Shape control over microwave hydrothermally grown Y2O3:Eu by europium concentration adjustment

Abstract

Two-step synthesis of Y2O3:Eu nanostructures was performed. It includes microwave driven hydrothermal and calcination stages. Performed route results in crystallization of Y4O(OH)9(NO3):Eu crystals initially, then Y2O3:Eu crystals after calcination. Arranged Eu contents in relation to overall cation quantity were set to 2 mol%, 10 mol% and 20 mol%. Varying europium concentrations influence habit of obtained Y4O(OH)9(NO3):Eu crystals from needle-like to plate-like and as a result, also shapes of final Y2O3:Eu nanostructures. Additionally, certain amount of Eu2+ ions was detected in as-grown material using laser spectroscopy and decay kinetics measurements. Obtained material was calcined at 1200 °C in the air, which results in oxidation of Eu2+ ions and crystallization of small number of cubic Eu2O3 nanocrystals. Characterization of obtained materials was performed using XRD, SEM, TEM, EDX, CL, Raman and photoluminescence spectroscopy.