A novel blue-emitting Ca2B5O9Br:Eu2+ phosphor prepared by a microwave calcination route

A blue-emitting Ca2B5O9Br:Eu2+ phosphor for white light-emitting diodes was synthesized via a microwave calcination route. The phosphor powders were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and fluorescence spectrophotometer, respectively. The obtained results revealed that the Ca2B5O9Br:Eu2+ phosphor prepared by the microwave calcination route possessed a rod-like morphology with the single phase orthorhombic structure. Based on the photoluminescence analysis, it was found that Ca2B5O9Br:Eu2+ phosphor exhibited a broad excitation band chiefly in the near ultraviolet region (270-420 nm) and a blue broad emission band of main peak at 452 nm under the strongest excitation of 411 nm. Further investigation on concentration-dependent emission spectra indicated that Ca2B5O9Br:0.03Eu2+ phosphor exhibited the strongest luminescent intensity, and the concentration quenching for the two Eu-site emission centers was caused by dipole-dipole interactions.