minas Gerais e de Brotas de Macaúbas, no Estado da Bahia. Outras jazidas localizadas no Estado da Bahia também se mostraram alternativas economicamente viáveis
Abstract: This work aimed to evaluate the use of Brazilian quartz in the manufacture of silica glass for high tech industries (specially focused in the production of quartz crucibles for the high purity silicon industry and in the production of optical glass transparent to UV radiation). The mines which were studied here were selected according to its economic importance in the past, its production levels, its chemical purity and the amount of mineral contained in it. All mines were evaluated according to its geology, its chemistry (using the ICP-MS technique), and its behavior during fusion. In order to conduct this fusion, two different fusion techniques were used: Verneuil method, for flame fusion, and Spark Plasma Sintering (SPS) for electrical fusion. After fusion, each glass was evaluated according to its optical transmittance. It was also proposed some ways of industrially processing the minerals in order to obtain a better powder for fusion. Obtained results show that Brazilian mines are highly capable of producing good quality glasses using simple processing methods. The work emphasize the quality of the minerals original from the Santa Helena Formation, in northern Minas Gerais State, and from Brotas de Macaúbas, in the State of Bahia. Other minerals from the state of Bahia might also be a viable alternative
Mestrado
Materiais e Processos de Fabricação
Mestre em Engenharia Mecânica
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Yukimitu, Keizo. "Eletrodifusão, absorção óptica e termoluminescência no quartzo e berilo." Universidade de São Paulo, 1993. http://www.teses.usp.br/teses/disponiveis/43/43131/tde-13092013-112622/.
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No presente trabalho, foi montado um sistema de eletrodifusão para o estudo dos efeitos da substituição de íons alcalinos, presentes no canal estrutural, por íons de hidrogênio (H POT. +), nas propriedades termoluminescentes e ópticas do quartzo. A corrente elétrica de eletrólise apresenta, na parte inicial de aquecimento, um ombro ou pico de corrente. Através da análise do comportamento deste pico e informações obtidas de dados de absorção óptica na região espectral do infravermelho, concluiu-se que o pico presente na curva inicial de eletrólise se deve ao complexo [AL POT. 3+/M POT. +]. As medidas de termoluminescência e absorção óptica na região espectral do visível e ultra-violeta foram feitas em amostras de quartzo eletrodifundidos e não eletrodifundidos e chegou-se à proposição de uma reação envolvendo os alcalinos presentes no canal. Nesta reação, os íons alcalinos fazem o papel de centros armadilhadores de íons de oxigênio O POT. produzidos pela radiação ionizante, e estabilizadores de vacâncias de oxigênio. O aquecimento, em tomo de 300 GRAUS C, provoca a desestabilização desses centros armadilhadores, liberando os íons alcalinos que reagem com os defeitos [ALO IND. 4] POT. 0 emitindo luz TL. Aproveitando a existência de canais estruturais, semelhantes ao quartzo, tentou-se eletrodifundir H POT + no berilo. Através de medidas de termoluminescência e corrente inicial de eletrólise, discute-se a possibilidade da existência do defeito [FE POT. 3+/M POT. +] no berilo.A system of electrodiffusion was made in the laboratory to investigate effects of exchanging alkali ions, usually present in the structural channels by protons, in the optical and thermoluminescent properties of quartz. In the initial part of heating, the sweeping current presents a peak at about 350 GRAUS C. The analysis of the behaviour of this peak with additional data of optical absorption in the region of infrared, it was concluded that the peak at 350 GRAUS C of the current is due to [AL POT. 3+/M POT. +] system. Thermoluminescence and optical absorption spectra in the visible and ultraviolet light region for swept and unswept quartz were compared. Based on this comparison it was shown that, once irradiated to gama- or X-rays, alkali ions are removed from [AL POT. 3+/ M POT. +] and either couple to o ions or capture electron and become interstitial alkali atom, leaving, further, [ALO IND. 4] POT. 0 hole center. Heating at about 300 GRAUS C electrons from M POT 0 or M POT +O POT recombine with holes in [ALO IND. 4] POT. 0, emitting TL light, besides regrouping Al POT. 3+ and M POT. + to reform [Al POT. 3+/M POT. +] system by coulomb attraction. The electrodiffusion experiment was extended to beryl crystal, because beryl has also structural channels. To explain initial sweeping current behaviour as well as thermoluminescent property a mechanism involving [FE POT. 3+/M POT. +] system is proposed.
