Microstructural and elastic behaviour of OCMG-processed NdBaCuO materials

A systematic investigation of an HTSC material viz; Nd1.8Ba2.4Cu3.4Oy super conductor prepared by the oxygen controlled melt growth (OCMG) process has been undertaken by studying its microstructure and elastic behaviour. The r esults are compared with those obtained on samples prepared by melt powder melt growth (MPMG) processed YBa2Cu3Oy material. The X-ray diffraction stud ies of the new material clearly indicate the predominant structure of NdBa2 Cu3Oy. The microstructural investigations performed by means of optical and scanning electron microscopy confirm the presence of a second phase formed due to the uniform distribution of Nd4Ba2Cu2O10 (Nd-422) particles of size 1-12 mu m size in the Nd-123 matrix. Further, magnetization measurements a lso show that the sample exhibits a pronounced secondary peak effect along with a critical current density value of 36 000 A/cm(2) at T = 77 K in a fi eld of 1.6 T applied parallel to the c-axis. Finally, the ultrasonic veloci ty measurements reveal that the elastic anomalies generally observed among most of the RE-123 materials, especially in the temperature region of 100-2 50 K are totally absent in the case of Nd-123 of the present investigation. (C) 1999 Elsevier Science S.A. All rights reserved.