虚晶近似法研究AlN-Al2O3固溶体系的力学性能和电子结构

基于密度泛函理论的第一性原理平面波赝势方法, 运用虚晶近似方法计算了AlN-Al₂O₃固溶区内尖晶石相氮氧化铝(Al₂₄O₂₄N₈, Al₂₃O₂₇N₅和Al₂₂O₃₀N₂)和α-Al₂O₃, AlN的力学性能和电子结构. 结果证明虚晶近似法应用到氮氧化铝结构计算中是可行的. 力学常数计算结果和弹性模量B, 剪切模量G, 杨氏模量E反映的材料硬度变化趋势与实验基本一致；Al₂O₃-AlN固 溶区内五种结构均为脆性性质且Al₂₃O₂₇N₅脆性最低, 硬度高、脆性低的特性反映了Al₂₃O₂₇N₅优异的抗弯强度性能. 五种结构满足力学结构上的稳定性, 立方尖晶石相氮氧化铝表现为弹性各向异性. 能带和态密度的计算分析表明这五种结构均为直接宽带隙结构. 在费米能级附近, 氮氧化铝结构中阴离子的2p态和阳离子的3s, 3p态发生了轨道杂化. 理论结果与实验数据基本符合, 为进一步研究提供了一定的理论方法和依据.

Investigation of the electronic and mechanical properties of Al2O3-AlN solid solution by virtual crystal approximation

Based on the density functional theory within plane-wave pesudopotential method,the band structure and elastic properties of spinel Al_（64+x）/3□_（8-x）/3O_（32-x）N_x（x=2,5,8） andα-Al₂O₃,A1N are calculated.The spinel Al_（64+x）/3□_（8-x）/3O_（32-x）N_x （x=2,5,8） are calculated by using the ’virtual crystal approximation’.The results prove it possible to study the Al_（64+x）/3□_（8-x）/3O_（32-x）N_x（x=2,5,8） by this approximation.The calculated elastic constants and hardness features accord well with the experimental results.The five structures in the Al₂O₃-AIN solid solution region all show brittle features and the Al₂₃O₂₇N₅ shows the lowest brittleness.High hardness and low brittleness reflect that Al₂₃O₂₇N₅ has a great flexural strength.Elastic property analysis confirms the mechanical stability,it also reveals that AlON has highly elastic anisotropy.Band structure analysis shows that the spinel AlON andα-Al₂O₃,A1N are both direct bandgap materials.Hybridizations take place between Al-3p,3s and O, N-2p orbitals near the Fermi level in the AlON.The calculated results are consistent with relevant experimental results,which provides a theoretical method and reference for the further study.