Pt-Ir-Y系化合物的结构稳定性研究

A Study on Structural Stability of Pt-Ir-Y Compounds

采用基于密度泛函理论的第一性原理方法,通过计算研究了Pt-Ir-Y系金属间化合物的生成焓和结合能、电子结构、弹性性质和结构稳定性.计算结合能和生成焓可以得出,在Pt-IrY系合金中,最容易生成Ir_2Y,其合金相也是最稳定的.由态密度图可以得出,合金稳定性顺序为Ir Y>Pt_3Y>Pt_4Y_5>Pt_2Y>Ir_2Y.由态密度图可以看出Ir-Y系中赝能隙较宽,说明Ir、Y较Pt、Y更容易生成化合物.由弹性常数,体模量B、切变模量G、弹性模量E、和泊松比ν得Pt-Ir-Y系五种金属间化合物中强度大小顺序为:Ir_2Y>Pt_2Y>Pt_3Y>IrY>Pt_4Y_5由塑脆转变的依据得,Pt-Ir-Y系五种金属间化合物中都有较好的塑性,其中塑性最好的为Pt_4Y_5.

By the first - principle approach based on the density functional theory, the formation enthalpy and binding energy, electronic structure, elastic properties and structural stability of Pt - Ir - Y intermetallie compounds were cal- culated and studied. The results of calculating the binding energy and enthalpy of formation show that the most easily generated and the most stable alloy is Ir2Y in the Pt -Ir -Y system. As can be seen from the density of states, the stability order of the alloy is IrY 〉 Pt3Y 〉 Pt4Y5 〉 Pt2Y 〉Ir2Y and the pseudo energy gap of the Ir -Y system is wi- der than that of Pt -Y system, which indicates that Ir and Y are more likely to produce compounds than Pt and Y. The results of calculating the elastic constants, the body modulus B, shear modulus G, elastic modulus E and Poisson ratio u of the Pt -Ir -Y five kinds of intermetallic compounds show that the order of strengths of these intermetallic compounds is Ir2Y 〉 PtzY 〉 Pt3Y 〉IrY 〉 Pt4Y5. According to the plastic brittle transition, all of the five intermetal- lic compounds of the Pt-Ir-Y system have better plasticity and the best of which is Pt4Y5.