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Correa, Monica. "Variedades gemológicas de quartzo na Bahia, geologia, mineralogia, causas de cor, e técnicas de tratamento." Universidade de São Paulo, 2010. http://www.teses.usp.br/teses/disponiveis/44/44144/tde-20012011-114502/.
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A Bahia tem sido, juntamente com Minas Gerais, Goiás e Rio Grande do Sul, destaque na produção de gemas naturais do Brasil, pais que detém grande parte das reservas mundiais desses bens minerais, com produção de gemas de qualidade reconhecidas internacionalmente. Os controles estatísticos registram a presença de mais de trinta variedades gemológicas em território baiano (Tavares et al, 1998). O quartzo é utilizado ultimamente em grande escala na produção de jóias. Isto se deve a sua grande abundância no território baiano, preços relativamente baixos de exploração, e a boa resposta do mesmo aos tratamentos térmico e de irradiação gema, visando mudanças ou o melhoramento da cor. As Serras do Espinhaço Setentrional e de Jacobina, bem como a região da Chapada Diamantina, concentram a maior parte das ocorrências de variedades, tanto coloridas como susceptíveis ao tratamento para induzir cor, deste mineral, o qual passou a ser visto como uma das principais matérias-prima para lapidários, comerciantes e joalheiros da região. Apesar da importância das mineralizações, existe uma carência de estudos científicos que abordem questões relacionadas com a evolução e controle geológico das mineralizações e com os tratamentos que são realizados para melhorar o potencial gemológico das regiões estudadas. Tendo em vista enriquecer o conhecimento deste potencial geológico do território baiano, a realização deste estudo representa um passo significativo no entendimento da evolução metalogenética das áreas estudadas, além de contribuir com o estudo geológico e gemológico das variedades coloridas do quartzo na Bahia. Os quartzos gemológicos estudados na Bahia encontram-se inseridos principalmente em ambientes hidrotermal, encaixados em rochas metareníticas e quartziticas do Supergrupo Espinhaço. A partir dos dados levantados em campo, pôde-se verificar que as mineralizações estudadas possuem um controle estrutural, e encontram-se posicionadas em fraturas de tração de baixo ângulo. Tais fraturas estão associadas com rampas de empurrão que se desenvolveram durante as deformações que culminaram com a estruturação do cinturão de dobramentos e cavalgamentos da Serra do Espinhaço. A cor da ametista é devido a presença de impurezas derivadas da família do ferro (FeO4)-4, e da radiação ionizante. O quartzo fumê desenvolve-se apenas com a presença de alumínio e lítio, e o fenômeno do \"centro de cor\" (defeito na estrutura cristalina causada pela falta de um elétron) é o responsável pela sua cor, onde o íon Al3+ ao substituir o íon Si4+ gera um desequilíbrio eletrônico que é compensado por íons de Li-. O citrino por sua vez, deve sua cor a uma combinação de AI-Li, semelhante ao do quartzo fumê. Os estudos também demonstraram que as aquisições de cores no quartzo obtidas através dos processos de irradiação gama e tratamento térmico, bem como a estabilidade das mesmas, estão amplamente condicionadas aos ambientes de formação dos cristais, e a presença de elementos químicos nos fluidos formadores dos cristais, os quais são responsáveis pela variação de suas cores. As características gemológicas encontradas demonstram que o quartzo baiano apresenta um elevado potencial comercial. Para o futuro sugere-se trabalhos de levantamentos geológicos e pesquisa mineral, desde que a exploração das gemas vem apresentando significativas reduções e limitações nas suas atividades minero-industriais, seja pela parcial exaustão das reservas conhecidas, ou pela necessidade de ampliá-las e, assim, incentivar novos investimentos. Pouquíssimos trabalhos com cunho gemológico tem sido publicados no Brasil com vista de esclarecer a correlação entre depósitos de quartzo e seu comportamento perante tratamentos de irradiação e de aquecimento.Besides Minas Gerais, Goiás and Rio Grande do Sul, Bahia is worldwide known for its richness in minerals of industrial and gemological interest. Up to this day, more than 30 minerals of gemological use are known (Tavares et. al. 1998) One of the main gemological material is quartz, used currently in large amounts for jewelry due to its fair value and good response of color treatments by irradiation and heat. Most of the quartz is found and mined in the Espinhaço , Chapada Diamantina and Jacobina belts either as colorless quartz or as amethyst. The colorless variety is sometimes prone to treatments that induce color centers resulting in black (Morion), brown (Smoky), yellow(Citrine), green (Prasiolite) gemstones. Very few work exists dealing with the geological evolution, control of mineralization, estimation of quantities and possible treatments of these materials. The results of this work is a contribution to the knowledge of the metalogenic evolution of the studied areas and includes the location of