Sensitization of Er3+/Ho3+ visible and NIR emission in NaY(MoO4)2 phosphors

Efficient, host-sensitized, visible and near-infrared emitting phosphors NaY(MoO4)(2), doped with Ln(3+) (Ln = Er and Ho) were synthesized by a conventional solid state reaction and characterized with X-ray diffraction, photoluminescence emission and excitation spectra. Rietveld refinement was performed to investigate the phase purity of the NaY(MoO4)(2) samples. Sensitization of Ln(3+) (Ln = Er and Ho) from the host with different doping concentrations of Ln(3+) were investigated. Under excitation at 310 nm, the phosphor gives intense and characteristic emission of Er3+ and Ho3+ in both the visible and NIR region due to sensitization by MoO42- group. In the excitation spectra there is a broad band ranging from 250 to 380 nm which is associated with the O2--Mo6+ charge transfer transition in the MoO42- group. An efficient energy transfer from MoO42- to Er3+ and MoO42- to Ho3+ is observed. The interesting luminescence properties highlight the significance of Er3+/Ho3+ doped NaY(MoO4)(2) phosphor for their use in optical and photonic devices.