Red emitting phosphors

Abstract

Eu activated LaPo 4 is being used as a red emitting phosphor for three-band lamp applications. Because of its low eye sensitivity, efforts are being made to explore new red emitting phosphors. One of the alternatives to LaPo 4 :Eu is Eu 3+ activated lanthanum Yttrium Phosphate (La 0.6 Y 0.4 PO 4 ) phosphor. La 0.6 Y 0.4 PO 4 phosphor samples are prepared by a solid-state reaction process. The phosphor of the present investigation, having uniform and non-spherical shape particles in the range of 2-5 μm is appropriate for thin phosphor screens required for lamp applications. It exhibits a narrow band emission in the red region, peaking at 612 nm and also a number of narrow bands in the UV region when excited by 254 and 260 nm radiation from a Hg gas mixture. Various possible transitions responsible for UV and visible emission from Eu 3+ ion are presented and compared with LaPo 4 : Eu 3 . These phosphors also exhibit good color saturation, better stability and eye sensitivity when excited with VUV radiation. Results related to morphology, excitation, emission, FTIR and particle size of these phosphors in the powder form are presented.