Formation of Cr 3+ stabilized ZrO 2 nanocrystals in a single cubic metastable phase by a novel chemical route with a sucrose–polyvinyl alcohol polymer matrix

Abstract

Cr 3+-stabilized ZrO 2 nanocrystals in a single metastable cubic (c) phase are prepared by a novel chemical method using a polymer matrix-based precursor with sucrose and polyvinyl alcohol. A pyrolysis of precursor over a hot plate at 250°C followed by calcination at temperatures between 400°C and 1000°C yields ZrO 2 nanocrystals in form of a powder. X-ray diffraction determines formation of a single c-ZrO 2 phase at 2–15 mol% Cr 3+ at 900°C or lower temperatures. Crystallites are in a near-spherical shape, 5–10-nm diameter, in electron micrograph as per the calcination temperature. A fast decomposition/combustion of Cr 3+ modified precursor over a narrow 250–500°C range during calcination controls formation of c-ZrO 2 nanocrystals in the confined size. It occurs with a vigorous exothermic signal with 70–80% loss in initial precursor mass. Average position of the exothermic peak shifts from 460°C to 442°C to 385°C at 1, 5 and 15 mol% Cr 3+, respectively, in the precursor.