Melting temperature of YBa2Cu3O7-x and GdBa2Cu3O7-x at subatmospheric partial pressure

Abstract

The melting temperature, Tm, of YBa2Cu3O7 x and GdBa2Cu3O7 x superconductor ceramic compounds has been measured by differential thermal analysis (DTA) over a large oxygen partial pressure range of five orders of magnitude (2$10 5 < PO2 < 1 bar). It is shown that the DTA peak and endset temperatures are closer to Tm than the onset temperature. Correct measurement of Tm requires low heating rates and subatmospheric pressure conditions to avoid temperature shifts due to local oxygen overpressure and kinetic effects.