PREPARATION OF ULTRAFINE SUPERCONDUCTING YBCO PARTICLES BY WET JET-MILL

An ultrafine YBCO particle was prepared using a wet jet-mill. Experime nts were carried out in a high pressure flow of methyl ethyl ketone: C H3COCH2CH3 (MEK). To obtain fine and highly homogeneous particles of t he YBCO superconductor, Y1Ba2Cu3Ox pellets were first crushed using a pulverizer, and then processed by wet jet-mill in which the maximum pr ocessing pressure is about 1300 kfg cm(-2) and the maximum running spe ed in the orifice is about 300 m s(-1). The ultrafine particles obtain ed are homogeneous, suspended in MEK. The ultrafine YBCO particle has an average size of 200-800 nm in diameter. From measurements of the re sistive transition with temperatures, the ultrafine YBCO particle show s the superconducting transition temperature (T-c) at 93 K (onset T-c) after being annealed at 935-950 degrees C for 12 h in oxygen.