Synthesis and photoluminescence properties of fluorite-related (Y1−xEux)10W2O21 phosphor

Eu3+-doped fluorite-related yttrium–tungsten oxide Y10W2O21 (5Y2O3·2WO3) was prepared using vibrating-mill-mixed powder and solid-state reactions. The synthesis temperature was investigated by thermogravimetric/differential thermal analysis and X-ray diffraction. The morphology of the phosphor was confirmed by scanning electron microscope (SEM) measurement. The photoluminescence (PL) properties, including the excitation and emission spectra, decay curves (lifetime), thermal stability and quantum efficiency, were investigated. The PL emission intensity was found to increase with Eu3+ content up to about 22.5 mol% and then decrease due to the concentration quenching effect. There were two kinds of coordinating site (seven-fold coordination and eight-fold coordination) of Y3+ ions in the fluorite-related structure of Y10W2O21. Eu3+ in different coordinating sites of Y3+ in the host could lead to energy-level splitting of the 5D0→7F2 transition, resulting in an emission peak red shift. The major intensity emission wavelengths, located at 612 nm and 627 nm for excitation at 392 nm, were attributed to replacement of the Eu3+ ions with 7 or 8 coordination sites of Y3+ ions.