Two-step synthesis of a novel red-emitting Ba2ZrF8:Mn4+ phosphor for warm white light-emitting diodes

A novel red-emitting Ba 2 ZrF 8 : Mn 4+ phosphor was prepared by two-step method at low temperature, where critical precursor K 2 MnF 6 was prepared first by the reduction of KMnO 4 using H 2 O2 as reducer. The crystal structure and morphology of the phosphor was characterized by X-ray diffraction (XRD), scanning electron microscope (SEM) equipped with energy-dispersive X-ray spectroscopy (EDS), showing single phase product. Luminescent properties of the phosphor were investigated by photoluminescence spectroscopy (PL) and decay curves. The molar ratio of KMnO 4 : KHF 2 was confirmed to play the key role in improving the luminous efficiency. More importantly, the phosphor exhibits a broadband excitation from 300 to 520 nm due to 4 A 2g → 4 T 1g and 4 A 2g → 4 T 2g transition of Mn 4+ , matching well with blue LED chips. Under 465 nm excitation, intense red emission at around 630 nm with high color purity is achieved, suggesting the red-emitting phosphor has great potential for white light-emitting diodes (wLEDs).