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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Liu, Chengyin, Xia, Zhiguo, Molokeev M. S., Liu, Quanlin
Заглавие : Synthesis, crystal structure, and enhanced luminescence of garnet-type Ca3Ga2Ge3O12:Cr3+ by codoping Bi3+
Место публикации : J. Am. Ceram. Soc.: Wiley-Blackwell, 2015. - Vol. 98, Is. 6. - P.1870-1876. - ISSN 0002, DOI 10.1111/jace.13553. - ISSN 15512916(eISSN)
Примечания : Cited References:24. - This work was supported by the National Natural Science Foundations of China (grant nos. 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: LIGHT-EMITTING-DIODES
INFRARED PERSISTENT LUMINESCENCE
ENERGY-TRANSFER
PHOSPHOR
RED
NANOPARTICLES
EFFICIENCY
Аннотация: Garnet-type compound Ca3Ga2Ge3O12 and Cr3+-doped or Cr3+/Bi3+ codped Ca3Ga2Ge3O12 phosphors were prepared by a solid-state reaction. The crystal structure of Ca3Ga2Ge3O12 host was studied by X-ray diffraction (XRD) analysis and further determined by the Rietveld refinement. Near-infrared (NIR) photoluminescence (PL) and long-lasting phosphorescence (LLP) emission can be observed from the Cr3+-doped Ca3Ga2Ge3O12 sample, and the enhanced NIR PL emission intensity and LLP decay time can be realized in Cr3+/Bi3+ codped samples. The optimum concentration of Cr3+ in Ca3Ga2Ge3O12 phosphor was about 6 mol%, and optimum Bi3+ concentration induced the energy-transfer (ET) process between Bi3+ and Cr3+ ions was about 30 mol%. Under different excitation wavelength from 280 to 453 nm, all the samples exhibit a broadband emission peaking at 739 nm and the intensity of NIR emission increases owing to the ET behavior from Bi3+ to Cr3+ ions. The critical ET distance has been calculated by the concentration-quenching method. The thermally stable luminescence properties were also studied and the introduction of Bi3+ can also improve the thermal stability of the NIR emission.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Atuchin V. V., Yelisseyev A. P., Galashov E. N., Molokeev M. S.
Заглавие : Synthesis and luminescence properties of Li2O–Y2O3–TeO2:Eu3+ tellurite glass
Коллективы : Ministry of Education and Science of the Russian Federation
Место публикации : Mater. Chem. Phys.: Elsevier Science, 2014. - Vol. 147, Is. 3. - P.1191-1194. - ISSN 0254-0584, DOI 10.1016/j.matchemphys.2014.07.003. - ISSN 1879-3312
Примечания : Cited References: 26. - This study is partly supported by the Ministry of Education and Science of the Russian Federation.
Предметные рубрики: LIGHT-EMITTING-DIODES
SPECTROSCOPIC PROPERTIES
OPTICAL-PROPERTIES
ENERGY-TRANSFER
CERAMICS
Eu3+
PHOTOLUMINESCENCE
TEMPERATURE
EMISSION
PHOSPHOR
Ключевые слова (''Своб.индексиров.''): glasses--heat treatment--photoluminescence spectroscopy--optical properties
Аннотация: The Eu3+-doped red-orange emitting phosphor of tellurite glass 0.25Li2O–0.20Y2O3–0.5TeO2–0.05Eu2O3 has been synthesized by the melt quenching method. The amorphous nature of the glass has been verified by XRD measurements. The photoluminescence excitation and emission spectra, the luminescence decay curves have been investigated for the composition. The phosphor can be efficiently excited by the near UV light to realize the intense narrow red emission line (611 nm) corresponding to forced electric dipole transition 5D0 → 7F2 of Eu3+ ions. The Li2O–Y2O3–TeO2:Eu3+glass phosphor is a potential red-orange emitting candidate for the application in WLEDs.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Chen M., Xia Z., Molokeev M. S., Liu Q.
