Li_(3)N与Na_(3)P的物理性质的对比研究  

Comparative studies on the physical properties of Li_(3)N and Na_(3)P

作　　者：祁美红 张小锋 曹昕睿 吴顺情 朱梓忠 QI Meihong;ZHANG Xiaofeng;CAO Xinrui;WU Shunqing;ZHU Zizhong(College of Physical Science and Technology,Xiamen University,Xiamen 361005,China;Fujian Provincial Key Laboratory of Theoretical and Computational Chemistry,Xiamen University,Xiamen 361005,China)

机构地区：[1]厦门大学物理科学与技术学院,福建厦门361005 [2]福建省理论与计算化学重点实验室,福建厦门361005

出　　处：《厦门大学学报（自然科学版）》2022年第2期194-201,共8页Journal of Xiamen University：Natural Science

基　　金：国家重点研发计划(2016YFA0202601)。

摘　　要：Li_(3)N可作为Li+电池的固态电解质,Na_(3)P可作为Na+电池的负极材料,特别是Li/Na以及N/P分别为同一族的元素,Li_(3)N和Na_(3)P的物理性质有很多典型的相同点和不同点,故对比两个材料的物理性质有助于推动Li+/Na+电池的研究.采用第一性原理研究了这两种材料的稳定结构、声子谱、弹性常数、电子结构、离子扩散势垒以及缺陷形成能等.计算表明:立方相的c-Li_(3)N最稳定,而六角相的β-Na_(3)P能量最低.结合c-(立方相),α-(六角相)和β-(六角相)的Li_(3)N与Na_(3)P的声子谱,确定c-Li_(3)N和c-Na_(3)P最稳定.弹性常数的计算表明所计算的6种结构都是有机械稳定性的.结果还表明,c-Li_(3)N和c-Na_(3)P都是间接带隙的半导体.电荷密度的计算体现了两种材料中不同的键合特点.Li+/Na+迁移势垒的计算给出了Li_(3)N与Na_(3)P作为离子晶体的特征.文中对所有物理性质的对比都与Li_(3)N材料比Na_(3)P材料有强得多的化学键的事实相一致.Li_(3)N is regarded as a solid electrolyte in Li+batteries,whereas Na_(3)P is used as an anode material in Na+batteries,especially Li/Na or N/P are in the same group of the periodic table,the physical properties of Li_(3)N and Na_(3)P have many typical similarities and differences,so it is meaningful to study comparatively the physical properties of the two materials in Li+/Na+batteries.By using a first-principle method,the stable structures,phonon spectra,elastic constants,electronic structures,ion diffusion barriers and vacancy formation energies are studied.Simulation results suggest that cubic Li_(3)N qualifies as the most stable phase,whereasβ-Na_(3)P secures the lowest binding energy,combined the phonon spectra calculations show that only the c-Li_(3)N and c-Na_(3)P is the most dynamically stable among the c-(cubic),α-(hexagonal)andβ-(hexagonal)phases of Li_(3)N and Na_(3)P.Elastic constant calculations indicate that all six structures studied appear mechanically stable.Electronic structures indicate that c-Li_(3)N and c-Na_(3)P belong to both indirect gap semiconductors.The charge density calculations display the different bonding characters in these two materials.The calculated migration potential barriers of Li+/Na+show clearly the characteristics of ionic crstals of Li_(3)N and Na_(3)P.All comparisons on physical properties of these two materials coincide with the fact that bonding in Li_(3)N is much stronger than that in Na_(3)P.

关 键 词：Li_(3)N Na_(3)P 结构稳定性 电子结构 离子导电性 第一性原理方法 

分 类 号：O48[理学—固体物理]