Microwave-assisted hydrothermal synthesis of Eu2O3-coated spherical Y2O3 ceramic particles

This paper reports on the synthesis of uncoated and Eu2O3-coated spherical Y2O3 ceramic particles using optimized hydrothermal (HM) and microwave-assisted hydrothermal (MWHM) routes. The integration of microwave and hydrothermal processes was shown to enhance the reaction kinetics during the synthesis of uncoated Y2O3. Spherical particles of pure Y2O3 phase with an average particle size of 600 nm and uniform size distribution were obtained via the MWHM process at 180 °C following reaction duration of only 1 h. Y2O3 spherical particles were coated with Eu2O3 via a hydrolysis method at room temperature. The band gap of the resulting phosphors was estimated at 5.7 eV. Eu2O3-coated Y2O3 particles synthesized via the HM and MWHM present bright red PL emission under UV excitations; however, Y2O3 particles obtained via the MWHM method are more efficient than those yielded via the HM technique. Eu2O3-coated Y2O3 particles derived using the optimized MWHM technique present efficient emissions of red light with color purity and down conversion efficiency of approximately 85% and 80%, respectively. The present study demonstrates the suitability of employing coated phosphors in optical display technologies.