Dissertations / Theses on the topic 'Rare earth ion dopants'
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Longdell, Jevon Joseph, and jevon longdell@anu edu au. "Quantum Information Processing in Rare Earth Ion Doped Insulators." The Australian National University. Research School of Physical Sciences and Engineering, 2004. http://thesis.anu.edu.au./public/adt-ANU20061010.105020.
Full textZhen, Y. S. "Oxygen ion conduction in doped rare earth oxides." Thesis, University of Leeds, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.383333.
Full textShen, Shaoxiong. "New rare earth ion-doped hosts for broadband fibre amplifier." Thesis, University of Leeds, 2000. http://etheses.whiterose.ac.uk/2379/.
Full textFraval, Elliot, and elliot fraval@gmail com. "Minimising the Decoherence of Rare Earth Ion Solid State Spin Qubits." The Australian National University. Research School of Physical Sciences and Engineering, 2006. http://thesis.anu.edu.au./public/adt-ANU20061010.124211.
Full textFraval, Elliot. "Minimising the decoherence of rare earth ion solid state spin qubits /." View thesis entry in Australian Digital Theses Program, 2005. http://thesis.anu.edu.au/public/adt-ANU20061010.124211/index.html.
Full textBurcher-Jones, Cody Owen. "Mineralogical and ion-exchange leaching study of a Rare Earth Element (REE) bearing ion-adsorption clay deposit." Master's thesis, Faculty of Engineering and the Built Environment, 2018. http://hdl.handle.net/11427/30161.
Full textWood, Timothy James. "Structural studies of rare earth silicides on silicon by medium-energy ion scattering." Thesis, University of York, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.434176.
Full textSakr, Hesham. "Towards mid-infrared fibre lasers : rare earth ion doped chalcogenide glasses and fibres." Thesis, University of Nottingham, 2016. http://eprints.nottingham.ac.uk/33338/.
Full textRidley, Mark K. "Gradient ion chromatographic determination of rare earth elements in coal and fly ash." Master's thesis, University of Cape Town, 1992. http://hdl.handle.net/11427/18597.
Full textGonçalves, Tássia de Souza. "Caracterização estrutural e espectroscópica de vidros fluorofosfatos dopados e co-dopados com Er3+ e Yb3+." Universidade de São Paulo, 2014. http://www.teses.usp.br/teses/disponiveis/18/18158/tde-18082014-150349/.
Full textCurrently, glasses and glass ceramics doped with trivalent rare earth ions RE3+ represent the most important class of materials for laser and other optical applications in the visible and near-infrared spectral regions. In this context, one of the challenges is to find host matrices that assure good optical quality and optimum performance of the dopant ions (high absorption and emission cross sections, low probability of non-radiative decays, sufficiently long excited state lifetimes), while still maintaining thermal and mechanical stabilities. Among the candidates, phosphate glasses with high capacity for RE3+ dispersion, low refractive index and superior thermo-optical properties than silicate, chalcogenide and fluoride glasses are largely studied. However, phosphates present high phonon energies, lower chemical and mechanical stabilities and they are hygroscopic, which can imply in significant luminescence quenching effects. If on one hand fluoride glasses may be designed with low phonon energies and higher chemical stability, they are frail and present less than ideal thermo-optical properties. In order to overcome these drawbacks, oxyfluoride glasses such as fluorophosphates have been explored with the promise to combine the merits of fluorides (low phonon energies and refractive index, extensive optical window) and of oxides (high chemical stability and chemical resistance, higher solubility of RE3+). From the viewpoint of applications, when it comes to the transmission and amplification of signal in telecommunications around 1.5 µm, and the generation of high power lasers around 1.0 µm, materials doped with Er3+ and Yb3+ are among the favorite. Furthermore, because Yb3+ presents higher absorption cross-section than Er3+ at the preferred excitation wavelength for both these ions (980 nm), the former can act as an efficient sensitizer of excitation energy with subsequent transfer to the latter. We present the synthesis, and structural and spectroscopic characterization of new flurophosphate glasses doped with Er3+ or Yb3+ and co-doped with both, in the compositional system 25BaF225SrF2(30x)Al(PO3)3 xAlF3 (20- z)YF3:zREF3 with x = 20 or 15, RE = Er3+ and/or Yb3+ and z = 0.25, 0.5, 1.0, 2.0, 3.0, 4.0 and 5.0 mol%. The samples were obtained by conventional melt quenching technique and characterized by Raman, solid state NMR and UV-VIS spectroscopy. From the NMR studies of 19F, it was shown that there is a maximum fluoride loss of 20% in the samples. Even so, the remaining quantity was enough to assure a favorable chemical environment to the RE3+ emissions. Little differences were detected between the samples with 20 and 15 mol% AlF3 for the same dopant concentration. For Er3+, lifetimes of the emitting level 4I13/2 of the order of 10 ms result in fluorescence quantum efficiency values (η = 85%), and similarly, for Yb3+, long lifetimes of the excited state 2F5/2 (τ = 1,7 ms) were measured. In co-doped samples with 4.0 mol% YbF3 and 0.25, 1.0 and 2.0 mol% ErF3 the decrease in lifetime of Yb3+ and increase in lifetime of Er3+ indicate that the Yb→Er energy transfer is efficient in this system. In general, the results indicate that the studied glasses are potential candidates for optical applications.
Aðalsteinsson, Sigurbjörn Már. "Study of rare-earth oxy-hydrides as candidates for photochromic materials." Thesis, Uppsala universitet, Tillämpad kärnfysik, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-396533.
Full textSampaio, Jurací Aparecido. "Preparação e caracterização de vidros aluminato de cálcio com baixa concentração de sílica dopados com Nd2O3 e Er2O3." Universidade de São Paulo, 2001. http://www.teses.usp.br/teses/disponiveis/76/76132/tde-24062008-162022/.
Full textThe development of compact solid-state lasers operating in the midinfrared wavelength region (2 -5 ?m) has been an area of considerable activity in the last few years. These devices offer great potential as light sources for applications as medical lasers as well as in remote chemical sensing devices. Light sources in the 2.8?m region are of particular interest for medical applications due to the strong water absorption in this spectral region. Apart from allowing extremely precise cutting and ablation of water-containing tissues, the other advantages of using light sources operating at 2.8 ?m are related to the possibilities of reducing skin burning in surgeries, decrease in the use of anesthesia and shortening of recovery time, especially in skin surgeries and in the cutting and remova1 of hard tissues, such as tooth enamel and bone. In order to achieve strong laser emission around 2.8 ?m the effort so far has been concentrated on the family of Er3+ doped non -oxide glasses such as heavy metal fluorides and chalcogenides. However the production of these glasses is expensive, and it is difficult to make them, besides they are toxic. On the other hand, the oxide glasses are cheaper, atoxic and easy to produce them. The disadvantaged, however, is its the relative high phonon energy that promote high nonradiative transition rates. Since calcium aluminate glasses are formed with non-network forms, CaO and Al2O3, they have high tendence towards devitrification. The addition of small amounts of alkali and alkaline earth elements enlarges the glass forming region. Several calcium aluminate glasses compostions containing SiO2, BaO and MgO are now reported in the literature. In this thesis, low silica calcium aluminosilicate glasses doped with Nd2O3 and Er2O3 were prepared. Since the sample compositions were close to the phase diagram glass formation, the rare earth doping was performed up to 8wt.%. The samples was melted under vacuum condition in a graphite crucible at 1500 °C, and in air in a platinum crucible. The influence of the rare earth doping on the thermal diffusivity, thermal conductivity and Vickers hardness was such that all these physical parameters decreased by roughly the same amount, namely 8%, between the undoped and 5 wt% of Nd2O3. The dependence of these parameters, as a function of the Nd2O3 doping, strongly supports the idea that the Nd3+ or Er3+ act as network modifiers. Elastic module (E, G, K, v) of calcium aluminosilicate glasses with < 10 mole% of SiO2 doped with Er2O3 and Yb2O3, melted in air and under vacuum conditions, have been measured using the pulse echo ultrasonic technique. There was a decrease of the elastic properties, about 5%, as rare earth doping increases from 0.2 to 1.5-mol% (about 8 wt%). The Young\'s modulus did not vary within errors of measurements. The Debye temperature varied between (369±9)K and 352±9 K, which is explained assuming that the rare earth ions acts as network modifiers disrupting the glasses structure. The undoped calcium aluminate glasses fracture toughness is (1.4±0.3) MPa m1/2 and the thermal shock resistance is (339±102) W/m. The fluorescence quantum efficiency determined by thermal lens spectroscopy, was found be about 80% for the 2wt% Nd2O3 doped calcium aluminosilicate glass. The fluorescence quenching was observed to doping higher than 2wt% Nd2O3. The variation of the refractive index as a function of the temperature, dn/dT, was found be 8.0 x 10-6/0c. Among the various glass system investigated, CA glasses presented greater mechanical properties and larger thermal shock resistance, indicating that these materials are candidates for solid state laser applications and other infrared applications.
