Thermal Decompositions of (RE)Ba2Cu3O6 (RE=Y,Nd, Er)

Thermogravimetric in situ measurements of oxygen loss from (RE)Ba₂Cu₃O₆ samples (RE=Y, Nd, Er) heated isothermally in a relatively high dynamic vacuum were made with a Cahn RG electrobalance. Single-phase orthorhombic samples of composition (RE)Ba₂Cu₃O_7-x (highest oxygen content) were synthesized from stoichiometric (1:2:3) mixtures of high-purity (RE)₂O₃, BaCO₃ and CuO. The original 1:2:3 mixture was prepared by the two-stage procedure described earlier. The crystal structure of the sample in the original orthorhombic phase was controlled by the X-ray powder method (CuKα radiation) using a Stadi P Stoe diffractometer with a position-sensitive detector. The decomposition curves are described by the sum of exponential terms corresponding to rapid and slow first-order processes in which differently sized grains of the powder samples are involved. The activation energies are estimated from appropriate Arrhenius plots. This revised version was published online in July 2006 with corrections to the Cover Date.