Luminescent properties of novel red-emitting phosphor Na₃TaF₈ with non-equivalent doping of Mn⁴⁺ for LED backlighting

Herein, a new red-emitting phosphor, Na₃TaF₈:Mn⁴⁺, was synthesized by non-equivalent doping of Mn⁴⁺ under mild condition. Its crystal structure and morphology were characterized by the powder X-ray diffraction (XRD), scanning electron microscopy (SEM). This sample is of single phase with monoclinic crystal structure. Mn⁴⁺ might occupy the site of Ta⁵⁺ in Na₃TaF₈, being located at the center of uniquely tetragonal anti-prism coordinated by eight F^-. The as-prepared Na₃TaF₈:Mn⁴⁺ has sharp red emissions with higher color purity under the blue light excitation. The luminescent behavior of Mn⁴⁺ in such host is similar with that in some hexafluorides with disordered octahedral structure. Intense red light can be observed from the single red LED based on Na₃TaF₈:Mn⁴⁺. These results show this phosphor to be a potentially red component for LED backlighting.