A strong zero phonon line of Mn4+ in a red-emitting phosphor BaGaF5:Mn4+

In this paper, a single-phase red-emitting phosphor BaGaF5:Mn4+ (BGFM) was synthesized by a hydrothermal method, and its crystal structure and luminescence properties were studied in detail. The results show that the excitation spectra of BGFM samples are mainly composed of two bands located at the near-ultraviolet and blue light region, respectively, while the emission spectra show multiple peaks in the red region. Due to the defects generated with the non-equivalent occupation of Ga3+ by Mn4+, the adjacent [MnF6] octahedron is highly distorted, resulting in a strong zero-phonon line (ZPL, 627 nm) in the emission spectrum. Additionally, the materials have shown a high internal quantum efficiency (QE = 63.7%) and good color stability. Finally, a white LED was obtained by mixing BGFM and commercial Y3Al5O12:Ce3+ yellow phosphor on a blue light-emitting diode (LED) chip.