| mechanical and thermodynamic properties of α-and β-Si3N4 ceramics： ab initio and quasi-harmonic Debye modeling |
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| 作者姓名： | 余本海 陈东 |
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| 作者单位： | College of Physics and Electronic Engineering, Xinyang Normal University, Xinyang 464000, China |
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| 基金项目： | Project supported by the National Natural Science Foundation of China （Grant Nos. 11105115 and 11005088） and the Project of Basic and Advanced Technology of Henan Province, China （Grant No. 112300410021）. |
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| 摘 要： | The plane-wave pseudo-potential method within the framework of ab initio technique is used to investigate the structural and elastic properties of α-and β-Si3N4. The ground-state parameters accord quite well with the experimental data. Our calculation reveals that α-Si3N4 can retain its stability to at least 40 GPa when compressed at 300 K. The α → β phase transformation would not occur in a pressure range of 0-40 （3Pa and a temperature range of 0 300 K. Actually, the α → β transition occurs at 1600 K and 7.98 GPa. For α-and β-Si3N4, the c axes are slightly more incompressible than the a axes. We conclude that β-Si3N4 is a hard material and ductile in nature. On the other hand, β-Si3N4 is also found to be an ionic material and can retain its mechanical stability in a pressure range of 0 - 010 GPa. Besides, the thermodynamic properties such as entropy, heat capacity, and Debye temperature of α-and β-Si3N4 are determined at various temperatures and pressures. Significant features in these properties are observed at high temperature. The calculated results are in good agreement with available experimental data and previous theoretical values. Many fundamental solid-state properties are reported at high pressure and high temperature. Therefore, our results may provide useful information for theoretical and experimental investigations of the Si3N4 polymorphs.
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| 关 键 词： | Si3N4陶瓷 机械稳定性 热力学性质 德拜模型 从头算 实验数据 压力范围 温度范围 |
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