【摘要】 对于掺杂合适的元素Sb,Te,Ag,Cu使得Mg Si基热电材料的热电性能大幅度提高的实验事实,欲从理论和计算上寻求支持,试图从原子、分子的层次上对此现象作出解释,因此建立了简化的Mg2Si量子化学计算模型,采用密度泛函离散变分Xα量子化学计算法,计算了物质内部的结构信息,如共价键级和态密度等.计算结果表明,掺杂以后,晶体的共价键级被削弱,态密度图中的禁带宽度明显变窄,这与实验测试的结果是一致的.更多还原

【Abstract】 Doping of moderate elements Sb,Te,Ag,Cu can greatly improve the thermoelectric properties of Mg-2Si. For explaning the experimental result,a calculable model is presented.It applies DV-Xα quantum chemistry computation to reveal the micro-structure information, such as the covalent bond grade and the density of state. The calculated results imply that the covalent bond grade of Mg-Si are decreased and the forbidden gaps become narrower after doping. This results appears to be consistent with the experiments.更多还原