Study of multiplet structures of Mn4+ activated in fluoride crystals

Novita, Mega; Honma, Tetsuo; Hong, Byung‐Chul; Ohishi, Atsushi; Ogasawara, Kazuyoshi

doi:10.1016/j.jlumin.2014.12.067

Cited by 44 publications

(24 citation statements)

References 22 publications

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“…Very recently, among the huge number of investigated materials, Mn 4+ ‐activated fluorides A 2 MF 6 (A=Li, Na, K, Rb, Cs and M=Si, Ti, Ge) turned out to be very promising due to their very narrow 2 E (g) → 4 A 2(g) emission of Mn 4+ ions in the red spectral range, and the simultaneous possibility to efficiently excite this activator with blue light . For this reason, their optical properties are currently being intensively investigated . The low crystal‐field splitting induced by the fluoride lattices maintains the entire emission in the visible range and the sharp emission characteristic to Mn 4+ lead to high color rendering indices.…”

Section: Figurementioning

confidence: 99%

“…[3] For this reason, their opticalp roperties are currently being intensively investigated. [4][5][6][7][8][9][10][11][12][13][14][15][16][17] The low crystal-field splitting induced by the fluoridel attices maintains the entire emission in the visible range and the sharp emission characteristic to Mn 4 + lead to high color rendering indices. Moreover these phosphors exhibit very high quantum yields, for example, 96 %e ven at 300 Kf or K 2 TiF 6 :Mn 4 + .…”

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confidence: 99%

“…In the literature,f our synthetic approaches were reported:t he solvothermal route, chemical etching, ionic exchange, andt he electrochemical route for Na 2 SiF 6 and FeSiF 6 ·6H 2 O. [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19] However,t hese usually involve the use of toxic HF as af luoride source.Recently,Huang et al published an HF-free hydrothermalr oute to synthesize K 2 SiF 6 :Mn 4 + . [20] They used KH 2 Fi nH 3 PO 4 as af luorides ource, which, however,a lso liberates HF in situ during the reaction.…”

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confidence: 99%

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Green Synthesis of A₂SiF₆ (A=Li–Cs) Nanoparticles using Ionic Liquids as Solvents and as Fluorine Sources: A Simple Approach without HF

Olchowka

Suta

Wickleder

2017

Chemistry A European J

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In this Communication, nanoparticles of the fluoridosilicates A2SiF6 (A=Li, Na, K, Rb, Cs), which are extremely promising host lattices for future LEDs, are presented for the first time. The preparation method we introduce here is a very simple and energy and time saving one, moreover the usage of toxic HF or elemental fluorine is avoided. In detail, the ionic liquid [Bmim]PF6 was used both as solvent and fluoride source in an ionothermally assisted microwave synthesis. The small size of the so‐obtained nanoparticles is of huge relevance for their applications as thin films or for the coverage of surfaces, for example in next‐generation white LEDs upon doping with Mn4+.

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Section: Figurementioning

confidence: 99%

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confidence: 99%

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confidence: 99%

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Green Synthesis of A₂SiF₆ (A=Li–Cs) Nanoparticles using Ionic Liquids as Solvents and as Fluorine Sources: A Simple Approach without HF

Olchowka

Suta

Wickleder

2017

Chemistry A European J

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“…The powdered Rb 2 SiF 6 :Mn 4+ phosphor in 5−20 μm size had a cubic Fm3m − O 5 h (225) symmetry with good thermal stability of T q > 600 K. It should be noted that no such high T q value has been reported on any Mn 4+ -activated alkaline hexafluorometallate phosphors. Nobita et al 7 also performed a theoretical study on the luminescence properties of some alkaline hexafluorometallate red-emitting phosphors, including Rb 2 MF 6 :Mn 4+ (M = Si, Ge, Mn). The motivation of this study is stimulated by the results of Fang et al 6 Here, we synthesize not only Rb 2 SiF 6 :Mn 4+ but also Rb 2 TiF 6 :Mn 4+ .…”

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confidence: 99%

Editors' Choice—Rb₂SiF₆:Mn⁴⁺and Rb₂TiF₆:Mn⁴⁺Red-Emitting Phosphors

Sakurai

Nakamura

Adachi

2016

ECS J. Solid State Sci. Technol.

