Eu^(3+):Ln_2O_2S(Ln=Lu,Y,Gd,La)晶体的角重迭晶场参数计算

Calculations of Angular Overlap Parameters for Eu^(3+):Ln_2O_2S(Ln=Lu,Y,Gd,La) Crystal Series

本文使用角重迭模型(AOM)在考虑其全部四个参数e_σ、e_π、e_δ和e_φ的基础上,对Eu^(3+):Ln_2O_2S(Ln=Lu,Y,Gd,La)晶体的角量迭晶场参数进行了计算。结果表明,与σ、π反键有关的参数e_σ、e_x的数值相对较大,特别是e_σ值在这四个参数中为最大,而e_δ和e_α值则较小,在近似计算中可以忽略。这四种稀土硫氧化物的成键本领(或能力)按由大到小排列,其次序为Lu>Y>Gd>La。

In this paper, for the Eu^(3+):Ln_2O_2S(Ln=Lu,Y,Gd,La) crystal series, the all four angular overlap parameters e_σ、e_π、e_δ、e_φ are considered by Angular Overlap Model(AOM). The results show that the values for e_σ and e_π which have relation with the σ- and π-antibonding effects from the point of view of molecular orbit theory(also for parameters e_δ and e_φ) are decreased with the order of Lu, Y, Gd and La. And σ、π effects are dominant over the δ and φ effects, especially a effect. Whereas δ and φ effects can be neglected with respect to the σ and π effects in approximate calculations. The magnitude of covalent ability between 4f electrons and ligands in the four crystals is Lu>Y>Gd>La.