Solution growth of millimeter‐scale Na₂SiF₆ single crystals for Mn⁴⁺‐doping as red phosphor

Abstract

Nowadays, the phosphor-converted white light-emitting diodes (LEDs) are pursuing better color rendering and lower correlated color temperature, by adding a red-emitting phosphor into the "blue LED + yellow-emitting garnet phosphor" system. Both Eu 2+ and Mn 4+ have been utilized as the blueto-red converting ions. Typically, the CaAlSiN 3 :Eu 2+ and (Ca, Sr) 2 Si 5 N 8 :Eu 2+ nitrides and the K 2 SiF 6 :Mn 4+ fluoride have been commercially employed in white LEDs for indoor lighting and wide-gamut displays. 1,2 The red phosphors activated by Mn 4+ show advantage over those activated by Eu 2+

Towards improved waterproofness of Mn4+-activated fluoride phosphors

“…Then, the NH 4 HF 2 solution dissolved with K 2 MnF 6 was injected to the above crystals, and the (NH 4 ) 2 SiF 6 :Mn 4+ and (NH 4 ) 3 SiF 7 :Mn 4+ crystals were obtained after a fast ion-exchange within one minute. In 2021, we 34 also prepared the Na 2 SiF 6 :Mn 4+ single crystal phosphor. The millimeter-sized Na 2 SiF 6 single crystals with a uniform columnar morphology (2–3 mm in length) were first grown in solution by slow cooling from 90 °C to 20 °C in a water bath, which were then soaked in the HF solution dissolved with K 2 MnF 6 to implement Mn 4+ doping via the cation exchange process (Fig.…”

“…11 Digital images of the Na 2 SiF 6 crystals doped with Mn 4+ : (a) under daylight, (b) under 365 nm ultraviolent (UV) light. The photoluminescence excitation (monitoring for 627 nm emission) and the emission (under 450 nm excitation) spectra were shown in (c) and (d), respectively 34.…”

Exploring dual-emission properties in Mn4+ distinctively activated BaTaF7 red emitting phosphor

“…Mn 4+ -activated fluoride phosphors have been extensively studied as red-emitting luminescent materials for white LEDs. [1][2][3][4] These fluoride phosphors, including A 2 XF 6 :Mn 4+ (A = Li, Na, K, Rb, and Cs; A 2 = Ba, Zn; X = Si, Ge, Sn, Ti, Zr, and Hf), A 3 MF 6 :Mn 4+ (M = Al, Ga, Sc, In), A 2 NF 7 :Mn 4+ (N = Nb, Ta), AZnF 3 :Mn 4+ , AHF 2 :Mn 4+ , and A 2 ZO 2 F 4 :Mn 4+ (Z = Mo, W), [5][6][7][8][9][10][11][12] have gained attention due to their broadband absorption in the blue region at B450 nm and sharp red-line emission at B630 nm. In recent years, extensive research has been conducted on Mn 4+ -doped fluoride materials due to their potential applications as red-emitting luminescent materials for white LEDs.…”

Designing bifunctional platforms for LED devices and luminescence lifetime thermometers: a case of non-rare-earth Mn4+ doped tantalate phosphors

“…[18][19][20][21][22] In light of the harmfulness of blue light and to broaden the selectivity of the excitation light source, Mn 4+ -activated metal oxides exhibiting a broad charge transfer band (CTB) have been explored, which can achieve far-red emission (∼650-800 nm), such as Li 2 Mg 3 TiO 6 :Mn 4+ , Sr 2 InSbO 6 :Mn 4+ , LaTiSbO 6 :Mn 4+ , Ca 2 InSbO 6 :Mn 4+ , and Ca 2 Y(Nb,Sb)O 6 :Mn 4+ phosphors. [13][14][15][16][17][18][19][20][21][22][23][24][25][26][27] It is well-known that metal oxides with the double-perovskite structure are promising as a kind of good host material for Mn 4+ doping. This is because the splitting of the crystal field of Mn 4+ could make it easy to enter and substitute the cation sites in their octahedral environments.…”

“…Note that Mn 4+ -activated fluorides could emit red emission (∼600–650 nm) under blue light (∼430–480 nm) excitation. 18–22 In light of the harmfulness of blue light and to broaden the selectivity of the excitation light source, Mn 4+ -activated metal oxides exhibiting a broad charge transfer band (CTB) have been explored, which can achieve far-red emission (∼650–800 nm), such as Li 2 Mg 3 TiO 6 :Mn 4+ , Sr 2 InSbO 6 :Mn 4+ , LaTiSbO 6 :Mn 4+ , Ca 2 InSbO 6 :Mn 4+ , and Ca 2 Y(Nb,Sb)O 6 :Mn 4+ phosphors. 13–27 It is well-known that metal oxides with the double-perovskite structure are promising as a kind of good host material for Mn 4+ doping.…”