Metastable phase selection and partitioning in ZrO sub 2 -MgO processed from liquid precursors
- College of Engineering, Univ. of California, Santa Barbara, CA (US)
This paper reports on aqueous mixtures of either zirconium acetate or zirconium nitrate and magnesium nitrate that were dried and subsequently pyrolyzed at fast heating rates (upquenching) to form metastable crystalline phases of ZrO{sub 2} with various degrees of MgO supersaturation. The crystallization temperature was determined to be 380{degrees} C for the zirconium acetate, and 270{degrees} C for the zirconium nitrate at a heating rate of 5{degrees} C/min. The crystalline structures were characterized as a function of MgO content and thermal history for specimens containing 0 to 30 mol % MgO. Upquenching to 900{degrees} C, where monoclinic (m) ZrO{sub 2} and MgO are the equilibrium phases, yielded single-phase tetragonal (t) ZrO{sub 2} ({lt}8 mol% MgO), single-phase cubic (c) ZrO{sub 2} (9 to 17 mol% MgO), and two-phase c-ZrO{sub 2} + MgO structures ({gt}17 mol% MgO). The composition for which T{sub 0}(t/c) = 900{degrees} C was estimated as 9 {plus minus} 1 mol% MgO.
- Sponsoring Organization:
- NSF; National Science Foundation, Washington, DC (United States)
- OSTI ID:
- 7202759
- Journal Information:
- Journal of the American Ceramic Society; (United States), Journal Name: Journal of the American Ceramic Society; (United States) Vol. 75:4; ISSN JACTA; ISSN 0002-7820
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
360202* -- Ceramics
Cermets
& Refractories-- Structure & Phase Studies
ALKALINE EARTH METAL COMPOUNDS
AQUEOUS SOLUTIONS
CHALCOGENIDES
CHEMICAL COMPOSITION
CRYSTAL LATTICES
CRYSTAL STRUCTURE
CRYSTALLIZATION
DISPERSIONS
ENERGY LEVELS
EQUILIBRIUM
EXCITED STATES
MAGNESIUM COMPOUNDS
MAGNESIUM OXIDES
METASTABLE STATES
MIXTURES
OXIDES
OXYGEN COMPOUNDS
PHASE STABILITY
PHASE STUDIES
PHASE TRANSFORMATIONS
PRECURSOR
SOLUTIONS
STABILITY
TEMPERATURE DEPENDENCE
TETRAGONAL LATTICES
TRANSITION ELEMENT COMPOUNDS
ZIRCONIUM COMPOUNDS
ZIRCONIUM OXIDES