Stabilized nanoparticles of metastable ZrO2 with Cr3+/Cr4+ cations:: preparation from a polymer precursor and the study of the thermal and structural properties

Nanoparticles of stabilized ZrO2 in a single cubic phase by 5-20 at.% (of total metal cations) Cr3+/Cr4+ addition are obtained through a chemical method using a polymer matrix made of sucrose and polyvinyl alcohol. On heating at 250-900 degreesC in air, the polymer network decomposes and burns out leaving behind a dispersed microstructure in 10 25 nm diameter particles of cubic ZrO2 in spherical shape. A modified microstructure comprises of 10 14 nm crystallites of dispersed tetragonal phase, or both tetragonal and monoclinic phases, in cubic phase appear on a prolong (2 h or larger) heating of precursor at 900-950 degreesC. Particles in tetragonal ZrO2 are in acicular shape, while the monoclinic phase is in the shape of platelets. The Cr3+/Cr4+ additive facilitates formation of cubic phase in small particles on a controlled decomposition and combustion of precursor. It stabilizes small particles by inhibiting their growth by forming a thin amorphous surface layer over them. (C) 2002 Elsevier Science Ltd. All rights reserved.