LuTaO$lt;sub$gt;4$lt;/sub$gt;相变及结构

LuTaO₄是最高密度的闪烁体基质, 研究它的结构及其相变对单晶制备具有指导意义. 用固相法制备了Lu₂O₃和Ta₂O₅摩尔比为1:1时在不同温度下形成的多晶粉末, 用X射线衍射及Rietveld全谱拟合研究了多晶粉末的物相和结构. 结果表明, Lu₂O₃: Ta₂O₅摩尔比为1:1的样品在1740 ℃时合成的物相为M'-LuTaO₄, 在1800 ℃时为M'-LuTaO₄和M-LuTaO₄的混合物, 在1840 ℃时全部转变为M-LuTaO₄. 当温度升高到2058 ℃时, 样品呈熔融状态, 对淬火得到的样品进行结构精修, 给出了M-LuTaO₄, Lu₃TaO₇和Ta₂O₅的晶胞和原子坐标参数, 它们的重量比分别占78.1%, 18.9%和3.0%. 这些结果为制备以LuTaO₄为基质的高密度闪烁体单晶具有参考价值. 关键词： 4')" href="#">LuTaO₄ 相变 粉末衍射 Rietveld精修

Phase transition and structure of LuTaO4

Since LuTaO₄ is a scintillator host with the highest density, it is important to investigate the structure and phase transition for its single crystal preparation. The polycrystalline formed by the mixture of Lu₂O₃:Ta₂O₅ with the molar ratio 1:1 is prepared by solid state reaction method at different temperatures. The phase transitions and structures of the polycrystalline powders are investigated by X-ray diffraction and Rietveld refinement. The results show that the polycrystalline has a single phase M'-LuTaO₄ when sample is prepared at 1740 ℃, it presents a mixture phase of M'-LuTaO₄ and M-LuTaO₄ at 1800 ℃, and it displays a single phase M-LuTaO₄ at 1840 ℃. The sample is melted when the calcined temperature is 2058 ℃, the melt is quenched and the polycrystalline is the mixture of M-LuTaO₄, Lu₃TaO₇ and Ta₂O₅, whose structural parameters, including the lattice parameters, atomic fraction coordinates, etc. are obtained by Rietveld refinement to their X-ray diffraction pattern, and the results show their weight ratios are 78.1%, 18.9% and 3.0%, respectively. These results are valuable for the single crystal growth of the heavy scintillators with the host LuTaO₄.
Keywords： 4')" href="#">LuTaO₄ phase transition powder X-ray diffraction Rietveld refinement