Crescimento e caracterização dos cristais de sulfato de níquel hexahidratado dopados com íons [MnH2O]2+ e com sulfato de magnésio heptahidratado
In this work, manganese ions doped nickel sulphate crystals (NSH:Mn) and magnesium ion doped nickel sulphate crystals (NMgSH) were grown and later characterized by X-ray diffraction and Raman spectroscopy techniques. The results obtained showed that the doped crystals possess a structure very sim...
| Autor principal: | FERREIRA JÚNIOR, Messias de Nazaré Guimarães |
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| Grau: | Dissertação |
| Idioma: | por |
| Publicado em: |
Universidade Federal do Pará
2014
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| Assuntos: | |
| Acesso em linha: |
http://repositorio.ufpa.br/jspui/handle/2011/5070 |
| Resumo: |
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In this work, manganese ions doped nickel sulphate crystals (NSH:Mn) and
magnesium ion doped nickel sulphate crystals (NMgSH) were grown and later characterized
by X-ray diffraction and Raman spectroscopy techniques. The results obtained showed that
the doped crystals possess a structure very similar to that of the pure nickel sulphate crystal
(NSH), with an anisotropic deformation in the unit cell dimensions compared to the pure
crystal, undergoing expansion in unit. The aim of the present study was to grow two new
single crystals of good optical quality to be used as optical bandpass filters. Nickel sulfate
hexahydrate (NHS) crystals are known to possess an optical transmission spectrum which has
attracted much attention because it presents two regions with high transmission efficiency of
approximately 80%, the first region being between 200 and 350 nm and the second between
400 and 600 nm, and a high absorption efficiency in other regions of the UV-VIS spectrum. A
light transmission spectrum with these characteristics is similar to an optical filter.
Termogravimetric (TGA) analyses were carried out for pure and doped crystals. The obtained
decomposition temperature of NSH was found to be 73 °C while that NSH: Mn and NMgSH
crystals present values of 82 ° C and 86 C respectively. As can be easily perceived, the
thermal stability of crystals with Mn or Mg ions in their structures is significantly higher. The
transmission band between 200 and 350 nm in the optical spectrum of NSH was found to be
narrower in the transmission spectrum of the doped crystal thus restricting the region of the
spectrum known as UVA. |