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

This work was funded by the Spanish Programa Nacional de Materiales through projects MAT2014-51778-C2-1-R and MAT2014-51778-C2-2-R. We also acknowledge: the Center of Excellence award Severo OchoaSEV-2015-0496, SGR753 and SGR948 from the Generalitat of Catalunya, the European Union through projects Eurotapes (EU-FP7 NMP-LA-2012-280432) and Ultrasupertape (ERC ADG-2014-669504), and the Universitat de Girona (MPCUdG2016/059)