Growth and Characterization of Homogeneous YBa2Cu3O7-δ Powders Prepared by a Freeze-Drying Method

Abstract
Homogeneous superconducting powders of YBa2Cu3O7-δ have been successfully prepared from a carbonate solution by means of a freeze-drying method. Sintered powders at 930°C were characterized by 100% volume fraction of the superconducting phase in measurements of field-cooled magnetization at 4.5 K in low fields (\lesssim2 Oe) using a SQUID magnetometer. It turned out that large plate-shaped grains (∼2×5×20 µm3) grew when the powders were heated in a short period (\gtrsim6 hours) and that the packing density was considerably high even without any pressing process.