Заглавие : Structural phase transformation and luminescent properties of Ca2-xSrxSiO4:Ce3+ orthosilicate phosphors
Место публикации : Inorg. Chem.: American Chemical Society, 2015. - Vol. 54, Is. 23. - P.11369-11376. - ISSN 00201669 (ISSN), DOI 10.1021/acs.inorgchem.5b01955
Примечания : Cited References: 38. - The present work was supported by the National Natural Science Foundations of China (Grant Nos. 51572023, 51272242, and 51511130035), Natural Science Foundations of Beijing (2132050), the Program for New Century Excellent Talents in Univ. of 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 Rare Earth Resource Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences (RERU2015022)
Предметные рубрики: LIGHT-EMITTING-DIODES
DICALCIUM SILICATE
CRYSTAL-STRUCTURE
SOLID-SOLUTION
BOND-VALENCE
Ce3+
Eu2+
β-Ca2SiO4
GREEN
TEMPERATURE
Аннотация: The orthosilicate phosphors demonstrate great potential in the field of solid-state lighting, and the understanding of the structure-property relationships depending on their versatile polymorphs and chemical compositions is highly desirable. Here we report the structural phase transformation of Ca2-xSrxSiO4:Ce3+ phosphor by Sr2+ substituting for Ca2+ within 0 ≤ x 2. The crystal structures of Ca2-xSrxSiO4:Ce3+ are divided into two groups, namely, β phase (0 ≤ x 0.15) and α′ phase (0.18 ≤ x 2), and the phase transition (β → α′) mechanism originated from the controlled chemical compositions is revealed. Our findings verified that the phase transition Pnma (α′-phase) ↔ P21/n (β-phase) can be ascribed to the second-order type, and Sr2+ ions in Ca2-xSrxSiO4 preferentially occupy the seven-coordinated Ca2+ sites rather than the eight-coordinated sites with increasing Sr2+ content, which was reflected from the Rietveld refinements and further clarified through the difference of the Ca-O bond length in the two polymorphs of Ca2SiO4. The emission peaks of Ce3+ shift from 417 to 433 nm in the composition range of 0 ≤ x ≤ 0.8, and the difference in the decay curves can also verify the phase transformation process. Thermal quenching properties of selected Ca2-xSrxSiO4:Ce3+ samples were evaluated, and the results show that the integral emission intensities at 200 °C maintain 90% of that at room temperature suggesting superior properties for the application as white light-emitting diodes (w-LEDs) phosphors. © 2015 American Chemical Society.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Atuchin V. V., Beisel N. F., Galashov E. N., Mandrik E. M., Molokeev M. S., Yelisseyev A. P., Yusuf A. A., Xia Z.
Заглавие : Pressure-stimulated synthesis and luminescence properties of microcrystalline (Lu,Y)3Al5O12:Ce3+ garnet phosphors
Место публикации : ACS Appl. Mater. Interfaces: American Chemical Society, 2015. - Vol. 7, Is. 47. - P.26235-26243. - ISSN 19448244 (ISSN), DOI 10.1021/acsami.5b08411
Примечания : Cited References: 75. - This work was partly supported by the National Natural Science Foundations of China (Grant Nos. 51272242 and 51511130035) and the Russian Foundation for Basic Research (Grant No. 15-52-53080 GFEN_a). V.V.A. was partly supported by the Ministry of Education and Science of the Russian Federation
Предметные рубрики: LASER MASS-SPECTROMETRY
LIGHT-EMITTING-DIODES
WHITE-LIGHT
SINGLE-CRYSTALS
OPTICAL-PROPERTIES
ELECTRONIC-STRUCTURE
VIBRATIONAL PROPERTIES
PHASE-TRANSITIONS
PARTICLE-SIZE
GROWTH
Ключевые слова (''Своб.индексиров.''): synthesis--pressure--garnet--structure--luminescence--phosphor
Аннотация: The Lu2.98Ce0.01Y0.01Al5O12 and Y2.99Ce0.01Al5O12 phosphors were synthesized by solid state reaction at temperature 1623 K and pressure 1.5 × 107 Pa in (95% N2 + 5% H2) atmosphere. Under the conditions, the compounds crystallize in the form of isolated euhedral partly faceted microcrystals ∼19 μm in size. The crystal structures of the Lu2.98Ce0.01Y0.01Al5O12 and Y2.99Ce0.01Al5O12 garnets have been obtained by Rietveld analysis. The photoluminescence (PL) and X-ray excited luminescence (XL) spectra obtained at room temperature indicate broad asymmetric bands with maxima near 519 and 540 nm for Y2.99Ce0.01Al5O12 and Lu2.98Ce0.01Y0.01Al5O12, respectively. The light source was fabricated using the powder Lu2.98Ce0.01Y0.01Al5O12 phosphor and commercial blue-emitting n-UV LED chips (λex = 450 nm). It is found that the CIE chromaticity coordinates are (x = 0.388, y = 0.563) with the warm white light emission correlated color temperature (CCT) of 6400 K and good luminous efficiency of 110 lm/W. © 2015 American Chemical Society.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Li G., Lin C. C., Chen W.-T., Molokeev M. S., Atuchin V. V., Chiang C.-Y., Zhou W., Wang C.-W., Li W.-H., Sheu H.-S., Chan T.-S., Ma C., Liu R.-S.
