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Made available in DSpace on 2018-11-26T17:55:51Z (GMT). No. of bitstreams: 0 Previous issue date: 2016-04-01. Added 1 bitstream(s) on 2021-07-15T14:32:23Z : No. of bitstreams: 1 S0100-40422016000300328.pdf: 5545326 bytes, checksum: 7e6829c8c6880aa7e049f21c77f3decb (MD5) 2015 is the Year of Light, according to UNESCO. Chemistry has a close relationship with light and one of the materials that allows such synergy is glass. Depending on the chemical composition of the glass, it is possible to achieve technological applications for the whole range of wavelengths extending from the region of the microwave to gamma rays. This diversity of applications opens a large range of research where chemistry, as a central science, overlaps the fields of physics, engineering, medicine, etc., generating a huge amount of knowledge and technological products used for humanity. This review article aimed at discussing some families of glasses, illustrating some applications. Due to the extension of the theme, and all points raised, we thought it would be good to divide the article into two parts. In the first part we focus on the properties of heavy metal oxide glasses, fluoride glasses and chalcogenide glasses. In the second part we emphasize the properties of glassy thin films prepared by sol-gel methodology and some applications, of both glasses as the films in photonics, and more attention was given to the nonlinear properties and uses of photonic fibers. Univ Estadual Paulista, Inst Quim, CP 355, BR-14800060 Araraquara, SP, Brazil Univ Sao Paulo, Fac Filosofia Ciencias & Letras Ribeirao Preto, Dept Quim, BR-14040901 Ribeirao Preto, SP, Brazil Univ Fed Alfenas, Inst Ciencia & Tecnol, Campus Pocos De Caldas, BR-37715400 Pocos De Caldas, MG, Brazil Univ Presbiteriana Mackenzie, BR-01302907 Sao Paulo, SP, Brazil Univ Sao Paulo, Inst Fis Sao Carlos, BR-13566590 Sao Carlos, SP, Brazil Univ Fed Pernambuco, Dept Quim, BR-50740560 Recife, PE, Brazil Univ Laval, Ctr Opt Photon & Laser, Quebec City, PQ G1K 7P4, Canada Univ Estadual Paulista, Inst Quim, CP 355, BR-14800060 Araraquara, SP, Brazil

Made available in DSpace on 2018-11-26T17:55:51Z (GMT). No. of bitstreams: 0 Previous issue date: 2016-04-01. Added 1 bitstream(s) on 2021-07-15T14:32:24Z : No. of bitstreams: 1 S0100-40422016000300340.pdf: 4072751 bytes, checksum: 635ad996b95ebc83868fbdbb081d0bae (MD5) In this second part it will be discussed some photonic applications of glassy and glass ceramic thin films which can be used as planar waveguides. Some photonic applications require certain specifications of glass, which can be quantified by studying the nonlinear optical properties of the materials. Therefore, a brief introduction of these phenomena is discussed, as well as the use of femtosecond lasers to manipulate the composition or for the preparation of waveguides into glasses. Finally, the article will address a brief introduction on microstructured optical fibers and commercial application prospects for these devices. Univ Estadual Paulista, Inst Quim, CP 355, BR-14800060 Araraquara, SP, Brazil Univ Sao Paulo, Fac Filosofia Ciencias & Letras Ribeirao Preto, Dept Quim, BR-14040901 Ribeirao Preto, SP, Brazil Univ Fed Alfenas, Inst Ciencia & Tecnol, Campus Pocos De Caldas, BR-37715400 Pocos De Caldas, MG, Brazil Univ Presbiteriana Mackenzie, BR-01302907 Sao Paulo, SP, Brazil Univ Sao Paulo, Inst Fis Sao Carlos, BR-13566590 Sao Carlos, SP, Brazil Univ Fed Pernambuco, Dept Quim, BR-50740560 Recife, PE, Brazil Univ Laval, Ctr Opt Photon & Laser, Quebec City, PQ G1K 7P4, Canada Univ Estadual Paulista, Inst Quim, CP 355, BR-14800060 Araraquara, SP, Brazil

A pesquisa desenvolvida neste projeto, procura sintetizar haletos de perovskitas duplas sem chumbo, tanto a base de bismuto quanto de índio dopadas com íons lantanídeos, procurando entender e investigar suas propriedades optoeletrônicas, almejando o desenvolvimento de novos materiais para o campo da fotônica. Ambas as perovskitas, tanto a base de índio quanto de bismuto, apresentam propriedades óticas distintas sendo adequadas para diferentes aplicações. As perovskitas de bismuto possuem uma atividade fotocatalítica promissora sendo interessantes no campo da fotocatálise, enquanto as perovskitas de índio são mais apropriadas para fins fotoluminescentes, como