Thermal changes in texture of aggregates of ultra-fine crystallites in hydrolysed zirconia particles

Zirconia particles of about 1000 × 1000 × 300 Å in size, which were aggregates of rectangular shaped and regularly oriented ultra-fine crystallites of about 30 × 100 Å, were prepared by hydrolysis from 0.1 moll -1 ZrOCl 2 solution. Changes in the texture of the particles on heating were studied by electron microscopy. The growth of the crystallites occurred predominantly at peripheries of the particles at 500°C and in the whole particles at 600°C, resulting in crystallites of 160–360 Å in diameter at 800°C. The voids which were present initially among the crystallites, coalesced and increased in size at temperatures up to 600°C, but diminished above 800°C. Single crystals and (100) twins were formed at 1000°C.