Discovery of an Environmentally Friendly Water-Soluble Luminous Material with Interstitial Site Occupancy

Abstract

As an essential precursor, K2MnF6 plays an important role in the preparation of Mn4+-activated fluoride materials, but its deterioration in pure water hampers development of a green route. Herein, we report a simple and high-speed synthetic route to obtain an environmentally friendly water-soluble KHF2:Mn4+ luminous material by engineering the interstitial Mn4+ site, which is confirmed by combining with DFT, XRD Rietveld refinement data, solid-state NMR, Raman spectrum, and TG/DSC curves. Meanwhile, KHF2:Mn4+ has red emissions centered at ∼602.2, 611.2, 615.6, 633.2, 637.2, and 650.0 nm, shows a zero-thermal-quenching characteristic and good quantum efficiency of 65%. KHF2:Mn4+, and as a green ion-exchange luminous material can be dissolved into pure water to produce anionic [MnF6]2– complexes for preparing Mn4+-activated fluoride phosphors such as K2GeF6, K2SiF6, K2TiF6, etc. This discovery reveals KHF2:Mn4+ is a potential candidate to substitute K2MnF6 to develop a green route for Mn4+-activated fluoride inorganic luminescent materials.

An organic–inorganic hybrid K2TiF6 : Mn4+ red-emitting phosphor with remarkable improvement of emission and luminescent thermal stability

“…In recent years, WLEDs (white light-emitting diodes) with stable performance, energy saving, and outstanding luminescent characteristics have increasingly become an important requirement in the display and lighting elds. [1][2][3][4][5] At the moment, the commercially available WLEDs are composed of yellow emitting phosphors and blue emitting chips. 6 Although the device can produce white light, due to the lack of a red light component, its corresponding disadvantages are low color rendering index (R a < 80) and high color temperature (CCT > 4500 K).…”

Highly Moisture-Stable and Enhanced Luminescence-Efficient Mn4+-Activated Red-Emitting Fluoride Phosphors via a Bi-hydrogen-Bond Organic Coating

“…The 1 H NMR spectrum of KSFM shows two signals at 1.39 and 6.08 ppm. The broad peak at 6.08 ppm corresponds to the O–H–O band of adsorbed water from the air atmosphere, while the peak at 1.39 is due to the interaction of proton nuclei from the atmosphere with the fluorine of KSFM . As for KSFM@OAm, there are five peaks as follows: a broad peak at 1.42 ppm for the methylene group (−CH 2 −), a peak at 1.01 ppm for the methyl group (−CH 3 ), a peak at 5.44 ppm for vinyl (−CH=CH−) protons, a peak at 2.13 ppm for (CH 2 –CH=CH−), and a peak at 2.76 ppm for CH 2 –NH 2 . − In the 1 H NMR spectrum of KSFM@OAm, it is difficult to distinguish the NH 2 peak at approximately 1.13 ppm and CH 2 –CH 2 –NH 2 peak at approximately 1.37 ppm due to the broad methylene peak.…”

HF‐Free Microwave‐Assisted Synthesis of Nano‐Micro‐Sized K2SiF6:Mn4+ for MicroLED Color Conversion

“…[14] In 2021, Han et al reported that KHF 2 :Mn 4+ water-soluble luminescent material could be used as a precursor to prepare Mn 4+ activated fluoride phosphors, successfully transferring Mn 4+ from pure water to K 2 SiF 6 host. [15] All the above synthesis methods can obtain particles within the micron size range, and the size distribution is not uniform, which is not suitable for MicroLED devices. More recently, Wang's research team developed a surfactant-free stepwise cation exchange synthesis in a non-HF system of cubic K 2 SiF 6 :Mn 4+ nano phosphor.…”