all known occurrences of quartz from Bahia. It could be shown that most of the quartz from Bahia state is located mainly in a hydrothermal environment crosscutting the quartzites and arkosic rocks of the Espinhaço Supergroup. Field data showed strong tectonic control of the quartz veins, filling low angle traction fractures associated with the thrust belts that formed the Serra do Espinhaço mountain range. The fluids passing through these fractures deposited quartz, as amethyst (Breijinho de Ametista, Jacobina e Sento Sé), colorless and milky quartz and sometimes as citrine. The color of amethyst is due to substitutional iron with oxidation degree 4+, formed by irradiation of ferric iron contained in the tetrahedral of the quartz structure. Smoky colors are formed by irradiation of mainly Al containing quartz, whereas yellow and yellow green colors are formed by the presence of Al and Li. Few occurrences of colorless quartz forming a green variety by irradiation have been documented. Some preliminary results show that the type and intensity of color is determined by the specific environment of formation. More work is clearly needed to clarify the correlation of formation environment and color produced by irradiation and heat treatments.
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Abrahamians, Khanghah Jean-Ochin. "Quartz probes for embedded micro-robotics and imaging." Thesis, Paris 6, 2016. http://www.theses.fr/2016PA066130/document.
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Les sondes basées sur des résonateurs en quartz sont des capteurs disposant d'une autonomie en termes d'excitation et d'acquisition, et à cet égard présentent de nombreux avantages par rapport aux poutres cantilever qui ont jusqu'à présent dominé dans les applications de micro-caractérisation directe. Un de ces avantages est qu'elles peuvent êtres embarquées et calibrées sans recours à un système de déflection laser. Ces outils plus compacts et autosuffisants peuvent en conséquence être aisément intégrés et contrôlés au sein d'un microscope électronique à balayage, qui permet une observation globale rapide souvent privilégiée dans la recherche en micro-robotique. Le développement de ces sondes est de plus avantagé de par le fait qu'elles sont constituées de composants électroniques standards répandus dans le commerce, et qu'elles peuvent être adaptées à des usages spécifiques par l'ajout d'une micro-pointe. Les sondes de quartz dans la littérature sont cependant souvent basées sur des composants à fréquence d'oscillation limitée, et une plus grande vitesse d'opération serait utile à l'ensemble de leurs applications. C'est dans ce contexte que nous nous intéressons à des composants à plus haute fréquence, et au contrôle de sondes dans un microscope électronique propre à leur utilisation ciblée en micro-robotique et en imagerie. Les propriétés de ces sondes sont tout d'abord examinées dans le but de pouvoir évaluer et exploiter des résonateurs à plus haute fréquence; nous montrons ensuite que des sondes basées sur des résonateurs à cisaillement d'épaisseur atteignent de plus hautes vitesses en imagerie, ce qui les rend prometteuses pour des applications rapides ne requérant pas une haute résolution. Enfin, nous intégrons une sonde diapason dans un MEB, et établissons ainsi une preuve de concept pour la cartographie en raideur de micro-membranes fragilesAs self-sensing and self-exciting tools, quartz probes present many advantages over the heretofore dominant silicon cantilevers for mechanical micro-sensing applications. One of these advantages is that they can be embedded and calibrated without the need for a laser deflection setup. The more compact and self-sufficient tools can therefore be readily integrated and controlled with Scanning Electron Microscopy, which is favoured at the smaller scales of micro-robotic research. More generally, the development and use of quartz probes is bolstered by the fact that they can be fabricated from widely commercialized quartz components and customised through the addition of a microtip. The quartz probes found in the literature are however largely based on components with limited oscillation frequencies, and could benefit from higher operating speeds. In this context, we address the frequency improvement and embedded control of AFM probes with regard to their use in targeted micro-robotics and imaging. The properties of quartz probes are first covered towards the evaluation and use of higher frequency components; we next demonstrate that faster scanning can be achieved with quartz probes made from thickness shear resonators, making them suitable for fast applications which do not require high sensitivity. Lastly, we integrate a tuning fork probe inside a SEM, and establish through it a proof of concept for the non-destructive stiffness mapping of fragile micro-membranes
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Narine, Suresh. "A high-resolution quartz microbalance for surface studies." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape15/PQDD_0004/MQ30227.pdf.
