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1.

Вид документа : Статья из сборника (однотомник)
Шифр издания :
Автор(ы) : Gunyakov V. A., Zhuikov V. A., Zyryanov V. Ya., Smorgon S. L., Shabanov V. F.
Заглавие : Two-color display based on polymer dispersed liquid crystals films
Коллективы : Summer European Liquid Crystals conference
Место публикации : First Summer European Liquid Crystal Conference: abstracts. - Vilnius, 1991. - Vol. 1. - P.90
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2.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Aleksandrovsky A. S., Arkhipkin V. G., Bezmaternykh L. N., Gudim I. A., Krylov A. S., Vagizov F.
Заглавие : Origin of color centers in the flux-grown europium gallium garnet
Место публикации : J. Appl. Phys.: AMER INST PHYSICS, 2008. - Vol. 103, Is. 8. - Ст.83102. - ISSN 0021-8979, DOI 10.1063/1.2902365
Примечания : Cited References: 7
Предметные рубрики: SPECTRA
IONS
Ключевые слова (''Своб.индексиров.''): absorption--europium alloys--garnets--ultraviolet radiation--calcium-free flux--flux-grown europium gallium garnet--color centers
Аннотация: Europium gallium garnet (EuGG) single crystals were grown from fluxes with various contents. Optical absorption spectra of EuGG grown from a flux containing calcium show an additional band in the ultraviolet and blue regions of the spectra as compared to the case of a calcium-free flux. Mossbauer spectra of the samples grown from the fluxes with different additives show no signs of other valence states of the europium ions except for 3+. However, they indicate changes in the crystal field due to the entrance of additive ions. The nature of the additional absorption must be the same as that for calcium-doped gadolinium gallium garnet, i.e., anion vacancies. Mossbauer isotope shifts and quadrupole splitting for EuGG are determined. (C) 2008 American Institute of Physics.
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3.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Wang Z. Y., Xia, Zhiguo, Molokeev M. S., Atuchin V. V., Liu Q. L.
Заглавие : Blue-shift of Eu2+ emission in (Ba,Sr)3Lu(PO4)3:Eu2+ eulytite solid-solution phosphors resulting from release of neighbouring-cation-induced stress
Место публикации : Dalton Trans.: Royal Society of Chemistry, 2014. - Vol. 43, Is. 44. - P.16800-16804. - ISSN 1477-9226, DOI 10.1039/c4dt02319f. - ISSN 1477-9234
Примечания : Cited References: 16. - The present work was supported by the National Natural Science Foundations of China (grant no. 51002146, no. 51272242), Natural Science Foundations of Beijing (2132050), the Program for New Century Excellent Talents in the University of the Ministry of Education of China (NCET-12-0950), Beijing Nova Program (Z131103000413047), Beijing Youth Excellent Talent Program (YETP0635) and the Funds of the State Key Laboratory of New Ceramics and Fine Processing, Tsinghua University (KF201306). V.V.A. is partly supported by the Ministry of Education and Science of the Russian Federation.
Предметные рубрики: TUNABLE COLOR TONE
EXCITED WHITE LEDS
CRYSTAL-STRUCTURE
TEMPERATURE
IONS
Аннотация: A series of iso-structural eulytite-type (Ba,Sr)(3)Lu(PO4)(3):Eu2+ solid-solution phosphors with different Sr/Ba ratios were synthesized by a solid-state reaction. Crystal structures of (Ba,Sr)(3)Lu(PO4)(3):Eu2+ were resolved by the Rietveld method, which shows an eulytite-type cubic Bi-4(SiO4)(3) structure with cations disordered in a single C-3 site while the oxygen atoms were distributed over two partially occupied sites. The emission peaks of Ba(3-x)SrxLu(PO4)(3):Eu2+ (0
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4.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Yu, Shixin, Xia, Zhiguo, Molokeev M. S., Miao, Hao, Atuchin V. V.
Заглавие : Synthesis and luminescence properties of blue-emitting phosphor Li3c2(PO4)3:Er2+
Место публикации : ECS J. Solid State Sci. Technol. - 2014. - Vol. 3, Is. 8. - P.R159-R163. - ISSN 2162-8769, DOI 10.1149/2.0071408jss. - ISSN 2162-8777
Примечания : Cited References: 33. - The present work was supported by the National Natural Science Foundations of China (Grant No. 51002146, No. 51272242), Natural Science Foundations of Beijing (2132050), the Program for New Century Excellent Talents in the University of the Ministry of Education of China (NCET-12-0950), Beijing Nova Program (Z131103000413047), Beijing Youth Excellent Talent Program (YETP0635) and the Funds of the State Key Laboratory of New Ceramics and Fine Processing, Tsinghua University (KF201306). Z. G. Xia is also grateful for the financial support from University of Science and Technology Beijing. V.V.A. gratefully acknowledge the Ministry of Education and Science of the Russian Federation for the financial support.
