【摘要】 针对目前较少有学者通过共掺杂其他元素对AgSnO₂触头热性能进行研究的现状。采用对SnO₂晶体进行非掺、单掺La和共掺La-W元素的方法,通过密度泛函理论、第一性原理以及CASTEP软件对掺杂体系的热学性质进行理论计算,得到了不同掺杂情况下SnO₂晶体的声子谱、声子态密度及分波态密度和相关热力学参量,对计算结果和曲线图进行了理论分析。结果表明:当掺杂浓度为16. 67%时,共掺杂La-W元素的SnO₂体系声子谱未出现虚频,而单掺La元素体系出现了虚频,说明共掺杂体系较稳定。通过分析态密度图及分波态密度图可以得到,W原子混合掺杂后可有效改善La原子的振动情况。通过SnO₂晶体热力学性质的分析,共掺杂后体系的熵、自由能以及焓的曲线有较好改善,为AgSnO₂触头材料在恶劣环境下受到损害后恢复到原状提供了有利条件。且掺杂后晶体的热容明显大于未掺杂晶体的热容,说明La-W元素的掺杂极大的激活了分子的运动活性。更多还原

【Abstract】 At present,there are few scholars who study the thermal properties of Ag SnO₂ contacts by co-doping other elements. In this paper,the non-doped,single-doped La and co-doped La-W elements of SnO₂ crystal were used to calculate the thermal properties of the doped system by density functional theory,first-principles and CASTEP software. The phonon spectrum,phonon state density and partial wave state density of SnO₂ crystals and related thermodynamic parameters were analyzed theoretically. The results show that when the doping concentration is 16. 67%,the phonon spectrum of the SnO₂ system with co-doped La-W element does not show a virtual frequency,while the single-doped La element system shows a virtual frequency,indicating that the co-doped system is stable. By analyzing the state density map and the partial wave density map,it can be obtained that the vibration of La atoms can be effectively improved by mixed doping of W atoms.Through the analysis of the thermodynamic properties of SnO₂ crystal,the entropy,free energy and enthalpy curve of the system after co-doping are better improved,which provides favorable conditions for the Ag SnO₂ contact material to recover to the original state after being damaged in harsh environment. Moreover,the heat capacity of the crystal after doping is significantly larger than that of the undoped crystal,indicating that the doping of La-W element greatly activates the molecular motion activity.更多还原