Influence of Sr/Hf ratio and annealing treatment on structural and scintillating properties of sol-gel Ce3+-doped strontium hafnate powders

Rare-earth-doped SrHfO3 has recently received great attention due to its potentiality as scintillating material. In this study, cerium (1 mol%)-doped strontium hafnate powders are elaborated using the sol-gel process. Different strontium/hafnium molar ratios and different annealing temperatures are investigated to follow the structural behaviour of the powder using X-rays diffraction, micro Raman spectroscopy and Fourier transformed infrared spectroscopy. The analyses are conducted on powders heat-treated up to 1200 °C. If the starting solution contains a strontium/hafnium ratio that equal or less to ≈1, the powders crystallize into a mixture of both HfO2 and SrHfO3 phases after heat treatment at high temperature. SrHfO3 powder is obtained for the molar ratio of the starting solution Sr/Hf = 1.22 and heat treatment up to 1000 °C. Strontium carbonate is observed when powders are elaborated with large excess of strontium whatever annealing temperature. The best scintillation efficiency is obtained using a starting solution with an equimolar ratio and a powder heat-treated at 1200 °C.