Предметные рубрики: ENERGY-TRANSFER
PHOTOLUMINESCENCE PROPERTIES
INORGANIC-COMPOUNDS
EMISSION COLOR
FULL-COLOR
DIODES
Eu2+
IONS
LEDS
Tb
Аннотация: A new blue-emitting phosphor Li3Sc2(PO4)3:Eu2+ was synthesized by a high temperature solid-state reaction method, and the crystal structure and photoluminescence properties were investigated in detail. The preferred crystallographic position of the Eu2+ ions in the Li3Sc2(PO4)3 host were determined from the structural analysis and spectroscopic properties. The as-prepared phosphor gave an intense blue emission band centered at 439 nm with the CIE coordinate of (0.1540, 0.0317) upon the excitation of the near ultraviolet light. The critical quenching concentration of Eu2+ in Li3Sc2(PO4)3:Eu2+ was about 15 mol%, and the corresponding concentration quenching mechanism was verified to be the dipole-quadrupole interaction. The fluorescence lifetime of Eu2+ emission and the thermal stable luminescence property have been investigated. Li3Sc2(PO4)3:Eu2+ was found to be a promising candidate as a blue-emitting n-UV convertible phosphor for the application in white light emitting diodes (w-LEDs).
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5.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Ji H. P., Huang Z. H., Xia, Zhiguo, Molokeev M. S., Atuchin V. V., Huang S. F.
Заглавие : Cation substitution dependent bimodal photoluminescence in whitlockite structural Ca3-xSrx(PO4)2:Eu2+ (0 ≤ x ≤ 2) solid solution phosphors
Место публикации : Inorg. Chem.: American Chemical Society, 2014. - Vol. 53, Is. 20. - P.11119-11124. - ISSN 0020-1669, DOI 10.1021/ic501679f. - ISSN 1520-510X
Примечания : Cited References: 37. - This work was supported by the National Natural Science Foundations of China (Grant Nos. 51032007, 51002146, 51272242), the Research Fund for the Doctoral Program of Higher Education of China (Grant No. 20130022110006), the Natural Science Foundations of Beijing (2132050), the Program for New Century Excellent Talents in University of Ministry of Education of China (NCET-12-0950), Beijing Nova Program (Z131103000413047), and Beijing Youth Excellent Talent Program (YETP0635). V.V.A. acknowledges the Ministry of Education and Science of the Russian Federation for financial support.
Предметные рубрики: LIGHT-EMITTING-DIODES
EFFICIENT ENERGY-TRANSFER
EMISSION-TUNABLE PHOSPHOR
EXCITED WHITE LEDS
CRYSTAL-STRUCTURE
LUMINESCENCE PROPERTIES
Mn2+ PHOSPHOR
COLOR TONE
PHASE
Eu2+
Аннотация: Cation substitution dependent tunable bimodal photoluminescence behavior was observed in the Ca3-xSrx(PO4)2:Eu2+ (0 ≤ x ≤ 2) solid solution phosphors. The Rietveld refinements verified the phase purity and whitlockite type crystal structure of the solid solutions. The tunable photoluminescence evolution was studied as a function of strontium content, over the composition range 0.1 ≤ x ≤ 2. In addition to the emission band peak at 416 nm in Ca3(PO4)2:Eu2+, the substitution of Ca2+ by Sr2+ induced the emerging broad-band peak at 493-532 nm. A dramatic red shift of the emission peak located in the green-yellow region was observed on an increase of x in the samples with 0.75 ≤ x ≤ 2.00. The two emission bands could be related to the EuOn-Ca9 and EuOn-Ca9-xSrx emitting blocks, respectively. The values for the two kinds of emitting blocks in the solid solutions can be fitted well with the observed intensity evolution of the two emission peaks.
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6.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Hsiao, Yu-Cheng, Timofeev I. V., Zyryanov V. Ya., Lee, Wei
Заглавие : Hybrid anchoring for a color-reflective dual-frequency cholesteric liquid crystal device switched by low voltages
Коллективы : Ministry of Science and Technology, Taiwan [103-2923-M-009-003-MY3]; Russian Foundation for Basic Research [14-02-31248]; Siberian Branch of the Russian Academy of Sciences (SB RAS) through an NSC-SB-RAS joint project between Taiwan and Russia
Место публикации : Opt. Mater. Express: Optical Society of America, 2015. - Vol. 5, Is. 11. - P.2715-2720. - ISSN 2159-3930, DOI 10.1364/OME.5.002715
Примечания : Cited References:17. - This work was financially sponsored by the Ministry of Science and Technology, Taiwan, under grant No. 103-2923-M-009-003-MY3, by the Russian Foundation for Basic Research (project No. 14-02-31248), and by the Siberian Branch of the Russian Academy of Sciences (SB RAS) through an NSC-SB-RAS joint project between Taiwan and Russia
Предметные рубрики: Photonic structure
Drive scheme
Modulation
Аннотация: Cholesteric liquid crystal (CLC) materials used in electro-optical (EO) devices are characterized by high operating voltage and slow response speed, which hinders their further development in display applications. Dual-frequency CLCs (DFCLCs) can solve the problem of slow bistable transition, but the operating voltage is still high, especially in color-reflective DFCLC cells. Here we report a simple approach to lowering the switching voltage as well as to shortening the response time. This technique adopts hybrid surface treatment to modulate the structural arrangement of CLC molecules. Both planar-and vertical-alignment layers are employed and coated on one and the other substrates separately to improve the electro-optical properties of DFCLCs. We show that the threshold voltage for switching can be decreased to as low as 5 V and the shortest response time is measured to be 0.8 ms, which renders CLC EO devices including displays more practical for commercial purpose.
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7.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Pustovarov V. A., Ogorodnikov I. N., Omelkov S. I., Molokeev M. S., Kozlov A. V., Isaenko L. I.
