Solid State Reaction of Ir with SiC and Ir with Y2O3

摘要:

研究了难熔金属铱与SiC及铱与Y2O3的固相反应，采用金属间化合物的标准生成吉布斯自由能等于标准形成焓的方法计算固相反应热力学，采用电子分布与晶体结构之间相关的Engel理论分析了铱与Y2O3的固相反应机制。结果表明，铱与SiC在1000 ℃开始反应生成Ir3Si和石墨，随着反应温度升高，Ir3Si与SiC进一步反应生成更高熔点的IrSi，当反应温度为1400 ℃时，固相反应产物为IrSi和石墨。在1800 ℃的还原性碳气氛下，铱与Y2O3能够发生固相反应生成Ir2Y和CO，Ir外围电子层失去电子形成d5sp2排布，Y外围电子层得到电子形成d3sp排布，成键电子数目由17个增加至21个，导致Ir-Y 键能大于Y-O键能。

Abstract:

Solid state reactions between Ir and SiC and between Ir and Y2O3 were studied. The thermodynamics and mechanism of solid state reaction were discussed. The results indicate that Ir reacts with SiC at 1000 °C to yield Ir3Si and graphitized carbon. The products of Ir silicide changes from Ir3Si and IrSi at 1200 °C to IrSi at 1400 °C. The solid state reaction between Ir and Y2O3 is thermodynamically favorable above 1800 °C in a reductive carbon atmosphere. The reaction mechanism between Ir and Y2O3 was analyzed based on the Engel correlation between electronic configuration and structures of metals and alloy crystal structure.