ON THE STABILITY REGION AND STRUCTURE OF THE ND1-XCU3OY SOLID-SOLUTION(XBA2)

We studied the low and upper stability boundaries and the structure ev olution of the Nd1+xBa2-xCu3Oz solid solution along its single-phase f ield. It was found that in oxygen the limit of the solid solution exte nds up to Nd1.9Ba1.1Cu3Oz at 950-1050 degrees C while at lower and hig her temperatures it becomes narrower. In nitrogen atmosphere the subst itution range is much smaller and x does not exceed 0.3 at 800 degrees C. The replacement of Ba2+ by Nd3+ is accompanied by decreasing both a and c lattice constants of quenched samples. At the same time in oxy gen at x greater than or equal to 0.6 ordering phenomena occur leading to the orthorhombic distortion of the tetragonal subcell. A model of the solid solution crystal structure with a B-centered unit cell and l attice parameters a = 2a(sub), b = b(sub) and c = 2c(sub) was suggeste d and refined.