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Electrical Conductivity of Nonstoichiometric α-Nb₂O₅

Journal Article · · Journal of the Electrochemical Society
DOI:https://doi.org/10.1149/1.2425504· OSTI ID:4836359
The electrical conductivity of reduced alpha-Nb₂O₅ was measured after prior reduction in 10⁻⁶ atm of air from 350 to 1150 deg K for both single crystals and sintered specimens. The conductivity of single crystals was found to be exponentially dependent on temperature with an activation energy of 0.9 ev in the range from 1150 to 650 deg K and 0.2 ev in the range from 650 to 350 deg K. The electrical conductivity of sintered specimens was also found to be exponentially dependent on temperature, but only a single activation energy was obtained over the entire temperature range. This activation energy was dependent on defect concentration and varied from 1.0 ev for the smallest degree of reduction to almost zero at the highest degree of reduction where the behavior was essentially that of a degenerate semiconductor. An explanation based on overlapping orbrials of trapped electrons is offered to explain both the dependence of activation energy on defect concentration and the absence of a low-temperature activation energy in sintered material. Finally, two mechanisms are discussed to explain the observed conductivity of reduced alpha-Nb₂O₅. Comparison of conductivity data and thermoluminescence data tends to favor a model in which two trapped electrons are excited from an oxygen vacancy to the d'' band of the niobium cations. (auth)
Research Organization:
Marquette Univ., Milwaukee
Sponsoring Organization:
USDOE
NSA Number:
NSA-16-022627
OSTI ID:
4836359
Journal Information:
Journal of the Electrochemical Society, Journal Name: Journal of the Electrochemical Society Journal Issue: 7 Vol. 109; ISSN JESOAN; ISSN 0013-4651
Publisher:
The Electrochemical Society
Country of Publication:
Country unknown/Code not available
Language:
English