Structural phase transition in substituted La2CuO4 and Pr2CuO4-y

The structural phase transition from orthorhombic (T) phase to tetragonal (T') phase in substituted La2-xRxCuO4 (R = Pr, Nd, Sm, Eu and Gd) and T' to T-phase in Pr2-xMxCuO4-y (M = Sr, Ca) has been studied by X-ray diffraction technique. The T-phase of La2CuO4 is transferred to T' phase abruptly at x = 0.8, 0.4, 0.4, 0.3 and 0.4 respectively for substitution of Pr, Nd, Sm, Eu and Gd for La in La2CuO4 without evidence of the T* phase. The T' structure of Pr2CuO4 (x = 0.0) gets transformed to the T* structure at 30% Ca doping (x = 0.6) and then to the T structure at 50% Ca doping (x = 1.0), while for Sr-content x = 0.0,0.4 and 1.0 it shows T', T* and T structure respectively.