Phase separation of Nd1+xBa2-xCu3O6+delta during annealing processing

In order to investigate phase separation in solid, Nd1+xBa2-xCu3O6+delta po wders with different compositions were annealed under different annealing c onditions. The temperature - substitution ratio - oxygen content phase diag ram of Nd1+xBa2-xCu3O6+delta solid solution (Nd123ss) was constructed. The condition to occur Nd123ss phase separation was clarified by investigating the compositional fluctuation, XRD pattern, the time dependences of T-c pro perties and oxygen content. Consequently, only orthorhombic phase with smal l x can separate into two orthorhombic phases with larger and smaller x by the spinodal decomposition mechanism. (C) 2001 Elsevier Science B.V. All ri ghts reserved.