Phase transformation of ZrO₂ nanoparticles produced from zircon

Abstract

This article focuses on the phase transformation of zirconia (ZrO₂) nanoparticles produced from zircon using a bottom-up approach. The influence of mechanical milling and thermal annealing on crystalline phase transformation of ZrO₂ nanoparticles was explored. It was found that the iron oxide, as an inherent impurity present in ZrO₂ nanoparticles, produced from zircon stabilises the cubic phase after calcination at 600°C. The stabilised cubic phase of ZrO₂ nanoparticles was disappeared and transformed into partial tetragonal and monoclinic phases after mechanical milling. The phase transformation occurred on account of the crystal defect induced by high-energy mechanical milling. The destabilisation of cubic phase into monoclinic phase was observed after the thermal annealing of ZrO₂ nanoparticles at 1000°C. The phase transitions observed are correlated to the exclusion of iron oxide from the zirconia crystal structure.

Keywords:

• zirconia nanoparticles
• iron impurity
• phase transformation
• mechanical milling
• thermal annealing

Acknowledgements

The authors thank the Department of Science and Technology, New Delhi, India for the financial support provided to carry out this research project (SR/S5/NM-40/2005 dated 26 June 2007).