Pressure and temperature dependences of the unit cell volumes of Y₂O₃’s three polymorphs (cubic, monoclinic, and hexagonal) have been measured by synchrotron energy dispersive x-ray diffraction in conjunction with a cubic anvil technique to pressures and temperatures up to 7.5 GPa and 1073 K, respectively. The measured pressure–volume–temperature (P–V–T) data were used to obtain thermoelastic parameters of the polymorphs by fitting the modified high temperature third-order Birch–Murnaghan equation of state and a thermal pressure approach. The thermoelastic properties that were determined in this study are the ambient bulk modulus with fixed pressure derivative of the bulk modulus $(K_0^{\mathrm{\prime }}=4.0)$, the isobaric temperature derivative of the bulk modulus ${(\mathrm{\partial }K/\mathrm{\partial }T)}_P$, the volumetric thermal expansion coefficient along with the isothermal pressure derivative of thermal expansion ${(\mathrm{\partial }\alpha /\mathrm{\partial }P)}_T$, and the isometric temperature derivative of the bulk modulus ${(\mathrm{\partial }K/\mathrm{\partial }T)}_V$. The ambient bulk modulus for cubic [152(7) GPa] and monoclinic [197(9) GPa] polymorphs agrees well with previous reports. There is no precedence for all other thermophysical properties of all three polymorphs of Y₂O₃ reported in this study. For instance, ${(\mathrm{\partial }K/\mathrm{\partial }T)}_P$ is the highest for the monoclinic polymorph, while ${(\mathrm{\partial }\alpha /\mathrm{\partial }P)}_T$ and ${(\mathrm{\partial }K/\mathrm{\partial }T)}_V$ are the highest for the cubic polymorph. The results of this study add to the stock of knowledge on the thermophysical properties of Y₂O₃, which is a technologically relevant solid state material.

中文翻译：

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Y2O3多态相的热状态方程研究

Y ₂ O ₃的三种多晶型物（立方，单斜晶和六方晶）的晶胞体积的压力和温度依赖性已通过同步加速器能量色散X射线衍射结合立方砧技术测量了高达₂₀₀ ℃的压力和温度。分别为7.5 GPa和1073K。通过拟合改进的高温三阶Birch-Murnaghan状态方程和热压方法，使用测得的压力-体积-温度（P–V–T）数据获得多晶型物的热弹性参数。在这项研究中确定的热弹性性质是环境体积模量与体积模量的固定压力导数$（{ķ}_0^{\mathrm{\prime }}=4.0）$，体积模量的等压温度导数 ${（\mathrm{\partial }ķ/\mathrm{\partial }Ť）}_P$，体积热膨胀系数以及热膨胀的等温压力导数 ${（\mathrm{\partial }\alpha /\mathrm{\partial }P）}_{Ť}$，以及体积模量的等距温度导数 ${（\mathrm{\partial }ķ/\mathrm{\partial }Ť）}_V$。立方[152（7）GPa]和单斜晶[197（9）GPa]多晶型物的环境体积模量与先前的报告非常吻合。在这项研究中报道的Y ₂ O ₃的所有三种多晶型物的所有其他热物理性质没有先例。例如，${（\mathrm{\partial }ķ/\mathrm{\partial }Ť）}_P$ 是单斜晶型的最高值，而 ${（\mathrm{\partial }\alpha /\mathrm{\partial }P）}_{Ť}$ 和 ${（\mathrm{\partial }ķ/\mathrm{\partial }Ť）}_V$是立方多晶型物的最高值。这项研究的结果增加了关于Y ₂ O ₃的热物理性质的知识储备，Y ₂ O ₃是技术上相关的固态材料。