Rastrelo, Lara Rossana. "Síntese, caracterização e fotoluminescência de titanatos de cálcio dopados com íons Tm³+, Tb³+ e Sm³+." Universidade Federal de Goiás, 2013. http://repositorio.bc.ufg.br/tede/handle/tede/4675.
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Rejected by Luciana Ferreira (lucgeral@gmail.com), reason: Mesmo não tendo currículo latters use o nomes do autor abreviado na citação, ou seja, no lugar de RASTRELO, Lara Rossana. Síntese, caracterização e fotoluminescência de titanatos de cálcio dopados com íons Tm³+, Tb³+ e Sm³+. 2013. 64 f. Dissertação (Mestrado em Química) - Universidade Federal de Goiás, Catalão, 2013. USE: RASTRELO, L. R. Síntese, caracterização e fotoluminescência de titanatos de cálcio dopados com íons Tm³+, Tb³+ e Sm³+. 2013. 64 f. Dissertação (Mestrado em Química) - Universidade Federal de Goiás, Catalão, 2013. on 2015-10-20T10:53:09Z (GMT)
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES
The photoluminescent properties (FL) has always aroused the interest of the scientific community, especially after the discovery of photoluminescence at room temperature, which favors applications in new optical-electronic devices. This work used the Polymeric Precursors Method to obtain CTO doped with rare earth ion: Tm3+, Tb3+ and Sm3+. The materials: CTO:Sm1,2%,Tb0,3%,Tm0,5% and CTO:Sm2%,Tb0,3%,Tm0,5% were calcined at temperatures of 450, 500, 550 and 600 ° C in order to correlate structural changes and photoluminescence emission. Other materials: CTO:Sm1,2%,Tm0,5%, CTO:Tm0,5%,Tb0,3%, CTO:Sm1,2%,Tb0,3%, CTO:Sm1,2%Tb0,3%, CTO:Tb0,3%, CTO:Tm0,5%, CTO:Sm1,2% and CTO:Sm2% were calcined at 600 ° C in order to comprehend the influence of rare earth ions in photoluminescence emission process. The structural organization of the materials over long distances CTO:Sm1,2%,Tb0,3%,Tm0,5% was correlated with the emission FL. The FL intensity can be linked directly to the structural system, and the material totally disorganized or completely organized does not present FL emission. The material CTO:Sm1,2%,Tb0,3%,Tm0,5% showed the highest intensity FL to materials heat treated at 500oC, while the material CTO:Sm2%,Tb0,3%,Tm0,5% showed the highest intensity FL to materials heat treated at 450 oC. The electronic transitions from rare earth ions was observed to the obtained materials.
A propriedade fotoluminescente (FL) sempre despertou o interesse da comunidade científica, principalmente a partir da descoberta da fotoluminescência a temperatura ambiente, o que favorece uma infinidade de aplicações em novos dispositivos óptico-eletrônicos. Neste trabalho sintetizaram-se pelo Método dos Precursores Poliméricos matrizes de CTO dopado com os íons Tm3+, Tb3+ e Sm3+. Os materiais: CTO:Sm1,2%,Tb0,3%,Tm0,5% e CTO:Sm1,2%,Tb0,3%,Tm0,5% foram calcinados nas temperaturas de 450, 500, 550 e 600ºC para a comparação de evolução estrutural e fotoluminescência. Outros materiais: CTO:Sm1,2%,Tm0,5%, CTO:Tm0,5%,Tb0,3%, CTO:Sm1,2%,Tb0,3%, CTO:Sm1,2%Tb0,3%, CTO:Tb0,3%, CTO:Tm0,5%, CTO:Sm1,2% e CTO:Sm2% foram calcinados a 600ºC para estudar a emissão apenas dos íons adicionados na matriz. A organização estrutural dos materiais a longa distância do CTO:Sm1,2%,Tb0,3%,Tm0,5% foi comparada com a emissão FL. A intensidade FL esta ligada diretamente ao ordenamento estrutural, se o material estiver totalmente desorganizado ou totalmente organizado não haverá emissão FL. O material CTO:Sm1,2%,Tb0,3%,Tm0,5% calcinado a 500ºC apresentou a maior intensidade FL. O material CTO:Sm2%,Tb0,3%,Tm0,5% quando calcinado a 450ºC apresentou a maior intensidade FL. Após a análise dos dados referentes à caracterização dos materiais foi possível atribuir às transições eletrônicas que ocorrem com os íons terras-raras e a influência da inserção de mais de um íon dopante na matriz titanato de cálcio na emissão FL.
Aull, Brian Francis. "The impact of ion-host interactions on the 5d-to-4f spectra of lanthanide rare earth ions." Thesis, Massachusetts Institute of Technology, 1985. http://hdl.handle.net/1721.1/40343.
Full textMICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING.
Includes bibliographical references.
by Brian Francis Aull.
Ph.D.
Pinto, Ricardo de Almeida. "Síntese e caracterização de vidros de telureto dopados com íons de Eu3+ e Tb3+ com nanopartículas metálicas." Universidade de São Paulo, 2009. http://www.teses.usp.br/teses/disponiveis/3/3140/tde-29062009-124648/.
Full textThis work presents the synthesis and characterization of luminescent properties of vitreous systems TeO2-ZnO e TeO2-ZnO-PbO-Na2O doped with ions of europium and terbium containing silver, gold and copper nanoparticles (NPs), for applications in photonic devices. These glasses have a large window transmission (350-6500 nm), chemical stability, mechanical and thermal resistance, low phonon energy (around 700 cm-1) and high refraction index (~2,0). The optical absorption measurement showed the incorporation of rareearths ions in the trivalent form, responsible for the luminescence phenomenon in the glasses and the presence of absorption bands related to the surface plasmons resonance (SPR), located in approximately 490 nm (in the case of silver NPs) in 500 nm (in the case of gold NPs) and around 800 nm (in the case of copper NPs). The characterization of the metallic NPs was perfomed with transmission electron microscopy (TEM) with the aid of electron diffraction and energy dispersive spectroscopy techniques that allowed the observation of metallic NPs, crystalline with several shapes and sizes. The measurements were made through with excitation of 405 nm for samples doped with Eu3+ and 377 nm for samples doped with Tb3+, using a fluorescence spectrometer, with Xenon lamp with pulses varying from 2 to 3 s. The bands associated to Eu3+ emission were measured at 580 nm, 590 nm, 614 nm, 650 nm and 695 nm due to the transitions 5D07FJ (with J = 0 to 4). The band situated at 614 nm related to electric dipole transition is the most intense because it is sensitive to changes in the local field, caused by the presence of metallic NPs. For samples doped with Tb3+ it was observed emissions at 485 nm, 550 nm, 590 nm and 623 nm, associated with the transitions 5D47FJ (with J = 6 to 3) being the 550 nm emission also related to electric dipole transition and consequently the most sensitive to changes in the local field, caused by the presence of metallic NPs. For the samples codoped with Eu3+ and Tb3+ ions it was observed significative enhancement of the luminescence at 614 nm emission in the presence of silver NPs. The achievement of the enhancement of the luminescence of Eu3+ ions only by energy transfer from Tb3+ is not a trivial mechanism. However, it was observed in samples prepared with different concentrations of acceptor and donors ions and intensified in the presence of NPs silver. The enhancement of the luminescence is probably caused by the increase of the local field around the rare earth ions and by processes of energy transfer between the metallic NPs and the rare earth ions. In these cases the distance between the rare earth ions and the metallic NPs ranges from 5 to 20 nm. Thus, the presence of metallic NPs plays an important role for the enhancement of the luminescence, allowing the development of new materials with application in photonic.
