Defect characterization of electronic conducting pseudo-perovskite systems. Final report
The goal of the program has been to study the interrelationships between electrical conductivity, oxidation-reduction kinetics, defect structure, and composition of n- and p-type binary and ternary transition metal oxides. The stimulus for making these studies was the observation that both conducting n and p type oxides displayed a dependence on oxygen activity that was not predicted by the defect chemistry of their majority defects. The project has focused primarily on the understanding of electronic and ionic conduction in the REBO{sub 3} oxides, where RE is a rare earth ion and B is a transition metal ion. This is being done by studying the interrelationships between the electronic and ionic conductivity, the electronic structure of the B site transition metal ion, and the acceptor concentration. The dependence of these characteristics on the oxygen activity, the temperature, and the defect chemistry of the oxide system is being determined. Theoretical mechanisms and models are being developed from the body of experimental results to provide a predictive tool. The effect of dopants and impurities, processing, electrical and thermal stability as a function of oxygen activity and temperature and their relationship to defect chemistry of the perovskite type oxides have been studied extensively by this research team. As a result of the difference in mobility between electronic and ionic defects, the electrical conductivity changes as the concentration of electronic defects changes. Thus, electrodes or resistors consisting of such oxides are susceptible to instabilities in resistance as they are cycled into temperature regimes where thermodynamic equilibrium may be attained. Many of the new energy conversion systems which use such oxides are encountering difficulties as a result of this instability in resistivity.
- Research Organization:
- Missouri Univ., Rolla, MO (United States)
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- DOE Contract Number:
- FG02-85ER45219
- OSTI ID:
- 10128800
- Report Number(s):
- DOE/ER/45219-T3; ON: DE95007487; BR: KC0201030; TRN: AHC29509%%33
- Resource Relation:
- Other Information: PBD: [1994]
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
PEROVSKITES
DEFECTS
ELECTRIC CONDUCTIVITY
REDOX REACTIONS
PROGRESS REPORT
CERAMICS
SEMICONDUCTOR MATERIALS
TITANIUM OXIDES
NIOBIUM OXIDES
BARIUM COMPOUNDS
LANTHANUM COMPOUNDS
TITANATES
CHROMATES
MAGNESIUM OXIDES
MANGANATES
MAGNESIUM COMPOUNDS
NIOBIUM COMPOUNDS
STRONTIUM COMPOUNDS
CALCIUM COMPOUNDS
ALUMINATES
ALUMINIUM OXIDES
BARIUM OXIDES
YTTRIUM OXIDES
COPPER OXIDES
YTTRIUM COMPOUNDS
COBALT OXIDES
NICKELATES
IRON OXIDES
CATALYSTS
FUEL CELLS
SUPERCONDUCTORS
THERMOELECTRIC GENERATORS
CAPACITORS
360200
360600
400201
CERAMICS, CERMETS, AND REFRACTORIES
OTHER MATERIALS
CHEMICAL AND PHYSICOCHEMICAL PROPERTIES