Tunable emission from LiBaBO3 :Eu3+ ;Bi3+ phosphor for solid-state lighting.

Abstract

Europium (Eu3+ ) and bismuth (Bi3+ ) co-activated LiBaBO3 powder phosphors were synthesized by a solid-state reaction and the structure, particle morphology, optical and photoluminescent properties were investigated. X-Ray diffraction patterns of the LiBaBO3 phosphors crystallized in a pure monoclinic phase, i.e. there were no secondary phases due to either incidental impurities or undecomposed starting materials. Scanning electron microscopy images showed that the powders were made up of fluffy needle-like particles that were randomly aligned. The band-gap of the LiBaBO3 host was estimated to be 3.33eV from the UV/vis absorption data. Blue emission was observed from the LiBaBO3 host, which is ascribed to self-activation of the host matrix. In addition, greenish-blue (493nm) and red (613nm) emissions were observed from europium-doped samples and were attributed to the emissions of Eu2+ and Eu3+ , respectively. Furthermore, after codoping with Bi3+ , the emission intensity of Eu3+ located at 613nm was significantly enhanced. From the Commission Internationale de I'Eclairage (CIE) color coordinates, white emission was observed from LiBa1-x BO3 :xEu3+ (x=0.020 and 0.025) phosphor powders with color coordinates of x=0.368, y=0.378 and x=0.376, y=0.366, respectively.