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Phase Transition Characters and Thermodynamics Modeling of the Newly-Discovered wII- and Post-Spinel Si3N4 Polymorphs： A First-Principles Investigation

ISSN号：1006-7191
期刊名称：《金属学报：英文版》
时间：0
分类：TQ174.758[化学工程—陶瓷工业;化学工程—硅酸盐工业] TM912.2[电气工程—电力电子与电力传动]
作者机构：[1]College of Physics and Electronic Engineering, Xinyang Normal University, Xinyang 464000, China
相关基金：Acknowledgements This work was financially supported by the National Natural Science Foundation of China （Nos. 11005088 and 11105115）, the Project of Basic and Advanced Technology of Henan Province of China （No. 112300410021）, the Key Project of Henan Educational Committee （No. 12A140010） and the Young Teacher＇s Program of Xinyang Normal University （No. 2011084）. The authors are grateful to Prof. M.A. Blanco and his colleagues for their Gibbs code.

作者： Benhai YU Dong CHEN[1]

关键词：尖晶石相, 相变压力, 第一原理, 力学建模, 氮化硅, 体积弹性模量, 压力范围, 晶型, First-principles, Nitride, Elastic constant, Phase transition

中文摘要：

平衡格子常数，有弹性的常数和 wII 尖晶石和尖晶石以后的 Si3N4 的有弹性的 moduli 分别地在 040 GPa 和 160240 GPa 的压力范围被调查了。这二个阶段被发现动态地稳定。尖晶石以后的阶段是还在极端压缩下面调查的最强壮的材料之一。一些基本性质和阶段转变人物从伪泛音近似被评估。到尖晶石以后的阶段的从阶段的转变压力是 152.5 GPa (在 300 K ) 并且 181.8 GPa (在 1500 K ) 。wII 和尖晶石以后的转变的阶段转变压力与温度的上升增加；因此，在更高的温度，综合要求更高的压力尖晶石以后的 Si3N4。热能力，热扩大和新阶段的体积模量作为压力和温度的功能被计算。尖晶石以后的 Si3N4 的热能力在高温度大并且仅仅微弱地迫使依赖者。

英文摘要：

The equilibrium lattice constants, elastic constants and elastic moduli of wll- and post-spinel Si3Na have been investigated in the pressure ranges of 0-40 GPa and 160-240 GPa, respectively. These two phases are found to be dynamically stable. The post-spinel phase is one of the strongest materials yet investigated under extreme compressions. Some fundamental properties and phase transition characters are evaluated from the quasi-harmonic approximation. The transition pressures from the γ phase to the post-spinel phase are 152.5 GPa （at 300 K） and 181.8 GPa （at 1500 K）. The phase transition pressures of theβ→wll and γ→postspinel transitions increase with the rise of temperature; hence, at higher temperature it requires higher pressure to synthesize post-spinel Si3Na. The heat capacity, thermal expansion and bulk modulus of the new phases are computed as functions of pressure and temperature. The heat capacity of post-spinel Si3Na is large at high temperature and only weakly pressure dependent.

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