ELASTIC BEHAVIOR OF MELT-POWDER-MELT-GROWTH PROCESSED YBa2Cu3O7-δ

Abstract

The ultrasonic velocity measurements of a Y-Ba-Cu-O material, prepared by Melt-Powder-Melt-Growth process (MPMG) with Nd-123 as a seed material, known as MPMG-II material, have been undertaken by the pulse transmission technique over a temperature range 80–300 K. It has been observed that the MPMG-II material, in contrast to Y-123 material also prepared by the Melt-Powder-Melt-Growth method without using any seed material, designated as MPMG-II, exhibits a very high Young's and rigidity modului, which are comparable with those of single crystalline ones. Further, it has also been observed that the longitudinal velocity is found to increase continuously with decreasing temperature right up to liquid nitrogen temperature, i.e. 80 K, without showing any anomaly, whatsoever, thereby indicating that the behavior resembles a normal solid having normal behavior. From these two observations, it has been speculated that MPMG-II material may be free from all types of lattice instabilities and that it may be approaching mechanically a single crystalline Y-123 material.