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Dielectric and Anelastic Relaxation in Ca‐Doped Cerium Dioxide
Author(s) -
Lay K. W.,
Whitmore D. H.
Publication year - 1971
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/pssb.2220430119
Subject(s) - dielectric , relaxation (psychology) , ion , cerium , materials science , doping , activation energy , condensed matter physics , electric field , redistribution (election) , vacancy defect , oxygen , atmospheric temperature range , dielectric loss , analytical chemistry (journal) , chemistry , thermodynamics , physics , metallurgy , optoelectronics , organic chemistry , psychology , social psychology , chromatography , quantum mechanics , politics , political science , law
Measurements of dielectric losses and internal friction in Ca‐doped CeO 2 have been made over the temperature range 253 to 573 °K on specimens with up to 2.5% of the Ce 4+ ions replaced by Ca 2+ ions. The observed internal friction and dielectric loss peaks have relaxation times which are in close accord with the predictions of an eight‐position, nearest‐neighbor model, namely, that the relaxation time for electrically‐active modes is equal to twice that for mechanically‐active modes. These relaxations occur because of the redistribution of oxygen vacancies (bound to substitutional Ca 2+ ions) among eight sites which are initially equivalent, but which become inequivalent in the presence of the external electric or mechanical stress field. From the temperature dependence of the relaxation times and the peak shape, the activation energy required for such oxygen vacancy jumps is calculated to be 0.86 eV, with the pre‐exponential factor estimated to be 2.4 × 10 14 s −1 .