Mishra, Jayanta Kumar [Verfasser], and A. [Akademischer Betreuer] Hangleiter. "Optical study of rare earth ion and transition metal impurities in nitrides / Jayanta Kumar Mishra ; Betreuer: A. Hangleiter." Braunschweig : Technische Universität Braunschweig, 2013. http://d-nb.info/1175822221/34.
Full textMello, Laura Bissoli de 1987. "Propriedades estruturais e óticas de vidros germanoniobofosfato dopados com íons terras raras." [s.n.], 2013. http://repositorio.unicamp.br/jspui/handle/REPOSIP/250548.
Full textDissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Química
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Resumo: No presente trabalho, buscou-se avaliar as mudanças promovidas pela substituição parcial e total de TiO2 por GeO2 em vidros niobofosfato co-dopados com Er/Yb previamente estudados pelo grupo. Uma série de sistemas vítreos de composições 20Na2O-30Nb2O5-(5-y-z)Al2O3-30P2O5-(15-x)TiO2-xGeO2-yEr2O3-zYb2O3 com x = (0; 5; 10; 15), y = (0; 1), z = (0; 2) mol%, obtidos por fusão-resfriamento, foram investigados quanto à sua estrutura, propriedades ópticas e de luminescência. Análises de FTIR e Raman sugerem que a estrutura de vidro não se altera de forma significativa ao longo da série de substituições de TiO2 por GeO2 e, consequentemente, a coordenação dos elementos devem se manter semelhantes. Na literatura reporta-se que íons Ge têm preferencialmente coordenação 4; entretanto, nos sistemas estudados, sugere-se que o Ge apresente coordenação 6, semelhante à do Ti substituído. Esta proposição é confirmada pelos espectros de P MAS-NMR, os quais indicam que os vidros possuem cadeias majoritariamente do tipo pirofosfato, sem mudança no grau de polimerização com as substituições. Também pôde-se confirmar a manutenção da coordenação com os resultados obtidos da fotoluminescência dos sistemas vítreos co-dopados, nos quais os tempos de vida de emissão do íon Er (5 ms) e parâmetros de intensidade de Judd-Ofelt dos diferentes sistemas vítreos são muito semelhantes entre si, e o processo de emissão de upconversion dos vidros dopados envolve 1,5 fótons. Quanto ao comportamento térmico, observa-se que os vidros contendo maior proporção de GeO2 têm maior estabilidade térmica e são, portanto, mais resistentes à desvitrificação quando comparado às composições contendo mais TiO2
Abstract: The aim of this work was to study the changes promoted by partial and complete substitution of TiO2 by GeO2 in Er/Yb co-doped niobophosphate glasses previously studied by the group. A series of glasses with composition 20Na2O-30Nb2O5-(5-y-z)Al2O3-30P2O5-(15-x)TiO2-xGeO2-yEr2O3-zYb2O3 with x = (0; 5; 10; 15), y = (0; 1), z = (0; 2) mol%, prepared by quenching-melt process, were investigated with respect to their structural, optical and luminescence properties. FTIR and Raman analysis suggest that the glassy chains didn¿t suffer relevant modifications with the TiO2 substitutions by GeO2 and as a consequence, the coordination of the ions weren¿t affected. The coordination of the Ge ion is reported as mainly thetraedral; however, in the present work, is suggested that Ge ion has an octahedral coordination, as well the TiO2 substituted. This proposition is confirmed by the P MAS-NMR spectra, which showed mainly pyrophosphate chains of the different glasses, without changings in their polymerization after the substitutions. The similar ions coordination was also confirmed by the photoluminescence behavior of the different co-doped samples, which showed equal Er emission decay lifetimes (5 ms) and Judd-Ofelt intensity parameters, and the upconversion emission process involved 1,5 photons. Regarding the thermal behavior, it is noted that the glasses containing higher proportions of GeO2 have higher thermal stability and are therefore more resistant to devitrification when compared to compositions containing more TiO2
Mestrado
Quimica Inorganica
Mestra em Química
Santos, Allysonn Jorge dos. "Sensor óptico de temperatura baseado no processo de conversão ascendente de energia em vidros fluorofosfatos dopados com Er3+." Universidade de São Paulo, 2016. http://www.teses.usp.br/teses/disponiveis/18/18158/tde-03052016-090614/.
Full textThe infrared-to-visible upconversion process is widely studied in materials doped with trivalent rare earth ions (RE3+) due to the various possibilities of technological applications. The process is based on the emission of photons with higher energy (in the visible) than the excitation photons (in the infrared) via the mechanisms of two-photon absorption and/or energy transfer between RE3+ ions. Among the studied materials emphasis is given to glasses and glass ceramics doped with Er3+, exhibiting intense emissions in the green and red, which can be efficiently excited by diode lasers in the near infrared region (980 nm). One application of this process is an optical temperature sensor based on the dependence of the ratio of the emission intensities of levels 2H11/2 and 4S3/2 of Er3+ on the temperature of the sample. Such sensor would be advantageous for operation in hostile environments, such as high voltage transformers, industrial processes, etc. Because the efficiency of upconversion also depends on the host matrix composition, flurophosphate glasses are interesting candidates due to their high chemical stability, good mechanical properties and relatively low phonon energy. Glasses with composition 25BaF225SrF2(30-x)Al(PO3)3xAlF3(20-z)YF3:zErF3 with x = 20 and z varying from 1.0 to 5.0 mol% were characterized and selected to develop the prototype employing the fluorescence of fluorophosphate glass doped with Er3+ for measuring temperatures with the following characteristics: low cost, high accuracy and fast response.
Martins, Vanessa Menezes. "Desenvolvimento e caracterização fototérmica de novos materiais vítreos dopados com íons emissores terras-raras." Universidade Federal de Uberlândia, 2009. https://repositorio.ufu.br/handle/123456789/19674.
Full textNeste trabalho foram desenvolvidas duas novas matrizes vítreas, uma fosfato e outra borato, denominadas PAN (40P2O5.20 Al2O3.40Na2CO3 (mol%)) e BAN (40B2O3.20 Al2O3 . 40Na2CO3 (mol%)), respectivamente. Estas matrizes foram dopadas com concentrações crescentes de íons de neodímio e praseodímio, visando o estudo de propriedades ópticas e térmicas nos mesmos. Para obter estas propriedades, inicialmente foram realizadas medidas de absorção óptica, fotoluminescência, tempo de vida, índice de refração, densidade mássica e calor específico. Em seguida aplicando a técnica de lente térmica de feixe duplo no modo descasado resolvida no tempo foram obtidas as propriedades fototérmicas das amostras. Verificou-se que as difusividades térmicas das matrizes PAN e BAN apresentaram valores similares. Determinou-se também a eficiência quântica de fluorescência das amostras dopadas com neodímio, através da técnica de lente térmica com o uso da amostra referência. Neste estudo ficou claro que a inserção de íons dopantes nas matrizes causa um efeito de supressão na luminescência. Este efeito tornou- se mais evidente na diminuição da eficiência quântica (e do tempo de vida) com o aumento da concentração. Por fim, à partir dos resultados da eficiência quântica e do tempo de vida, pôde-se calcular a taxa de decaimento não radiativo. Todos os resultados foram analisados em função da concentração de dopante, e em particular, para o caso do íon de neodímio inseridos na matriz PAN, constatou-se que estes vidros possuem uma boa combinação das propriedades termo- ópticas, que são essenciais para possíveis aplicações em materiais para meio ativo em lasers de estado sólido.
