Photoluminescence of manganese-doped LiNaGe4O9 crystals

Omel’chenko, K. S.; Хмеленко, О. В.; Panchenko, T. V.; Volnyanskiı̆, M. D.

doi:10.1134/s1063783414040246

Cited by 13 publications

(12 citation statements)

References 11 publications

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“…The focus of the present investigation was on the discovery of novel deep red phosphors with emission wavelengths that shift slightly to a longer region (up to 660 nm) in order to achieve a larger color gamut and thereby to fulfill ITU-R BT.2020-2 recommendations . In this regard, Mn 4+ -doped A–Ge–O (A = Li, K, Rb,) systems such as Li 2 Ge 4 O 9 , LiNaGe 4 O 9 , , Rb 2 Ge 4 O 9 , K 2 Ge 4 O 9 , , and MGe 4 O 9 (M = Sr, Ba) have recently been discovered and extensively investigated as suitable phosphor hosts for deep red emissions in the desired wavelength region under UV and blue excitation. Although the chemical formulas of these host compounds look very similar, the crystal structures are different.…”

Section: Introductionmentioning

confidence: 99%

Discovery of a Red-Emitting Li₃RbGe₈O₁₈:Mn⁴⁺ Phosphor in the Alkali-Germanate System: Structural Determination and Electronic Calculations

et al. 2016

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A solid-state combinatorial chemistry approach, which used the A-Ge-O (A = Li, K, Rb) system doped with a small amount of Mn as an activator, was adopted in a search for novel red-emitting phosphors. The A site may have been composed of either a single alkali metal ion or of a combination of them. This approach led to the discovery of a novel phosphor in the above system with the chemical formula LiRbGeO:Mn. The crystal structure of this novel phosphor was solved via direct methods, and subsequent Rietveld refinement revealed a trigonal structure in the P3̅1m space group. The discovered phosphor is believed to be novel in the sense that neither the crystal structure nor the chemical formula matches any of the prototype structures available in the crystallographic information database (ICDD or ICSD). The measured photoluminescence intensity that peaked at a wavelength of 667 nm was found to be much higher than the best intensity obtained among all the existing AGeO (A = Li, K, Rb) compounds in the alkali-germanate system. An ab initio calculation based on density function theory (DFT) was conducted to verify the crystal structure model and compare the calculated value of the optical band gap with the experimental results. The optical band gap obtained from diffuse reflectance measurement (5.26 eV) and DFT calculation (4.64 eV) results were in very good agreement. The emission wavelength of this phosphor that exists in the deep red region of the electromagnetic spectrum may be very useful for increasing the color gamut of LED-based display devices such as ultrahigh-definition television (UHDTV) as per the ITU-R BT.2020-2 recommendations and also for down-converter phosphors that are used in solar-cell applications.

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Section: Introductionmentioning

confidence: 99%

Discovery of a Red-Emitting Li₃RbGe₈O₁₈:Mn⁴⁺ Phosphor in the Alkali-Germanate System: Structural Determination and Electronic Calculations

et al. 2016

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“…observed red emission in a lithium‐tetragermanate (Li 2 Ge 4 O 9 ) doped with Mn 4+ , and it was later found that the quenching temperature can be enhanced by Na substitution in Li(Na)Ge 4 O 9 . The site occupancy of Mn in the paraelectric and ferroelectric phases LiNaGe 4 O 9 : Mn crystals was later elucidated based on spectroscopy and structural analysis . Synthesis of these oxide crystals can be made easily by solid state reaction, while special care should be taken to the control of the oxidation state for Mn ions.…”

Section: Introductionmentioning

confidence: 99%

“…1 The site occupancy of Mn in the paraelectric and ferroelectric phases LiNaGe 4 O 9 : Mn crystals was later elucidated based on spectroscopy and structural analysis. 13 Synthesis of these oxide crystals can be made easily by solid state reaction, while special care should be taken to the control of the oxidation state for Mn ions. An oxidizing atmosphere is usually employed when using MnO as the starting material, and oxidation of Mn 2+ is expected to occur in the solid state reaction, which, however, is usually complicated and relies on the proper choice of starting materials.…”

Section: Introductionmentioning

confidence: 99%

Crystallization‐induced valence state change of Mn²⁺ → Mn⁴⁺ in LiNaGe₄O₉ glass‐ceramics

2020

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Tetra‐valent manganese (Mn4+) has been regarded as an efficient non‐rare‐earth red‐light emitting ion, which has stimulated continued search of robust hosts and efficient synthetic methods to stabilize Mn4+ centers with strong photoluminescence. In this work, we demonstrate a facile synthetic method for Mn4+ doped glass‐ceramic (GC) based on crystallization‐induced oxidation state change in an oxide glass. The parent glass with a formula of LiNaGe4O9 is fabricated by melt‐quenching and crystallization is induced by thermal treatment in air. Oxidation of Mn2+ in glass to Mn4+ in the GC is confirmed by both optical spectroscopy and electron paramagnetic resonance (EPR) measurements. After thermal treatment, the characteristic reddish photoluminescence (PL) of Mn2+ in the glass centered at 611 nm disappears and a strong photoluminescence peak at 660 nm attributed to Mn4+ is observed. The conversion to Mn4+ after crystallization in the examined system may have strong implications for synthesis of Mn4+ doped phosphors which always requires rigorous control of the redox equilibrium during synthesis.

