R. Jossen, M. C. Heine, S. E. Pratsinis and M. K. Akhtar
The thermal stability of pure and doped zirconia fabricated by flame-spray pyrolysis is studied by calcination at various temperatures and residence times. Powders are analyzed by X-ray diffraction, nitrogen adsorption, energy-dispersive X-ray spectroscopy, and transmission electron microscopy. The metastable tetragonal structure of flame-made ZrO2 transformed to monoclinic phase after sintering. Doping zirconia with yttria, ceria, lanthanum oxide, alumina, or silica increased the thermal stability and also hindered phase transformation.