In this work two new glass matrices has been developed, a phosphate and borate one, PAN (40P2O5.20 Al2O3. 40Na2CO3 (mol%)) and BAN (40B2O3. 20 M2O3. 40Na2CO3 (mol%)), namely. The matrices were doped with increasing concentration of neodimium and praseodymium rare-earth ions in order to study its thermal and optical properties. To obtain these properties, initially, measurements of optical absorption, photoluminescence, lifetime, refractive index, mass density and specific heat were performed. In addition, applying the time resolved mode mismatched dual beam thermal lens technique the thermal-optical properties were found. It was found that the PAN and BAN thermal diffusivities were quite similar. By using a reference sample the quantum efficiency of the neodymium sample were determined. It was noticed that the insertion of dopant fens causes a luminescence quenching. This effect became more evident in the decreasing of the quantum efficiency (and lifetime) when concentration is increased. Finally, from the above results it was possible to calculate the nonradiative relaxation rate. All the found results were analised as a function of concentration. In particular, the PAN matrix presents a good combination of thermal and optical properties, which are essential to possible aplication in optical devices.
Dissertação (Mestrado)
Assumpção, Thiago Alexandre Alves de. "Desenvolvimento de técnica para nucleação de nanopartículas metálicas em vidros de germanato dopados com íons de túlio para aplicações em dispositivos fotônicos." Universidade de São Paulo, 2010. http://www.teses.usp.br/teses/disponiveis/3/3140/tde-18082010-163909/.
Full textThis work presents the preparation and the methodology used for the nucleation of silver nanoparticles (NPs), and the investigation of the luminescent properties of PbO-GeO2 glass system doped with thulium ions and codoped with thulium and ytterbium ions, in the presence of NPs silver, for application in photonic devices. This glass system presents a large transmission window (400 4500 nm) when compared to silicates, borates and phosphates, high refractive index (2.0), low phonon energy (700 cm-1), high mechanical strength and chemical durability. In order to obtain greater control over the process of nucleation of NPs, different processes were used for the heat-treatment, varying mainly the time and the temperature. From the transmission electron microscopy (TEM), the presence of NPs in the glassy material could be confirmed, and from Energy Dispersive Spectroscopy (EDS) analysis, it was determined that the NPs have silver in their composition. The NPs may be purely metallic and, in some cases, composed by silver and elements of the matrix glass. Optical Absorption measurements showed the incorporation of Tm3+ and Yb3+ ions in the trivalent form, and the presence of absorption bands related to the Surface Plasmon Resonance (SPR) of silver, located in the range of 420 to 550 nm. Bands associated to Tm3+ upconversion (UPC) frequency centered around 480, 650 and 800 nm were observed due to transitions 1G4 3H6, 1G4 3F4, 3H4 3H6, respectively. The SPR of silver NPs were not observed for the samples heat-treated at 420 °C, which contained silver NPs in their composition. However, an increase in the luminescence was observed and the presence of NPs was confirmed by TEM analyses. For the samples heat-treated by continuous and non-continuous time intervals, we observed the tendency of the formation of smaller, larger and aggregated NPs, and a higher tendency of enhancement of the luminescence for the second case. For the samples heat-treated at different temperatures in short time interval, we observed the formation of the SPR band for temperatures higher than 500 °C, and a considerable increase in the luminescence. Variations in the process of NPs nucleation were related to the different heat-treatments adopted. The study of the luminescence intensity variation as function of the laser power excitation showed that the NPs do not interfere in the Tm3+ UPC luminescence processes. Thus, the enhancement in the luminescence was attributed to local field enhancement in the proximities of rare-earth ions (REIs). Therefore, the development of an appropriate method of heat-treatment plays an important role in the process of NPs nucleation, and enables a considerable increase in the luminescence from the REIs, and gives new properties to materials which are of great interest for applications in photonic devices.
Silva, Diego Silvério da. "Vidros de germanato com nanopartículas metálicas e semicondutoras dopados com terras-raras para aplicações em fotônica." Universidade de São Paulo, 2010. http://www.teses.usp.br/teses/disponiveis/3/3140/tde-06122010-103231/.
Full textThis work presents a spectroscopic study about Eu3+, Nd3+ and Er3+ rare-earth doped germanate glasses containing metallic and semiconductor nanoparticles (NPs) aiming the development of new materials for photonic applications. These glasses have a large transmission window (400-4500 nm), high refractive index (~ 1.9), low phonon energy (700 cm-1), high mechanic resistance and chemical durability. Transmission Electronic Microscopy analysis was performed to verify the metallic and semiconductor NPs nucleation, and indicated the presence of metallic and semiconductor NPs. X ray fluorescence by energy dispersive spectroscopic (EDS) and electron diffraction analysis showed the chemical nature of the NPs. Optic absorption measurement proved the trivalent incorporation of the rare-earth ions, the responsible phenomenon for the luminescence of the glasses that allowed the measurement of the absorption bands related to the superficial plasmon resonance. Emission measurements were performed with different procedures, related to nature of the rare-earth. High emission bands of Eu3+ were measured related to the 7F J (J=0 to 6) -> 5D 0 transitions; emission bands associated to the frequency upconversion of Er3+ in 530, 550 and 670nm related to the 2H 11/2 -> 4I 15/2, 4S 3/2 -> 4I 15/2 e 4F 9/2 -> 4I 15/2 transitions were observed, and as well as emission bands of Nd3+ in 900, 1076 and 1350 nm related with the 4F 3/2 -> 4I 9/2, 4F 3/2 -> 4I 11/2 e 4F 3/2 -> 4I 13/2 transitions. A significant enhancement of the red light luminescence of Eu3+ was observed in the samples containing silver, gold, and silver together with gold NPs. For the samples containing silicon NPs it was observed a considerable enhancement of the frequency upconversion emission of the erbium. The luminescence enhancement of the samples with metallic NPs is due to the enhancement of the local field nearby the rare-earth ions and/or to the energy transfer between the NPs and the rare-earth ions. The luminescence enhancement of the samples with semiconductor NPs are due to the efficient energy transfer between the NPs and the rare-earth ions originated from the excitons recombination inside the semiconductor NPs. Therefore, the presence of the NPs plays an important role on the luminescence enhancement, allowing de development of new materials for nanophotonic applications.
Pereao, Omoniyi Kolawole. "Functionalisation of electrospun nanofibre for lanthanide ion adsorption from aqueous solution." University of the Western Cape, 2018. http://hdl.handle.net/11394/6393.
Full textRare earth elements (REEs) have widespread use and importance for industrial applications due to their metallurgical, optical and electronic properties. Several typical hydrometallurgical techniques such as adsorption, chemical precipitation, filtration, ion exchange and solvent extraction techniques have been used for separation and recovery of the rare earth metals from aqueous solutions. Adsorption was recognised as one of the most promising methods due to its simplicity, high efficiency and availability. Many adsorbents are being investigated but there are few adsorbents containing specific functional groups in practical use for REEs recovery. This aim of this study was to develop a nanofibre based adsorbent containing glycolic acid functional groups for the recovery of rare earth metals. Polystyrene (PS) and polyethylene terephthalate (PET) nanofibres were prepared by the electrospinning technique, glycolic acid functional groups were grafted onto the PS or PET nanofibres and the potential of the two modified nanofibre adsorbents for adsorption of Ce3+ or Nd3+ from aqueous solution were investigated and compared. The adsorption experiments were carried out to investigate the effect of different adsorption parameters such as pH, contact time and initial concentration in a batch system in order to achieve the objectives of this research.
Lovrić, Marko [Verfasser], Dieter [Akademischer Betreuer] Suter, and Philippe [Akademischer Betreuer] Goldner. "Hyperfine characterisation and enhanced optical to spin storage in rare earth ion doped crystals / Marko Lovrić. Betreuer: Dieter Suter. Gutachter: Philippe Goldner." Dortmund : Universitätsbibliothek Dortmund, 2012. http://d-nb.info/1098312368/34.
Full textFreitas, Alysson Miranda de. "Estudo dos parâmetros de emissão laser de vidros fosfatos dopados com nanocristais de ZnTe e co-dopados com íons de Yb3+." Universidade Federal de Juiz de Fora (UFJF), 2015. https://repositorio.ufjf.br/jspui/handle/ufjf/4903.
