Intrinsic size dependence of the phase transformation temperature in zirconia microcrystals

It is argued that because the tetragonal (t) to monoclinic (m) transformation in zirconia is exothermic, this guarantees that the surface free energy of the former is less than that of the latter structure. It is argued further that for pristine, unconstrained single crystals, A sub s approx M sub s approx 1447K. It follows then, from a thermodynamic analysis, that the reciprocal crystallite size is a linear function of the transformation temp. Quantitative agreement was obtained between calculated and experimental crystallite size--temp. data which ranged over three orders of magnitude. 17 ref.--AA