摘要
Ⅰ. INTRODUCTIONThe crystal structure of RBa<sub>2</sub>CU<sub>3</sub>O<sub>7-x</sub> superconductor has been determined （where R includes La, Y, Eu and T1）. However, the preparation of high T<sub>C</sub> superconductor with high quality may meet some difficulties as the quality of materials would be influenced by many factors, such as the distribution of grain size, the grain orientation and other microstructure features （the grain boundary, void, impurity phase and defects, etc.）. It is very important