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“…In this work, we will focus on Mn 4+ -doped germanate phosphors since they usually show higher efficiency as compared to the rest of oxide phosphors. 27 Another is in 2015, Mn 4+ -doped Li(Li,Na)Ge 4 O 9 solid solution was made by crystallizing germanate glass samples. 22 As the absorption spectrum of the phosphor shows (see curve 1 in Fig.…”

Section: Introductionmentioning

confidence: 99%

“…One appeared in 2014, and it says single crystal of Mn 4+ -doped LiNaGe 4 O 9 was grown by Czochralski method, and it shows the red photoluminescence. 27 Another is in 2015, Mn 4+ -doped Li(Li,Na)Ge 4 O 9 solid solution was made by crystallizing germanate glass samples. 28 In this work, we first will systematically study the effects of synthesis temperature, Mn 4+ ions concentration, and holding time on LiNaGe 4 O 9 :Mn 4+ to optimize the preparation conditions for high-temperature solid-state reaction.…”

Section: Introductionmentioning

confidence: 99%

Synthesis, Structure, and Performance of Efficient Red Phosphor LiNaGe₄O₉:Mn⁴⁺ and Its Application in Warm WLEDs

Tan

Wang

et al. 2016

J. Am. Ceram. Soc.

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For phosphor‐converted warm white light‐emitting diodes (WLEDs), it is essential to find highly efficient red oxide phosphors, which are better chemically stable and benign to environment and can be prepared in a much milder condition. Here, we report a red phosphor LiNaGe4O9:Mn4+ with a quantum yield up to 78% after systematic optimization in synthesis temperature, dopant concentration of Mn4+, and sintering time. Best performance of the phosphor can be reached when it is synthesized in a mild reaction condition, that is, at 850°C for 3 h in air. The integrated emission intensity is more than four times stronger than commercial red phosphor 3.5MgO·0.5MgF2·GeO2:Mn4+ (MFG:Mn4+) under a blue light excitation at 470 nm. Crystal structural analysis reveals that the high efficiency Mn4+ exhibits in the compound is mainly due to the well separation of GeO6 groups from each other by GeO4 tetrahedra in the neighborhood and the ideal substitution of octahedral Ge4+ site by Mn4+ in view of both size and charge matches. The high performance of the phosphor encourages us to apply the blue absorbing red phosphor to WLED, which is based on combination of a blue LED chip and YAG:Ce3+, and the warm perception WLED is therefore achieved with a color temperature of 3353 K.

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Photoluminescence of manganese-doped LiNaGe4O9 crystals

Cited by 13 publications

References 11 publications

Discovery of a Red-Emitting Li₃RbGe₈O₁₈:Mn⁴⁺ Phosphor in the Alkali-Germanate System: Structural Determination and Electronic Calculations

Discovery of a Red-Emitting Li₃RbGe₈O₁₈:Mn⁴⁺ Phosphor in the Alkali-Germanate System: Structural Determination and Electronic Calculations

Crystallization‐induced valence state change of Mn²⁺ → Mn⁴⁺ in LiNaGe₄O₉ glass‐ceramics

Synthesis, Structure, and Performance of Efficient Red Phosphor LiNaGe₄O₉:Mn⁴⁺ and Its Application in Warm WLEDs

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Photoluminescence of manganese-doped LiNaGe4O9 crystals

Cited by 13 publications

References 11 publications

Discovery of a Red-Emitting Li3RbGe8O18:Mn4+ Phosphor in the Alkali-Germanate System: Structural Determination and Electronic Calculations

Discovery of a Red-Emitting Li3RbGe8O18:Mn4+ Phosphor in the Alkali-Germanate System: Structural Determination and Electronic Calculations

Crystallization‐induced valence state change of Mn2+ → Mn4+ in LiNaGe4O9 glass‐ceramics

Synthesis, Structure, and Performance of Efficient Red Phosphor LiNaGe4O9:Mn4+ and Its Application in Warm WLEDs

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Discovery of a Red-Emitting Li₃RbGe₈O₁₈:Mn⁴⁺ Phosphor in the Alkali-Germanate System: Structural Determination and Electronic Calculations

Discovery of a Red-Emitting Li₃RbGe₈O₁₈:Mn⁴⁺ Phosphor in the Alkali-Germanate System: Structural Determination and Electronic Calculations

Crystallization‐induced valence state change of Mn²⁺ → Mn⁴⁺ in LiNaGe₄O₉ glass‐ceramics

Synthesis, Structure, and Performance of Efficient Red Phosphor LiNaGe₄O₉:Mn⁴⁺ and Its Application in Warm WLEDs