铝酸钇晶体光学性质和热力学性质的第一性原理研究

First-principles Study on Optical and Thermodynamic Properties of YAlO 3

铝酸钇(YAlO_(3),YAP)材料的光学和热力学性能优异,在固体激光、发光显示等领域显现出巨大的应用前景。本工作采用基于密度泛函理论的第一性原理研究,计算了YAP晶体的电子结构、光学和热力学性质。结果表明,YAP属于宽禁带绝缘体材料,价带主要是由O的2p电子态贡献,导带基本上是由Y的4d电子态确定,较宽的带隙为众多激活离子的掺杂提供了可能,有利于设计不同材料组成的发光体系,光学性质计算得到了YAP晶体三个不同方向上的介电函数谱、吸收谱、反射谱、折射率谱和能量损失谱,表明YAP材料的光学性质具有各向异性、定向可控的特点,通过对YAP材料声子色散谱的计算,确定了德拜温度随热力学温度的变化规律,在46 K时出现了德拜温度的极小值特征点571 K,处于高温极限时YAP的德拜温度稳定在830 K,证实了自由能、熵、焓、热容等热力学基本参数的温度依赖性。本工作从原子尺度分析了YAP材料的光学性质和热力学性质,为材料的性能研究,特别是YAP材料在低温下的应用提供了基础数据支持。

With excellent optical and thermodynamic properties,YAlO_(3)(YAP)materials have potential applications in the fields of solid-state lasers and light-emitting displays.In this study,the electronic structure,and the optical and thermodynamic properties of YAP crystals were calculated by first-principles based on density functional theory.The results show that YAP is a wide band gap insulator material,the valence band mainly consists of the 2p electronic state of O atoms,and the conduction band mainly consists of the 4d electronic state of Y atoms.The wide band gap suggests that it is possible for many activated ions to be doped-a property that is conducive to the design of luminescence systems composed of different materials.The dielectric function spectrum,absorption spectrum,reflection spectrum,refractive index spectrum,and energy loss spectrum of YAP were calculated.The calculations revealed that the optical properties of YAP materials are anisotropic and directional controllable.The variation law of Debye temperature with thermodynamic temperature was determined by calculating the phonon dispersion spectrum of YAP.At 46 K,the minimum characteristic point of the Debye temperature was 571 K,stabilizing at 830 K in the high temperature limit.Thus,the temperature dependence of basic thermodynamic parameters,such as free energy,entropy,enthalpy and heat capacity,is confirmed.This study can provide basic data support for material performance research,especially for the application of YAP materials at low temperature,as the optical and thermodynamic properties of YAP materials were analyzed from an atomic viewpoint.