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Title: Thermodynamics of solid electrolytes and related oxide ceramics based on the fluorite structure

Abstract

Oxides based on the fluorite structure are important as electrolytes in solid oxide fuel cells, thermal barrier coatings, gate dielectrics, catalysts, and nuclear materials. Though the parent fluorite structure is simple, the substitution of trivalent for tetravalent cations, coupled with the presence of charge-balancing oxygen vacancies, leads to a wealth of short-range and long-range ordered structures and complex thermodynamic properties. The location of vacancies and the nature of clusters affect the energetics of mixing in rare earth doped zirconia, hafnia, ceria, urania, and thoria, with systematic trends in energetics as a function of cation radius. High temperature oxide melt solution calorimetry has provided direct measurement of formation enthalpies of these refractory materials. Surface and interfacial energies have also been measured in yttria stabilized zirconia (YSZ) nanomaterials. Other ionic conductors having perovskite, apatite, and mellilite structures are discussed briefly.

Authors:
 [1]
  1. Univ. of California, Davis, CA (United States). Nanomaterials in the Environment, Agriculture, and Technology Organized Research Unit (NEAT ORU) and Peter A. Rock Thermochemistry Lab.
Publication Date:
Research Org.:
Energy Frontier Research Centers (EFRC); Materials Science of Actinides (MSA)
Sponsoring Org.:
USDOE
OSTI Identifier:
1066001
DOE Contract Number:
SC0001089
Resource Type:
Journal Article
Resource Relation:
Journal Name: JOURNAL OF MATERIALS CHEMISTRY; Journal Volume: 20; Journal Issue: 47; Related Information: MSA partners with University of Notre Dame (lead); University of California, Davis; Florida State University; George Washington University; University of Michigan; University of Minnesota; Oak Ridge National Laboratory; Oregon state University; Rensselaer Polytechnic Institute; Savannah River National Laboratory
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; nuclear (including radiation effects), materials and chemistry by design, synthesis (novel materials), synthesis (self-assembly)

Citation Formats

Navrotsky, Alexandra. Thermodynamics of solid electrolytes and related oxide ceramics based on the fluorite structure. United States: N. p., 2010. Web. doi:10.1039/c0jm01521k.
Navrotsky, Alexandra. Thermodynamics of solid electrolytes and related oxide ceramics based on the fluorite structure. United States. doi:10.1039/c0jm01521k.
Navrotsky, Alexandra. 2010. "Thermodynamics of solid electrolytes and related oxide ceramics based on the fluorite structure". United States. doi:10.1039/c0jm01521k.
@article{osti_1066001,
title = {Thermodynamics of solid electrolytes and related oxide ceramics based on the fluorite structure},
author = {Navrotsky, Alexandra},
abstractNote = {Oxides based on the fluorite structure are important as electrolytes in solid oxide fuel cells, thermal barrier coatings, gate dielectrics, catalysts, and nuclear materials. Though the parent fluorite structure is simple, the substitution of trivalent for tetravalent cations, coupled with the presence of charge-balancing oxygen vacancies, leads to a wealth of short-range and long-range ordered structures and complex thermodynamic properties. The location of vacancies and the nature of clusters affect the energetics of mixing in rare earth doped zirconia, hafnia, ceria, urania, and thoria, with systematic trends in energetics as a function of cation radius. High temperature oxide melt solution calorimetry has provided direct measurement of formation enthalpies of these refractory materials. Surface and interfacial energies have also been measured in yttria stabilized zirconia (YSZ) nanomaterials. Other ionic conductors having perovskite, apatite, and mellilite structures are discussed briefly.},
doi = {10.1039/c0jm01521k},
journal = {JOURNAL OF MATERIALS CHEMISTRY},
number = 47,
volume = 20,
place = {United States},
year = 2010,
month = 1
}
  • Ionic conductivity data of yttria zirconia, Y/sub 4x/Zr/sub 1-4x/O/sub 2-2x/, reported in the literature as functions of oxygen vacancy concentration, x, and temperature, T, have been analyzed according to a theoretical model developed in a previous paper and applied to calcia stabilized zirconia. Because of the different charge compensation mechanism in yttria stabilized zirconia, Y/sub 4x/Zr/sub 1-4x/O/sub 2-2x/, than that in calcia stabilized zirconia, Ca/sub 2x/Zr/sub 1-2x/O/sub 2-2x/, the theory predicts the occurrence of a maximum of ionic conductivity at an oxygen vacancy concentration, x = 0.03125 (= 1/32), which is just half the oxygen vacancy concentration at the maximum,more » x = 0.0625 (= 1/16), in calcia stabilized zirconia. This was clearly confirmed by recent experimental results of Ioffe et al. and appears to substantiate further the basic validity of the theoretical model. Results of the theoretical analysis on yttria stabilized zirconia obtained herein are compared with those on calcia stabilized zirconia are also discussed in relation to the ionic conductivity data of the various rare earth oxide-stabilized zirconia systems. The basic assumptions and limitations of the theoretical model are critically examined, and possible modifications of the theoretical model are suggested.« less
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