Заглавие : Photoluminescence of monoclinic Li3AlF6 crystals under vacuum ultraviolet and soft X-ray excitations
Место публикации : Opt. Mater.: Elsevier, 2015. - Vol. 49. - P.201-207. - ISSN 0925-3467, DOI 10.1016/j.optmat.2015.09.011
Примечания : Cited References: 49. - This work was partly supported by the Ministry of Education and Science of the Russian Federation (the basic part of the government mandate); Center of Excellence "Radiation and Nuclear Technologies" (Competitiveness Enhancement Program of Ural Federal University, Russia), HASYLAB DESY (Projects Nos. 20110843, 20080119EC), European Social Fund ("Mobilitas" program, MJD219), Estonian Research Council (Institutional Research Funding IUT02-26) and Baltic Science Link project coordinated by the Swedish Research Council, VR
Предметные рубрики: LiBaAlF6 single-crystals
F-type centers
LiBaF3 crystals
Color-centers
Recombination luminescence
Rietveld refinement
VUV spectroscopy
Trapped excitons
Energy-transfer
Pure
Ключевые слова (''Своб.индексиров.''): li3alf6--time-resolved luminescence--vuv spectroscopy--defects
Аннотация: Using Bridgman technique we have grown monoclinic β-LiAF crystals suitable for optical studies, performed XRD-identification and Rietveld refinement of the crystal structure and carried out a photoluminescence study upon vacuum ultraviolet (VUV) and extreme ultraviolet (XUV)-excitations, using the low-temperature (T = 7.2 K) time-resolved VUV-spectroscopy technique. The intrinsic PL emission band at 340–350 nm has been identified as due to radiative recombination of self-trapped excitons. The electronic structure parameters were determined: bandgap E g ≈ 12.5 eV, energy threshold for creation of unrelaxed excitons 11.8 eV < E n < 12.5 eV . The PL emission bands at 320–325 and 450 nm were attributed to luminescence caused by lattice defects. We have discovered an efficient excitation of PL emission bands in the energy range of interband transitions ( E ex > 13.5 eV), as well as in the energy range of core transitions at 130 eV. We have revealed UV–VUV PL emission bands at 170 and 208 nm due to defects. A reasonable assumptions about the origin of the UV–VUV bands were discussed.
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8.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Miao, Shihai, Xia, Zhiguo, Molokeev M. S., Chen, Mingyue, Zhang, Jie, Liu, Quanlin
Заглавие : Effect of Al/Si substitution on the structure and luminescence properties of CaSrSiO4:Ce3+ phosphors: analysis based on the polyhedra distortion
Место публикации : J. Mater. Chem. C: Royal Society of Chemistry, 2015. - Vol. 3, Is. 18. - P.4616-4622. - ISSN 2050, DOI 10.1039/c5tc00339c. - ISSN 20507534(eISSN)
Примечания : Cited References:30. - The present work was supported by the National Natural Science Foundations of China (Grant No. 51002146, 51272242), Natural Science Foundations of Beijing (2132050), the Program for New Century Excellent Talents in the University of the Ministry of Education of China (NCET-12-0950), Beijing Nova Program (Z131103000413047), Beijing Youth Excellent Talent Program (YETP0635), the Funds of the State Key Laboratory of New Ceramics and Fine Processing, Tsinghua University (KF201306) and the excellent tutor section of the Fundamental Research Funds for the Central Universities of China University of Geosciences, Beijing (2652015027).Cover image: Artwork representing main idea of this article
Предметные рубрики: LIGHT-EMITTING-DIODES
COLOR-TUNABLE PHOSPHOR
ENERGY-TRANSFER
Аннотация: Blue-emitting CaSrSiO4:Ce3+,Li+ phosphors were prepared by a high temperature solid-state method, and the effect of substituting Al3+ for Si4+ in CaSrSiO4:Ce3+,Li+ has been studied. Crystal structures of the as-prepared Ca1−ySr1−ySi1−xAlxO4:yCe3+,yLi+ phosphors were resolved by the Rietveld method, which suggested that all the samples belonged to the orthorhombic symmetry (Pnma) group of α-CaSrSiO4. The photoluminescence (PL) emission and excitation spectra, the lifetime, and the effect of Al3+ concentration on the PL properties were investigated in detail. The emission peaks of the CaSrSi1−xAlxO4:Ce3+,Li+ (x = 0–0.10) phosphors were red-shifted from 452 to 472 nm with increasing Al/Si ratio. The red-shift of the Ce3+ emission is ascribed to the polyhedra distortion of the cations, originating from the variation in the neighboring [(Si,Al)O4] polyhedra, and the detailed mechanism has been discussed.
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9.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Liu C., Xia, Zhiguo, Chen M., Molokeev M. S., Liu Q.
Заглавие : Near-infrared luminescence and color tunable chromophores based on Cr3+-Doped Mullite-Type Bi2(Ga,Al)4O9 solid solutions
Место публикации : Inorg. Chem.: American Chemical Society, 2015. - Vol. 54, Is. 4. - P.1876-1882. - ISSN 0020-1669, DOI 10.1021/ic502779d
Примечания : Cited References: 26. - The present work was supported by the National Natural Science Foundations of China (Grants 51002146, 51272242), Natural Science Foundations of Beijing (2132050), the Program for New Century Excellent Talents in University of Ministry of Education of China (NCET-12-0950), Beijing Nova Program (Z131103000413047), Beijing Youth Excellent Talent Program (YETP0635), the Funds of the State Key Laboratory of New Ceramics and Fine Processing, Tsinghua University (KF201306), and Fundamental Research Funds for the Central Universities (FRF-TP-14-005A1).
