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

A novel red-emitting Ba2ZrF8:Mn4+ phosphor was prepared by two-step method at low temperature, where critical precursor K2MnF6 was prepared first by the reduction of KMnO4 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 KMnO4: KHF2 was confirmed to play the key role in improving the luminous efficiency. More importantly, the phosphor exhibits a broadband excitation from 300 to 520 rim due to (4)A(2g)-> T-4(1g) and (4)A(2g)-> T-4(2g) transition of Mn4+, 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).