Stability of monoclinic and orthohombic zirconia; Studies by high-pressure phase equilibria and calorimetry

Journal Article · Fri Mar 01 04:00:00 EST 1991 · Journal of the American Ceramic Society; (United States)

DOI:https://doi.org/10.1111/j.1151-2916.1991.tb04051.x· OSTI ID:5156821

Ohtaka, O; Yamanaka, T; Kume, S ^[1]; Ito, E ^[2]; Navrotsky, A ^[3]

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1. College of General Education, Osaka Univ., Toyonaka 560 (JP)
2. Inst. for Study of the Earth's Interior, Okayama Univ., Misasa 682-02 (JP)
3. Dept. of Geological and Geophysical Sciences, Princeton Univ., Princeton, NJ (US)

The stability fields of two high-pressure polymorphs of ZrO{sub 2} (ortho I and ortho II) were determined by both calorimetry and phase equilibrium experiments. Enthalpies of transition were measured by transposed temperature drop calorimetry. The entropies of transition and slopes of phase boundaries were calculated using the measured enthalpies and free energies calculated from the results of phase equilibrium experiments. From the thermodynamic measurements, it is seen that the entropy increases and the volume decreases during the monoclinic-ortho I transition, whereas both the entropy and the volume decrease during the ortho I-ortho II transition. Accordingly, the gradient of phase boundaries, dP/dT, is negative in the former and positive in the latter. These trends are consistent with those of phase equilibrium experiments.

• Sponsoring Organization: NSF; National Science Foundation, Washington, DC (United States)
• OSTI ID: 5156821
• Journal Information: Journal of the American Ceramic Society; (United States), Journal Name: Journal of the American Ceramic Society; (United States) Vol. 74:3; ISSN JACTA; ISSN 0002-7820
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360202* -- Ceramics
Cermets
& Refractories-- Structure & Phase Studies
CALORIMETRY
CHALCOGENIDES
ENTROPY
OXIDES
OXYGEN COMPOUNDS
PHASE STABILITY
PHASE STUDIES
PHYSICAL PROPERTIES
STABILITY
THERMODYNAMIC PROPERTIES
TRANSITION ELEMENT COMPOUNDS
VOLUME
ZIRCONIUM COMPOUNDS
ZIRCONIUM OXIDES