Preparation of ultrafine superconducting YBCO particles by wet jet-mill

摘要

An ultrafine YBCO particle was prepared using a wet jet-mill. Experiments were carried out in a high pressure flow of methyl ethyl ketone: CH_3COCH_2CH_3 (MEK). To obtain fine and highly homogeneous particles of the YBCO superconductor, Y_1Ba_2Cu_3O_x pellets were first crushed using a pulverizer, and then processed by wet jet-mill in which the maximum processing pressure is about 1300 kfg cm~(-2) and the maximum running speed in the orifice is about 300 m s~(-1). The ultrafine particles obtained are homogeneous, suspended in MEK. The ultrafine YBCO particle has an average size of 200-800 nm in diameter. From measurements of the resistive transition with temperatures, the ultrafine YBCO particle shows the superconducting transition temperature (T_c) at 93 K (onset T_c) after being annealed at 935-950℃ for 12 h in oxygen.