para diodos emissores de luz (LEDs), termometria ótica e fotovoltaicos. Além do mais, neste trabalho foram incorporados íons lantanídeos na matriz das perovskitas de índio, visando o melhoramento das propriedades óticas da perovskita de In. Os íons lantanídeos são reconhecidos por suas propriedades espectroscópicas únicas, tornando possível expandir as aplicações das perovskitas de índio. Os íons Ln3+ são capazes de emitir fótons nas regiões do UV-Vis-IV, bem como participar de processos de transferência de energia como os mecanismos de conversão ascendente, conversão descendente e downshifting, ampliando a aplicação do material. Para sintetizar as perovskitas propostas, foi adotado uma síntese em um meio aquoso, gerando micro cristais das perovskitas. Após o término da síntese, os micro cristais obtidos foram então lavados com álcool isopropílico, centrifugado à 8000 rpm por 10 minutos e por fim, foram levados à uma estufa aquecida à 110oC por 24h. Ambas perovskitas duplas sem chumbo foram submetidas à várias técnicas de caracterização, almejando entender por completo sua estrutura, química e propriedades óticas. Além das caracterizações, foram avaliados sua atividade fotocatalítica e suas propriedades fotoluminescentes, para as perovskitas de bismuto e índio, respectivamente. Para a perovskita de bismuto, foram investigadas as influências dos haletos (Cl e Br) e da prata em sua fotocatálise, resultando em dados interessantes relacionando esses elementos e a atividade fotocatalítica da perovskita. Por fim, foram investigadas as propriedades óticas para as perovskitas de In não dopadas e as dopadas, e os resultados de luminescência mostraram a possibilidade de expandir ainda mais a aplicabilidade desse material. Nesse sentido, este trabalho está focando no campo da fotocatálise e da termometria ótica, contribuindo com os dados obtidos sobre suas propriedades optoeletrônicas bem como ampliando a aplicação desses materiais. The research developed in this project seeks to synthesize lead-free undoped, Bi- and Ln3+-doped In-based halide double perovskites, in order to understand and investigate their optoelectronic properties searching for the development of new materials for the photonics field. Both these perovskites, Bi- and In-based, exhibit different optical properties being suitable for distinct applications. Bi-based perovskites show a very promising photocatalytic activity desirable for photocatalysis while In-based perovskites are more appropriate for photoluminescent purposes, such as light-emission-diodes (LEDs), optical thermometry and photovoltaics. Furthermore, this present work intends to incorporate lanthanide ions into In-based double perovskite matrix, scoping the enhancement of In-perovskite optical properties. Lanthanide ions are well-known for their unique spectroscopic properties being able to expand In-based perovskite applications. Ln3+ ions are capable of emitting photons in UV- Vis-IR range as well as participate in some energy conversion processes like upconversion, downshifting and downconversion mechanism, broadening and improving its application. To synthesize both perovskites, a wet chemical route was adopted, resulting in perovskite microcrystals. After the synthesis was completed, these obtained microcrystals were washed with isopropyl alcohol then centrifugated at 8000 rpm for 10 minutes, posteriorly they were dried in an oven at 110 oC for 24h. Both lead-free double halide perovskites were analyzed using several characterization techniques in order to fully understand its structure, chemical and optical characteristics. Beyond that, was evaluated the photocatalysis performance and the photoluminescence properties of Bi- and In-based perovskite, respectively. For Bi-based perovskite, the influence of silver and halides (Cl and Br) on its photocatalysis was investigated leading to some interesting insights correlating these elements and perovskite photocatalytic performance. Besides, an investigation of undoped and Ln3+-doped In-based perovskite showed new photoluminescent properties for the doped samples being able to expand even more their application. In that sense, this work had centralized efforts in photocatalysis and optical thermometry fields contributing with insights about its optoelectronic properties as well as extending its application.