Предметные рубрики: PERSISTENT LUMINESCENCE
PHOSPHORS
PIGMENT
GARNET
OXIDES
FIELD
RED
Аннотация: Cr3+-activated mullite-type Bi2Ga(4-x)AlxO9 (x = 0, 1, 2, 3, and 4) solid solutions were prepared by the solid state reaction, and their spectroscopic properties were investigated in conjunction with the structural evolution. Under excitation at 610 nm, Bi2[Ga(4-y)Aly]3.97O9:0.03Cr3+ (y = 0, 1, 2, 3, and 4) phosphors exhibited broad-band near-infrared (NIR) emission peaking at ?710 nm in the range 650?850 nm, and the optimum Cr3+ concentrations and concentration quenching mechanism were determined. Except for the interesting NIR emission, the body color changed from white (at x = 0) to green (at x = 0.08) for Bi2Ga4?xO9:xCr3+, and from light yellow (at x = 0) to deep brown (at x = 0.08) for Bi2Al4?xO9:xCr3+, respectively. Moreover, as a result of variable Al/Ga ratio, the observed body color for Bi2[Ga(4-y)Aly]3.97O9:0.03Cr3+ (y = 0, 1, 2, 3, and 4) varied from deep brown to green. The relationship between the observed colors and their diffuse reflectance spectra were also studied for the understanding of the different absorption bands. The results indicated that Cr3+-doped Bi2Ga(4-x)AlxO9 solid solutions appeared as the bifunctional materials with NIR phosphors and color-tunable pigments.
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10.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Guo Q., Liao L., Molokeev M. S., Mei L., Liu H.
Заглавие : Color tunable emission and energy transfer of Ce3+ and Tb3+ co-doped novel La6Sr4(SiO4)6F2 phosphors with apatite structure
Место публикации : Mater. Res. Bull.: Elsevier, 2015. - Vol. 72. - P.245-251. - ISSN 0025-5408, DOI 10.1016/j.materresbull.2015.07.029
Примечания : Cited References: 37. - This present work is supported by the National Natural Science Foundations of China (Grant No. 41172053).
Предметные рубрики: LIGHT-EMITTING-DIODES
LUMINESCENCE PROPERTIES
PHOTOLUMINESCENCE PROPERTIES
EU2+
LEDS
Ключевые слова (''Своб.индексиров.''): inorganic compounds--luminescence--phosphors--optical properties--crystal structure
Аннотация: Single-phase La6Sr4(SiO4)6F2: Ce3+, Tb3+ samples with apatite-like structure have been synthesized via solid-state reaction method. The phase structure, luminescence properties, lifetime, the PL thermal stability, as well as the fluorescence decay curves of the samples were investigated to characterize the resulting samples. Effective energy transfer occurs from Ce3+ to Tb3+ in La6Sr4(SiO4)6F2, which shows more intense Blue-Green light under UV light excitation. In addition, a possible mechanism of the energy-transfer from Ce3+ to Tb3+ ion is also proposed. The critical distance RC of Ce3+ to Tb3+ ions in La6Sr4(SiO4)6F2 host was calculated to be 11.878 Å. All the results indicate that La6Sr4(SiO4)6F2:Ce3+, Tb3+ phosphors have potential applications to be used as near UV-convertible phosphors for white light-emitting diodes. © 2015 Elsevier Ltd. All rights reserved.
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11.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Ji H., Wang L., Molokeev M. S., Hirosaki N., Xie R., Huang Z., Xia Z., Ten Kate O. M., Liu L., Atuchin V. V.
Заглавие : Structure evolution and photoluminescence of Lu3(Al,Mg)2(Al,Si)3O12:Ce3+ phosphors: New yellow-color converters for blue LED-driven solid state lighting
Место публикации : J. Mater. Chem. C: Royal Society of Chemistry, 2016. - Vol. 4, Is. 28. - P.6855-6863. - ISSN 20507534 (ISSN), DOI 10.1039/c6tc00966b
Примечания : Cited References: 44. - This work was partially supported by the National Natural Science Foundations of China (Grant No. 51511130035, 51272259, 61575182, 51561135015, and 51572232) and the Russian Foundation for Basic Research (Grant No. 15-52-53080). We are also grateful to financial support from the JSPS KAKENHI (No. 15K06448). H. J. thanks the China Scholarship Council (CSC) for scholarship support. V. V. A. was partially supported by the Ministry of Education and Science of the Russian Federation.
Предметные рубрики: WHITE LEDS
LUMINESCENCE PROPERTIES
EMITTING-DIODES
GARNET PHOSPHORS
SUBSTITUTION
Ce3+
PHASE
Ca
Аннотация: This paper reports the development of new phosphors using the chemical unit cosubstituting solid solution design strategy. Starting from Lu3Al5O12, the Al3+-Al3+ couple in respective octahedral and tetrahedral coordination was simultaneously substituted by a Mg2+-Si4+ pair forming the Lu3(Al2-xMgx)(Al3-xSix)O12:Ce3+ (x = 0.5-2.0) series; as a result, the CeO8 polyhedrons were compressed and the emission got red-shifted from green to yellow together with the broadening. The evolution of, the unit cell, the local structural geometry as well as the optical properties of Ce3+ in these garnet creations, in response to the gradual Mg-Si substitution for Al-Al, were studied by combined techniques of structural refinement and luminescence measurements. The new composition Lu2.97Ce0.03Mg0.5Al4Si0.5O12 was comprehensively evaluated regarding its potential application in blue LED-driven solid state white lighting: the maximum emission is at 550 nm under ?ex = 450 nm; the internal and external quantum efficiencies can reach 85% and 49%, respectively; a 1-phosphor-converted wLED lamp fabricated using the as-prepared phosphor exhibits the luminous efficacy of 105 lm W-1, the correlated color temperature of 6164 K and the color rendering index (Ra) of 75.6. The new solid solution composition series is open for further optimization to enhance the competence for commercial consideration. © 2016 The Royal Society of Chemistry.
