ZrAl4C4、Zr2Al4C5和Zr3Al4C6结构、弹性和电子性质对比

A Comparative of the Structure,Elastic and Electronic Properties of ZrAl4C4,Zr2Al4C5 and Zr3Al4C6

采用第一性原理方法,对比研究了Zr-Al-C体系纳米层状化合物ZrAl 4C 4、Zr 2Al 4C 5和Zr3Al4C6的结构、弹性和电子性质,并探寻其规律性。结果表明:从晶体结构角度分析,三种材料均可看作由(ZrC)和(Al4C3)两个独立单元以不同比例组合而成,可统一表示为(ZrC)nAl4C3(n=1,2,3),且三者的晶格常数a近似相等,晶格常数c随着ZrC含量的增大而变大。三种化合物弹性性质中,体模量、剪切模量、杨氏模量的大小关系满足:ZrAl4C4<Zr2Al4C5<Zr 3Al4C6。通过对三者电子态密度和Mulliken布局分析得到,ZrAl4C4、Zr 2Al4C5和Zr3Al4C6均具有金属键、离子键和共价键的特征,且Zr—C键强于Al—C键,从微观电子角度解释了在(ZrC)nAl4C3(n=1,2,3)体系中Zr—C键含量越高则对应材料的体模量、剪切模量、杨氏模量等弹性性质越大。计算结果与已有实验值和理论值吻合较好。

The structure,elastic and electronic properties of ZrAl4C4,Zr2Al4C5 and Zr3Al4C6 were explored by first-principles calculations.The results show that these compounds are composed of two independent units(Zr C)and(Al4C3)in different proportions,and these compounds can be expressed as(Zr C)nAl4 C3(n=1,2,3)from the perspective of structural relations.The bulk modulus,shear modulus,and Young’s modulus follow the relationship of ZrAl4C4<Zr2Al4C5<Zr3Al4C6.Through the analysis of the electronic density of states and the Mulliken population,it is found that that the bonding nature of ZrAl4C4,Zr2Al4C5 and Zr3Al4C6 is a combination of covalent,ionic and metallic,and the order of bond strength follows Zr-C>Al-C.In the(Zr C)nAl4C3(n=1,2,3)system,with the larger ratio of the Zr-C bond content,the elastic modulus have the larger values.The calculation results in this paper agree well with the existing experimental and theoretical values.