THE STUDY OF MOSSBAUER-EFFECT IN EUBA2CU3O7-Y

EuBa2(Cu1-xFex)3O7-y has been investigated by the Fe-57 and Eu-151 Mossbauer effect. The Fe-57 Mossbauer spectra of the EuBa2(Cu1xFex)3O7-y without or with DC electric current (the current strength I = 0.5A) around the superconducting transition temperature have been measured. The results indicate that the isomer shift (IS) and the quadrupole splitting (QS) of the Fe replacing the Cu(2) vary neither with increasing the Fe content nor with the small DC eletric current passing the superconductor and that the IS and the QS of the Fe replacing the Cu(1) vary with the Fe content. Especially, the IS and the QS of the Fe (D3) replacing the Cu(1) are changed when the small electric current passes the superconductor at 80K.

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

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。

Eu~(3+):Ln_2O_2S(Ln=Lu,Y,Gd,La)晶体的角重迭参数计算

本文使用角重迭模型(AOM),针对Eu~(3+):Ln_2O_2S(Ln=Lu,Y,Gd,La)晶体系列,在考虑硫和氧两种不同格位的情况下,对f电子的全部四个角重迭参数e_σ、e_π、e_δ和e_φ进行了计算,得到了一些基本规律,即中心离子与配位体之间的共价性大小次序为Lu～Y>Gd>La,并且Ln-O键的共价性要强于Ln-S键.