Temperature-induced phase transformations in Na2WO4 and Na2MoO4 crystals

被引：48

作者：

Lima, C. Luz ^{[2
]}

Saraiva, G. D. ^{[1
]}

Freire, P. T. C. ^{[2
]}

Maczka, M. ^{[3
]}

Paraguassu, W. ^{[4
]}

de Sousa, F. F. ^{[5
]}

Mendes Filho, J. ^{[2
]}

机构：

[1] Univ Estadual Ceara, Fac Educ Ciencias & Letras Sertao Cent, BR-63900000 Quixada, CE, Brazil

[2] Univ Fed Ceara, Dept Fis, BR-60455970 Fortaleza, Ceara, Brazil

[3] Polish Acad Sci, Inst Low Temp & Struct Res, PL-50950 Wroclaw 2, Poland

[4] Univ Fed Maranhao, Dept Fis, BR-65080040 Sao Luis, MA, Brazil

[5] Fed Univ Para, Fac Ciencias Exatas & Nat, BR-68507970 Maraba, PA, Brazil

来源：

JOURNAL OF RAMAN SPECTROSCOPY | 2011年 / 42卷 / 04期

关键词：

sodium molybdate; sodium tungstate; phase transition; Raman scattering; SODIUM TUNGSTATE; SYSTEM;

D O I：

10.1002/jrs.2759

中图分类号：

O433 [光谱学];

学科分类号：

0703 ; 070302 ;

摘要：

Temperature-dependent Raman studies on Na2WO4 and Na2MoO4 crystals were performed in order to obtain information on structural changes induced by temperature evolution. The stability of the cubic phase of Na2WO4 and Na2MoO4 crystals was assessed and our results indicate that this phase is stable in the 8-823 K and 15-773 K ranges for Na2WO4 and Na2MoO4, respectively. The crystal of Na2WO4 shows a phase transition occurring at 833 K. Na2MoO4 undergoes a sequence of three phase transitions, which were observed at 783-803, 823-913 and 943-950 K. In both crystals, a strong first-order phase transition occurs as indicated by the behavior of the Raman modes: the Raman bands split and new bands appear below 100 cm(-1). These transitions are connected with tilting and/or rotations of the WO(4)and MoO4 tetrahedra, which leads to a disorder at the WO(4)and MoO4 sites. Copyright (C) 2010 John Wiley & Sons, Ltd.

引用

页码：799 / 802

页数：4

共 16 条

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