Universal dielectric response of variously doped CeO{sub 2} ionically conducting ceramics
- Materials Science Division, School of Mines, Columbia University, New York, New York 10027 (United States)
The Jonscher power law, or {open_quotes}universal dielectric response{close_quotes} (UDR) behavior was studied for a range of CeO{sub 2} solid solutions with Y{sup 3+} and Gd{sup 3+} dopants, with particular emphasis on dilute systems which possess relatively simple defect structures. The results show power-law frequency dependence of the ac conductivity, with exponent s=0.61{plus_minus}0.03, independent of temperature and concentration. The conductivity data also show scaling behavior in terms of a time constant {tau}, whose activation energy is very close to that of the dc conductivity. For 1{percent} Y and 1{percent} Gd samples, an additional Debye-type relaxation is observed due to dopant{endash}oxygen-vacancy pairs. Such samples are clearly in the association range (stage III). These results contradict the assumption by Almond and West that {tau}{sup {minus}1} is the hopping frequency of the carrier defects. At very low concentrations ({approximately}0.01{percent}), UDR behavior virtually disappears. The present results are then compared to the principal theories that describe UDR behavior. It is found that, while each theory suffers from some drawbacks, the more phenomenological theories fare better. {copyright} {ital 1998} {ital The American Physical Society}
- OSTI ID:
- 659323
- Journal Information:
- Physical Review, B: Condensed Matter, Journal Name: Physical Review, B: Condensed Matter Journal Issue: 13 Vol. 58; ISSN PRBMDO; ISSN 0163-1829
- Country of Publication:
- United States
- Language:
- English
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