Abstract: A ceramic sintered body and a method for manufacturing the same in which the body includes a first material having at least one of a precursor and a metastable material of the final sintered body and a second material morphologically related to the first material and added to the first material to affect transformation of said first material into the desired crystalline form of the ceramic sintered body, in which method transformation of a metal oxide compound from one phase to another, where the compound has a high activation energy and is confronted with a high nucleation energy barrier to the transformation, produces the body and includes the steps of making a mixture by bringing a multiplicity of particles of the compound into intimate contact with the multiplicity of nucleation particles having crystallographically related structure to act as nuclei for the transformation and sintering the resulting mixture to transform the compound from one phase to another by nucleation and growth, independently of gro