MoSi_2和WSi_2相结构和性能的电子理论研究

STUDY ON THE STRUCTURE AND PROPERTIES FOR MoSi_2 AND WSi_2 PHASES BY ELECTRON THEORY

根据固体与分子经验电子理论 ,对MoSi2 和WSi2 相进行价电子结构分析 ,通过键距差 (BLD)方法 ,计算了MoSi2 和WSi2 晶体中各键上的共价电子数 .结果表明 :MoSi2 和WSi2 相是靠键距为2a2 +(c3) 2 2的Mof—Sic,Wf—Sic 最强键连接的 ,该键上共价电子数的大小将影响化合物的硬度 ,并且该键的键能大小将影响化合物的熔点 ,化合物的强度可由 η=nc/nt来衡量 .

Valence electron structures of MoSi 2 and WSi 2 phases were analyzed on the basis of Yu's empirical electron theory of solids and molecules. The valence electron number of every bond in MoSi 2 and WSi 2 phases was calculated by using bond length difference (BLD) method. The results show that in unit cell of MoSi 2 and WSi 2 phases, the strongest bond is Me f—Si c(Me=Mo,W)bond(A bond), whose length is 2 a 2+(c3) 2 2. The valence electron number and the bond energy of the strongest bond have strong influence on the hardness and melting point of MoSi 2 and WSi 2 phases respectively. The strength of MoSi 2 and WSi 2 phases may be judged by the ratio between n c and n t.