The Strain-Driven Pyrochlore to “Defect Fluorite” Phase Transition in Rare Earth Sesquioxide Stabilized Cubic Zirconias

• Published in: Journal of solid state chemistry Vol. 159; no. 1; pp. 121 - 129
• Main Authors: Tabira, Y., Withers, R.L., Barry, J.C., Elcoro, L.
• Format: Journal Article
• Language: English
• Published: San Diego, CA Elsevier Inc 01.06.2001; Elsevier
• Subjects: 30 DIRECT ENERGY CONVERSION; CATIONS; Condensed matter: structure, mechanical and thermal properties; CRYSTAL DEFECTS; Crystalline state (including molecular motions in solids); Crystallographic aspects of phase transformations; pressure effects; CUBIC LATTICES; DEFECTS; DISTRIBUTION; ELECTRON DIFFRACTION; Exact sciences and technology; FLUORITE; MATERIALS SCIENCE; ORIGIN; OXYGEN; PHASE TRANSFORMATIONS; Physics; PYROCHLORE; RARE EARTHS; SOLID OXIDE FUEL CELLS; STRAINS; Structure of solids and liquids; crystallography; ZIRCONIUM OXIDES; Order-disorder transformations; Inorganic compounds; Phase transformations; Electron diffraction; Rare earths Oxides; Transition element compounds; Stabilized zirconia; Ionic radius; Rare earth compounds; Experimental study; Pyrochlore type compound; High-resolution methods; Solid solutions; Zirconium oxides; Chemical composition; Models; Fluorite structure; TEM
• ISSN: 0022-4596; 1095-726X
• DOI: 10.1006/jssc.2001.9139

The relationship between the ordering characteristic of the pyrochlore structure type and that characteristic of the “defect fluorite” structure type (immediately on either side of two phase regions separating the two structure types) in a range of rare eath sesquioxide stabilized cubic zirconias is investigated via electron diffraction and imaging. Systematic structural change as a function of composition and relative size of the constituent metal ions is highlighted and a multi-q to single-q=1/2 [111]* model proposed for the observed pyrochlore to defect fluorite phase transition. Strain introduced into the close-packed {111} metal ion planes of the defect fluorite average structure by the local cation and oxygen vacancy distribution is pointed to as the likely origin of the observed behavior.