Relative densities were measured by Archimede’s method and absolute density was based on a 5.031 g/cm3 theoretical density which was calculated from lattice parameter measurements. After isostatic pressing at 200 MPa, sintering was performed in a home-made furnace. The grain morphology was obtained from scanning electronic microscope observations (SEM, JEOL 840) after optical polishing and thermal etching of a ceramic section. The intercept method was used.