Comparative analysis of crystal field effects and optical spectroscopy of six-coordinated Mn4+ ion in the Y2Ti2O7 and Y2Sn2O7 pyrochlores

Brik, M.G.; Srivastava, A.M.; Avram, N.M.

doi:10.1016/j.optmat.2011.05.008

Cited by 106 publications

(35 citation statements)

References 49 publications

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“…Williams [18] reported the emission of Mn 4+ doped magnesium germanate red phosphor in 1947. Later, Kemeny et al [19] [20][21][22][23][24][25][26][27][28]. At present, Mn 4+ -doped phosphors are seldom used in WLEDs, so, in order to meet the requirement for practical application in WLEDs, it is necessary to further study the luminescence properties of Mn 4+ doped novel materials.…”

Section: A N U S C R I P Tmentioning

confidence: 99%

Synthesis and luminescence properties of novel red phosphors LiRGe2O6:Mn4+ (R = Al or Ga)

Cao

Luo

Xiong

et al. 2015

Journal of Alloys and Compounds

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Section: A N U S C R I P Tmentioning

confidence: 99%

Synthesis and luminescence properties of novel red phosphors LiRGe2O6:Mn4+ (R = Al or Ga)

Cao

Luo

Xiong

et al. 2015

Journal of Alloys and Compounds

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“…Additionally, their optical properties are strongly influenced by local crystal field environments. For example, the excitation and emission peaks of Mn 4 þ in oxide hosts are usually at B300 and B650 nm, respectively [27][28][29] . However, when Mn 4 þ ions are situated at fluoride hosts with octahedral coordination, they exhibit the most intense broadband excitation at B460 nm with a bandwidth of B50 nm and very sharp emission lines peaking at B630 nm as a result of weaker crystal field for Mn 4 þ (refs [30][31][32].…”

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confidence: 99%

Highly efficient non-rare-earth red emitting phosphor for warm white light-emitting diodes

et al. 2014

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Mn 4 þ -activated fluoride compounds, as an alternative to commercial (oxy)nitride phosphors, are emerging as a new class of non-rare-earth red phosphors for high-efficacy warm white LEDs. Currently, it remains a challenge to synthesize these phosphors with high photoluminescence quantum yields through a convenient chemical route. Herein we propose a general but convenient strategy based on efficient cation exchange reaction, which had been originally regarded only effective in synthesizing nano-sized materials before, for the synthesis of Mn 4 þ -activated fluoride microcrystals such as K 2 TiF 6 , K 2 SiF 6 , NaGdF 4 and NaYF 4 . Particularly we achieve a photoluminescence quantum yield as high as 98% for K 2 TiF 6 :Mn 4 þ . By employing it as red phosphor, we fabricate a high-performance white LED with low correlated colour temperature (3,556 K), high-colour-rendering index (R a ¼ 81) and luminous efficacy of 116 lm W À 1 . These findings show great promise of K 2 TiF 6 :Mn 4 þ as a commercial red phosphor in warm white LEDs, and open up new avenues for the exploration of novel non-rare-earth red emitting phosphors.

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“…8,9 For instance in the oxide phosphors, GdAlO 3 :Mn 4+ , SrTiO 3 :Mn 4+ and Y 2 Sn 2 O 7 :Mn 4+ the emission is well beyond 650 nm and thus unsuitable for visible displays or lighting. [10][11][12] The interest in K 2 SiF 6 :Mn 4+ as a red phosphor started with the development of a synthesis method by Adachi and Takahashi, etching Si wafers in HF in the presence of KMnO 4 . 13,14 This ambient wet chemical synthesis is cost effective compared to standard phosphor syntheses, which take place at high firing temperatures in controlled * Electrochemical Society Active Member.…”

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Luminescent Behavior of the K₂SiF₆:Mn⁴⁺Red Phosphor at High Fluxes and at the Microscopic Level

Sijbom

Joos

Martin

et al. 2015

ECS J. Solid State Sci. Technol.

