1.8 A Summary of the status of the investigation on high temperature superconductivity at dalat nuclear research institute and the need for neutron scattering data acquisition

摘要

The application of the filtered neutron beams of the research reactor for basic and applied research is one of the most important activities of Dalat Nuclear Research Institute (DNRI). The status reports of the program on neutron beam utilization have been presented at previous sub-workshops in 1996 and 1997 years. So that in this report we would like to present the status of the beginning investigation on some characteristics of high temperature superconductivity (HTS) type BSCCO and to emphasizes the need for neutron data in this field. The critical temperature effects of varying systematic substitutions of ions antimony for bismuth in compound type Bi-Sb-Sr-Ca-Cu-O have been investigated. Preparation of the specimens has been carried out by solid state reaction in the air. The samples were sintered at temperature between 870 deg C - 880 deg C for 96 hours - 130 hours and then annealed in different conditions and cooled in open furnace. The critical temperatures of specimens of specimens as determined by standard four - probe technique were higher than 80 deg K, especially for one specimen (E2) has reached 100 deg K. Phase identification by X-ray powder diffraction technique indicated that the phases 2212 and 2223 were surpassing phases in this sample. These primary experimental data were shown that the critical temperatures and the phase compositions of samples very sensitively depend on the substitution of antimony ions for bismuth and the thermal conditions in synthesized processing of the specimens. Unfortunately, the atomic arrangement in all prepared specimens was still not clearly. These samples should be sent to other institutions in the Region for neutron scattering data acquisition in order to study more deeply.