Massive transformation in Gd{sub 2}O{sub 3}-Bi{sub 2}O{sub 3} ceramics

Journal Article · Thu Feb 01 04:00:00 EST 1996 · Journal of the American Ceramic Society

DOI:https://doi.org/10.1111/j.1151-2916.1996.tb08131.x· OSTI ID:211696

Su, P; Virkar, A V ^[1]

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1. Univ. of Utah, Salt Lake City, UT (United States). Dept. of Materials Science and Engineering

Gd{sub 2}O{sub 3}-doped Bi{sub 2}O{sub 3} polycrystalline ceramic samples containing between 10 and 26 mol% Gd{sub 2}O{sub 3} were fabricated by pressureless sintering of powder compacts. As-sintered samples were cubic (CaF{sub 2} structure). The cubic solid solutions underwent transformation to a rhombohedral phase when annealed at lower temperatures. Under certain conditions, the cubic phase fully transformed to the rhombohedral phase of the same composition, and the kinetics were thermally activated. This suggested that the cubic {yields} rhombohedral transformation was a massive transformation. The transition temperatures for the occurrence of a massive transformation were experimentally determined by measuring the conductivity as a function of temperature, as well as by measuring growth rate of the rhombohedral precipitates as a function of temperature. The activation enthalpy for interface motion was measured to be {approximately}200 kJ/mol for the samples studied. The kinetics of cubic {yields} rhombohedral transformation could be described by the Johnson-Mehl-Avrami equation.

• Sponsoring Organization: USDOE
• OSTI ID: 211696
• Journal Information: Journal of the American Ceramic Society, Journal Name: Journal of the American Ceramic Society Journal Issue: 2 Vol. 79; ISSN 0002-7820; ISSN JACTAW
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ANNEALING
BISMUTH OXIDES
CRYSTAL-PHASE TRANSFORMATIONS
CUBIC LATTICES
ELECTRIC CONDUCTIVITY
GADOLINIUM OXIDES
KINETICS
OPTICAL MICROSCOPY
POWDERS
PRECIPITATION
SINTERING
TEMPERATURE DEPENDENCE
TRIGONAL LATTICES
X-RAY DIFFRACTION