In this dissertation, the effects of preparation processes and microstructure of YBaCuO compound on superconductivity have been studied. It has been found that the superconducting transition temperature is dominated by the lattice distortion of 123 orthorhombic phase, and the critical current density of superconductors strongly depends on the density of materials, inhomogeneity of composition as well as grain boundary morphology. Based on the investigations of reaction kinectics and thermodynamics during the formation of YBa_2Cu_3O_(7-x) superconductor via solid state reaction, new preparation technologies of vacuum heat treatment and sintering at high oxygen partial pressure are suggested to improve the superconductivity of sintered bulk sample. According to the study on solidification behavior of YBaCuO compound, laser floating zone melting technology is developed to grow YBaCuO superconducting crystals, and the microstructure and superconductivity of the crystal have been discussed. Moreover, influence of rapid solidification on microstructure and property of YBa_2Cu_3O_(7-x) compound has been explored.
修改评论