Use este identificador para citar ou linkar para este item: http://www.repositorio.ufc.br/handle/riufc/2478
Título: The optical and 57Fe Mössbauer spectra of Llithium Diborate (Li2B4O7) in Borophosphate glass-ceramics
Autor(es): Almeida, Ana Fabíola Leite
Vasconcelos, Igor Frota de
Valente, Manoel Almeida
Sombra, Antônio Sérgio Bezerra
Palavras-chave: Espectroscopia
Raios X - difração
Data do documento: 2002
Editor: Physica B
Citação: ALMEIDA, A. F. L. ; VASCONCELOS, I. F. ; VALENTE, M. A. ; SOMBRA, A. S. B. (2002)
Abstract: In this paper lithium borophosphate glasses and glass-ceramics in the system 66.6|xB2O3·(100−x)P2O5|. 33.3Li2O:yFe2O3 with 0⩽x⩽100 mol% and y=4 mol%, were studied by X-ray powder diffraction, 57Fe Mössbauer and infrared spectroscopy. All the samples in the system present a glass or glass-ceramics behavior which is confirmed by X-ray diffraction. The substitution of P5+ by B3+ associated with the increase of the ratio B2O3/P2O5 leads to oxidation of the iron in the samples which was detected by Mössbauer spectroscopy. From our Mössbauer analysis, high-spin Fe2+ and Fe3+ in a distorted octahedral coordination are present in all samples. For heat-treated samples we have the precipitation of crystalline phase of Li2B4O7 and for others lithium borate phases which was confirmed by X-ray powder diffraction. The Mössbauer spectra for some heat-treated samples show, besides the paramagnetic doublets, a magnetic sextet component with hyperfine magnetic field (Bhf=50 T). These magnetic phases were not identified up to this point in our study but we believe that these parameters are quite close to Hematite (α-Fe2O3). The boric acid phase H3BO3 were also identified by the X-ray diffraction, and infrared spectroscopy for x=26.6, 40 and 53.3 mol%. Such glasses and glass-ceramics containing nonlinear optical materials formed in a controlled crystallization process would be interesting candidates for application in new electro-optic devices.
Descrição: ALMEIDA, A. F. L. et al. The Optical and 57Fe Mössbauer spectra of Lithium Diborate (Li2B4O7) in Borophosphate glass-ceramics. Physica. B, v. 322, p. 276-288, 2002.
URI: http://www.repositorio.ufc.br/handle/riufc/2478
ISSN: 0921-4526
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