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Pressure‐Temperature Phase Diagram of Zirconia
Author(s) -
BLOCK S.,
JORNADA J. A. H.,
PIERMARINI G. J.
Publication year - 1985
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.1151-2916.1985.tb15817.x
Subject(s) - monoclinic crystal system , tetragonal crystal system , orthorhombic crystal system , phase diagram , crystallography , materials science , phase transition , phase (matter) , diamond anvil cell , triple point , cubic zirconia , crystal structure , x ray crystallography , diffraction , chemistry , analytical chemistry (journal) , thermodynamics , optics , metallurgy , ceramic , physics , organic chemistry , chromatography
The pressure‐temperature phase diagram of zirconia was determined by optical microscopy and X‐ray diffraction techniques using a diamond anvil pressure cell. At room temperature, monoclinic ZrO 2 transforms to a tetragonal phase ( t II) which is related to the high‐temperature tetragonal structure ( t I). The transformation pressure exhibits hysteresis and is cycle dependent. At room temperature, the initial transformation pressure for the monoclinic‐ t II transition on a virgin monoclinic crystal can be as high as 4.4 GPa; on subsequent cycling the transition pressure ultimately lowers to 3.29 ± 0.06 GPa. The pressure for the reverse transition is essentially constant at 2.75 ± 0.06 GPa. At pressures > 16.6 GPa, the t II form transforms to the orthorhombic cotunnite (PbCl 2 ) structure. With increasing temperature, the t II form transforms to the high‐temperature tetragonal phase. For increasing P and T , the monoclinic‐ t I‐ t II triple point is located at T = 596°± 18°C and P = 2.26 ± 0.28 GPa, whereas for decreasing P and T , the triple point is found at T = 535°± 25°C and P = 1.7 ± 0.28 GPa.