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

Abstract

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 C_3v 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 (R_a = 81.2), indicating its potential for application as a red phosphor for WLEDs.