Emission enhancement of LiLaMo2O8:Eu3+ phosphor by co-doping with Bi3+ and Sm3+ ions

A series of LiLaMo2O8:Eu3+, R (R = Bi3+ and Sm3+) phosphors are synthesized by a high temperature solid-state reaction method in air. The crystal structures, fluorescence lifetimes, and luminescence properties are investigated in detail. LiLaMo2O8:Eu3+ phosphor with excitation 395 rim shows red light in the range of 525-725 nm and it photoluminescence intensity may be enhanced similar to 2.35 times due to energy transfer (ET) from a sensitizing species (Bi3+ or Sm3+) to Eu3+ ion after Bi3+ or Sm3+ ion is co-doped. The optimal Eu3+, Bi3+, and Sm3+ ion concentrations are 4%. Luminous mechanism of LiLaMo2O8:Eu3+, R (R = Bi3+ and Sm3+) phosphors and ET processes between Eu3+ and Bi3+/Sm3+ ions are analyzed and explained by their excitation and emission spectra and energy level diagrams of Eu3+, Bi3+, and SM3+ ions. The experimental results indicate that LiLaMo2O8:Eu3+, R (R = Bi3+ and Si3+) phosphors may be used as potenial red emitting materials for white light emitting diodes (LEDs) based on either a near ultraviolet (similar to 395 nm) or blue (similar to 465 nm) chip.