The cubic-tetragonal phase equilibria in the ZrO2-R2O3 (R = Y, Gd, Sm, Nd) systems
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The cubic-tetragonal (c-t) phase equilibria in the ZrO2-R2O3 (R = Nd, Sm, Gd, Y) systems are examined both experimentally and theoretically. The width of the c-t two-phase field is not simply described as a function of oxygen vacancies as proposed by Hillert and Sakuma (Ref 6) but is dependent on ionic radius of trivalent cations. The larger the ionic radius, the wider the two-phase field. The result is satisfactorily explained by the addition of the excess energy term caused by strain energy in cubic solid solutions to the original model.
KeywordsZirconia Phase Equilibrium Oxygen Vacancy Ionic Radius Excess Gibbs Energy
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