CRYSTALLIZATION OF METASTABLE TETRAGONAL ZIRCONIA FROM THE DECOMPOSITION OF A ZIRCONIUM ALKOXIDE DERIVATIVE

A zirconium alkoxide derivative, dibutoxybis(acetylacetonato) zirconiu m, was polymerized at 120 degrees C and 300 millitorr for 3 h to form oligomers, as characterized by gel permeation chromatography and Fouri er transform infra-red spectroscopy. Pyrolysis of the precursor at 675 degrees C in flowing 5% H-2 in N-2 followed by cooling to room temper ature, produced nano-scale, tetragonal ZrO2 considerably below the tet ragonal-to-monoclinic transformation temperature (approximately 1200 d egrees C). Subsequent heat treatment of the same precursor in flowing air under otherwise identical conditions produced approximately 8 vol% monoclinic ZrO2. The possible formation of oxygen vacancies from poly mer pyrolysis and their role in nucleating the metastable tetragonal p hase are discussed.