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Rb-based hexafluoride red-emitting phosphors, Rb 2 SiF 6 :Mn 4+ and Rb 2 TiF 6 :Mn 4+ , were synthesized by the coprecipitation method. Optical microscopy observation, X-ray diffraction (XRD) measurement, photoluminescence (PL) analysis, PL excitation (PLE) spectroscopy, and luminescence decay characteristics measurements were used to study the structural and optical properties of the phosphors. The photographs of the bulk samples showed clear crystallographic habits originating from the cubic and trigonal symmetries of the Rb 2 SiF 6 and Rb 2 TiF 6 hosts, respectively, in agreement with the XRD results. The phosphors exhibited an intense narrow-band Mn 4+ ( 2 E g → 4 A 2g ) red emission with internal quantum efficiencies higher than 90% upon blue light excitation. The Franck−Condon analysis of the PLE data yielded the Mn 4+ intra-d-shell transitions to occur at ∼2.47 eV (∼2.34 eV) for the 4 A 2g → 4 T 2g transition and at ∼2.86 eV (∼2.83 eV) for the 4 A 2g → 4 T 1g transition in the Rb 2 SiF 6 :Mn 4+ (Rb 2 TiF 6 :Mn 4+ ) phosphor. Temperature dependence of the PL spectra from T = 20 to 500 K gave the quenching temperature values (T q 's) at which the PL intensity has fallen to half its maximum value to be T q ∼ 490 and ∼450 K for Rb 2 SiF 6 :Mn 4+ . To the best of our knowledge, only one paper has been published on Rb 2 TiF 6 reporting that it crystallizes in the trigonal structure with a = 0.5892 nm and a = 0.4795 nm. Our synthesized phosphors were examined by the X-ray diffraction (XRD) measurement, PL, PLE, and PL decay curve measurements. Temperature dependence of the PL properties was also examined from T = 20 to 500 K in 10-K increments. Efficient sharp red emissions with internal quantum efficiencies larger than 90% were observed from our phosphors that may promise improving a color rendering index of the conventional white-LED lamps.z E-mail: tnakamura@gunma-u.ac.jp; adachi@gunma-u.ac.jp ExperimentalThe rubidium hexafluorometallate phosphors were grown by the coprecipitation method. First, XO 2 (X = Si, Ti) and Rb 2 CO 3 in molar ratio of 1 : 1 were dissolved in an HF solution. Then, KMnO 4 powder was added in the HF solution at 300 K. This mixed solution was left in dark for a few days and resulted in a large single-crystalline phosphor growth (see Fig. 2 below). The resultant bulk single-crystalline phosphors were paper-filtered and dried in room ambient. They were grained in an agate mortar and then used for various measurements.The crystal structures of the synthesized phosphors were examined by performing an XRD analysis using a SmartLab X-ray diffractometer (Rigaku) with Cu Kα radiation at λ = 0.1542 nm. PL measurements were carried out using a single monochromator equipped with a charge-coupled device (Princeton Instruments PIXIS 100) in a CryoMini cryostat (Iwatani Industrial Gases) and a stainless cryostat (Technolo Kogyo) at T = 20 − 500 K in increments of 10 K. A He−Cd laser at λ ex = 325 nm (Kimmon IK3302R-E) was used as the excitation light source.PLE measurements were performed at 300 K...

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“…The optical properties of Mn 4+ in some crystals, in particular in K 2 GeF 6 , which are closely related to the type of crystal lattice of the investigated materials, were investigated in [11,12].…”

Section: Issn 2226-3780mentioning

confidence: 99%

K2GeF6 compound crystalline structure analysis

Zavodyannyy¹

2018

TAPR

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Study of multiplet structures of Mn4+ activated in fluoride crystals

Cited by 44 publications

References 22 publications

Green Synthesis of A₂SiF₆ (A=Li–Cs) Nanoparticles using Ionic Liquids as Solvents and as Fluorine Sources: A Simple Approach without HF

Green Synthesis of A₂SiF₆ (A=Li–Cs) Nanoparticles using Ionic Liquids as Solvents and as Fluorine Sources: A Simple Approach without HF

Editors' Choice—Rb₂SiF₆:Mn⁴⁺and Rb₂TiF₆:Mn⁴⁺Red-Emitting Phosphors

K2GeF6 compound crystalline structure analysis

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Study of multiplet structures of Mn4+ activated in fluoride crystals

Cited by 44 publications

References 22 publications

Green Synthesis of A2SiF6 (A=Li–Cs) Nanoparticles using Ionic Liquids as Solvents and as Fluorine Sources: A Simple Approach without HF

Green Synthesis of A2SiF6 (A=Li–Cs) Nanoparticles using Ionic Liquids as Solvents and as Fluorine Sources: A Simple Approach without HF

Editors' Choice—Rb2SiF6:Mn4+and Rb2TiF6:Mn4+Red-Emitting Phosphors

K2GeF6 compound crystalline structure analysis

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Green Synthesis of A₂SiF₆ (A=Li–Cs) Nanoparticles using Ionic Liquids as Solvents and as Fluorine Sources: A Simple Approach without HF

Green Synthesis of A₂SiF₆ (A=Li–Cs) Nanoparticles using Ionic Liquids as Solvents and as Fluorine Sources: A Simple Approach without HF

Editors' Choice—Rb₂SiF₆:Mn⁴⁺and Rb₂TiF₆:Mn⁴⁺Red-Emitting Phosphors