A novel Mn⁴⁺‐activated red phosphor for use in light emitting diodes, K₃SiF₇:Mn⁴⁺

Abstract

Phosphors that exhibit a narrow red emission are particularly interesting due to the advantage of providing a more extensive color gamut and better rendering in LED applications such as displays and solid‐state lighting. Although some Eu2+‐activated nitridosilicates have been discovered in this regard, K2SiF6:Mn4+ phosphors are the only option in actual LED applications thus far. We discovered a novel phosphor, K3SiF7:Mn4+, with P4/mbm symmetry. The luminescent properties of K3SiF7:Mn4+ are almost identical to those of the K2SiF6:Mn4+ phosphor, but its materials identity is distinct due to a completely different crystallographic structure, which leads to reduced decay time. The fast decay is one of the most serious disadvantages of existing K2SiF6:Mn4+ phosphors. The K3SiF7:Mn4+ phosphor was examined in comparison to the K2SiF6:Mn4+ via density functional theory calculation, Rietveld refinement, X‐ray photoelectron spectroscopy, X‐ray absorption near‐edge structure spectroscopy, and time‐resolved photoluminescence.

HF‐Free Solid‐State Synthesis of the Oxyfluoride Phosphor K3MoOF7:Mn4+

“…Wang and co‐workers discovered the fist HF‐free route in 2016, where they managed to stabilize Mn 4+ in a H 3 PO 4 /KHF 2 liquid . More HF‐free synthetic routes were reported in 2018, one using a low‐toxic NH 4 F/HCl liquid and other ones even described the development of HF‐free solid‐state methods to prepare K 2 TiF 6 :Mn 4+ or K 3 SiF 7 :Mn 4+ phosphors . Additionally, we reported about another solid‐state route to Li 2 SiF 6 :Mn 4+ via a high‐pressure/high‐temperature approach …”

Mn(IV)‐Substituted Metal(II) Hexafluorido Metallates(IV): Synthesis, Crystal Structures, and Luminescence Properties

“…In both cases HF is formed in situ. Solid‐state syntheses for K 3 SiF 7 : Mn were implemented by Sohn and coworkers by grinding mixtures of KHF 2 , K 2 SiF 6 and K 2 MnF 6 under acetone, followed by drying and heating in a stream of H 2 /N 2 for removal of residual HF [13] . A second solid‐state route was implemented by Jiao and coworkers.…”

Alkali Metal Hexafluorido Plumbates(IV) A2[PbF6] (A=Na−Cs) and Luminescence of the Mn4+‐substituted Compounds A2[PbF6] : Mn (A=Li−Cs) and Li2[MF6] : Mn (M=Ti, Ge, Sn)

“…Solid state reactions to obtain K 3 [SiF 6 ]F : Mn and K 2 [TiF 6 ] : Mn were implemented recently. For the synthesis of K 3 [SiF 6 ]F : Mn, a mixture of KHF 2 , K 2 [SiF 6 ] and K 2 [MnF 6 ] was ground under acetone, dried and heated in a stream of H 2 /N 2 [42] . To obtain K 2 [TiF 6 ] : Mn, a mixture of K 2 [TiF 6 ], K 2 [MnF 6 ] and KHF 2 was pestled, placed into a PTFE‐vessel and heated [43] .…”