The optical and ⁵⁷Fe Mössbauer spectra of lithium diborate (Lib>2b>Bb>4b>Ob>7b>) in borophosphate glass-ceramics

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• 作者：Almeida ; A.F.L. ; Vasconcelos ; I.F. ; Valente ; M.A. ; Sombra ; A.S.B.
• 关键词：M&ouml ; ssbauer spectroscopy ; Lib>2b>Bb>4b>Ob>7b> ; Glass ceramics ; Borophosphate glasses
• 刊名：Physica B
• 出版年：2002
• 期刊代码：53_09214526
• 类别：ph
• 出版时间：September, 2002
• 卷：322
• 期：3-4
• 页码：276-288
• 文件大小：291 K

摘要

In this paper lithium borophosphate glasses and glass-ceramics in the system 66.6|xBb>2b>Ob>3b>·(100−x)Pb>2b>Ob>5b>|. 33.3Lib>2b>O:yFeb>2b>Ob>3b> with 0≤x≤100mol%and y=4mol%, 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 Bb>2b>Ob>3b>/Pb>2b>Ob>5b> 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 Lib>2b>Bb>4b>Ob>7b> 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 (Bb>hf