Synthesis and photoluminescence characteristics of a novel Eu and Tb doped Li2MoO4 phosphor

Abstract

Li2MoO4:x Eu3+ and Li2MoO4:xTb3+ phosphors, where x = 0.5, 1, 2, 3, 5 and 7 wt%, were synthesized through a gel-combustion method. The XRD data reveals that Eu3+ and Tb3+ doped Li2MoO4 phosphors exhibit a Rhombohedral structure belonging to the space group R3 which matched well with the standard JCPDS files (No.012-0763). We present photoluminescence (PL) spectra from Eu and Tb doped Li2MoO4 under 349 nm Nd:YLF pulses laser excitation over the temperature range of 10–300 K. Undoped Li2MoO4 shows a wide broad band around 600 nm because of the intrinsic PL emission of tetrahedral of MoO42− which was in good agreement with previous findings. Under the excitation of 394 nm, the as-synthesized phosphors exhibited sharp and strong intensity PL emission signals in the red (612 nm, 5D0→7F2 transition) and green (544 nm, 5D4→7F5 transition), respectively. The critical doping concentration of Eu3+ and Tb3+ ions in the Li2MoO4 were estimated to be 2 wt%. The concentration quenching phenomena were discussed, and the critical distances for energy transfer have also been evaluated by the concentration quenching.