Crystallite and Grain-Size-Dependent Phase Transformations in Yttria-Doped Zirconia
In pure zirconia, ultrafine powders are often observed to take on the high‐temperature tetragonal phase instead of the “equilibrium” monoclinic phase. The present experiments and analysis show that this observation is one manifestation of a much more general phenomenon in which phase transformation...
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Published in | Journal of the American Ceramic Society Vol. 86; no. 2; pp. 360 - 362 |
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Main Authors | , , , |
Format | Journal Article |
Language | English |
Published |
Westerville, Ohio
American Ceramics Society
01.02.2003
Blackwell Wiley Subscription Services, Inc |
Subjects | |
Online Access | Get full text |
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Summary: | In pure zirconia, ultrafine powders are often observed to take on the high‐temperature tetragonal phase instead of the “equilibrium” monoclinic phase. The present experiments and analysis show that this observation is one manifestation of a much more general phenomenon in which phase transformation temperatures shift with crystallite/grain size. In the present study, the effect of crystallite (for powders) and grain (for solids) size on the tetragonal → monoclinic phase transformation is examined more broadly across the yttria–zirconia system. Using dilatometry and high‐temperature differential scanning calorimetry on zirconia samples with varying crystallite/grain sizes and yttria content, we are able to show that the tetragonal → monoclinic phase transformation temperature varies linearly with inverse crystallite/grain size. This experimental behavior is consistent with thermodynamic predictions that incorporate a surface energy difference term in the calculation of free‐energy equilibrium between two phases. |
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Bibliography: | ark:/67375/WNG-MKH11LHD-J istex:CFA56B1F032AC12FA43EB43BF64C09AB91F5CCD9 ArticleID:JACE360 Supported by the U. S. Dept. of Energy, under Contract No. DE‐FG02‐98ER45700 and the High Temperature Materials Laboratory User Program, Oak Ridge National Laboratory, managed by UT‐Battelle, LLC, for the U.S. Dept. of Energy, under Contract No. DE‐AC05‐00OR22725. Member, American Ceramic Society. Currently adjunct to the University of Maryland, Dept. of Materials and Nuclear Engineering, College Park, MD 20742‐2115. M. Frey—contributing editor Now at Analog Devices, Inc., Wilmington, MA 01887. ObjectType-Article-2 SourceType-Scholarly Journals-1 ObjectType-Feature-1 content type line 23 |
ISSN: | 0002-7820 1551-2916 |
DOI: | 10.1111/j.1151-2916.2003.tb00025.x |