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Crystal Structure and Equation of State of Cotunnite‐Type Zirconia
Author(s) -
Haines Julian,
Léger Jean Michel,
Atouf Abdeltif
Publication year - 1995
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1151-2916.1995.tb08822.x
Subject(s) - orthorhombic crystal system , monoclinic crystal system , bulk modulus , crystallography , equation of state , rietveld refinement , diamond anvil cell , powder diffraction , cubic zirconia , crystal structure , ambient pressure , x ray crystallography , chemistry , materials science , diffraction , thermodynamics , ceramic , composite material , physics , optics
Cotunnite‐type zirconia was studied by angular‐dispersive X‐ray diffraction in a diamond anvil cell after laser heating at 18 and 26.7 GPa. The structure, space group Pnam, Z = 4, was refined in situ at several different pressures on decompression and at ambient using the Rietveld method. The nine polyhedral Zr‐O distances range from 2.10 to 2.56 A at ambient pressure, which represents both an increase in the average and the minimum Zr‐O distance relative to the monoclinic and orthorhombic lower‐pressure forms. In addition, data obtained on an unheated sample indicate that the irreversible transition to the cotunnite phase began above 25 GPa and 70% conversion was achieved by 48.5 GPa. Tne compressibility of cotunnite‐type zirconia was found to be slightly anisotropic and a Birch‐Murnaghan equation‐of‐state fit of the p‐V data yielded a bulk modulus of 332(8) GPa with a first derivative of 2.3(4), which is in good agreement with the value predicted by previous ab ini‐tio calculations.