氮化铝热膨胀系数及高温弹性系数的第一性原理研究

摘要

结合连续弹性理论和第一性原理方法,对氮化铝晶体的热膨胀系数和高温弹性系数进行了理论计算.计算结果表明,当温度高于500K时,六角和立方氮化铝的热膨胀系数随温度升高呈线性增加.当温度为2 000K时,六角氮化铝a轴、c轴的热膨胀系数分别为0.853 49×10-5 K-1和0.849 64×10-5 K-1；立方氮化铝a轴的热膨胀系数为1.353 7×10-5K-1.当温度从0K升高到2 000K六角氮化铝的弹性系数c11,c12,c13,c33和c44下降幅度分别为10.61％,-4.52％,-2.0％,13.80％和20.76％,而立方氮化铝的弹性系数c11,c12和c44的下降幅度分别为29.23％,35.33％和21.10％.%By combining continual elastic theory and first principle calculation, the thermal expansion coefficients and elastic constants of AIN have been studied in this work.It was indicated that the thermal expansion coefficient for both hexagonal and cubic AIN increases linearly with temperature above 500 K.At 2 000 K, the thermal expansion coefficient for hexagonal AIN is 0.853× 10-5 K-1 and 0.850×10-5 K-1 along lattice a and c, respectively, while for cubic AIN, the thermal expansion coefficient is 1.353× 10-5 K-1.Within the temperature range from 0 to 2 000 K, for hexagonal AIN, the elastic constants c11, c12, c13, c33 and c44 decrease by 10.61%, -4.52%, -2.0%, 13.80% and 20.76%, respectively, while for cubic AIN, the elastic constants c11, c12 and c44 decrease by 29.23%, 35.33% and 21.10%, respectively.