ISSN:
1573-4803
Source:
Springer Online Journal Archives 1860-2000
Topics:
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
Notes:
Abstract The electrical conductivity, σ, and thermoelectric power, S, of copper chromite (CuCr2O4) are reported in the temperature range 295 to 815 K. A break (T B) in the slope of the plot of log σ against T −1 was observed around 556 K. Apart from this break, the curves are linear, and their slopes correspond to activation energies of 0.60 eV (T B〈556 K) and 1.22 eV (T B〉556 K). A break (T′ B) in the slope of the -S against T −1 plot was also observed round 556 K. Apart from the break at this temperature, the S against T −1 curves are linear. At T′ B〉556, S can be expressed by the relation $$S = - \left[ {\left( {\frac{{0.65 eV}}{{{\text{2}}eT}}} \right) + (0.42) mV K^{ - {\text{1}}} } \right]$$ The mechanism involved in the electrical transport is the hopping of holes from Cr4+ centres to neighbouring Cr3+ ions. The typical hopping mobility of the holes is of the order of 106 m2 V−1 sec−1. The mobility activation energy of the holes in CuCr2O4 decreases with temperature due to the smoothing of the potential barriers between Cr4+ and Cr3+ sites.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00549826
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