Diffraction at 900°C indicates that peaks are very broad and diffused. This is probably
because fine crystalline size of calcined powders. The diffused peaks were identified to be
tetragonal zirconia. The peaks become sharper and shift slightly towards lower diffraction
angles with increasing calcinations temperature. This may be a combined effect of fine
particle size and the constraint placed by alumina. That no diffraction peaks of alumina are
observed below calcination at 900°C may be partly because of the low atomic scattering
factor of aluminium and partly because of the poor crystallization of the phase. It thus
appears that alumina and zirconia inhibit mutual crystallization and growth.