Thermal and X-Ray Analyses of High Temperature Superconductor YBa₂Cu₃O_6.74

Abstract

In situ observation of oxygen absorption and desorption during heating and cooling cycle with TG and DTA was done to determine the optimum preparation conditions of high T c Y-Ba-Cu-O compounds. We suggest the best recipe in air is to fire the raw mixture of 1/2Y 2 O 3 , 2BaCO 3 and 3CuO at 930°C for more than 10 h, followed by slow cooling in the furnace to take as much oxygen as possible within the specimen. With this method single phase material of an orthorhombic superconducting oxide YBa 2 Cu 3 O 6.74 with T c =91.3 K was synthesized, with orthorhombic unit cell dimensions of a =3.8180(6) Å, b =3.8888(7) Å, and c =11.668(2) Å.