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CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior
Neste trabalho, propomos uma nova matriz vítrea, denominada de PZABP, de composição nominal 60P205 . 15ZnO . 5A/203 . 10Ba0 . 10Pb0, em mol %, nanoestruturada com nanocristais de ZnTe e dopada com íons de Yb3+ e avaliamos a viabilidade de utilização deste material para aplicações em dispositivos fotônicos, tais como, lasers de alta potência, fibras ópticas lasers, lasers de pulsos ultra-curtos e lasers sintonizáveis na região do infravermelho. As amostras foram produzidas através do método de fusão-resfriamento, sendo confeccionado dois conjuntos. Um deles, PZABP + xYb, foi dopado apenas com íons de Yb3+ em concentrações que variam de 0% a 10%, em wt%, com acréscimos de 1%. Outro conjunto, PZABP + 1ZnTe + xYb, foi dopado com 1% de nanocristais semicondutores de ZnTe e íons de Yb3+ em concentrações que variam de 0% a 5%, em wt%. As propriedades ópticas das amostras e as interações entre os íons de Yb3+ vizinhos e entre os nanocristais de ZnTe e os íons Yb3+ foram estudadas através das técnicas de Absorção Óptica, Fotoluminescência e Fotoluminescência Resolvida no Tempo. A Espectroscopia de Lente Térmica e a técnica de Capacidade Térmica Volumétrica, também conhecida como pc, foram utilizadas para caracterizar as propriedades térmicas das amostras. Alguns dos principais parâmetros que analisam o desempenho e o limiar de ação laser do material foram estimados a partir da determinação das seções de choque de absorção e emissão dos íons de Yb3+ quando inseridos nessa matriz. De forma geral, a matriz vítrea PZABP demonstrou-se um excelente material hospedeiro para os íons de Yb3+ por apresentar uma ampla janela óptica, ser tolerante a altas concentrações de dopantes e não formar aglomerados de íons de Yb3+, garantindo assim uma boa qualidade óptica para aplicações em fotônica. Parâmetros importantes como o tempo de vida e a eficiência quântica do material apresentaram valores comparáveis aos encontrados na literatura. Foi verificado que a presença dos nanocristais de ZnTe intensificou a emissão dos íons de Yb3+, indicando que houve transferência de energia entre os nanocristais e os íons. Com relação a análise térmica, foram encontrados valores desejáveis para aplicações que envolvem ambientes superaquecidos. A alta difusividade e condutividade térmica das amostras as permitem dissipar calor rapidamente e a baixa variação do caminho óptico com a temperatura (ds/dT) indica que o feixe não sofre desvios muito acentuados no interior da cavidade óptica. Os parâmetros de emissão laser encontrados estão comparáveis aos de outras matrizes vítreas já estudadas, embora a presença dos nanocristais de ZnTe pareça prejudicar esses parâmetros. Portanto, de acordo com os resultados encontrados e com base nas possíveis melhoras que podem ser realizadas, concluímos que a matriz vítrea PZABP nanoestruturada com nanocristais semicondutores de ZnTe e dopada com íons de Yb3+ é um material viável para aplicações em dispositivos fotônicos de alta potência.
In this work, we have proposed a new glass matrix, called PZABP, with nominal composition 60P205 . 15ZnO . 5A/203 . 10Ba0 . 10Pb0, in mol %, nanostructured with ZnTe semiconductor nanocrystals and doped with Yb3+ ions, then, we analized its availability to photonics devices application like high power lasers, optical fiber lasers, ultra-short pulses lasers and tunable lasers in the infrared region. The samples were produced by fusion method, being made two sets. One, PZABP + xYb, was doped with Yb3+ ions at various concentrations from 0% to 10%, in wt%.The other one, PZABP + 1ZnTe + xYb, was doped with semiconductors nanocrystals of ZnTe and Yb3+ ions at concentrations from 0% to 5%, in wt%. The optical properties of the samples and the interactions between neighbors Yb3+ ions and between semiconductors nanocrystals of ZnTe and Yb3+ ions were studied by Optical Absorption, Photoluminescence and Time Resolved Photoluminescence techniques. Thermal Lens Spectroscopy and Heat Volumetric Capacity, also know as pc, were used to characterize the thermal properties of the samples. The main parameters that avail the performance laser and the threshold action laser were estimated by the determination of absorption and emission cross section of the Yb3+ ions when they are inserted in this matrix. The PZABP glass matrix showed to be an excellent host material to Yb3+ ions because it present a large optical window, it is tolerant to high dopants concentration and not showed Yb3+ clusters. Important parameters like lifetime and quantum efficience showed values comparable to others found in the literature. It was verified that the presence of ZnTe nanocrystals had enhanced the emission of the Yb3+ ions, indicating that have occurred energy transfer between ZnTe nanocrystals and Yb3+ ions. Thermal properties have presented interesting values to applications that involved superheated environment. The high thermal diffusivity and high thermal conductivity allow the sample to dissipate the heat quickly. The low variation of the optical path with the temperature (ds/dT) indicate that the laser beam not strongly deviates into the optical cavity. The laser performance parameters obtained are comparable to the other glass matrix found in the literature, although the presence of the ZnTe nanocrystals seems to prejudice these parameters. According with the results found and the improvement that could be done, we have conclude that the glass matrix PZABP nanostructured with semiconductores nanocrystals of ZnTe and doped with Yb3+ ions is a viable material to application in high power photonics devices materials.
Santos, Simei Tarse Sobrinho. "Síntese e caracterização de materiais híbridos siloxano-PMMA dopados com íons Eu(III)." Pós-Graduação em Química, 2014. https://ri.ufs.br/handle/riufs/6058.
Full textNeste trabalho materiais híbridos Siloxano-Polimetacrilato de metila (PMMA) foram sintetizados e dopados com íons Eu(III) provenientes de cloreto e nitrato de európio (III) sólidos, cloreto de európio (III) em solução alcoólica e complexo 3-aminopirazina-2-Carboxílato de lantânio e európio. O hibrido foi preparado a partir dometacrilato de metila (MMA) e do 3-metacriloxi-propil-trimetoxisilano (MPTS), utilizando-se como agente inicializador de polimerização o peróxido de benzoila (BPO). A utilização dametodologia de síntese sol-gel por catálise ácida possibilitou a obtenção de materiais sólidos puros e dopados com diferentes fontes de európio, com características amorfas, como ficou evidente pelos dados de difração de raios X de pó. A inserção de complexo de európiopolicristalino na matriz não alterou as características estruturais da amostra.Observou-se que os materiais que foram dopados com európio em solução, apresentaram maior quantidade de solventes adsorvidos e características estruturais que alteraram as suas propriedades espectroscópicas. As amostras dopadas com sais sólidos apresentaram características estruturais semelhantes. Observou-se que os tempos de vida médios das emissões radiativas aumentam com o tratamento térmico, o que indica que o tratamentoreduz o número de grupos supressores de luminescência no ambiente de coordenação do íon lantanídeo e o caráter não monoexponencial do decaimento é indicativo da presença de diferentes ambientes de coordenação. Pelo RMN do 29Si para as amostras dopadas com solução alcoólica de cloreto de európio são observadas espécies monoméricas(R-Si(OSi)(OH)2), diméricas(R-Si(OSi)2(OH)) e totalmente condensadas(R-Si(OSi)3) com um grau de policondensação de até 78%. Os materiais dopados com o complexo apresentam forte luminescência, exceto as amostras tratadas a 200°C, o que é indicativo da degradação térmica do complexo de coordenação. Observou-se que a presença de solvente alterou a estabilidade térmica das amostras, e que a diferentes tratamentos térmicos e a dopagem com diferentes fontes de európio influenciaram sensivelmente o ambiente de coordenação dos íons Eu(III) nos materiais híbridos orgânico-inorgânicos.
Car, Benjamin. "Étude de la dynamique des spins autour d'un ion erbium pour le développement de mémoires quantiques." Thesis, Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLS251/document.
