A new red phosphor BaGeF₆:Mn⁴⁺: hydrothermal synthesis, photo-luminescence properties, and its application in warm white LED devices

In this work, we report a new and efficient red phosphor BaGeF₆:Mn⁴⁺ (denoted as BGFM) by hydrothermally etching BaCO₃ and GeO₂ in HF solution with an optimized KMnO₄ concentration. The crystal structure and morphology were characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS) in detail. The influence of synthesis conditions on its photo-luminescent (PL) properties has been investigated comprehensively. It can present broad adsorption and sharp emissions in blue and red ranges respectively. The white LED device made of a blue GaN chip merged with a YAG:Ce–BGFM mixture presents warmer white light than that merged with only one YAG:Ce component.