LiNbO_3光学性质与热力学性质的第一性原理计算

On First-Principles Calculations of Optical and Thermodynamic Properties of LiNbO_3

采用基于第一性原理的赝势平面波法系统计算了LiNbO3晶体的电子结构、晶格振动和热力学性质,分析了掺杂抗光散射离子Mg2+和Sc3+对光学性质的影响.结果表明:室温时LiNbO3晶体的恒容热容为22J/mol·K,600K时,徳拜温度达到772.LiNbO3晶体中掺入Mg2+或Sc3+离子,导致光学性质发生明显改变,极限介电常数由4.8降低到3.7,极限折射率n0由2.2降低到1.9.

First‐principles calculations of electronic structure ,lattice dynamic and thermodynamic proper‐ties of LiNbO3 have been performed in plane‐wave pseudopotential method .The effect of doping anti‐scat‐tering ions M g2＋ and Sc3＋ on optical properties has been analyzed .It is show n that the heat capacity at constant volume of the LiNbO3 crystal is 22 J/mol ＆#183; K at room temperature and the Debye temperature reachs 772 at 600 K .The optical properties are changed obviously when the anti‐scattering ions Mg2＋ or Sc3＋ are doped in LiNbO3 crystal ,the zero frequency limit of dielectric constant is reduced from 4 .8 to 3 . 7 and the zero frequency limit of refractive index n0 is decreased from 2 .2 to 1 .9 .