High temperature X-ray diffraction studies on sodium yttrium fluoride
High temperature X-ray diffraction studies on sodium yttrium fluoride
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DOI：
10.1016/j.jallcom.2003.12.043
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发表时间：
2004-09
影响因子：
6.2
通讯作者：
M. D. Mathews;B. Ambekar;A. K. Tyagi;J. Köhler
中科院分区：
文献类型：
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作者：
M. D. Mathews;B. Ambekar;A. K. Tyagi;J. Köhler
用高温X射线衍射仪研究了氟化钠Na1.5Y1.5F6(六方相)和NaYF4(立方相)在293-1073K真空中的高温行为。研究表明，这两种修饰在773K都是稳定的。在293-773K范围内，估算了化合物的晶格参数和平均晶格热膨胀系数的温度变化。NaYF4的平均体积热膨胀系数(αv=81.68×10-6K−1)远大于Na1.5Y1.5F6的平均体积热膨胀系数(αv=66.25×10−6K−1)。在较高的温度下(>；1000K)，Na1.5Y1.5F6(六方)和NaYF4(立方)分解成新的相，可能是由于NaF的损失。在原位观察到了相的演化。
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 293–1073K in vacuum. The studies revealed that both modifications are stable up to 773K. 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 293–773K. The coefficient of the average volume thermal expansion of NaYF4(αv=81.68×10-6K−1) was found to be much higher than that of Na1.5Y1.5F6(αv=66.25×10−6K−1). At higher temperatures (>1000K), 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.