Eleventh International Conference on Internal Friction and Ultrasonic Attenuation in Solids
J. Phys. IV France 06 (1996) C8-637-C8-641
Anelastic Relaxation of Protonic Defects in M3+-Doped BaCeO3Y. Du and A.S. Nowick
Materials Science Division, School of Mines, Columbia University, New-York, NY 10027, U.S.A.
When perovskite-structured BaCeO3 is doped with M3+ ions (e.g., Nd3+, Gd3+, Yb3+) that substitute on Ce4+ sites, oxygen-ion vacancies are created for charge compensation. However, when treated in water vapor, the vacancies are replaced by protons, which take the form of OH ions. This treatment makes the materials a good protonic conductor. Questions about the defect structure of the protons are here investigated by means of internal friction measurements, at frequencies ≈6kHz. As many as three broadened Debye peaks have been found in the temperature range from 200 - 500 K, the relaxation strengths of which vary as the square of the dopant concentration. Defect clusters considered responsible include the M(OH) pair and the M2(OH) triplet.
© EDP Sciences 1996