高温超导体(La_(1-x)M_x)_2CuO_4(M=Ba,Sr)的化学键性质和Mssbauer谱研究

Chemical Bond Properities of (La1-x Mx)2CuO4(M=Ba,Sr) and its Mossbauer Spectroscopy

利用复杂晶体化学键电介质的平均能带模型研究了(La_(1-x)M_x)_2CuO_4(M=Ba,Sr)的化学键特性,得到Cu-O键的平均共价性为0.3,La-O键的平均共价性为0.03。应用由共价性和极化率定义的化学环境因子计算了^(57)Fe在La_2CuO_4中的Mossbauer同质异能位移,确定了^(57)Fe在La_2CuO_4中的价态和占位情况。

By using the average band-gap model, the chemical bond properties of (La1-xMx) 2CuO4 (M=Ba, Sr) werecal-culated . The calculated covalencies for Cu-O and La-O bond in the compounds are 0.3 and 0.03 respectively. Mo ssbauer isomer shifts of57Fe doped in La2CuO4was calculated by using the chemical surrounding factor, h, defined by co-valency and electronic polarizability . Four valence state tin and three valence iron sites was identified in 'Fe doped La2CuO4 superconductor.