Optical and X-Ray Single Crystal Studies of the Monoclinic Tetragonal Transition in ZrO2

Autor: S. T. Buljan, Vladimir S. Stubican, Herbert A. McKinstry
Rok vydání: 1976
Předmět:
Zdroj: Journal of the American Ceramic Society. 59:351-354
ISSN: 1551-2916
0002-7820
DOI: 10.1111/j.1151-2916.1976.tb10982.x
Popis: The monoclinic ⇌ tetragonal phase transition in ZrO2 single crystals was studied at temperature by transmission optical microscopy and X-ray diffraction techniques. A series of timelapse photographs illustrated the relations between the events that occur during the transition. The events themselves were recognized by direct observation using a high-temperature microscope stage and by scrutiny of several high-temperature Laue photographs. During heating the monoclinic phase transforms to the tetragonal by the motion of an interface parallel to the (100)m plane; simultaneous twinning also occurs behind the advancing interface. The tetragonal phase is usually twinned on the (12)bct or (12)bct plane, and the extent of twinning is influenced by the heating rate. Cooling transforms the untwinned tetragonal form into a twinned monoclinic form with the orientation of the monoclinic twins parallel to the trace of the (001)m plane when observations are made in the (100)m plane. Transformation of a twinned tetragonal crystal results in twins on the {110}m and {001}m planes. Orientation relations in the ZrO2 transformation are: (100)m‖(110)bct, [010]m‖[001]bct, and by the virtue of twinning, (100)m‖(110)bct, [001]m‖[001]bct. During cooling the same topotaxial relations are maintained.
Databáze: OpenAIRE
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