High temperature X-ray diffraction studies on sodium yttrium fluoride

被引：33

作者：

Mathews, MD

Ambekar, BR

Tyagi, AK ^{[1
]}

Köhler, J

机构：

[1] Bhabha Atom Res Ctr, Div Appl Chem, Bombay 400085, Maharashtra, India

[2] Max Planck Inst Solid State Res, D-70569 Stuttgart, Germany

来源：

JOURNAL OF ALLOYS AND COMPOUNDS | 2004年 / 377卷 / 1-2期

关键词：

fluorides; X-ray diffraction; thermal expansion; phase transition;

D O I：

10.1016/j.jallcom.2003.12.043

中图分类号：

O64 [物理化学（理论化学）、化学物理学];

学科分类号：

070304 ; 081704 ;

摘要：

The high temperature behaviour of two forms of sodium yttrium fluoride, i.e. Na1.5Y1.5F6 (hexagonal) and NaYF4 (cubic), have been studied using high temperature X-ray diffraction (HT-XRD) in the temperature range of 293-1073 K in vacuum. The studies revealed that both modifications are stable up to 773 K. The temperature variation of the lattice parameters as well as the coefficients of the average lattice thermal expansion of the compounds have been evaluated in the range 293-773 K. The coefficient of the average volume thermal expansion of NaYF4 (alpha(v) = 81.68 x 10(-6) K-1) was found to be much higher than that of Na1.5Y1.5F6 (alpha(v) = 66.25 x 10(-6) K-1). At higher temperatures (>1000 K), Na1.5Y1.5F6 (hexagonal) and NaYF4 (cubic) decompose into a new phase, probably due to loss of NaF. The phase evolution has been identified in situ. (C) 2004 Elsevier B.V. All rights reserved.

引用

页码：162 / 166

页数：5

共 13 条

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