Local structure modulation of Mn⁴⁺-doped Na₂Si_1−yGe_yF₆ red phosphors for enhancement of emission intensity, moisture resistance, thermal stability and application in warm pc-WLEDs

Abstract

Nowadays, the discovery of Mn4+-activated fluoride phosphor with efficient water and thermal stabilities is still a pivotal challenge to prolong the service life and stabilize the light output for phosphor-converted...

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

“…In order to quantitatively describe the color stability, the eqn (S5) † is used to calculate the chromaticity shi (DE) of KTF : MEAH + , Mn 4+ at different temperatures. 39,40 As shown in Fig. 5(f), as the temperature increases, the chromaticity shi of KTF : MEAH + , Mn 4+ gradually increases.…”

Towards improved waterproofness of Mn4+-activated fluoride phosphors

“…In 2020, Lang et al 37 prepared K 2 GeF 6 :Mn 4+ and the K 2 (Ge 0.7 Si 0.3 )F 6 :Mn 4+ solid solution phosphor by co-precipitation. After soaking in water, the body color of K 2 GeF 6 :Mn 4+ quickly turned brown and then black, while the body color of K 2 (Ge 0.7 Si 0.3 )F 6 :Mn 4+ showed a slight change and the integrated luminescence intensity was retained at 78% of the initial value after 168 h. In 2020, Wang et al 38 prepared Na 2 Si 1- x Ge x F 6 :Mn 4+ ( x = 0, 0.5, and 1) phosphors by co-precipitation. The luminescence intensity of the x = 0.5 solid solution phosphor was retained at 71% after soaking in water for 5 h, which is twice as much as that of the Na 2 SiF 6 :0.06Mn 4+ (32%) and Na 2 GeF 6 :0.06Mn 4+ (33%) phosphors.…”

“…In 2020, Lang et al 37 prepared K 2 GeF 6 :Mn 4+ and the K 2 (Ge 0.7 Si 0.3 )F 6 :Mn 4+ solid solution phosphor by coprecipitation. After soaking in water, the body color of K 2 GeF 6 :Mn 4+ quickly turned brown and then black, while the body color of K 2 (Ge 0.7 Si 0.3 )F 6 :Mn 4+ showed a slight change and the integrated luminescence intensity retained 78% of the initial value after 168 h. In 2020, Wang et al 38 prepared Na 2 Si 1-…”

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

“…Among the so‐far reported fluorides, the Mn 4+ 2 E g → 4 A 2 g transition in Na 2 SiF 6 emits the shortest wavelength peaking at 627 nm with an intense zero phonon line (ZPL) emission 24 . To date, there are 12 reports on Na 2 SiF 6 :Mn 4+ and its derivates (such as KNaSiF 6 :Mn 4+ ) 25‐36 . However, the growth of single‐crystal Na 2 SiF 6 :Mn 4+ has not reported yet.…”

“…24 To date, there are 12 reports on Na 2 SiF 6 :Mn 4+ and its derivates (such as KNaSiF 6 :Mn 4+ ). [25][26][27][28][29][30][31][32][33][34][35][36] (30.0%−32.0% solution, GR, Aladdin) were used as raw chemicals. A quasi-saturated Na 2 SiF 6 transparent solution (0.10 mol/L, 80 ml) was prepared in a plastic centrifugal tube (100 ml) by dissolving one of the sodium-bearing precursors with H 2 SiF 6 at 90°C (water bath) and held at this temperature for 10 min.…”