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,As ∼Ms ∼ 1447 K. It follows then, from a thermodynamic analysis that the reciprocal crystallite size is a linear function of the transformation temperature. Quantitative agreement was obtained between calculated and experimental crystallite size-temperature data which ranged over three orders of magnitude.