Full textAt low temperatures, rare-earth doped matrices are promising supports for the development of quantum memories. Among them, Er³⁺:Y₂SiO₅ is well adapted to the current communication networks because of its transition at Telecom wavelength. However, quantum storage has a very limited efficiency and a short duration in this material. In this thesis, I study the interactions that hinder the coherence at low magnetic fields. In this regime, the dominant processes are flip-flops between opposite electronic spins of erbium ions and the super-hyperfine interaction with nuclear spins of yttrium ligands. I have included the strong anisotropy of the Y₂SiO₅ matrix in the calculation of these two dipolar interactions. In order to check the anisotropy of the flip-flops between erbium spins, I have used two different optical techniques : spectral hole-burning and transient excitation. I have showed that their rate is maximum when the magnetic field is perpendicular to the principal axis of the effective spin tensor. Moreover, the flip-flop probability globally increases as the square of the doping concentration and as the inverse of the field. Then I have also checked the calculations of super-hyperfine interactions by measuring photon echo modulations. I have found a particular situation where an erbium ion is strongly coupled to a single yttrium. On the contrary, the coupling to several ligands at very low magnetic fields drastically reduces the coherence time
Cordeiro, Neto Marcelino. "Espectroscopia óptica dos vidros PZABP dopados com terras-raras e nanopartículas semicondutoras." Universidade Federal de Juiz de Fora (UFJF), 2014. https://repositorio.ufjf.br/jspui/handle/ufjf/5356.
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CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior
O objetivo desta tese é analisar se as propriedades ópticas apresentadas neste trabalho qualificam o sistema vítreo PZABP, com composição nominal 60P2O5.15ZnO.5Al2O3.10BaO.10PbO (% mol), dopado com íons terras-raras trivalentes, itérbio (Yb3+) e európio (Eu3+) e, também, com nanopartículas semicondutoras de telureto de zinco (ZnTe) como potencialmente útil para construção de dispositivos de emissão de luz na região de 920 nm a 1060 nm. A teoria de Judd-Ofelt é usada nos cálculos dos parâmetros de intensidade Ωλ(λ = 2,4,6). Técnicas de microscopia de força atômica (AFM), absorção óptica (AO), fotoluminescência (FL) e fotoluminescência resolvida no tempo (FLRT) caracterizam o sistema vítreo. A finalidade do ZnTe é aumentar a seção de choque de absorção do sistema vítreo PZABP e transferir energia para os íonsEu3+ e/ouYb3+. A formação de dois tipos de nanopartículas semicondutoras de telureto de zinco ZnTe-propriedades de bulk e pontos quânticos – foram identificados. FL e FLRT sugerem transferência de energia dos íons de Eu3+ e/ou ZnTe para os íons deYb3+.
The aim of this thesis is to analyze if the optical properties presented in this work qualify the glass system PZABP, with nominal composition 60P2O5.15ZnO.5Al2O3.10BaO.10PbO(% mol), doped with trivalent rare earth ions, ytterbium (Yb3+) and europium (Eu3+) as well as zinc telluride (ZnTe) as potentially useful for light emission devices in the infrared region from 920 nm to 1060 nm. The Judd-Ofelt theory is used to calculate the intensity parameters Ωλ(λ = 2,4,6). Atomic force microscopy (AFM), optical absorption (OA), photoluminescence (PL) and time-resolved photoluminescence (TRPL) techniques characterized the vitreous system. The formation of two kinds of ZnTe semiconductor nanoparticles - bulk-like and quantum dots –were identified. PL and TRPL suggest the energy transfer from Eu3+ ions and/orZnTetoYb3+ ions.
Queiroz, Thiago Branquinho de. "Caracterizações estruturais e espectroscópicas de cerâmicas ferroelétricas de PLZT dopadas com íons de terras raras trivalentes." Universidade de São Paulo, 2009. http://www.teses.usp.br/teses/disponiveis/76/76131/tde-10032009-111852/.
Full textIn recent years, there has been a great interest for rare-earth (RE) doped transparent ceramics as near-infrared laser active media. Particularly, Nd3+ and Yb3+-doped ceramics are of special interest due to the possibility of generating high power emissions at around 1.0 mm. Even though lead lanthanum zirconate titanate (PLZT) ceramics, with composition La/Zr/Ti = 9/65/35, are mostly known by their ferroelectric and electro-optic properties, recent works by de Camargo et al. have also indicated their potentiality as laser active media. In this regard, the most promising system is PLZT:Nd (as compared to YAG:Nd - neodymium-doped yttrium aluminium garnet), however, laser action of the former has not yet been possible, the reason lying in the presence of secondary phases (invisible to the naked eye) that compromise the optical quality of the ceramics, especially for samples with concentration higher than 1.0 wt% Nd2O3. Since the structural quality of samples has a direct implication on their spectroscopic and optical qualities, the goals pursued in this work are to present means to obtain highly transparent samples with higher incorporation of dopants, as well as to understand some fundamental questions regarding the microstructure of PLZT:RE ceramics. Thus, an alternative method, based on the obtainment of RE-doped precursor oxides, is presented for the synthesis of PLZT:RE and several techniques (XRD, DTA-TG, FT-IR, Raman, NMR and Luminescence) are used to characterize the samples, as a function of doping concentration (0,1 4,0 wt% RE2O3). These studies are done in comparison to the conventional method used in previous works. Solid state NMR spectroscopy of 207Pb proved to be a very useful tool for the understanding of these complex systems. Because Nd3+ and Yb3+ are paramagnetic and thus inaccessible by NMR, the strategy used for the characterization of their spatial distribution was to study samples doped with their respective diamagnetic mimics Sc3+ and Y3+ (45Sc and 89Y nuclei). XRD results have shown formation of less secondary phase for samples prepared by alternative method, being identified as secondary phase pyrochlore structure (La,Nd)2(Zr,Ti)2O7, partially monoclinic/cubic ZrO2 and cubic ZrO2 of the samples doped with Nd3+, Y3+ and Yb3+ respectively. NMR measurements allowed to make proposals about dopant ion insertion while secondary phase is formed and showed homogeneous distribution of dopant into the matrix, aswell luminescence measurements with maximum dopant solubility being less than enough to show any suppression of luminescence.
Wang, Wei. "Computational Spectroscopic Analysis of Orbital Hybridization and Crystal Field Interaction for Trivalent Uranium Ion in Crystals of Hexagonal Symmetry." University of Cincinnati / OhioLINK, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1258479110.
Full textMhibik, Oussama. "Développement des sources lasers solides continues, visibles et stabilisées en fréquence : une alternative aux lasers à colorants." Phd thesis, Université Paris Sud - Paris XI, 2011. http://tel.archives-ouvertes.fr/tel-00656426.
Full textQUEIROZ, CARLOS A. da S. "Terras raras: fracionamento, purificação e controle analítico." reponame:Repositório Institucional do IPEN, 1988. http://repositorio.ipen.br:8080/xmlui/handle/123456789/11634.
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Dissertacao (Mestrado)
IEA/D
Instituto de Quimica, Universidade de Sao Paulo - IQ/USP
FUJIMOTO, TALITA G. "Microestrutura e propriedades elétricas e dielétricas do titanato de estrôncio puro e contendo aditivos." reponame:Repositório Institucional do IPEN, 2016. http://repositorio.ipen.br:8080/xmlui/handle/123456789/26933.
