Red-emitting enhancement by inducing lower crystal field symmetry of Eu3+ site in CaWO4:Eu3+ phosphor for n-UV w-LEDs

A series of enhanced red-emitting phosphors Ca1-x-yMgxSryWO4:zEu(3+) (x = 0.00-0.30, y = 0.00-0.12, z = 0.00-0.16) were successfully synthesized via a high temperature solid-state reaction method. The phase structure, photoluminescence properties and thermal stability were investigated detailedly. All as-prepared samples, especially Ca0.65Mg0.20Sr0.05WO4:0.10Eu(3+) phosphors exhibit an extremely enhanced red emission peaking at 616 nm originating from D-5(0)-F-7(2) transition of Eu3+ under the 392 nm n-UV excitation. Mg2+ and Sr2+ were introduced into CaWO4: 0.10Eu(3+) to induce crystallographic parameters and crystal symmetry changes of Eu3+ ions in CaWO4 host. Enhanced red emission, broadband excitation spectra (from 200 to 600 nm), strong ultraviolet absorption matched well with n-UV LEDs chips (350 -420 nm) and high color purity (the R/O value is up to 7.52) indicate that as-prepared Ca0.65Mg0.20Sr0.05WO4:0.10Eu(3+) sample can be a potential candidate red phosphor for n-UV white light-emitting diodes. (c) 2017 Elsevier B.V. All rights reserved.