Photo-induced degradation and thermal decomposition in ZnSnF6·6H2O:Mn4+ red-emitting phosphor

Hoshino, Ryôsuke; Adachi, Sadao

doi:10.1016/j.optmat.2015.07.019

Cited by 46 publications

(37 citation statements)

References 54 publications

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“…These characteristics make Mn 4+ -doped fluorides interesting narrow band red phosphors for w-LEDs. In recent years, a large number of Mn 4+ -activated fluorides with the general chemical formulas A 2 MF 6 :Mn 4+ (A = Na, K, Rb, Cs and NH 4 ; M = Si, Ge, Ti, Zr and Sn) and BaMF 6 :Mn 4+ (M = Si, Ge, Ti and Sn) have been reported [11,12,13]. In these compounds Mn 4+ substitutes for the M 4+ cation that is octahedrally coordinated by six F − ions.…”

Section: Introductionmentioning

confidence: 99%

Co-Precipitation Synthesis and Optical Properties of Mn4+-Doped Hexafluoroaluminate w-LED Phosphors

2017

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Mn4+-activated hexafluoroaluminates are promising red-emitting phosphors for white light emitting diodes (w-LEDs). Here, we report the synthesis of Na3AlF6:Mn4+, K3AlF6:Mn4+ and K2NaAlF6:Mn4+ phosphors through a simple two-step co-precipitation method. Highly monodisperse large (~20 μm) smoothed-octahedron shaped crystallites are obtained for K2NaAlF6:Mn4+. The large size, regular shape and small size distribution are favorable for application in w-LEDs. All Mn4+-doped hexafluoroaluminates show bright red Mn4+ luminescence under blue light excitation. We compare the optical properties of Na3AlF6:Mn4+, K3AlF6:Mn4+ and K2NaAlF6:Mn4+ at room temperature and 4 K. The luminescence measurements reveal that multiple Mn4+ sites exist in M3AlF6:Mn4+ (M = Na, K), which is explained by the charge compensation that is required for Mn4+ on Al3+ sites. Thermal cycling experiments show that the site distribution changes after annealing. Finally, we investigate thermal quenching and show that the luminescence quenching temperature is high, around 460–490 K, which makes these Mn4+-doped hexafluoroaluminates interesting red phosphors for w-LEDs. The new insights reported on the synthesis and optical properties of Mn4+ in the chemically and thermally stable hexafluoroaluminates can contribute to the optimization of red-emitting Mn4+ phosphors for w-LEDs.

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Section: Introductionmentioning

confidence: 99%

Co-Precipitation Synthesis and Optical Properties of Mn4+-Doped Hexafluoroaluminate w-LED Phosphors

2017

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“…At the same time, Mn 4+ doped red phosphors have been recognized as alternative candidates for the red component in WLED devices, because Mn 4+ usually exhibits a broad and strong absorption band between 250 and 500 nm, and narrow red emission with a main band between 610 and 730 nm, in octahedral coordination . However, presently proposed Mn 4+ ‐activated fluoride phosphors suffer from chemical instability and potential environmental issues which arise during material preparation and use . In addition, the fluoride environment provides a highly ionic ligand field, which may be undesirable for specific tuning of the emission behavior due to the low directionality of bonds.…”

Section: Introductionmentioning

confidence: 99%

Tuning Mn⁴⁺ Red Photoluminescence in (K,Rb)₂Ge₄O₉:Mn⁴⁺ Solid Solutions by Partial Alkali Substitution

Wondraczek

Peng

et al. 2016

J. Am. Ceram. Soc.

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We report on intense photoluminescence from materials of the (Rb,K) 2 Ge 4 O 9 :Mn 4+ solid solution as a novel class of redemitting oxide phosphors. In these compounds, luminescence originates from a virtually ideal substitution of Mn 4+ for Ge 4+ on octahedral lattice sites which are well-isolated from each other within the unit cell by intermediate GeO 4 species. Complete isostructural substitution of K for Rb is possible across the join. The associated slight shrinkage of the unit cell has only little effect on the apparent Mn 4+ interionic distance, but enables tuning of the absorption cross section and of the band structure, hence, of the emission lifetime, of the excitation band shape, and of emission quantum yield. Partial substitution was also found to reduce thermal quenching of the Mn 4+ -related emission, apparently due to the lower polarizability of the K + ion. In addition, random substitution of Rb by K enables modulation of the interaction of Mn 4+ with its surrounding field at lower symmetry, leading to increasing emission bandwidth, i.e., 595 cm -1 in K respectively.

