A narrow red-emitting phosphor of NaLa_4[Mo_3O_15]F:Eu^3+ with broad excitation band extending in blue wavelength region

Abstract

Abstract: Eu3+-doped NaLa4Mo3O15F was prepared by solid-state method and characterized by X-ray powder diffraction (XRD) and scanning electron microscope (SEM). The luminescence properties such as the excitation and emission spectra, the internal quantum efficiency (QE) and the thermal stability were investigated. The optimal level of Eu3+-doping was determined by the luminescence intensities and QEs. The phosphor exhibits a bright red luminescence at 615 nm corresponding to the electric dipole transition 5D0→7F2, which is more efficient than the commercial phosphor of Y2O2S:Eu3+. With the increase of Eu3+-doping the charge transfer band (CTB) shows an obvious red-shift, which presents a longer wavelength than any other reported Eu3+-doped molydates with non-cubic structures. NaLa4Mo3O15F:Eu3+ has excellent properties such as the high quantum efficiency excited in near-UV and blue wavelength, the high thermal stability, etc. This is benefited from its structural characteristics: the cubic crystalline phase with MoO6 groups and the incorporation of F- ions in the host lattices.