The oxygen stoichlometry of the EuBa2Cu3O7 − x phase investigated by thermogravimetry

The exact oxygen concentration of the EuBa2Cu3O7 − x phase, Eu〈123〉, is not exactly known. By reducing Eu〈123〉 with an argon plus hydrogen mixture in a thermobalance, the absolute oxygen concentration was obtained as well as the oxygen stoichiometry as a function of temperature and oxygen partial pressure, p02. Using the results obtaine, the boundary of the orthorhombic-to-tetragonal phase transition, log p02 (Pa) = −7194.5/T + 11.29, was derived under the assumption that this transition occurs at (7 − x) = 6.5.