A NEW ASSESSMENT OF IONIC-CONDUCTIVITY OF YBA2CU3OX VIA AC-IMPEDANCE SPECTROSCOPY COMBINED WITH DC RELAXATION

The ionic conductivity of YBa2Cu3Ox has been determined from the Warbu rg impedance at the lowest end of a full impedance spectrum which was constructed by combining a partial spectrum directly measured by ac im pedance spectroscopy and the Fourier-Laplace transform of de relaxatio n. In the tetragonal. regime, the ionic conductivity has been found to be essentially independent of oxygen partial pressure with an activat ion energy of 2.46 +/- 0.05 eV. It is also suggested that the conducti vity in the orthorhombic regime is Little dependent on oxygen partial pressure but with an activation energy of 1.58 +/- 0.03 eV. The report ed data on ionic transport are exhaustively reviewed in comparison wit h the present result.