超快过程中电子激发效应对γ-LiAlO_(2)损伤的影响研究  

Study on the damage ofγ-LiAlO_(2) crystal by electron excitation in ultrafast process

作　　者：何南燐 何翠 张娥 陈静 庄慧慧 杜启明 严觉民 程新路[3] HE Nan-lin;HE Cui;ZHANG E;CHEN Jing;ZHUANG Hui-hui;DU Qi-ming;YAN Jue-min;CHENG Xin-lu(The Armed Police College of PAP,Chengdu 610213,Sichuan,China;Southwestern Institute of Physics,Chengdu 610041,Sichuan,China;Institute of Atomic and Molecular Physics,Sichuan University,Chengdu 610065,Sichuan,China)

机构地区：[1]武警警官学院,四川,成都610213 [2]核工业西南物理研究院,四川,成都610041 [3]四川大学原子与分子物理研究所,四川,成都610065

出　　处：《云南大学学报（自然科学版）》2022年第5期949-955,共7页Journal of Yunnan University(Natural Sciences Edition)

基　　金：国家重点研发计划(2017YFE300602);国家自然科学基金(11905047);国防科技工业核材料技术创新中心项目(ICNM-2022-ZH-20)。

摘　　要：电子激发效应在超快激光对材料进行辐照的过程中承担着重要的作用.然而,关于超快过程中电子激发效应对γ-LiAlO_(2)晶体基本性质影响的研究较少.基于密度泛函理论,计算不同电子温度下γ-LiAlO_(2)的声子频率曲线、电子态密度和弹性模量,采用准简谐近似的方法研究了电子激发对晶体的热力学性质影响.当电子温度低于2 eV时声子谱图未出现虚频,弹性模量、德拜温度和熔化温度几乎不受影响.但电子温度继续增大后电子态密度能带间隙逐渐减小,德拜温度和熔化温度逐渐下降,声子熵逐渐增大,体系混乱度增大.当电子温度达到5 eV时,声子谱图出现虚频,总电子态密度的带隙消失,晶体经历熔化转变到金属态,弹性剪切常数已不能满足波恩稳定准则,说明电子温度为5 eV时电子激发效应对γ-LiAlO_(2)晶体产生了破坏性损伤.The effect of electron excitation plays an important role in ultrafast laser or fast ion irradiation.However,the existing knowledge on the fundamental properties ofγ-LiAlO_(2)is limited and insufficient with regard to ultrafast irradiation.In this paper,we investigated the phonon spectrum,density of states and elastic modulus ofγ-LiAlO_(2)at different electron temperature using the density functional perturbation theory(DFPT).The influence of electron excitation on the thermodynamic properties was calculated by quasi-harmonic approximation.From T=0 eV to 2 eV the elastic modulus,Debye temperature and melting temperature remain almost unchanged,in addition,the phonon frequency didn’t present negative value.Subsequently,the calculated band gad,Debye temperature and melting temperature decreased as the electronic temperature increased,but the phonon entropy revealed an inverse trend which confirm that the randomness ofγ-LiAlO_(2)increases as the effect of electronic excitation is enhanced.Particularly,partial phonon frequencies begin to include imaginary frequencies,which signify the instability of the lattice at T=5 eV.At the same time,the band gap disappeared,and the elastic shear constants do not satisfy the Born stability criteria.It is shown that the electron excitation of 5 eV has a destructive damage to theγ-LiAlO_(2)crystal.

关 键 词：电子激发 声子谱 熔化温度 γ-LiAlO_(2) 密度泛函理论 

分 类 号：O56[理学—原子与分子物理]