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O titanato de estrôncio (SrTiO3) possui estrutura cristalina do tipo perovsquita. Materiais com este tipo de estrutura são utilizados para diversas aplicações, tais como, sensores, atuadores, em células a combustível de óxido sólido, entre outros. Devido as suas interessantes propriedades físicas, o SrTiO3 vem sendo intensamente estudado, em especial com a introdução de dopantes. Portanto, neste trabalho foi investigada a influência de diferentes teores de Ca (1; 2,5 e 5% mol) e Pr (0,025; 0,050; 0,075 e 1% mol) na microestrutura e propriedades elétricas e dielétricas do SrTiO3, assim como o material sem aditivos (puro). Os resultados mostram que após a sinterização do SrTiO3 puro, a microestrutura consiste de grãos poligonais com tamanho médio micrométrico, além de texturas lisas e rugosas. A condutividade elétrica das amostras sintetizadas sinterizadas a 1450 e 1500ºC é máxima para 2 horas de patamar. Apenas as amostras de SrTiO3 contendo 1% em mol de Ca apresentam fase única. O tamanho médio de grãos das amostras contendo 1% em mol de Ca é 10,65 ± 0,28 µm e para teores acima deste valor ocorre crescimento significativo dos grãos. As medidas de condutividade elétrica mostraram que as amostras contendo a adição de 1% em mol de Ca possuem maior condutividade dos grãos em relação ao material puro. Para as amostras contendo teores de até 0,075% mol de Pr, pode-se observar alguns grãos lisos e outros rugosos e não há variação considerável do tamanho médio de grãos. As amostras contendo menor teor de Pr (0,025% mol) apresentam maior condutividade dos grãos e contornos de grãos. As amostras de SrTiO3 sintetizado sinterizadas a 1450ºC/10 h apresentaram permissividade elétrica colossal em temperatura ambiente em altas frequências.
Dissertação (Mestrado em Tecnologia Nuclear)
IPEN/D
Instituto de Pesquisas Energéticas e Nucleares - IPEN-CNEN/SP
Magne, Sylvain. "Etat de l'art des lasers à fibre : étude d'un laser à fibre dopée ytterbium et spectroscopie laser de fibres dopées." Saint-Etienne, 1993. http://www.theses.fr/1993STET4027.
Full textLongdell, J. "Quantum Information Processing in Rare Earth Ion Doped Insulators." Phd thesis, 2003. http://hdl.handle.net/1885/47689.
Full textYan, Kunlun. "Rare-earth ion doped chalcogenide waveguide amplifiers." Phd thesis, 2018. http://hdl.handle.net/1885/162514.
Full textCho, Junghyun. "Role of rare-earth dopants on the improved creep properties of aluminum oxide /." Diss., 1998. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:9919142.
Full textTissue, Brian Max. "Energy transfer in rare earth ion clusters and fluorescence from rare earth doped La₁ ̣₈₅Sr₀ ̣₁₅CuO₄ superconductors." 1988. http://catalog.hathitrust.org/api/volumes/oclc/20189246.html.
Full textBartholomew, John Glen. "Investigation of the scalability of rare-earth-ion quantum hardware." Phd thesis, 2014. http://hdl.handle.net/1885/150124.
Full textMarzban, Sara. "Rare-earth ion doped planar waveguides for integrated quantum photonics." Phd thesis, 2017. http://hdl.handle.net/1885/144606.
Full textFraval, Elliot. "Minimising the Decoherence of Rare Earth Ion Solid State Spin Qubits." Phd thesis, 2005. http://hdl.handle.net/1885/47058.
Full textHan-LinHsu and 徐漢霖. "Synthesis and luminescent properties of rare-earth ion doped Li3Ba2La3(MoO4)8 phosphors." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/42024449184955709194.
Full text國立成功大學
材料科學及工程學系碩博士班
98
Rare-earth (RE) ion doped phosphors, Li3Ba2La3-xREx(MoO4)8 (RE = Eu3+, Dy3+), were synthesized by a solid-state reaction process at 800C. The structural and photoluminescent properties of the prepared phosphors were investigated by X-ray diffraction, scanning electron microscopy, Raman scatter spectroscopy, UV-visible absorption, and photoluminescence (PL) spectroscopy. The aim of the research was to develop novel phosphors for the UV-LED to white light conversions. The experimental results showed that the dominant emissions of the Li3Ba2La3-xEux(MoO4)8 phosphors under the UV excitation (394 nm) were at 593 nm and 618 nm, originating from the electronic transitions between the trivalent RE states. Due to the high phonon frequency of the host lattice, the transitions from the emitting levels higher than 5D0 were not observed in the PL spectra. The above two observed emissions were due to the 5D0->7F1 (593 nm) and 5D0->7F2 (618 nm) transitions. In particular, the 5D0->7F2 emission was very strong and for the x=2.1 samples, its peak intensity was about 3.3 times more than the commercial phosphors ZnS:(Mn2+,Te2+). The CIE chromaticity coordinate of the Li3Ba2La0.9Eu2.1(MoO4)8 red emissions was calculated to be at (0.67, 0.33), which is almost the same as the standard red chromaticity of the NTSC system. In the Li3Ba2La3-xDyx(MoO4)8 (x=0.01-0.24) series, the dominant emissions under the UV excitation (388 nm) were from the 4F9/2->6H15/2 (blue) and 4F9/2->6H13/2 (yellow) transitions, and the intensity of the later was stronger. The mixture of all the emissions had the CIE chromaticity coordinates at (0.35, 0.40), which is at the yellowish-white color region.
Thiel, Charles Warren. "Energies of rare-earth ion states relative to host bands in optical materials from electron photoemission spectroscopy." 2003. http://etd.lib.montana.edu/etd/2003/thiel/ThielC03.pdf.
Full textChang, Yee-Cheng, and 張翌誠. "Synthesis and photo-luminescence properties of rare earth ion doped Li3Ba2Gd3(MoO4)8 phosphors." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/03947122628165768871.
Full text國立成功大學
材料科學及工程學系碩博士班
97
The objet of this study is to synthesize Li3Ba2Gd3(MoO4)8 doped with various activators(Eu3+,Tb3+,Dy3+,Er3+,Sm3+), and the raw material had been mechanically activated by grinding in high energy vibromill followed by calcined at temperature of 900℃ for 12 h. By using XRD, SEM, PL spectra, and UV-visable spectra, the characterization of structure, morphology of powders and photo-luminescent properties of phosphors were analized. The dominant emission peaks of Li3Ba2Gd3(MoO4)8:Eu3+ phosphor are 5D0→7F1(591nm)、5D0 →7F2(614nm) which are originate from intra-4f transitions of excited state. The intensity of the emission from 5D0 to 7F2 is stronger than 5D0 to 7F1 and three times more than commercial phosphors, ZnS:Mn2+,Te2+ when Eu3+ concentration in x=2.4. The CIE chromaticity coordinates of red emission of the Li3Ba2Gd0.6Eu2.4(MoO4)8 phosphor is (0.67, 0.33) which is just at NTSC system standard red chromaticity. There are two regions in the excitation spectra of Li3Ba2Gd2 Tb1(MoO4)8 phosphor;one is assigned from 4f��5d transition in 200 to 300 nm, and the others are from intra-4f transitions in 350 to 500 nm. The dominant emission peak of Li3Ba2Gd2Tb1(MoO4)8 phosphor is 5D4��7F5 under excitation of 307nm. The CIE chromaticity coordinates of green emission of the Li3Ba2Gd2 Tb1(MoO4)8 phosphor is (0.25, 0.58). The the other series of green phosphor is Li3Ba2Gd2.95Er0.05(MoO4)8.Because its emission peaks locates in the light of green region, it has better color rendering index than Li3Ba2Gd2 Tb1(MoO4)8. However, the valence electrons are shielded by the 5s and 5p outer electrons, the valance electrons of trivalent rare earth ions are weakly affected by ligand ions in crystals, so the features of optical spectra of the most phosphors doped with trivalent rare earth, such as Li3Ba2Gd3(MoO4)8:Dy3+ and Li3Ba2Gd3(MoO4)8:Sm3+ is similar to those expected for free ions.
Chen, Hou-Ren, and 陳厚仁. "Passive Mode Locking of Rare-Earth Ion Doped and Semiconductor Optical Amplifier Based Lasers." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/93059022344171104008.