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12.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Xia Y., Chen J., Liu Y.-G., Molokeev M. S., Guan M., Huang Z., Fang M.
Заглавие : Crystal structure evolution and luminescence properties of color tunable solid solution phosphors Ca2+xLa8-x(SiO4)6-x(PO4)xO2:Eu2+
Место публикации : Dalton Trans.: Royal Society of Chemistry, 2016. - Vol. 45, Is. 3. - P.1007-1015. - ISSN 14779226 (ISSN), DOI 10.1039/c5dt03786g
Примечания : Cited References: 42. - This work was sponsored by National Natural Science Foundation of China (Grant No. 51472223), the Program for New Century Excellent Talents in University of Ministry of Education of China (Grant No. NCET-12-0951) and the Fundamental Research Funds for the Central Universities (Grant No. 2652015020).
Предметные рубрики: LIGHT-EMITTING-DIODES
WHITE-LIGHT
ENERGY-TRANSFER
SILICATE GLASS
SINGLE-PHASE
EU2+
LEDS
PHOTOLUMINESCENCE
EMISSION
UV
Аннотация: A series of apatite solid solution phosphors Ca2+xLa8-x(SiO4)6-x(PO4)xO2:Eu2+ (x = 0,2,4,6) were synthesized by a conventional higherature solid-state reaction. The phase purity was examined using XRD, XPS and XRF. The crystal structure information, such as the concentration, cell parameters and occupation rate, was analyzed using a Rietveld refinement, demonstrating that the Eu2+ activated the Ca2La8(SiO4)6O2 and Ca8La2(PO4)6O2 to form continuous solid solution phosphors. Different behaviors of luminescence evolution in response to structural variation were verified among the series of phosphors. Two kinds of Eu2+ ion sites were proved using low temperature PL spectra (8k) and room temperature decay curves. The substitution of large La3+ ions by small Ca2+ ions induced a decreased crystal field splitting of the Eu2+ ions, which caused an increase in emission energy from the 5d excited state to the 4f ground state and a resultant blue-shift from 508 nm to 460 nm. Therefore, with the crystal structure evolution, the emitted color of the series of phosphors could be tuned from green to blue by adjusting the ratio of Ca/La. © 2016 The Royal Society of Chemistry.
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13.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Ma, Bin, Guo Q. F., Molokeev M. S., Lv, Zhenfei, Yao, Jun, Mei, Lefu, Huang, Zhaohui
Заглавие : Crystal structure and luminescence properties of green-emitting Sr1−xAl12O19:xEu2+ phosphors
Место публикации : Ceram. Int.: Elsevier Science, 2016. - Vol. 42, Is. 5. - P.5995-5999. - ISSN 0272-8842, DOI 10.1016/j.ceramint.2015.12.149. - ISSN 1873-3956(eISSN)
Примечания : Cited References: 30. - This work was supported by the National Natural Science Foundation of China (Grant nos. 51032007 and 51372232) and the Fundamental Research Funds for the Central Universities (Grant no. 2652015024).
Предметные рубрики: COLOR-TUNABLE PHOSPHOR
ENERGY-TRANSFER
Dy3+ PHOSPHORS
NEAR-UV
Eu2+
DIODES
PHASE
STATE
Ce3+
Ключевые слова (''Своб.индексиров.''): crystal structure--magnetoplumbite--phosphor
Аннотация: In this paper, a series of novel luminescent Sr1−xAl12O19:xEu2+ phosphors were synthesized by a high temperature solid-state reaction. The phase structure, photoluminescence (PL) properties, as well as the decay curves were investigated. The quenching concentration of Eu2+ in SrAl12O19 was about 0.15 (mol). Upon excitation at 378 nm, the composition-optimized Sr0.85Al12O19:0.15Eu2+ exhibited strong broad-band green emission at 530 nm with the CIE chromaticity (0.2917, 0.5736). The results indicate that Sr1−xAl12O19:xEu2+ phosphors have potential applications as green-emitting phosphors for UV-pumped white-light LEDs.
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14.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Wang X., Li J. -G., Molokeev M. S., Zhu Q., Li X., Sun X.
Заглавие : Layered hydroxyl sulfate: Controlled crystallization, structure analysis, and green derivation of multi-color luminescent (La,RE)2O2SO4 and (La,RE)2O2S phosphors (RE = Pr, Sm, Eu, Tb, and Dy)
Место публикации : Chem. Eng. J.: Elsevier, 2016. - Vol. 302. - P.577-586. - ISSN 13858947 (ISSN), DOI 10.1016/j.cej.2016.05.089
Примечания : Cited References: 50. - This work is supported in part by the National Natural Science Foundation of China (Grants Nos. 51172038, 51302032, and U1302272), the Fundamental Research Fund for the Central Universities (Grant No. N140204002), Grants-in-Aid for Scientific Research (KAKENHI No. 26420686), and the Russian Foundation for Basic Research (15-52-53080). X.J. Wang acknowledges financial support from the China Scholarship Council for her overseas Ph.D. study (Contract No. 201406080035) and the assistance of Q. Q. Zhu (University of Science and Technology of China) for his help with calcination.