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Phosphor-converted white light-emitting diodes (LEDs) are becoming increasingly popular for general lighting. The non-rare-earth phosphor K 2 SiF 6 :Mn 4+ , showing promising saturated red d-d-line emission, was investigated. To evaluate the application potential of this phosphor, the luminescence behavior was studied at high excitation intensities and on the microscopic level. The emission shows a sublinear behavior at excitation powers exceeding 40 W/cm 2 , caused by ground-state depletion due to the ms range luminescence lifetime. The thermal properties of the luminescence in K 2 SiF 6 :Mn 4+ were investigated up to 450 K, with thermal quenching only setting in above 400 K. The luminescence lifetime decreases with increasing temperature, even before thermal quenching sets in, which is favorable to counteract the sublinear response at high excitation intensity. A second, faster, decay component emerges above 295 K, which, according to crystal field calculations, is related to a fraction of the Mn 4+ ions incorporated on tetragonally deformed lattice sites. A combined investigation of structural and luminescence properties in a scanning electron microscope using energy-dispersive X-ray spectroscopy and cathodoluminescence mappings showed both phosphor degradation at high fluxes and a preferential location of the light outcoupling at irregularities in the crystal facets. The use of K 2 SiF 6 :Mn 4+ in a remote phosphor configuration is discussed. Most phosphor-converted white LEDs contain phosphors doped with rare earths such as divalent europium and trivalent cerium. These ions feature relatively broad emission bands based on the parity allowed 5d-4f transition. They are often easily excited with blue light and can show high quantum efficiency, even at elevated temperature. To improve the color rendering of white LEDs, red phosphors are added to the traditional blue LED and yellow Y 3 Al 5 O 12 :Ce (YAG:Ce) phosphor combination. These red phosphors need to be stable and have a high quantum efficiency. The emission spectrum should both be sufficiently red (>600 nm) and well within the eye sensitivity curve, to obtain a high luminous efficacy.1 Sulfide phosphors doped with Eu 2+ , such as (Ca,Sr)S:Eu 2+ are known for their efficient red emission, 2 but they lack stability in humid environments and the eye sensitivity is low for part of their broad emission band.3 Nitride phosphors doped with Eu 2+ are often chemically more stable, but their synthesis at high pressure and temperature is a drawback.4 Most europium-doped nitride phosphors show a relatively broad emission band. 5,6 Cost and supply issues of the rare-earth materials pave the way for transition-metal-doped phosphors. 7 In particular the Mn 4+ ion is a promising alternative for Eu 2+ as it shows line emission from parity and spin-forbidden d-d transitions in the red and near-infrared spectral region. Investigation of the optical properties of the Mn 4+ dopant showed that fluoride hosts are preferred for LED phosphors over oxide hosts, since only the io...

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Comparative analysis of crystal field effects and optical spectroscopy of six-coordinated Mn4+ ion in the Y2Ti2O7 and Y2Sn2O7 pyrochlores

Cited by 106 publications

References 49 publications

Synthesis and luminescence properties of novel red phosphors LiRGe2O6:Mn4+ (R = Al or Ga)

Synthesis and luminescence properties of novel red phosphors LiRGe2O6:Mn4+ (R = Al or Ga)

Highly efficient non-rare-earth red emitting phosphor for warm white light-emitting diodes

Luminescent Behavior of the K₂SiF₆:Mn⁴⁺Red Phosphor at High Fluxes and at the Microscopic Level

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Comparative analysis of crystal field effects and optical spectroscopy of six-coordinated Mn4+ ion in the Y2Ti2O7 and Y2Sn2O7 pyrochlores

Cited by 106 publications

References 49 publications

Synthesis and luminescence properties of novel red phosphors LiRGe2O6:Mn4+ (R = Al or Ga)

Synthesis and luminescence properties of novel red phosphors LiRGe2O6:Mn4+ (R = Al or Ga)

Highly efficient non-rare-earth red emitting phosphor for warm white light-emitting diodes

Luminescent Behavior of the K2SiF6:Mn4+Red Phosphor at High Fluxes and at the Microscopic Level

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Luminescent Behavior of the K₂SiF₆:Mn⁴⁺Red Phosphor at High Fluxes and at the Microscopic Level