Pressure induced phase transformations in NaZr2(PO4)3 studied by X-ray diffraction and Raman spectroscopy
Pressure induced phase transformations in NaZr2(PO4)3 studied by X-ray diffraction and Raman spectroscopy
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DOI：
10.1016/j.jssc.2014.10.017
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发表时间：
2015-01
影响因子：
3.3
通讯作者：
K. Kamali;T R Ravindran;N. Shekar;K. Pandey;Surinder M. Sharma
中科院分区：
文献类型：
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作者：
K. Kamali;T R Ravindran;N. Shekar;K. Pandey;Surinder M. Sharma
对 NaZr2(PO4)3 进行了高达 30 GPa 的拉曼光谱和 X 射线衍射测量，在紧密的压力间隔下进行，揭示了 5 和 6.6 GPa 左右的两个结构相变。 5.4 GPa 下的第二相被索引为类似于 RbTi2(PO4)3 的 R3 空间群。在高于 5 GPa 的第二相中，体积模量从 53 GPa (B'=4) 突然下降到 36 GPa (B'=4)。 8.2 GPa 下的 III 相结构被索引为斜方晶系，类似于单斜晶 LiZr2(PO4)3 的高温相的情况。该相 III 的体积模量为 65 GPa (B'=4)，高于环境相的体积模量。在高压拉曼研究中，对应于 72 和 112 cm−1 的模式在环境相中软化，而在 5 GPa 左右，60、105、125 和 190 cm−1 的模式会软化，压力对整体热膨胀产生负面影响。
Raman spectroscopic and x-ray diffraction measurements on NaZr2(PO4)3were carried out up to 30 GPa at close intervals of pressure, revealing two structural phase transformations around 5 and 6.6 GPa. The second phase at 5.4 GPa is indexed toR3 space group similar to that of RbTi2(PO4)3. Bulk modulus decreases abruptly from 53 GPa (B′=4) to 36 GPa (B′=4) in the second phase above 5 GPa. The structure of the phase III at 8.2 GPa is indexed as orthorhombic similar to the case of high temperature phase of monoclinic LiZr2(PO4)3. Bulk modulus of this phase III is found to be 65 GPa (B′=4), which is higher than that of the ambient phase. In high pressure Raman studies, modes corresponding to 72 and 112 cm−1soften in the ambient phase whereas around 5 GPa, the ones at 60, 105, 125 and 190 cm−1soften with pressure contributing negatively to overall thermal expansion.