RE2Ti2O7(RE=Gd,Y,Ho,Er)的结构、机械性能及热学性质的第一性原理研究(英文)

本文利用第一性原理和准谐近似的方法研究了一系列钛酸盐烧绿石，即RE₂Ti₂O₇（RE=Gd，Y，Ho，Er）的结构、机械性能及热学性质。研究结果表明，在基态下RE₂Ti₂O₇具有良好的抗压、抗剪切能力。并且，由于这些化合物的齐纳指数接近于1，可近似地看作各向同性材料。此外，计算得到的热膨胀系数在高温区与实验值符合得较好。在500~1 500 K温度区间内，平均热膨胀系数为（10.4~13.1）×10-6 K-1。基于Slack模型，我们还计算了这些材料的晶格热导率，当温度等于1 000 K时，这四种物质的热导率在区间（1.5~4.9）W·m-1·K-1内。

First-principles Study of Structural,Mechanical and Thermal Properties of RE2Ti2O7 (RE=Gd,Y, Ho,Er)

In this work, we studied the structural, mechanical, and thermal properties of RE₂Ti₂O₇ (RE=Gd, Y, Ho, Er) pyrochlores by the first-principles calculations combining with the quasi-harmonic approximation. Our study reveals that RE₂Ti₂O₇ possess excellent resistance to compression and shear at the ground state. Moreover, these compounds can be approximate to elastically isotropic materials because their Zener ratios are close to 1. The obtained thermal expansion coefficient agrees well with the experimental results at high temperature. The mean thermal expansion coefficient of the RE₂Ti₂O₇ compound is about (10.4~13.1)×10-6 K-1 in the temperature range of 500~1 500 K. We also employed Slack's model to estimate thermal conductivity, and the results located in the range of 1.5~4.9 W·m-1·K-1 at 1 000 K.