Predicting Physical Properties of Tetragonal,Monoclinic and Orthorhombic M_3N_4(M=C,Si,Sn) Polymorphs via First-Principles Calculations

作     者：仓玉萍 连帅彬 杨慧明 陈东 

作者机构：College of Physics and Electronic EngineeringXinyang Normal University 

出 版 物：《Chinese Physics Letters》 (中国物理快报（英文版）)

年 卷 期：2016年第33卷第6期

页      面：90-94页

核心收录：

学科分类：07[理学] 070205[理学-凝聚态物理] 0805[工学-材料科学与工程（可授工学、理学学位）] 0704[理学-天文学] 0702[理学-物理学] 

基　　金：Supported by the National Natural Science Foundation of China under Grant Nos 61475132 and 61501392 

主　　题：Si M=C,Si,Sn on of Predicting Physical Properties of Tetragonal,Monoclinic and Orthorhombic M3N4 M Polymorphs via First-Principles Calculations that in is 

摘      要：The recently discovered tetragonal, monoclinie and orthorhombic polymorphs of M3N4 （M=C, Si, Sn） are in- vestigated by using first-principles calculations. A set of anisotropic elastic quantities, i.e., the bulk and shear moduli, Young＇s modulus, Poisson ratio, H/G ratio and rickets hardness of M3N4 （M=C, Si, Sn） are predicted. The quasi-harmonic Debye model, assuming that the solids are isotopic, may lead to large errors for the non-cubic crystals. The thermal effects are obtained by the traditional quasi-harmonic approach. The dependences of heat capacity, thermal expansion coefficient and Debye temperature on temperature and pressure are systematically discussed in the pressure range of 0 IOGPa and in the temperature range of 0-1100 K. More importantly, o- C3N4 is a negative thermal expansion material. Our results may have important consequences in shaping the understanding of the fundamental properties of these binary nitrides.