Cubic Eu‐doped Hafnia Ultrafine Particles crystallized under hydrothermal conditions

Abstract

AbstractThe crystallization of HfO2–Eu2O3 amorphous co‐precipitates was Studied under hydrothermal conditions. The precipitates with the weight ratio of HfO2:Eu2O3 = 80:20 and 70:30 co‐precipitated by NH4OH from the solution HfOCl2 and EuCl3 and dried at 90°C for 100 h, yielded a single phase cubic solid solution Hf1‐xEuxO2‐x/2 (x = 0.230 and 0.339) with a fluorite lattice by hydrothermal treatment at 300°C under 10 MPa for 3 h. These products consist of non‐aggregated, ultrafine, narrow‐sized and single‐crystalline particles of about 10 nm and 8 nm in size for 20 wt% and 30 wt% Eu2O3 samples, respectively. It was confirmed by the TEM observation, X‐ray diffraction and specific surface area measurement by BET method which gave almost the same particle size. The maximum compositional fluctuation in the products was less than 2 wt% by energy dispersive spectroscopy for each particle and by precise X‐ray profile analysis of all the diffraction lines of the cubic phase using a Williamson‐Hall plotting (β cos Θ/λ vs sin Θ/λ).