Предметные рубрики: PHOTOLUMINESCENCE PROPERTIES
OXYSULFATE/OXYSULFIDE SYSTEMS
CRYSTAL-STRUCTURE
OXYGEN-STORAGE
Ln
NANOCOMPOSITES
EMISSION
CAPACITY
FAMILY
FABRICATION
Ключевые слова (''Своб.индексиров.''): sulfate type layered rare earth hydroxide--luminescence--oxysulfate--oxysulfide
Аннотация: The two important groups of Ln2O2SO4 and Ln2O2S compounds are traditionally synthesized with the involvements of environmentally harmful sulfur-containing reagents. We developed in this work a unique green approach for their synthesis, using Ln2(OH)4SO4·2H2O layered hydroxyl sulfate as the precursor (Ln-241 phase). Phase selective crystallization of La-241 under both atmospheric pressure and hydrothermal conditions was firstly optimized, followed by transformation into La2O2S and La2O2SO4 by controlled calcination. Rietveld structure refinement was performed for La-241, La(OH)SO4, La2O2SO4, and La2O2S, and the crystal structure and cell parameters of La-241 were originally reported. The photoluminescence performances of several important activators (Pr3+, Sm3+, Eu3+, Tb3+, and Dy3+) in the two hosts, in terms of excitation, emission, quantum yield, and color coordinates of emission, were thoroughly investigated, and multi-color luminescence including bright red, green, orange red, and yellow was obtained under ultraviolet excitation. Detailed investigations of Tb3+ photoluminescence revealed that the lack of 5D3 emission in La2O2S and the gradual quenching of 5D3 blue emission at a higher Tb3+ content (hence decreasing I488/I545 ratio and changing color coordinates) in La2O2SO4 were suggested to be due to thermal activation of the 5D3 electrons into the conduction band and cross relaxation between adjacent Tb3+, respectively. The synthesis approach developed in this work for La2O2SO4 and La2O2S, with water vapor as the only exhaust gas, is environmentally benign and holds great potential in the facile synthesis of analogous compounds of other lanthanides. © 2016 Elsevier B.V.
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15.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Chen M., Xia Z., Molokeev M. S., Lin C. C., Su C., Chuang Y. -C., Liu Q.
Заглавие : Probing Eu2+ luminescence from different crystallographic sites in Ca10M(PO4)7:Eu2+ (M = Li, Na, and K) with β-Ca3(PO4)2-type structure
Место публикации : Chem. Mater.: American Chemical Society, 2017. - Vol. 29, Is. 17. - P.7563-7570. - ISSN 08974756 (ISSN), DOI 10.1021/acs.chemmater.7b02724
Примечания : Cited References: 34. - The present work was supported by the National Natural Science Foundation of China (Grants 51722202, 91622125, and 51572023), Natural Science Foundations of Beijing (2172036), and Fundamental Research Funds for the Central Universities (FRF-TP-16-002A3). C.C.L. and C.C.S. acknowledge the financial support from the Ministry of Science and Technology of Taiwan (Contract No. MOST 104-2113-M-027-007-MY3), and M. Molokeev acknowledges support of the Russian Foundation for Basic Research (17-52-53031).
Ключевые слова (''Своб.индексиров.''): calcium--doping (additives)--excited states--light emission--lithium--luminescence--phosphors--photoluminescence--positive ions--rietveld refinement--single crystals--color tuning--crystallographic sites--different distributions--emission bands--local environments--long wavelength bands--luminescent centers--power diffraction data--europium
Аннотация: Eu2+ local environments in various crystallographic sites enable the different distributions of the emission and excitation energies and then realize the photoluminescence tuning of the Eu2+ doped solid state phosphors. Herein we report the Eu2+-doped Ca10M(PO4)7 (M = Li, Na, and K) phosphors with β-Ca3(PO4)2-type structure, in which there are five cation crystallographic sites, and the phosphors show a color tuning from bluish-violet to blue and yellow with the variation of M ions. The difference in decay rate monitored at selected wavelengths is related to multiple luminescent centers in Ca10M(PO4)7:Eu2+, and the occupied rates of Eu2+ in Ca(1), Ca(2), Ca(3), Na(4), and Ca(5) sites from Rietveld refinements using synchrotron power diffraction data confirm that Eu2+ enters into four cation sites except for Ca(5). Since the average bond lengths d(Ca-O) remain invariable in the Ca10M(PO4)7:Eu2+, the drastic changes of bond lengths d(M-O) and Eu2+ emission depending on the variation from Li to Na and K can provide insight into the distribution of Eu2+ ions. It is found that the emission band at 410 nm is ascribed to the occupation of Eu2+ in the Ca(1), Ca(2), and Ca(3) sites with similar local environments, while the long-wavelength band (466 or 511 nm) is attributed to Eu2+ at the M(4) site (M = Na and K). We show that the crystal-site engineering approach discussed herein can be applied to probe the luminescence of the dopants and provide a new method for photoluminescence tuning.
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16.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Zhang Y., Liu H., Mei L., Molokeev M. S., Wang Y., Huang Z.
