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Electrical conductivities of single phase fluorite structure compositions in the HfO/sub 2/-Er/sub 2/O/sub 3/ and HfO/sub 2/-Er/sub 2/O/sub 3/-Ta/sub 2/O/sub 5/ systems

Technical Report ·
OSTI ID:6831621
Electrical conductivities of pure HfO/sub 2/, binary systems containing HfO/sub 2/, and ternary and quaternary systems were surveyed. The electrical conductivities of broad ranges of compositions of fluorite structure solid solutions in the HfO/sub 2/-Er/sub 2/O/sub 3/ and HfO/sub 2/-Er/sub 2/O/sub 3/-Ta/sub 2/O/sub 5/ systems were determined 510 to 1070/sup 0/C and oxygen partial pressures 1 to 10/sup -20/ atm. Open circuit emf was used to determine ionic transference numbers. For Er/sub 2/O/sub 3/-stabilized HfO/sub 2/, the bulk electrical conductivities decreased and the activation energies conduction generally increased with the dopant level reaching plateaus 20 to 35 mol% ER/sub 2/O/sub 3/. Grain boundary contributions to total conductivities, and effects of surface finish, aspect ratio, and porosity were negligible. All compositions had high ionic conductivities and were solid electrolytes similar to other RE/sub 2/O/sub 3/-HfO/sub 2/ (ArO/sub 2/) fluorite structure solid solutions. Oxygen diffusion coefficients were calculated. Ta/sub 2/O/sub 5/ doping suppressed of oxygen vacancies and caused the total electrical conductivities to decrease, but had little effect on the total conductivity attributable to ion movement. In fact, all fluorite HfO/sub 2/-Er/sub 2/O/sub 3/-Ta/sub 2/O/sub 5/ compositions exhibited predominantly ionic conductivities, and several compositions evidenced electrolytic conductivities over broad ranges of temperature and oxygen partial pressures. Highest bulk conductivities were observed for high HfO/sub 2/ contents and low concentrations of oxygen vacancies. Activation conduction energies of the ternary alloys were functions of temperature, but were independent of oxygen partial pressure and depended little on composition. The defect structure of ternary fluorite solid solutions were consistent with an anion site occupancy model.
Research Organization:
Ames Lab., IA (USA)
DOE Contract Number:
W-7405-ENG-82
OSTI ID:
6831621
Report Number(s):
IS-T-1092; ON: DE84013982
Country of Publication:
United States
Language:
English

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Related Subjects

36 MATERIALS SCIENCE
360204* -- Ceramics
Cermets
& Refractories-- Physical Properties
ACTIVATION ENERGY
BIBLIOGRAPHIES
CHALCOGENIDES
DISPERSIONS
DOCUMENT TYPES
ELECTRIC CONDUCTIVITY
ELECTRICAL PROPERTIES
ENERGY
ERBIUM COMPOUNDS
ERBIUM OXIDES
FREE ENTHALPY
HAFNIUM COMPOUNDS
HAFNIUM OXIDES
IONIC CONDUCTIVITY
MIXTURES
OXIDES
OXYGEN COMPOUNDS
OXYGEN POTENTIAL
PHYSICAL PROPERTIES
RARE EARTH COMPOUNDS
REVIEWS
SOLID SOLUTIONS
SOLUTIONS
TANTALUM COMPOUNDS
TANTALUM OXIDES
TEMPERATURE DEPENDENCE
THERMODYNAMIC PROPERTIES
TRANSITION ELEMENT COMPOUNDS
ZIRCONIUM COMPOUNDS
ZIRCONIUM OXIDES