作　　者： ; ; ; ;

机构地区： 宜宾学院

出　　处： 《稀有金属材料与工程》 2013年第7期1454-1458,共5页

摘　　要： 基于准谐Debye-Grüneisen模型,运用第一性原理缀加投影平面波方法研究了Re的热力学性质,拟合了Re的状态方程,计算了Re不同压强下弹性模量、吉布斯自由能、焓、熵、热容和体膨胀系数随温度的变化关系。结果表明:采用八阶Birch-Murnaghan方程拟合得到的Re压强-体积曲线与实验测量结果吻合较好;计算的零压下吉布斯自由能、焓、熵、热容和体膨胀系数随温度的变化均与实验值符合较好;在零压,50、100、150和200GPa压强下,Re的弹性模量和吉布斯自由能随温度升高而减小;焓、熵随温度升高而增加;Re的电子等容热容随温度线性增加,晶格振动等容热容在低温下符合3T幂次规律并随温度增加而迅速增大,且在高温时逐渐接近Dulong-Petit极限;预测的德拜温度约为430K,与实验结果一致。 Within the framework of the quasiharmonic Debye-Grtineisen approximation, the equation of state and thermodynamics properties, including bulk modulus, Gibbs free energy, enthalpy, entropy, heat capacity and volume thermal expansion coefficient of Re have been studied using the first-principles projector-augmented wave method. The results reveal that the pressure-volume curve from the eight-order Birch-Murnaghan is in good agreement with the e^perimentat measurements. Gibbs free energy, enthalpy, entropy, heat capacity and volume thermal expansion coefficient of Re at 0 GPa as a function of temperature are consistent well with the experimental data. At 0, 50, 100, 150 and 200 GPa, bulk modulus and Gibbs free energy decrease with the increasing of temperature, but enthalpy and entropy increase. As the temperature increases, the electronic heat capacity increases linearly, but the vibrational heat capacity increases following T3 law at low temperature and it nearly approaches to the Dulong-Petit result 3nNnkB at high temperature. The estimated Debye temperature of Re from heat capacity at constant volume is 430 K that is in agreement with the available measurements.

关 键 词： 模型 第一性原理 热力学

领　　域： [理学] [理学] [理学]