Effects of annealing temperature, doping concentration, and excitation wavelength on photoluminescence characteristics of GdOCl:Bi3+ phosphor powders

Abstract

This study presents a novel investigation of the structure, particle morphology and photoluminescence (PL) characteristics of Gd 1-x OCl:Bi x phosphors prepared by a solid-state reaction method. X-ray diffraction data confirmed the formation of the tetrahedral GdOCl phase. The phosphors emitted peculiar photoluminescence that was dependent on the excitation wavelength, annealing temperature and doping concentration. When undoped GdOCl host was excited at 275 nm, a narrowband ultraviolet B (UVB) was observed at 315 nm. This emission is ascribed to the 8 S 7/2 → 6 I J transition of Gd 3+ . After doping with Bi 3+ , two excitation bands were observed at 275 nm (major excitation) and 336 nm (minor excitation). Exciting Bi 3+ doped GdOCl at 275 and 366 nm resulted in two broad emission bands at 455 nm (bluish green) and 428 nm (blue) ascribed to and 3 P 0,1 → 1 S 0 transitions of Bi 3+ . The PL peak intensities of these emissions were found to vary with Bi 3+ doping concentrations and annealing temperatures. The decay characteristics and photoluminescence quantum yield of the blue photoluminescence were determined, and the mechanism of the blue Bi 3+ emission is proposed.