稀土-铁石榴石的共价极化行为对光谱和穆斯堡尔谱的影响

Influence of Polarizability and Covalency on Spectrum and Mossbauer spectra in Rare Earth-Fe Garnets

利用平均能带模型研究了稀土 铁石榴石晶体化学键的性质 ,结果表明 ,这些晶体虽然包含的稀土离子不同 ,但计算得到的化学键参数值几乎相同。在每个化合物当中 ,金属离子与氧配体之间共价性随着Ln3+ (2 4c)、Fe3+ (16a)、Fc3+ (16d)的次序而增大。利用由共价性和极化率定义的化学环境因子h计算YIG中Fe3+ 的拉卡参数与实验值一致。建立了穆斯堡尔同质异能位移与h值的线性关系 ,讨论了居里温度与h值的相关性。

By using the average band gap model,chemical bond properties of rare earth Fe garnets are studied.Calculated results show that in this series of compounds,chemical bond properties of crystals containing different rare earth ions are similar,and in each compound,the covalency values increase with the increasing order from Ln 3+ (24 c ),Fe 3+ (16 a ) to Fe 3+ (16 d ),Racah parameters of Fe 3+ ion in YIG are calculated by using the chemical surrounding factor ( h ) definited by covalency and electronic polarizability,and the results are in agreement with the experimental values.A linear relationship between the Mossbauer isomer shifts of Fe 3+ and h values was obtained.The relation between Curie temperatures and h values was discussed too.