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Topnik, Jason Marc. "Iron in wastewater, effect on quartz sleeve scale." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape8/PQDD_0018/MQ47108.pdf.
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Robinson, P. T. "Magnetic resonance studies of radiation processes in quartz." Thesis, University of Oxford, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.355772.
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Fan, Anchuan, and 范安川. "Quartz OSL dating of quaternary sediments from China." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2010. http://hub.hku.hk/bib/B45700187.
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Cheung, See Nga Cecilia. "Experimental deformation in sandstone, carbonates and quartz aggregate." Thesis, State University of New York at Stony Brook, 2015. http://pqdtopen.proquest.com/#viewpdf?dispub=3717020.
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The first part of my thesis is mainly focused on the effect of grain size distribution on compaction localization in porous sandstone. To identify the microstructural parameters that influence compaction band formation, I conducted a systematic study of mechanical deformation, failure mode and microstructural evolution in Bleurswiller and Boise sandstones, of similar porosity (∼25%) and mineralogy but different sorting. Discrete compaction bands were observed to develop over a wide range of pressure in the Bleurswiller sandstone that has a relatively uniform grain size distribution. In contrast, compaction localization was not observed in the poorly sorted Boise sandstone. My results demonstrate that grain size distribution exerts important influence on compaction band development, in agreement with recently published data from Valley of Fire and Buckskin Gulch, as well as numerical studies.
The second part aimed to improve current knowledge on inelastic behavior, failure mode and brittle-ductile transition in another sedimentary rock, porous carbonates. A micritic Tavel (porosity of ∼13%) and an allochemical Indiana (∼18%) limestones were deformed under compaction in wet and dry conditions. At lower confining pressures, shear localization occurred in brittle faulting regime. Through transitional regime, the deformation switched to cataclastic flow regime at higher confining pressure. Specifically in the cataclastic regime, the (dry and wet) Tavel and dry Indiana failed by distributed cataclastic flow, while in contrast, wet Indiana failed as compaction localization. My results demonstrate that different failure modes and mechanical behaviors under different deformation regimes and water saturation are fundamental prior to any geophysical application in porous carbonates.
The third part aimed to focus on investigating compaction on quartz aggregate starting at low (MPa) using X-ray diffraction. We report the diffraction peak evolution of quartz with increasing pressures. Through evaluating the unit cell lattice parameters and the volume of the quartz sample, macroscopic stress and strain were resolved. Moreover, we observed quartz peak broadened asymmetrically at low pressure, such extent is more prominent in axial than in radial direction. Our evaluation on peak [101] (highest intensity among peaks) demonstrated that full width at half maximum can be a good proxy for microscopic stress distribution. We observed deviations in the pressure-volume curves at P = ∼0.4 GPa and speculated that it was the point of which onset of grain crushing and pore collapse occur in quartz. This is on the same order of which onset of grain crushing (commonly known as P*) is observed in sandstones in the rock mechanics literature. This demonstrated that there is potential in estimating grain crushing and pore collapse pressure with our technique.
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Ash, Dean Christopher. "The liquid droplet quartz crystal microbalance micro viscometer." Thesis, Lancaster University, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.423557.