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“…Red phosphors composed of Mn 4+ activated complex fluorides show a broad absorption band that overlapped with the electroluminescence (EL) band of InGaN chip . The problem of reabsorption can be resolved by mixing Mn 4+ activated complex fluorides and phosphor YAG:Ce to WLEDs because of the larger stokes shift of Mn 4+ ‐activated complex fluorides (there is no overlapping between their excitation and emission spectra).…”

Section: Introductionmentioning

confidence: 99%

“…In these synthetic procedures, the starting materials of metallic tin are cost‐effective. In addition, the host lattice crystals of K 2 SnF 6 .6H 2 O and ZnSnF 6 .6H 2 O that include constitution water are not stable for LED applications because of their low thermal stability . Adachi et al have also synthesized red fluostannate phosphors Na 2 SnF 6 :Mn 4+ and Cs 2 SnF 6 :Mn 4+ by chemical reaction in HF/NaMnO 4 (CsMnO 4 )/H 2 O 2 /H 2 O mixed solutions immersed with metallic tin and studied their photoluminescence properties and Raman scattering .…”

Section: Introductionmentioning

confidence: 99%

“…6,7 Mn 4+ ions with 3d 3 electronic configuration possess a group of sharp emission peaks in red region and a broad band excitation with a maximum in blue region, which makes Mn 4+ ions doped red phosphors play as alternative candidates for compensating red components for WLEDs. [8][9][10][11][12][13][14][15][16][17][18][19][20][21][22] Mn 4+ -doped alkaline aluminates show promise in WLEDs but repeated sintering processes at high temperature (>1200°C) are needed for synthesis of these phosphors. [8][9][10][11] Red phosphors composed of Mn 4+ activated complex fluorides show a broad absorption band that overlapped with the electroluminescence (EL) band of InGaN chip.…”

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confidence: 99%

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Optimized photoluminescence of red phosphor Na₂SnF₆:Mn⁴⁺ as red phosphor in the application in “warm” white LEDs

Pan

Chen

et al. 2017

J Am Ceram Soc

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The Mn4+ activated fluostannate Na2SnF6 red phosphor was synthesized from starting materials metallic tin shots, NaF, and K2MnF6 in HF solution at room temperature by a two‐step method. The formation mechanism responsible for preparing Na2SnF6:Mn4+ (NSF:Mn) has been investigated. The influences of synthetic parameters: such as concentrations of HF and K2MnF6 in reaction system, reaction time, and temperature on crystallinity, microstructure, and luminescence intensity of NSF:Mn have been investigated based on detailed experimental results. The actual doping concentration of Mn4+ in the NSF:Mn host lattice is less than 0.12 mol%. The most of K2MnF6 is decomposed in HF solution especially in hydrothermal system at elevated temperatures. The color of the as‐prepared NSF:Mn samples changes from orange to white when the temperature is higher than 120°C, which indicates the lower concentration of luminescence centers in the crystals. A series of “warm” white light‐emitting diodes with color rendering index (CRI) higher than 88 and correlated color temperatures between 3146 and 5172 K were obtained by encapsulating the as‐prepared red phosphors NSF:Mn with yellow one Y3Al5O12:Ce3+ (YAG:Ce) on 450 nm blue InGaN chips. The advantage of the synthetic strategy to obtain NSF:Mn can be extended to developing Mn4+‐doped red phosphors from low‐costing metals at room temperature for large‐scale industrial applications.

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Photo-induced degradation and thermal decomposition in ZnSnF6·6H2O:Mn4+ red-emitting phosphor

Cited by 46 publications

References 54 publications

Co-Precipitation Synthesis and Optical Properties of Mn4+-Doped Hexafluoroaluminate w-LED Phosphors

Co-Precipitation Synthesis and Optical Properties of Mn4+-Doped Hexafluoroaluminate w-LED Phosphors

Tuning Mn⁴⁺ Red Photoluminescence in (K,Rb)₂Ge₄O₉:Mn⁴⁺ Solid Solutions by Partial Alkali Substitution

Optimized photoluminescence of red phosphor Na₂SnF₆:Mn⁴⁺ as red phosphor in the application in “warm” white LEDs

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Photo-induced degradation and thermal decomposition in ZnSnF6·6H2O:Mn4+ red-emitting phosphor

Cited by 46 publications

References 54 publications

Co-Precipitation Synthesis and Optical Properties of Mn4+-Doped Hexafluoroaluminate w-LED Phosphors

Co-Precipitation Synthesis and Optical Properties of Mn4+-Doped Hexafluoroaluminate w-LED Phosphors

Tuning Mn4+ Red Photoluminescence in (K,Rb)2Ge4O9:Mn4+ Solid Solutions by Partial Alkali Substitution

Optimized photoluminescence of red phosphor Na2SnF6:Mn4+ as red phosphor in the application in “warm” white LEDs

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Tuning Mn⁴⁺ Red Photoluminescence in (K,Rb)₂Ge₄O₉:Mn⁴⁺ Solid Solutions by Partial Alkali Substitution

Optimized photoluminescence of red phosphor Na₂SnF₆:Mn⁴⁺ as red phosphor in the application in “warm” white LEDs