Polarization currents in zinc oxide varistors from 77 to 450 K
- Department of Physics, University of Richmond, Virginia 23173 (United States)
- Solid State Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-6030 (United States)
The time and temperature dependencies of polarization currents are investigated to higher temperatures and with greater temperature resolution than has been reported previously for zinc oxide varistors. Arrhenius plots of these transient polarization currents yield two thermal activation energies near 140 and 8 meV, which are in reasonable agreement with values reported recently, as well as an additional thermally activated level at 0.66 eV, which becomes evident in the extension of the measurements to [ital T][gt]300 K. Conductance data in this higher temperature range yield the nearly identical energy of 0.68 eV for the intergranular (Schottky) barrier height. The temperature dependence of the exponent [ital m] in the power-law expression for the current-time dependence [ital I]=[ital I][sub 0][ital t][sup [minus][ital m]] was carefully examined and found to change twice from 0.5 to 1.0. The nonmonotonic behavior of [ital m]([ital T]) can be interpreted as due to resolution of polarization currents from two different traps, each of which evolves from diffusive to dispersive transport as temperature is lowered rather than, for example, a complicated distribution of relaxation times.
- OSTI ID:
- 6995330
- Journal Information:
- Journal of Applied Physics; (United States), Journal Name: Journal of Applied Physics; (United States) Vol. 76:11; ISSN JAPIAU; ISSN 0021-8979
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
360606* -- Other Materials-- Physical Properties-- (1992-)
ACTIVATION ENERGY
CHALCOGENIDES
CURRENTS
ELECTRICAL EQUIPMENT
ENERGY
EQUIPMENT
OXIDES
OXYGEN COMPOUNDS
POLARIZATION
RESISTORS
TEMPERATURE DEPENDENCE
TEMPERATURE RANGE
TEMPERATURE RANGE 0065-0273 K
TEMPERATURE RANGE 0273-0400 K
TIME DEPENDENCE
TRANSIENTS
ZINC COMPOUNDS
ZINC OXIDES