Abstract
The magnetic susceptibility X of YBa2Cu3O7-x was measured from room temperature to 900 °C under oxygen pressures of 0.1, 0.2 and 0.3 atm. The change of temperature gradient of X was observed at about 600, 660 and 680 °C under 0.1, 0.2 and 0.3 atm 02, respectively. This transition was attributed to the orthorhombic-to-tetragonal transition. The ortho-II phase was obtained by quench method. Observed Pelf with variation of quenching temperature has a minimum at about 800-850 °C which origin is not clear as yet.