Full textAbstract:
Presented here is a novel use of the Quartz Crystal Microbalance QCM as a droplet micro-viscometer. The droplet micro-viscometer is so named as it requires only a micro litre of liquid in the form of a droplet in order to determine the liquid viscosity. The crystal operates using the inverse piezoelectric effect and the droplet is applied to one electrode of the freely oscillating crystal. Loading the crystal surface this way produces a frequency change .11 in the oscillating frequency of the crystal, as a function of the liquid viscosity. Monitoring of this frequency allows for determination of the liquid viscosity. Jointly sponsored by the EPSRC and British Nuclear Fuels plc, this research was proposed by BNFL as a way of maintaining tighter control on an important parameter of a solvent extraction nuclear fuel reprocessing process. Research in this area started with the assessment of the QCM to give meaningful results for viscosity from a single droplet of liquid, initially, alcohols whose physical parameters were well documented. Encouraging results prompted further experimentation with tri-n-butyl phosphate or TBP, diluted with odourless kerosene, OK. Wider potential was realised and motor oils and fuel oils were targeted as a potential use for this technology. Motor oil as viscosity is a first indicator of the oil condition/quality and fuel oils specifically in the identification of red diesel when diluted in white diesel.As this technology was intended for use as a sensor it was important, for financial reasons, that the sensor element in contact with the liquid could be cleaned thoroughly enough to allow re-use without degradation of the results produced. A cleaning regime is covered in this work showing that cleaning is feasible but has limits in the amount of times this can successfully be performed before a replacement QCM is required. Some simple experiments on samples of whisky were performed in pursuit of a use in the foodstuffs industry with the institute of food research. These show a possible method of identification but no further work was done on this as other research demanded the time. Results show that the QCM results clearly demonstrate the use of a liquid droplet on one face does produce meaningful results with relation to the viscosity of the liquid. Various diJutions ofTBP and OK are distinguishable from each other as are various dilutions of red diesel in white diesel and oils of varying viscosity. The droplet QCM micro viscometer has the advantage over most other methods of viscometry not in its accuracy of absolute viscosity measurement but in the very small amount of sample liquid needed for test. This is a very desirable factor in situations where repeat sampling of a fixed volume of liquid is required as the samples taken need not significantly reduce the sample volume.
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Tinguy, Pierre. "Etude et développement d'un oscillateur à quartz intégré." Phd thesis, Université de Franche-Comté, 2011. http://tel.archives-ouvertes.fr/tel-00675277.
Full textAbstract:
Le besoin croissant de réduction du volume, de la masse et de la consommation des dispositifs électroniques sans pertes deperformances concerne aussi les oscillateurs à quartz utilisés dans les applications métrologiques (bases de temps, capteurs),la téléphonie, la navigation... Dans le cadre de cette problématique, nous avons développé un ASIC (Application SpecificIntegrated Circuit) en technologie 0,35 μm SiGe BiCMOS (Austriamicrosystems®) fonctionnant sous 3,3 V (±10%) pourréaliser un oscillateur à quartz miniature opérationnel sur une gamme en fréquence allant de 10 MHz à 100 MHz. Ce circuitdont la surface ne dépasse pas les 4 mm2 est composé de diverses cellules RF, depuis le système d'entretien de type Colpitts,la mise en forme et jusqu'à l'adaptation du signal à sa charge d'utilisation (50 W ou HCMOS). Ces cellules sont toutespolarisées par une référence de tension interne de type bandgap CMOS. La consommation totale du circuit en charge resteinférieure à 100 mW pour un bruit blanc de phase visé de −150 dBc/Hz à 40 MHz. Pour minimiser la sensibilité thermiquedu résonateur et ainsi pouvoir s'orienter également vers des applications OCXO (Oven Controlled Crystal Oscillator),nous avons partiellement intégré une régulation de température dans notre ASIC. Cette régulation fortement dépendante del'architecture thermo-mécanique a été dimensionnée puis validée au travers de modélisations par analogie sous Spectre®.Notre électronique intégrée nécessite peu de composants externes et nous l'avons reportée par flip chip sur une interfacespécifique pour