Заглавие : Structure and color-tunable luminescence properties of Ce3+ and Tb3+-activated Mg2La8(SiO4)6O2 phosphors based on energy transfer behavior
Место публикации : J. Solid State Chem. - 2017. - Vol. 255. - P.36-41. - ISSN 00224596 (ISSN), DOI 10.1016/j.jssc.2017.07.026
Примечания : Cited References: 45. - This present work was supported by the National Natural Science Foundations of China (Grant no. 41172053), the Fundamental Research Funds for the Central Universities (Grant nos. 2652016083 and 2652016037), and Science and Technology Innovation Fund of the China University of Geosciences (Beijing).
Ключевые слова (''Своб.индексиров.''): crystal structure--luminescence properties--phosphors--apatite structure
Аннотация: A series of novel luminescent emission-tunable phosphors Mg2La8(SiO4)6O2:Ce3+,Tb3+ (MLS:Ce3+,Tb3+) have been prepared by a solid-state reaction. The phase formation was firstly confirmed through X-ray diffraction technique and refined by the Rietveld method. The MLS:Ce3+,Tb3+ phosphors, which crystallized in apatite-type hexagonal phase, exhibited a broad excitation band ranging from 200 to 400 nm and several emission bands centered at 426 nm and 551 nm. Energy transfer from Ce3+ to Tb3+ ions via a dipole-dipole mechanism occurred in the as-synthesized phosphors upon ultraviolet (UV) excitation. The energy transfer efficiency increases with increasing doping content of Tb3+ ions, which was confirmed by the luminescence spectra and fluorescence decay curves of corresponding ions simultaneously. The energy transfer critical distance was calculated and evaluated by both the concentration quenching and spectral overlap methods. The chromaticity of emission-tunable phosphors was also characterized by the Commission International de l'eclairage (CIE) chromaticity indexes, and the color tone can be tuned from blue (0.179, 0.122) to green (0.267, 0.408) by controlling the ratio of Ce3+/Tb3+. © 2017 Elsevier Inc.
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17.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Zhao M., Xia Z., Molokeev M. S., Ning L., Liu Q.
Заглавие : Temperature and Eu2+-doping induced phase selection in NaAlSiO4 polymorphs and the controlled yellow/blue emission
Место публикации : Chem. Mater.: American Chemical Society, 2017. - Vol. 29, Is. 15. - P.6552-6559. - ISSN 08974756 (ISSN), DOI 10.1021/acs.chemmater.7b02548
Примечания : Cited References: 48. - The present work was supported by the National Natural Science Foundation of China (Grants 91622125 and 51572023 and 11574003), Natural Science Foundations of Beijing (2172036), and Fundamental Research Funds for the Central Universities (FRF-TP-16-002A3). L.N. acknowledges the support from the Special and Excellent Research Fund of Anhui Normal University.
Ключевые слова (''Своб.индексиров.''): chemical modification--coordination reactions--europium--light emitting diodes--photoluminescence--functional properties--high color rendering index--local coordination structures--near ultraviolet excitations--structural transformation--synthesis temperatures--temperature dependent--white light emitting diodes--density functional theory
Аннотация: The union of temperature-dependent phase transition and relating structural transformation via modification of chemical compositions is of fundamental importance for the discovery of new materials or their functional properties optimization. Herein, the synthesis temperature and Eu2+-doping content induced phase selection and variations of the local structures in nepheline, low-carnegieite and high-carnegieite types of NaAlSiO4 polymorphs were studied in detail. The luminescence of Eu2+ in low-carnegieite and nepheline phases shows blue (460 nm) and yellow (540 nm) broad-band emissions, respectively, under near-ultraviolet excitation. The photoluminescence evolution can be triggered by the different synthesis temperatures in relation to the Eu2+-doping concentration, as corroborated by density functional theory calculations on the local coordination structures and corresponding mechanical stabilities in terms of the Debye temperature. The fabricated white light-emitting diode device with high color rendering index demonstrates that the multicolor phosphors from one system provides a new gateway for the photoluminescence tuning. © 2017 American Chemical Society.
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18.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Liao, Hongxu, Zhao, Ming, Molokeev M. S., Liu, Quanlin, Xia, Zhiguo
Заглавие : Learning from a mineral structure toward an ultra-narrow-band blue-emitting silicate phosphor RbNa3(Li3SiO4)4:Eu2+
Место публикации : Angew. Chem. - Int. Edit. - 2018. - Vol. 57, Is. 36. - P.11728-11731. - ISSN 1433-7851, DOI 10.1002/anie.201807087. - ISSN 1521-3773(eISSN)
Примечания : Cited References: 22. - This work was supported by the National Natural Science Foundations of China (Grant Nos. 51722202, 91622125 and 51572023), and Natural Science Foundations of Beijing (2172036), and M.S.M. acknowledges support of the Russian Foundation for Basic Research (17-52-53031).
