Spectroscopy characteristics of vanadate Ca9Dy(VO4)7 for application of white-light-emitting diodes

A vanadate, Ca9Dy(VO4)7, was synthesized by the general high temperature solid-state reaction in air atmosphere. X-ray powder diffraction analysis confirmed the formation of single phase Ca9Dy(VO4)7. Photoluminescence excitation spectrum showed that the phosphor could be efficiently excited by UV–visible light from 250 to 500 nm. The characteristic emission peaks of Dy3+ were observed in the emission spectra due to the transitions of 4F9/2 → 6H15/2 at 483 nm and 4F9/2 → 6H13/2 at 573 nm. The photoluminescence measurements showed that the Ca9Dy(VO4)7 exhibited an improved chromaticity compared with YVO4:Dy3+. This was ascribed to lower site symmetry and disordered cation sites in Ca9Dy(VO4)7. The luminescence characteristics of Ca9Dy(VO4) indicated that this phosphor has a possible application for white-light-emitting diode. Luminescence mechanism and site occupancies of Dy3+ ions in Ca9Dy(VO4)7 lattices were discussed.