A strong zero-phonon line red phosphor BaNbF7:Mn4+ for white LEDs

A novel red fluoride phosphor BaNbF7:Mn4+ was synthesized via the conventional co-precipitation method. The structure and luminescence properties of BaNbF7:Mn4+ were investigated and discussed under various conditions. The BaNbF7:Mn4+ phosphor shows strong ZPL emission intensity at about 630 nm under ultraviolet (UV) and blue light excitation. It originated from the highly distorted Mn4+ octahedral coordination environment in the C3v group symmetry surrounding. A WLED fabricated with a blend of YAG:Ce3+ and the BaNbF7:Mn4+ phosphor exhibits a low color temperature (CCT = 3715 K) and a high color rendering index (Ra = 81.2), indicating its potential for application as a red phosphor for WLEDs.