| Issue |
J. Phys. Colloques
Volume 46, Number C10, Décembre 1985
Eighth International Conference on Internal Friction and Ultrasonic Attenuation in Solids
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| Page(s) | C10-553 - C10-556 | |
| DOI | https://doi.org/10.1051/jphyscol:198510123 | |
J. Phys. Colloques 46 (1985) C10-553-C10-556
DOI: 10.1051/jphyscol:198510123
COMPOSITION DEPENDENT HIGH TEMPERATURE INTERNAL FRICTION IN MgO (Al2O3)n SPINELS
J. WOIRGARD1, P. MAZOT1 and M. HALBWACKS21 Laboratoire de Mécanique et Physique des Matériaux, UA CNRS 863, ENSMA, 86034 Poitiers Cedex, France
2 Université de Savoie, BP 1104, 73011 Chambery Cedex, France
Abstract
Isothermal damping spectra obtained between 800 K and 1100 K in non stoichiometric spinel specimens revealed an important relaxation Peak for torsional vibration frequencies ranging between 10-4 Hz and 10 Hz. The corresponding activatjon energy (H = 3.84 eV) is in good agreement with cationic diffusion , indicating that the relaxation probably arises from stress induced reorientation of elastic dipoles formed by the association of Mg2+ cations and structural cationic vacancies. In single crystals the orientation dependence of the relaxation strength has been investigated leading to a <110> possible orientation for the elastic dipoles. The composition dependence of the relaxation strength has also been investigated in both poly and single crystals for n ranging between 1 and 10. The maximum relaxation strength corresponds to n values between 2 and 3.