Physical, magnetic and mechanical properties of Bi-2212 superconductors prepared by high pelletization pressure

摘要

In this work, ceramic superconductors with nominal composition Bi_(1.8)Sr_2Ca_(1.1)Cu_(2.1)O_y were produced by different pelletization pressures at high values varied from 1.5 GPa to 6 GPa. The effects of high pelletization pressure on the structural and magnetic properties of samples fabricated in this work were investigated by means of X-ray powder diffraction, scanning electron microscopy, dc electrical resistivity, magnetic hysteresis loop measurements and Vickers microhardness measurements. The room temperature resistivity of the samples significantly decreases when pelletization pressure is increased. M-H measurements were performed at T = 10 K and 25 K, respectively. In order to examine the J_C characterization of samples, Bean's critical model was used. It was found that sample D including pelletization pressures of 6 GPa have higher values of magnetization in all applied magnetic fields, indicating good connectivity between grains. Additionally, mechanical properties of samples are also characterized by microhardness measurements at room temperatures, indicating that microhardness values as well as J_c values in sample D enhanced due to its stronger couplings between grains compared to other samples.