Discovery of a novel yellow-orange-emitting low oxygen nitride phosphor Lu6.254Si11N20.762O0.238:Ce3+ for white LED

A novel broadband orange emitting phosphor Lu6.254Si11N20.762O0.238:Ce3+ was prepared via solid state reaction from the series of compounds R6+x/3Si11N20+xO1-x (R = Y and Gd→Lu, x = 1 or 0.762). The results of TEM, XRD and refinements verified the phase purity and crystal structure and also indicated that Ce3+ was successfully integrated into the main lattice to replace the Lu3+ ions. The phosphor Lu6.254Si11N20.762O0.238:Ce3+ presents a broadband bright orange emission peaking at 556 nm with a full width at half-maximum (FWHM) of 110 nm. The unique photoluminescence properties arise from the fact that Ce3+ occupies three different crystallographic sites, which is verified by spectral Gaussian fitting and three-exponential fluorescence decay curves. The PL emission intensity at 150 °C maintained 54.2% of that at room temperature (25 °C), the relatively poor thermal stability of this phosphor may be determined to the octahedrals [LuO6]1, [Lu(O/N)6]2 and [Lu(O/N)7]3 are connected each other so closing, which enhances the nonradiation transition. A w-LED device with CCT (5100 K) and high CRI (96.5) was fabricated by combining commercial blue phosphor SPOCl:Eu2+, green phosphor BSSO:Eu2+, red phosphor SCASN:Eu2+ and LSNO:0.24Ce3+ phosphor with 410 nm n-UV LED. Thus, this work provide an low oxygen nitride phosphor for application in high color rendering and full-spectrum warm white lighting.