Structure and photoluminescence properties of Ce3+-doped novel silicon-oxynitride Ba4−zMzSi8O20−3xN2x (M=Mg, Ca, Sr)

Structural and photoluminescence properties of undoped and Ce3+-doped novel silicon-oxynitride phosphors of Ba4−zMzSi8O20−3xN2x (M=Mg, Sr, Ca) are reported. Single-phase solid solutions of Ba4−zMzSi8O20−3xN2x oxynitride were synthesized by partial substitutions of 3O2−→2N3− and Ba→M (M=Mg, Ca, Sr) in orthorhombic Ba2Si4O10. The influences of the type of alkaline earth ions of M, the Ce3+ concentration on the photoluminescence properties and thermal quenching behaviors of Ba3MSi8O20−3xN2x (M=Mg, Ca, Sr, x=0.5) were investigated. Under excitation at about 330 nm, Ba3MSi8O20−3xN2x:Ce3+ (x=0.5) exhibits efficient blue emission centered at 400–450 nm in the range of 350–650 nm owing to the 5d→4f transition of Ce3+. The emission band of Ce3+ shifts to long wavelength by increasing the ionic size of M due to the modification of the crystal field, as well as the Ce3+ concentrations due to the Stokes shift and energy transfer or reabsorption of Ce3+ ions. Among the silicon-oxynitride phosphors of Ba3MSi8O18.5N:Ce3+, M=Sr0.6Ca0.4 possesses the best thermal stability probably related to its high onset of the absorption edge of Ce3+.

Excitation and emission spectra of Ba3MSi8O18.5N:Ce3+ (M=Ca, Ce3+=1 mol%) demonstrate that Ce3+-doped novel silicon oxynitride emits blue light with a broad emission band in the range of 410–450 nm varying with the Ce3+ concentration under excitation at 330 nm. The luminescence properties are determined by the local crystal structure around Ba/Ca atom, where the activator ion of Ce3+ is occupied on the crystallographic site of Ba/Ca.Figure optionsDownload as PowerPoint slideHighlights
► Ce3+-activated novel alkaline earth silicon-oxynitride phosphors were invented.
► Crystal structure of the host was determined by the Rietveld method of powder XRD.
► Incorporation of M (Mg, Ca, Sr) can largely increase the solid solubility of N.
► Ba3MSi8O20−3xN2x:Ce3+ exhibits efficiently blue emission peaking at 400–450 nm.
► Thermal quenching temperature of silicon-oxynitride phosphors is above 130 °C.