ZCSC和CMSC晶体热学性质的理论研究

Theory Research on Thermal Properties of ZCSC and CMSC Crystals

采用密度泛函理论计算了ZnCd(SeCN)_4(简称ZCSC)和CdHg(SeCN)_4(简称CMSC)晶体的声子色散谱、声子态密度,系统研究了这两种晶体的比热容、热膨胀率、热导率、热扩散率等热学性质。理论计算得到常温下ZCSC和CMSC晶体的比热容分别为0.454 J·g^(-1)·K^(-1)和0.374 J·g^(-1)·K^(-1),而本文通过差示扫描量热仪实验测量这两种晶体的比热容分别为0.460 J·g^(-1)·K^(-1)和0.306 J·g^(-1)·K^(-1),理论计算与实验结果相符。研究结果还表明ZCSC晶体的热导率及热扩散率均为CMSC晶体的5~7倍,而ZCSC晶体的热膨胀率约是CMSC晶体的1/3,因此ZCSC晶体是热学性质优异抗激光损伤能力强的非线性光学晶体。

Based on density functional theory （ DFT） , the phonon dispersion spectrums and phonon density of states of ZnCd（ SeCN ） 4 （ ZCSC ） and CdHg（ SeCN ） 4 （ CMSC ） crystals were calculated, and the specific heat, thermal expansivity, thermal conductivity and thermal diffusivity of two crystals were researched systematically. The theoretical values of specific heat of ZCSC and CMSC crystals at room temperature are 0.454 J · g^-1 · K^-1 and 0. 374 J · g^-1 · K^-1 respectively, which are consistent with the differential scanning calorimeter （DSC） experimental values that are 0.460 J · g^-1 · K^-1 and 0. 306 J · g^-1 · K^-1espectively. The research result reveals that the thermal conductivity and thermal diffusivity of ZCSC crystal are both as 5-7 times as that of CMSC crystal, and thermal expansivity of ZCSC crystal is one third of that of CMSC crystal. In summary, ZCSC crystal is a kind of nonlinear optical crystal with excellent thermal properties and laser damage-resistance ability.