Microstructural and elastic behaviour of OCMG-processed NdBaCuO materials

A systematic investigation of an HTSC material viz; Nd_1.8Ba_2.4Cu_3.4O_y superconductor prepared by the oxygen controlled melt growth (OCMG) process has been undertaken by studying its microstructure and elastic behaviour. The results are compared with those obtained on samples prepared by melt powder melt growth (MPMG) processed YBa₂Cu₃O_y material. The X-ray diffraction studies of the new material clearly indicate the predominant structure of NdBa₂Cu₃O_y. 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 μm size in the Nd-123 matrix. Further, magnetization measurements also show that the sample exhibits a pronounced secondary peak effect along with a critical current density value of 36 000 A/cm² at T = 77 K in a field of 1.6 T applied parallel to the c-axis. Finally, the ultrasonic velocity measurements reveal that the elastic anomalies generally observed among most of the RE-123 materials, especially in the temperature region of 100-250 K are totally absent in the case of Nd-123 of the present investigation.