Eu3+:CdWO4 single-phased white-light-emitting phosphor: pH controlled luminescence properties

Eu3+:CdWO4 single-phased phosphor for white-light-emitting diode (W-LED) was prepared by a hydrothermal method. The products were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) as well as photoluminescence (PL) spectra. The main luminescence center changed between WO42− groups and Eu3+ ions at different pH values, which led to different light-emitting properties of the samples. Under the excitation of 296 nm UV light, stable and independent white emission could be achieved when the pH value of the precursor was 7. The CIE chromaticity coordinates of the Eu3+:CdWO4 phosphor synthesized at pH=7 were x=0.323 and y=0.317, which were close to the values of standard chromaticity (x=0.33 and y=0.33) for an NTSC system. The CIE chromaticity calculation demonstrated its potential application in white light emission devices based on UV chips.