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

Title: 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

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Abstract

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 temperaturemore »« less

Authors:: Jordan, G W

Publication Date:: 1984-07-01

Research Org.:: Ames Lab., IA (USA)

OSTI Identifier:: 6831621

Report Number(s):: IS-T-1092
ON: DE84013982

DOE Contract Number:: W-7405-ENG-82

Resource Type:: Technical Report

Resource Relation:: Other Information: Thesis. Submitted to Iowa State Univ., Ames

Country of Publication:: United States

Language:: English

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

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                    Jordan, G W. 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.  United States: N. p., 1984. 
        Web.

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                    Jordan, G W. 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.  United States.

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                    Jordan, G W. Sun .  
        "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".  United States.

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@article{osti_6831621,

  title        = {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},

  author       = {Jordan, G W},

  abstractNote = {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.},

  doi          = {},

  url          = {https://www.osti.gov/biblio/6831621},
  journal      = {},
number       = ,

  volume       = ,

  place        = {United States},

  year         = {1984},

  month        = {7}

}

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A mathematical model of the liquidus surface based on a reduced polynomial method was proposed for the system HfO{sub 2}-Y{sub 2}O{sub 3}-Er{sub 2}O{sub 3}. The results of calculations according to this model agree fairly well with the experimental data. Phase equilibria in the system HfO{sub 2}-Y{sub 2}O{sub 3}-Er{sub 2}O{sub 3} were studied on melted (as-cast) and annealed samples using X-ray diffraction (at room and high temperatures) and microstructural and petrographic analyses. The crystallization paths in the system HfO{sub 2}-Y{sub 2}O{sub 3}-Er{sub 2}O{sub 3} were established. The system HfO{sub 2}-Y{sub 2}O{sub 3}-Er{sub 2}O{sub 3} is characterized by the formation of extendedmore »« less
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