Thermal kinetics and phase stability of 8Â mol% samaria doped zirconia nanopowders prepared via reverse coprecipitation

Nanocrystalline samaria (8 mol%) doped zirconium oxide (8SmSZ) was synthesized using reverse co-precipitation technique, the calcination temperature ranging from 873 K to 1273 K for 2 h. XRD structural analysis results confirm the tetragonal(t) nature of the synthesized 8SmSZ nanocrystalline powder. The calculated crystallite size of tetragonal zirconia calcined at 873 K is around 9.0±0.5 nm and with increase in calcination temperature the size increases to 16.0±0.8 nm (1273 K). Thermogravimetric-Differential thermal analysis (TG-DTA) was carried out to study the crystallisation kinetics and growth behaviour of the 8SmSZ. The activation energy for the crystallisation of tetragonal ZrO2 formation in the 8SmSZ powder was found to be 308.1 kJ/mol by a non-isothermal DTA method. The growth morphology parameter was found to be n=2 indicating two-dimensional growth. The phase stability of the samples after annealing at 1573 K for 100 h was investigated by Raman spectroscopy and it was found that samaria doped zirconia exhibits better phase stability. These preliminary results confirmed the higher phase stability at elevated temperature thereby confirming its suitability in thermal barrier coating (TBC) applications.