Small polaron electron transport in reduced CeO2 single crystals

doi:10.1016/0022-3697(77)90124-X

Journal of Physics and Chemistry of Solids

Volume 38, Issue 8, 1977, Pages 859-867

https://doi.org/10.1016/0022-3697(77)90124-X Get rights and content

Abstract

An investigation of the electrical properties of reduced ceria, CeO_2−x, carried out on single crystals, shows that CeO_2−x provides one of the clearest examples of hopping conduction and the small polaron mechanism. Included are conductivity and Seebeck coefficient measurements at constant x, obtained by sealing off the specimen chamber after reduction. The Seebeck coefficient is independent of temperature, suggesting that the number of carriers is constant. On the other hand, the mobility is activated, with activation energy E_h = 0.40 eV at small x and increasing to 0.52 eV at x = 0.25. The results for the mobility preexponential are consistent with the adiabatic theory of small polaron behavior. A puzzling feature of the Seebeck data as a function of x is that, for low x, the data fit the well-known Heikes formula, without a degeneracy factor of 2 for spin. Nevertheless, these data are interpreted to show that the proportion of mobile carriers decreases as x increases, presumably because of the presence of short-range ordered configurations which immobilize some carriers.

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Small polaron electron transport in reduced CeO2 single crystals

Abstract

J. Phys. Chem. Solids

Ann. Phys. (N.Y.)

Ann. Phys. (N.Y.)

Mat. Res. Bull.

J. Inorg. Nucl. Chem.

J. Phys. Chem. Solids

J. Inorg. Nucl. Chem.

J. Inorg. Nucl. Chem.

J. Solid State Chem.

Can. J. Phys.

J. Solid State Chem.

Solid State Phys.

Adv. Phys.

Adv. Phys.

Small polaron electron transport in reduced CeO₂ single crystals