Temperature-dependent photoluminescence properties of (Ba,Sr)2SiO4:Eu2+ phosphors for white LEDs applications

(Ba,Sr)(2)SiO4: Eu2+ phosphors with various Eu2+ concentrations and Ba/Sr ratios were synthesized by solid-state reactions and their temperature-dependent photoluminescence properties were studied between 30 and 200 degrees C. Thermal quenching properties of (Ba1-xSrx)(2)SiO4: Eu2+ phosphors barely depend on Eu2+ concentrations, but exhibit a complex dependence on Ba/Sr ratios. With the increase of the Sr content, the luminescent thermostability is gradually improved for x < 0.5 and then becomes worse as x> 0.5. Considering changes in Stokes shifts, emission wavelengths and host lattice bandgaps for samples with various Ba/Sr ratios, this anomalous quenching behavior was discussed in terms of the configuration coordinate model and photo-ionization theory. (C) 2014 Elsevier B.V. All rights reserved.