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La_2CuO_(4+δ)是La系氧化物超导体的母体化合物,该化合物经碱土离子的La位替代或增加超计量的氧(如通过高氧压、电化学氧化等途径)可转变为超导体.La_2CuO_(4+δ)是一种Moot绝缘体,晶胞中存在有Cu-O面,它表现出的三维反铁磁绝缘体性质与Cu位上的强烈库仑相互作用有关.X光及中子衍射结果表明:当温度T>530K时,La_2CuO_(4+δ)为四方结构,T<533K时它由四方结构转变为正交结构.Johnston等人的研究表明 La_2CuO_(4+δ)体系中的T-0转变,Neel温度及电磁输运性质与试样氧含量关系密切利用内耗的灵敏性,文献[7,8]中曾对高T_c超导体YBCO中氧缺陷的运动和微结构的变化进行过较深入的研究.
La_2CuO_ (4 + δ) is the parent compound of La-based oxide superconductors which can be transformed into superconductors by substituting the La sites of alkaline earth ions or increasing the excess of oxygen (such as by high oxygen pressure, electrochemical oxidation, etc.) (4 + δ) is an Moot insulator with a Cu-O surface in the unit cell, which shows the nature of the three-dimensional antiferromagnetic insulator and the strong Coulomb interaction at the Cu site.The X-ray and neutron diffraction results show that : La_2CuO_ (4 + δ) has a tetragonal structure at temperature T> 530K and it changes from tetragonal to orthorhombic at T <533 K. Studies by Johnston et al. Have shown that T_ 0 in La_2CuO_ (4 + δ) The Neel temperature and electromagnetic transport properties and the oxygen content of the sample are closely related to the sensitivity of internal friction. In the literature [7,8], the changes in the movement and microstructure of oxygen defects in high Tc superconductor YBCO were studied in depth the study.