The phase conversion of precursor powders for powder melting process YBa_2Cu_3O_(7_x) superconductors

摘要

The effects of heating rate and holding time on the formation of YBa_2Cu_3O_(7_x) phase in precursor powders for YBa_2Cu_3O_(7_x) superconducting bulks prepared by powder melting process have been investigated. The phase conversion of the precursor powders is studied by X-ray diffraction and found to be different for different heating rates during heating. The YBa_2Cu_3O_(7_x) phase is formed during heating to peritectic temperature at 100 and 400 ℃/h, but not at 6,000 ℃/h. The longer the holding time, the more the amount of YBa_2Cu_3O_(7_x) phase between 880 ℃ and about 950 ℃. The results are useful for understanding the mechanism of powder melting process and controlling the process conditions.