Propriedades ópticas e vibracionais de amostras de turmalina natural
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Data
2023-12-12
Autores
Teixeira, Aline Bento
Orientadores
Künzel, Roseli
Tipo
Trabalho de conclusão de curso de graduação
Título da Revista
ISSN da Revista
Título de Volume
Resumo
A turmalina é um dos compostos mais populares entre as gemas minerais,
apresentando a combinação ideal de beleza, durabilidade e raridade. Este material possui
excelentes propriedades ópticas e permite diversas aplicações tecnológicas no
desenvolvimento de dispositivos elétricos, químicos, entre outros. A rica variedade de cores
da turmalina deve-se a sua complexa composição química, podendo exibir uma ampla gama
de tonalidades, as quais variam conforme os íons contaminantes incorporados em sua
estrutura. Neste trabalho, a composição química das amostras estudadas foi avaliada por meio
da espectroscopia por energia dispersiva (EDS) e a fluorescência de raios X. Os resultados das
análises de EDS mostram que os principais componentes das amostras de turmalina estudadas
podem ser atribuídas principalmente a oxigênio, silício, alumínio e ferro. Na fluorescência de
raios X foram observados os elementos característicos da turmalina como Si, Al, Ca, Fe e Mn.
O espectro Raman das amostras do estudo se caracteriza por um conjunto de linhas alargadas,
indicando a baixa cristalinidade das amostras estudadas ou a sobreposição de bandas
provenientes de diversos grupos funcionais. Os dados Raman ilustram bandas atribuídas à
ligação Al-O na turmalina rosa em 375 cm-1, enquanto na turmalina verde o Fe é visto na
faixa 186 cm-1, e um pico intenso em 1003 cm-1 característico da ligação Si-O. Os resultados
sugerem que o aquecimento das amostras de turmalina rosa e verde acarreta modificações
estruturais e, potencialmente, alterações de fase nas amostras tratadas a uma temperatura de
1100 °C durante uma hora. A espectroscopia ultravioleta-visível (UV-Vis) mostra que o
espectro registrado para as amostras com partículas maiores (75 𝛍���������m ≤x ≤ 180 𝛍���������m) possuem
bandas de absorção mais definidas que aqueles registrados para partículas com x ≤ 75 𝛍���������m.
Tourmaline is one of the most popular compounds among mineral gemstones, presenting the ideal combination of beauty, durability and rarity. This material has excellent optical properties and allows for diverse technological applications in the development of electrical and chemical devices, among others. The rich variety of colors of tourmaline is due to its complex chemical composition, being able to display a wide range of shades, which vary depending on the contaminating ions incorporated into its structure. In this work, the chemical composition of the studied samples was evaluated using energy dispersive spectroscopy (EDS) and x-ray fluorescence. The results of EDS analyzes show that the main components of the studied tourmaline samples can be attributed mainly to oxygen, silicon, aluminum and iron. In X-ray fluorescence, the characteristic elements of tourmaline were observed, such as Si, Al, Ca, Fe and Mn. The Raman spectrum is characterized by a set of broad lines, indicating the low crystallinity of the samples studied or the overlap of bands originating from different functional groups. Raman's data illustrate bands attributed to the Al-O bond in pink tourmaline at 375 cm-1, while in green tourmaline Fe is seen in the 186 cm-1 band, and an intense peak at 1003 cm-1 characteristic of the Si-O bond. The results suggest that heating the pink and green tourmaline samples leads to structural modifications and, potentially, phase changes in the samples treated at a temperature of 1100 °C for one hour. Ultraviolet-visible spectroscopy (UV-Vis) shows that the spectrum recorded for samples with larger particles (75 𝛍������m ≤x ≤ 180 𝛍������m) have more defined absorption bands than those recorded for particles with x ≤ 75 𝛍������m.
Tourmaline is one of the most popular compounds among mineral gemstones, presenting the ideal combination of beauty, durability and rarity. This material has excellent optical properties and allows for diverse technological applications in the development of electrical and chemical devices, among others. The rich variety of colors of tourmaline is due to its complex chemical composition, being able to display a wide range of shades, which vary depending on the contaminating ions incorporated into its structure. In this work, the chemical composition of the studied samples was evaluated using energy dispersive spectroscopy (EDS) and x-ray fluorescence. The results of EDS analyzes show that the main components of the studied tourmaline samples can be attributed mainly to oxygen, silicon, aluminum and iron. In X-ray fluorescence, the characteristic elements of tourmaline were observed, such as Si, Al, Ca, Fe and Mn. The Raman spectrum is characterized by a set of broad lines, indicating the low crystallinity of the samples studied or the overlap of bands originating from different functional groups. Raman's data illustrate bands attributed to the Al-O bond in pink tourmaline at 375 cm-1, while in green tourmaline Fe is seen in the 186 cm-1 band, and an intense peak at 1003 cm-1 characteristic of the Si-O bond. The results suggest that heating the pink and green tourmaline samples leads to structural modifications and, potentially, phase changes in the samples treated at a temperature of 1100 °C for one hour. Ultraviolet-visible spectroscopy (UV-Vis) shows that the spectrum recorded for samples with larger particles (75 𝛍������m ≤x ≤ 180 𝛍������m) have more defined absorption bands than those recorded for particles with x ≤ 75 𝛍������m.