Предметные рубрики: RED PHOSPHORS
COLOR-GAMUT
LUMINESCENCE
Ключевые слова (''Своб.индексиров.''): luminescence--minerals--phosphors--rigid structure--silicates
Аннотация: Learning from natural mineral structures is an efficient way to develop potential host lattices for applications in phosphor converted (pc)LEDs. A narrow‐band blue‐emitting silicate phosphor, RbNa3(Li3SiO4)4:Eu2+ (RNLSO:Eu2+), was derived from the UCr4C4‐type mineral model. The broad excitation spectrum (320–440 nm) indicates this phosphor can be well matched with the near ultraviolet (n‐UV) LED chip. Owing to the UCr4C4‐type highly condensed and rigid framework, RNLSO:Eu2+ exhibits an extremely small Stokes shift and an unprecedented ultra‐narrow (full‐width at half‐maximum, FWHM=22.4 nm) blue emission band (λem=471 nm) as well as excellent thermal stability (96 %@150 °C of the initial integrated intensity at 25 °C). The color gamut of the as‐fabricated (pc)LEDs is 75 % NTSC for the application in liquid crystal displays from the prototype design of an n‐UV LED chip and the narrow‐band RNLSO:Eu2+ (blue), β‐SiAlON:Eu2+ (green), and K2SiF6:Mn4+ (red) components as RGB emitters.
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19.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Deng J., Zhang H., Zhang X., Molokeev M. S., Qiu J., Liu Y., Lei B., Ma L., Wang X.
Заглавие : Enhanced luminescence performance of CaO:Ce3+,Li+,F- phosphor and its phosphor-in-glass based high-power warm LED properties
Место публикации : J. Mater. Chem. C. - 2018. - Vol. 6, Is. 15. - P.4077-4086. - ISSN 20507534 (ISSN), DOI 10.1039/c8tc00813b
Примечания : Cited References: 44. - The present study was supported by the National Natural Science Foundation of China (Grant No. 21671070), the Project for Construction of High-level University in Guangdong Province, the Teamwork Projects funded by the Guangdong Natural Science Foundation (Grant No. S2013030012842), the Guangzhou Science & Technology Project (No. 201704030086) and the Open Project Fund from Key Laboratory of Advanced of Materials of Yunnan Province (No. 2018KF01).
Ключевые слова (''Своб.индексиров.''): correlated color temperature--critical concentration--doping concentration--enhanced luminescence--high color rendering index--high power white led--high temperature solid-state reaction--thermal and chemical stabilities
Аннотация: To obtain white light-emitted diodes (wLEDs) with a low correlated color temperature (CCT) and a high color rendering index (CRI), red-emission is indispensable in their emission spectra. Herein, CaO:Ce3+,Li+,F- yellow phosphors with more red spectral component have been prepared via a high temperature solid-state reaction. As compared to the F- undoped samples, CaO:Ce3+,Li+,F- phosphor have lower critical doping concentration of Ce3+ and show stronger luminescence. At the critical concentration, a quantum efficiency of 66.4% and enhanced thermal and chemical stability were obtained in CaO:Ce3+,Li+,F-. Furthermore, a CaO:Ce3+,Li+,F--based phosphor-in-glass (PiG) using the red-emitting glass system with the composition of SiO2-Na2CO3-Al2O3-CaO:Eu3+ as the host material was constructed and used for high-power white LED applications. Such PiG samples with different phosphor doping concentrations can satisfy various light color demands and display higher reliability than the CaO:Ce3+,Li+,F- phosphor. An optimal PiG-based wLED exhibits color coordinates of (0.3769, 0.3386), a CCT of 3774 K, a CRI of 82.5 and a LE of 73.1 when the mass ratio of phosphor to glass matrix was 7:50 in PiG. Moreover, such PiG-based wLED also showed acceptable color stability under different drive currents. All the above results demonstrate that CaO:Ce3+,Li+,F- can be expected to be a potential alternative yellow phosphor for blue light excited PiG based warm wLEDs, particularly for high-power devices.
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20.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Liao H., Zhao M., Zhou Y., Molokeev M. S., Liu Q., Zhang Q., Xia Z.
Заглавие : Polyhedron Transformation toward Stable Narrow-Band Green Phosphors for Wide-Color-Gamut Liquid Crystal Display
Место публикации : Adv. Funct. Mater. - 2019. - Vol. 29, Is. 30. - Ст.1901988. - ISSN 1616301X (ISSN) , DOI 10.1002/adfm.201901988
Примечания : Cited References: 34. - The present work was supported by the National Natural Science Foundations of China (Grant Nos. 51722202, 91622125, and 51572023), Natural Science Foundations of Beijing (2172036), Fundamental Research Funds for the Central Universities (FRF‐TP‐18‐002C1), and the Guangdong Provincial Science & Technology Project (No. 2018A050506004).
Аннотация: A robust and stable narrow-band green emitter is recognized as a key enabler for wide-color-gamut liquid crystal display (LCD) backlights. Herein, an emerging rare earth silicate phosphor, RbNa(Li3SiO4)2:Eu2+ (RN:Eu2+) with exceptional optical properties and excellent thermal stability, is reported. The resulting RN:Eu2+ phosphor presents a narrow green emission band centered at 523 nm with a full width at half maximum of 41 nm and excellent thermal stability (102%@425 K of the integrated emission intensity at 300 K). RN:Eu2+ also shows a high quantum efficiency, an improved chemical stability, and a reduced Stokes shift owing to the modified local environment, in which [NaO8] cubes replace [LiO4] squares in RbLi(Li3SiO4)2:Eu2+ via polyhedron transformation. White light-emitting diode (wLED) devices with a wide color gamut (113% National Television System Committee (NTSC)) and high luminous efficacy (111.08 lm W−1) are obtained by combining RN:Eu2+ as the green emitter, K2SiF6:Mn4+ as the red emitter, and blue-emitting InGaN chips. Using these wLEDs as backlights, a prototype 20.5 in. LCD screen is fabricated, demonstrating the bright future of stable RN:Eu2+ for wide-color-gamut LCD backlight application.
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