A broad band yellow-emitting Sr8CaBi(PO4)(7):Eu2+ phosphor for n-UV pumped white light emitting devices

摘要

A novel broad band yellow-emitting Sr8CaBi(PO4)(7):Eu2+ (SCBP:Eu2+) phosphor was synthesized via conventional high-temperature solid-state reaction. It's crystal structure and phase were investigated with X-ray diffraction (XRD), Rietveld refinement method and transmission electron microscopy (TEM). The photoluminescence spectra as well as fluorescence decay curves were measured and discussed. The SCBP:Eu2+ phosphor can exhibit a broad excitation band in the range from 260 to 425 nm, while the emission spectrum exhibits a broad asymmetric yellow emission band peaking at 606 nm under 400 nm excitation. By analyzing their structure and fluorescence decay lifetimes, five different Eu2+ luminescence centers in SCBP:Eu2+ phosphor were confirmed. Then the concentration quenching mechanism as well as the thermal stability has been discussed in detail. Furthermore, a white LED lamp which can exhibit good performance has been fabricated via combining a 400 nm near-ultraviolet (n-UV) chip with the commercial BAM:Eu2+ phosphor and the present SCBP:0.04Eu(2+)sample. These results suggest that the SCBP:Eu2+ can be a promising yellow-emitting n-UV phosphor for white light emitting diodes.