Abstract The present manuscript reports structural evolutions in nano-crystalline Europium sesquioxide (Eu2O3) with increasing pressure up to 22 GPa at ambient temperature and at a varying temperature in the range from 80 K to 440 K. The sample was characterized at ambient and was found to be cubic in structure with nano-size using various characterization routes. External pressure was applied on the sample using the diamond anvil cell (DAC) up to about 22 GPa and the ensuing changes were investigated using Raman spectroscopy. The material showed a structural phase transition from cubic to the hexagonal phase which was initiated around 4.79 GPa and completed around 15 GPa. The material exhibited this hexagonal phase up to the highest pressure of 22 GPa. From the pressure dependent phonon mode variation, the mode Gruneisen parameters were estimated and reported for the first time. For the most prominent Fg mode for the present sample, the mode Gruneisen parameter was found to be 1.36. The temperature dependent study on the cubic sample, revealed the stability of the material up to 440 K with new bands developing towards higher wavenumbers. These new bands might be a result of the resonant Raman transitions of the cubic phase. Further, the temperature dependent shifts were used to deduce the anharmonic constants which showed the softening of the phonon modes and the dominance of three-phonon decay process.

中文翻译：

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不同热力学参数对纳米晶倍半氧化铕结构行为的影响

摘要 本手稿报告了纳米晶倍半氧化铕 (Eu2O3) 在环境温度和 80 K 至 440 K 范围内不同温度下压力增加至 22 GPa 时的结构演变。使用各种表征途径在纳米尺寸的立方体结构。使用金刚石砧座 (DAC) 对样品施加高达约 22 GPa 的外部压力，并使用拉曼光谱研究随后的变化。该材料显示出从立方相到六方相的结构相变，该相变在 4.79 GPa 左右开始并在 15 GPa 左右完成。该材料在最高压力为 22 GPa 时表现出这种六方相。从压力相关的声子模式变化，首次估计并报告了模式 Gruneisen 参数。对于本样本最突出的 Fg 模式，发现模式 Gruneisen 参数为 1.36。对立方体样品的温度相关研究揭示了材料在高达 440 K 时的稳定性，新带向更高波数发展。这些新带可能是立方相的共振拉曼跃迁的结果。此外，温度相关的位移被用来推导出非谐常数，它显示了声子模式的软化和三声子衰变过程的优势。揭示了材料在高达 440 K 时的稳定性，新的波段向更高的波数发展。这些新带可能是立方相的共振拉曼跃迁的结果。此外，温度相关的位移被用来推导出非谐常数，它显示了声子模式的软化和三声子衰变过程的优势。揭示了材料在高达 440 K 时的稳定性，新的波段向更高的波数发展。这些新带可能是立方相的共振拉曼跃迁的结果。此外，温度相关的位移被用来推导出非谐常数，它显示了声子模式的软化和三声子衰变过程的优势。