铌酸锂晶体的结构与性能关系研究

Relationship between the structure and property of lithium niobate single crystals

在实验测定的结晶学数据基础上,键价模型和化学键方法都被应用于定量或定性的研究铌酸锂晶体的物理性质,例如介电性质(包括折射指数no和二阶非线性光学系数dij)、居里温度Tc和自发极化率Ps。在前期工作中提出的Nb5+位依赖Li+位敏感的模型已成功地应用于铌酸锂晶体多种物理性质的研究。结果显示,其物理性质对晶体组成有强烈的依赖性。 Nb5+位对于铌酸锂晶体的机械性质具有很强的影响;而Li+位也与晶体的介电性质密切相关,同时Li+位也是对+1～+5价不同掺杂剂敏感的晶格位置。

On the basis of crystallographic data of various pure and doped lithium niobate crystals, the bond valence sum model and the chemical bond method are employed to understand crystallographic modification of physical properties of lithium niobate. The physical properties such as dielectric responses (including the refractive indices no ,second-order nonlinear optical coefficient dij,Curie temperature Tc and spontaneous polarization P, are quantitatively or qualitatively studied. A Nb5+-site-dependent and Li+-site-sensitive model is proposed to successfully describe various physical properties of lithium niobate crystals. The present work shows the physical properties of the crystals are strongly dependent on the crystal composition. The Nb5+ -site can give a strong effect on the mechanical properties of crystals.the Li+-site was closely correlated to the dielectric properties of crystals, which was an sensitive lattice site available for various dopants with the valence ranging from +1 to +5.