Effects of Ag addition on the synthesis of RE-123 phase through the diffusion process

Effects of Ag addition on the synthesis of different rare earth (RE) (Ho, D y, Gd, Eu, Sm, Nd)-based high-T-c oxides through the diffusion process are reported. In the diffusion composites of 035/RE-211 (e.g. 035: atomic ratio of RE:Ba:Cu), only RE-123 layer is formed in Ho, Dy, Gd and Eu-based oxide composites, while RE-224 layer is formed between 123 layer and 211 substra te in Sm. and Nd-based oxide composites. The 32 wt.% Ag2O (30 wt.% Ag) addi tion to the 035 coating layer eliminates the formation of RE-224 layer in S m and Nd-based oxide composites. Ag accumulates near the 123/211 phase boun dary in the RE-123 layer. The formation temperature of 123 phase appreciabl y decreases by the Ag addition to the coating layer in all RE-based oxide c omposites. The reaction temperature required to attain a T-c of about 90 K is also reduced by about 70 K by the Ag addition to the coating layer. The O-2 partial pressure in the reaction atmosphere exhibits an appreciable eff ect on the diffusion behavior. (C) 2001 Elsevier Science B.V. All rights re served.