Reactivity between Nd_(1+x)Ba_(2-x)Cu_3O_(7-delta+x/2) and Nd_(4-2z)Ba_(2+2z)Cu_(2-z)O_(10-2z) phases in superconducting NdBaCuO powders and melt textured bulk samples

摘要

The high temperature reaction between the superconducting Nd123(x) (Nd_(1+x)Ba_(2-x)Cu_3O_(7-delta+x/2) phase and Nd422(z) (Nd_(4-2z)Ba_(2+2z)Cu_(2-z)O_(10-2z), leading to substitutions of Nd in the Ba sites of Nd123, was analysed. For this purpose, differential thermal analysis (DTA) was performed on powders with different Nd422 addition. Measurement results were compared with the values, reported in the literature, of the peritectic temperatures in function of Nd123 substitution. The superconducting transition critical temperature analysis of melt-textured samples shows that the use of Barium rich Nd422 allows significant improvements of the superconducting parameters of produced samples, avoiding the occurrence of the Nd-Ba substitutions.