High temperature mechanical spectroscopy of CaO-ZrO2 cubic single crystals

The high temperature anelastic properties of cubic CaO-ZrO2 single crystals have been studied by mechanical spectroscopy. A relaxation peak superimposed on an exponential background has been observed at 1580 K for a frequency of 1 Hz. The mechanism giving rise to the peak is thermally activated, the activation energy is 4.3 eV and the limit relaxation time is about 4 x 10(-15) s. The peak depends on the crystal orientation and the intensity of the relaxation follows a Curie-Weiss type law. These characteristics lead to the interpretation that this peak is the stress induced ordering of substitutional Ca-Ca pairs (orthorhombic [011] elastic dipoles). The deviations of the relaxation time from the Arrhenius behavior and of the relaxation intensity from the Curie-Weiss law observed below 1440 K might result from the order-disorder transition occurring in this temperature range. The exponential background may be attributed to dislocation motion. The apparent activation energy associated with this background was found to be 6.4 eV. (C) 1998 Acta metallurgica Inc. Published by Elsevier Science Ltd. All rights reserved.