Full text國立交通大學
光電工程研究所
101
In the thesis, we investigate two topics. First, we use a new fabrication method for single-walled carbon nanotube (SWCNT) and graphene oxide (GO) saturable absorbers (SAs) to sustain high-power illumination. Using a series of SAs incorporating different amounts of SWCNTs and GOs, we demonstrate mode-locking for Nd:GdVO4 and Nd:LuVO4 lasers in the 1 μm spectral range. Using SWCNT-SAs for Nd:GdVO4 laser, continuous-wave mode-locking (CWML) with a maximum output power of 3.6W at 1063 nm and high noise extinction of 61 dB has been achieved to give the highest pulse peak power of 3.6 kW and pulse energy of 30 nJ under 15-W pumping. For Nd:LuVO4 laser, GOSAs are used and CWML pulses with maximal output power of 3.89 W at 1065.7 nm are obtained under 15-W pumping to give the highest pulse peak power of 5.44 kW and pulse energy of 32 nJ, for which the high noise extinction of 66 dB has been achieved. To our knowledge, those are the highest reported output power for CWML lasers with SWCNT-SAs and GO-SAs, respectively. The measured nonlinear absorption of the SWCNT-SAs shows a modulation depth of ~3% with subpicosecond recovery time of ~630 fs. For GOSAs, the nonlinear absorption shows the modulation depth of about 2.54%, 4.14%, and 5.36% for GO amounts of 0.6, 0.9, and 1.25 mg. On the other hand, in order to insert the GOSAs between two fiber connectors, we fabricate the polymer-based GOSAs to be use in the all fiber laser system. Broadband graphene oxide/PVA films, which are used as saturable absorbers in the mode locking of erbium-doped and ytterbium-doped fiber lasers, have been demonstrated. They provide modulation depths of 2.95% and 6% at 1.06 μm and 1.55 μm, respectively. Stable self-starting mode-locked pulses are obtained for both lasers, confirming that graphene oxide does not have wavelength selectivity and is cost effective for 1.06-μm and 1.55-μm pulse generations. Second, we report the generation of passively harmonic mode-locked pulses using a 1.06 μm semiconductor optical amplifier (SOA) in a figure-eight laser configuration operated in the all-normal-dispersion regime. Different orders of harmonic mode locking can be obtained from 30 MHz to 12.02 GHz by tuning the injection current of the SOA from 80 to 660 mA together with the adjustment of polarization controllers. The highest pulse repetition rate increases almost linearly with the SOA current. As SOA current is set to 660 mA, we obtain the intracavity power of 46 mW at the highest repetition rate of 12.02 GHz, corresponding to the 1202th harmonic of the fundamental mode locking frequency. To our best knowledge, this is the lowest intracavity power to generate the highest repetition rate with a passively mode-locked laser in the all-normal-dispersion regime.
(6624245), Angel A. Pena. "Evaluation of Rare-Earth Element Dopants (Sm and Er) Effect on the Ablation Resistance and Emittance Tailoring of ZrB2/SiC Sintered Billets." Thesis, 2019.
Find full textHypersonic flight causes ultra-high surface temperatures which are most intense on sharp leading edges. One way of reducing the surface temperature is to apply a high emittance ceramic (HEC) on the leading edge, increasing the radiation component of heat transfer. An ideal HEC must have a high emittance, while also possessing a strong ablation resistance. From a scientific standpoint, it would be helpful if emittance could be tailored at different wavelengths. For example, materials with tailorable emittance could be used to improve the efficiency of engines, thermo-photo voltaic cells, and other applications. The approach used to create a ceramic with tailorable emittance was to use two different rare-earth elements, adding them to an ultra-high temperature ceramic (UHTC) in small quantities. The samarium element was added to increase the emittance of the UHTC over a large wavelength range (visible to near infrared wavelengths, consistent with the temperature range expected for hypersonic flight), and the erbium element was added to decrease the emittance at specific wavelength ranges. The goal of this study was to create an UHTC with tailorable emittance while maintaining the required ablation resistance. Therefore, ZBS billets with five different Sm to Er ratios and with a nominal total amount of 3 mol.% dopant incorporated were prepared by sintering in vacuum to 2000 °C. The ablation resistance was evaluated by using an oxyacetylene torch and observing at exposure times of 60 s and 300 s, whereas the emittance was evaluated at the Air Force Research Lab facilities via a laser heating testing. The results for the ablation testing showed that ZrB2-SiC (ZBS) billets co-doped with Sm and Er formed a beneficial c1-(Sm/Er)0.2Zr0.8O1.9 oxide scale as the majority phase, which is more thermally stable than the m-ZrO2 oxide scale typically formed in oxidized ZBS systems, resulting in a more adherent oxide scale to the unreacted material. The crystalline oxide scale and the amorphous phase were formed by a convection cell mechanism where the c1-(Sm/Er)0.2Zr0.8O1.9 crystalline islands precipitate, grow, and coalesce. Moreover, differences in surface temperatures between ZBS samples with different dopant ratios suggest differences in spectral absorptance/emittance between each of the five compositions evaluated. Despite that the emittance profiles with varying Sm:Er molar ratios were similar because m-ZrO2 was formed as the major oxide phase, the emittance study showed that the erbium oxide influences the emittance profile, as can be noted by the maximum and minimum emittance peaks. Furthermore, results showed that the emittance varies as a function of dopant(s) molar ratios and temperature at shorter wavelength ranges. These changes in the emittance are caused by the different Sm and Er concentration on the surface. Future work should be focused on producing the beneficial c1-(Sm/Er)0.2Zr0.9O1.8 phase directly from the manufacturing process, and therefore, maximize the effect of varying the Sm:Er molar ratios to tailor the emittance. Nonetheless, this study represents the first generation and reported emittance data of UHTC doping ZBS systems with both Sm and Er elements.
Wu, Wun-Hao, and 吳文皓. "The effect of rare earth element doping on the characteristics of LiFePO4 for Lithium-ion Batteries." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/74568834725211127373.
Full text國立雲林科技大學
化學工程與材料工程系碩士班
100
In this study, iron ore was used as Fe-precursor to produce iron phosphate by co-precipitation. By utilizing the product and lithium carbonate as a precursor, and ascorbic acid as a carbon source, LiFePO4 and LiNdxFe1-xPO4(x=0.3、0.5、1、2 mole% ) can be produced by solid method as cathode materials for secondary lithium ion batteries. In order to investigate the effect of charge-discharge property, lattice structure, conductivity, particel size, surface morphology of Nd-doped and undoped FePO4 and Nd-doped and undoped LiFePO4/C were study. In addition, the P/Fe molar ratio of iron phosphate was determined. The prepared sample were characterized by X-ray Diffraction(XRD), Ultraviolet/Visible (UV/vis), Thermogravimetric Analysis(TGA), Atomic Absorption Spectrometer(AAS), Dynamic Light Scattering(DLS), Filed Emission Scanning Electron Microscope (FE-SEM), Transmission Electron Microscope (TEM), Energy Dispersive Spectrometer(EDS), conductivity measurement, galvanostatic charge-discharge analyses. According to XRD result, the change in lattice parameter from Nd doping, indicating the peak shifted for FePO4 and LiFePO4/C is from 0.04° to 0.08° and 0.02° to 0.06°, respectively. The 0.3 mol.% Nd-doped FePO4 and the LiFePO4 exhibits small average particle size of 62 nm and 104 nm, respectively. In addition, SEM images show that agglomeration occurs in both FePO4 and LiFePO4/C when the doping content exceeds 0.5 mol.% Nd, which affects the charge-discharge capacity. The results, suggest that crystal growth of FePO4 in uniform solution leads to agglomeration and thus larger particle size. The charge-discharge test results show that the 0.3 mole% Nd-doped LiFePO4/C remains at the initial capacity of 91.5%、90.5% and 90.5% at rates of 0.5C、1C and 3C respectively, after 50 cycle. The undoped LiFePO4/C were remains at initial capacity of 70.3%、77.6% and 87.7% at rates of 0.5C、1C and 3C, respectively, after 50 cycle. As a result, the Nd-doped LiFePO4/C shows a better cycle capability than that of the undoped LiFePO4/C.
Ferguson, Katherine Rose. "Generation and storage of optical entanglement in a solid state spin-wave quantum memory." Phd thesis, 2016. http://hdl.handle.net/1885/109193.
Full textHonnavar, Gajanan V. "Mixed Alkali Effect in Oxyfluoro Vanadate Glasses And The Effect of Rare Earth Ions on Oxyfluoro Tellurite Glasses - A Spectroscopic Study." Thesis, 2016. http://etd.iisc.ernet.in/handle/2005/2667.
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