A novel blue emitting phosphor NaBa0.98Eu0.02PO4 and the improvement of its luminescence properties

Abstract

A novel blue-emitting phosphor NaBa0.98Eu0.02PO4 was synthesized by conventional solid state reaction, and it exhibits efficient blue emission under near-ultraviolet (n-UV) excitation. The emission spectrum shows a single band centered at about 440 nm, which corresponds to the 4f65d1-4f7 transition of Eu2+. The excitation spectrum is a broad band in the wavelength range between 200 and 450 nm, which can match the emission of white light emitting diodes (LEDs) by the method of n-UV conversion. The Ca2+, Sr2+ and Mg2+ were co-doped into NaBa0.98Eu0.02PO4 respectively. Special attention was paid to the sample co-doped with Ca2+ that could possess a higher luminous efficacy than the analogs co-doped with Sr2+ and Mg2+. With the co-doping of Ca2+, the enhanced intensity of the excitation and emission band appears. The optimum co-doping concentration of Ca2+ is 7 mol.%. The emission intensity of NaBa0.91Ca0.07Eu0.02PO4 phosphoris about 1.68 times than that of NaBa0.98Eu0.02PO4 phosphor. The as-prepared phosphors are the potential blue phosphors for application in white LEDs.