O trabalho apresenta o estudo da redução do Te4+ para Te0 em vidros teluritos dopados com PbS e PbO/ZnS e busca induzir, de maneira controlada, este processo redox através da técnica de microfabricação fazendo uso de laser pulsado em escala de femtosegundos, com o objetivo final de produzir um guia de onda planar. As amostras de vidros teluritos foram sintetizadas variando a composição da matriz e a concentração de dopantes e suas propriedades térmicas e estruturais foram determinadas através de análises por diversas técnicas de caracterização, como a calorimetria exploratória diferencial (DSC), difratometria de raios X (DRX), espectroscopia de espalhamento Raman, microscopia eletrônica de transmissão (TEM), difração eletrônica de área selecionada (SAED) e espectroscopia de fotoelétrons de raios-X (XPS). Os vidros teluritos dopados com sulfetos apresentaram, na maioria das amostras, coloração marrom ou preta (efeito darkening). Após análises por espectroscopia Raman e SAED, constatou-se a presença de Te0 nas amostras, indicando que os íons S2- provocam a redução do Te4+ da matriz vítrea, causando o efeito darkening. O estudo do fenômeno da redução de telúrio na matriz vítrea torna-se muito importante e promissor, uma vez que a redução controlada de telúrio pode gerar alterações no índice de refração (guias de onda) e/ou escurecimento da amostra (armazenamento de dados e materiais fotossensíveis). Assim, a técnica de microfabricação com laser de femtosegundos foi utilizada em amostras transparentes a fim de realizar a redução localizada do Te4+ no volume do vidro. O trabalho investiga, ainda, a formação de quantum dots (QDs) de CdS em vidros oxifluoretos à base de fosfatos e suas respectivas propriedades fotoluminescentes. Espectros de absorção, emissão e excitação foram obtidos, e os resultados indicam a formação de QDs na matriz. No entanto, não foi possível, com os métodos empregados neste trabalho, controlar a formação e o crescimento dos QDs de CdS. The work presents the study of the reduction of Te4+ to Te0 in tellurite glasses doped with PbS and PbO/ZnS and seeks to induce, in a controlled manner, this redox process through the microfabrication technique using a pulsed laser on a femtosecond scale, with the goal of produce a planar waveguide. The tellurite glass samples were synthesized by varying the matrix composition and the dopants concentration and their thermal and structural properties were determined through various characterization techniques, such as differential scanning calorimetry (DSC), X-ray diffraction (XRD), Raman scattering spectroscopy, transmission electron microscopy (TEM), selected area electronic diffraction (SAED) and X-ray photoelectron spectroscopy (XPS). The tellurite glasses doped with sulfides showed, in most samples, brown or black color (darkening effect). After analysis by Raman spectroscopy and SAED, the presence of Te0 in the samples was found, indicating that the S2- ions cause the Te4+ reduction in the vitreous matrix, causing the darkening effect. The study of tellurium reduction in the vitreous matrix becomes very important and promising, since the controlled reduction of tellurium can generate changes in the refractive index (waveguides) and/or darkening of the sample (data storage and photosensitive materials). Thus, the femtosecond laser microfabrication technique was used in transparent samples in order to achieve a localized reduction of Te4+ in the volume of the glass. The work also investigates the formation of quantum dots (QDs) of CdS in phosphate-based oxyfluoride glasses and their respective photoluminescent properties. Absorption, emission and excitation spectra were obtained, and the results indicate the formation of QDs in the matrix. However, it was not possible, with the methods employed in this work, to control the formation and growth of CdS QDs.