水镁石与方镁石的热力学及热导特征的第一性原理研究  

First Principles Study on Thermodynamics and Thermal Conductivity of Brucite and Periclase

作　　者：於造林 宋亚兰 马超杰 何开华[1] 姬广富[2] YU Zaolin;SONG Yalan;HE Kaihua;JI Guangfu(Faculty of Maths and Physics,China University of Geosciences,Wuhan 430074,Hubei;Institute of Shock Wave and Detonation Physics Research,Institute of Fluid Physics,China Academy of Engineering Physics,Mianyang 621900,Sichuan)

机构地区：[1]中国地质大学数学与物理学院,湖北武汉430074 [2]中国工程物理研究院流体物理研究所冲击波物理与爆轰物理国防科技重点实验室,四川绵阳621900

出　　处：《四川师范大学学报（自然科学版）》2018年第6期794-799,共6页Journal of Sichuan Normal University（Natural Science）

基　　金：国家自然科学基金(41402034)

摘　　要：利用第一性原理计算,结合准谐Debye理论以及玻尔兹曼传输原理,对水镁石(Mg(OH)2)及其脱水后形成的方镁石(MgO)的热力学性质及热导特征进行比较研究.通过分析发现,2种矿物的性质存在较大的差异.2种矿物的热膨胀系数都会随着温度的升高而升高,但Mg(OH)2在较高温度时会呈现出减小的趋势.在压力的作用下,Mg(OH)2的热膨胀系数会增大,而MgO的热膨胀系数会减小.2种矿物间的热膨胀系数的差异源于格林艾森常数和体变模量的变化.2种矿物在压力作用下的晶格热导率的变化与热膨胀系数的变化相似,但是两者间的大小相差很大,MgO的晶格热导率比Mg(OH)2的要高2个数量级,说明脱水对热导的影响很大.经分析得到脱水热导率增大的原因在于其非谐散射率减小,声子寿命增大.Using first principles calculations in combination with quasiharmonic Debye theory and Boltzmann transport equation,we studied the thermal properties of brucite and periclase(Mg(OH)2 and MgO)comparatively.We found big difference between the two minerals.The thermal expansivity increases with increasing temperature,while at higher temperature,the decreased trend of Mg(OH)2 is presented.With effect of pressure,the thermal expansivity of Mg(OH)2 increases,while that of MgO has an opposite variation.The difference between the two minerals stems from their different variation of Grüneisen constant and bulk modulus.The lattice thermal conductivity has similar changes with those of thermal expansivity with the effect of pressure.However,the amplitude has giant difference between the two minerals,and the lattice thermal conductivity of MgO is two orders higher than that of Mg(OH)2,and the lower scattering rates of phonons,meaning longer lifetime,accounts for the high conductivity of MgO.This work indicates that the dehydration has significant effect on thermal properties.

关 键 词：水镁石与方镁石 热膨胀系数 热导 第一性原理 

分 类 号：O482[理学—固体物理]