Sol–gel preparation and photoluminescence properties of LiLa(MoO4)2:Eu3+ phosphors

LiLa(MoO4)2:Eu3+ (in brief LLM:Eu) phosphors have been prepared by sol–gel method. The properties of the resulting phosphors are characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), photoluminescence (PL) spectra and decay curve. The excitation spectra of LLM:Eu phosphors are mainly attributed to O2− → Mo6+ charge-transfer (CT) band at about 280 nm and some sharp lines of Eu3+ f–f transitions in near-UV and visible regions with two strong peaks at 395 and 465 nm, respectively. The emission spectra were used to probe the local environments of Eu3+ ion in LLM crystal. Under the 395 nm excitation, intense red emission peaked at 616 nm corresponding to 5D0 → 7F2 transition of Eu3+ are observed for 55 at.% LLM:Eu phosphors as the optimal doping concentration. The luminescence indicates that the local symmetry of Eu3+ ion in LLM crystal lattice has no inversion center. The luminescence properties suggest that LLM:Eu phosphor may be regarded as a potential red phosphor candidate for near-UV light emitting diodes (LEDs).

► The LiLa(MoO4)2:Eu phosphors can be synthesized by sol–gel process. ► The luminescence indicates that the local symmetry of Eu3+ ion in LLM crystal lattice occupies S4 site with no inversion center. ► LLM:Eu phosphors show the strong red emission at 616 nm under excitation of 395 nm.