Properties of nanophase grains of superconducting YBCO prepared by wet-type jet mill

Abstract Superconducting ultrafine particles of YBCO were prepared by a wet-type jet mill in a high pressure flow of methyl-ethyl-ketone (CH 3 COCH 2 CH 3 ). As a result, when the mill is operated at a pressure of 1300 kg cm −2 , ultrafine particles of YBCO show oriented polycrystal structures with a particle size 80–120 A in diameter and with the lattice parameter of 3.9 A in the [001] orientation from transmission electron microscopy studies. The particles show the T c to be at 93 K (onset) after annealing at 935–950°C for 12 h in oxygen.