不同温度下LaAlO_3:Eu的光谱分析

Spectral Analysis of Eu^(3+) Ion in LaAlO_3:Eu at Varied Temperature

本文基于双层点电荷配位场(DSCPCF)模型,计算分析了77K,300K和500K温度下Eu_(3+)离子在LaAlO_3中的配位场微扰能级及其光谱行为,结果与实验吻合较好.由于随着温度的升高,Eu_(3+)点的对称性发生变化(D_3→O_h),而使计算参数的取值有微小差别,计算得到的配位场参数也有规律性的变化,尤其是500K时B_0~2值变号。

Based on the double - sphere coordination point - charge field (DSCPCF) model, the coordination field perturbation levels were calculated and the f - f transition spectra of Eu3 + ion in LaAlO3: Eu were analyzed at 77,300 and 500K. The results are in reasonably good agreement with experimental observation. With the increase of temperature, the small variations of thecalculating parameters are noted owing to a shift in symmetry at the europium site ( D3→Oh ) , i.e. , the parameter x which described completely the crystal structure approximates 0. 5, the average bonding distances of the three types of coordinated atoms tend to be the same. The coordination field parameters obtained were varied regularly. Especially, the sign of B02 at 500K was changed to negative so that the calculated DSCPCF levels differed from that at the other two temperatures.