Заглавие : Photoluminescence tuning via cation substitution in oxonitridosilicate phosphors: DFT calculations, different site occupations, and luminescence mechanisms
Место публикации : Chem. Mater.: American Chemical Society, 2014. - Vol. 26, Is. 9. - P.2991-3001. - ISSN 0897-4756, DOI 10.1021/cm500844v. - ISSN 1520-5002
Примечания : Cited References: 62. - The authors would like to thank the Ministry of Science and Technology of Taiwan (Contract No. MOST 101-2113-M-002-014-MY3), the National Synchrotron Radiation Research Center, Taiwan, the National Natural Science Foundation of China (Grant No. NSFC 21301162), and the Fundamental Research Funds for the Central Universities (Grant No. CUG 130402) for financially supporting this research. Victor V. Atuchin gratefully acknowledges the Ministry of Education and Science of the Russian Federation for the financial support.
Предметные рубрики: LIGHT-EMITTING-DIODES
HIGH-TEMPERATURE SYNTHESIS
LED CONVERSION PHOSPHORS
CRYSTAL X-RAY
WHITE-LIGHT
ORDERED DISTRIBUTION
GREEN PHOSPHOR
LAYERED OXONITRIDOSILICATE
REAL STRUCTURE
AB-INITIO
Аннотация: Tuning and optimizing luminescent properties of oxonitridosilicates phosphors are important for white light-emitting diode (WLED) applications. To improve the color rendering index, correlated color temperature and thermal stability of layer-structured MSi2O2N2:Eu (M = Sr, Ba) phosphors, cation substitutions have been used to adjust their luminescent properties. However, the underlying mechanisms are still unclear. In this research, a series of (Sr1-xBax)Si2O2N2:Eu (0 ≤ x ≤ 1) compounds were prepared by solid-state reaction, after which systematic emission variations were investigated. The crystal structures of (Sr1-xBax)Si2O2N2:Eu (0 ≤ x ≤ 1) are nominally divided into three sections, namely, Phase 1 (0 ≤ x ≤ 0.65), Phase 2 (0.65 x 0.80), and Phase 3 (0.80 ≤ x ≤ 1) based on the X-ray diffraction measurements. These experimental results are further confirmed by optimizing the crystal structure data with first-principle calculations. Continuous luminescence adjustments from green to yellow are observed in Phase 1 with gradual replacement of Sr2+ with Ba2+, and the abnormal redshift is clarified through extended X-ray absorption fine structure analysis. Sr(Eu)-O/N bond length shrinkage in local structure causes the redshift emission, and the corresponding luminescence mechanism is proposed. Controllable luminescence in Phase 2 (from blue to white) and Phase 3 (from cyan to yellowish green) are observed. Based on the high-resolution transmission electron microscopy and selected area electron diffraction analysis, the two kinds of luminescence tuning are attributed to phase segregation. This study serves as a guide in developing oxonitride luminescent materials with controllable optical properties based on variations in local coordination environments through cation substitutions.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Chen M., Xia Z., Molokeev M. S., Liu Q.
Заглавие : Morphology and phase transformation from NaCaSiO3OH to Na2Ca2Si2O7 and photoluminescence evolution: Via Eu3+/Tb3+ doping
Место публикации : Chem. Commun.: Royal Society of Chemistry, 2016. - Vol. 52, Is. 75. - P.11292-11295. - ISSN 13597345 (ISSN), DOI 10.1039/c6cc06375f
Примечания : Cited References: 26. - The present work was supported by the National Natural Science Foundation of China (Grant No. 51572023 and 51272242), the Fundamental Research Funds for the Central Universities (FRF-TP-15-003A2) and the Russian Foundation for Basic Research (Grant No. 15-52-53080 GFEN_a).
Предметные рубрики: LIGHT-EMITTING-DIODES
ENERGY-TRANSFER
SPECTROSCOPIC PROPERTIES
PHOSPHORS
LUMINESCENCE
Аннотация: A facile and controllable ethanol/water aided hydrothermal process was developed to prepare the NaCaSiO3OH:Tb3+/Eu3+ phosphor. The morphologies were in situ constructed with the phase transformation from NaCaSiO3OH to Na2Ca2Si2O7, and the intrinsic crystal structural transformation mechanism and the dependence of their photoluminescence tuning on the Tb3+/Eu3+ ratio have been discussed. © 2016 The Royal Society of Chemistry.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Chen M., Xia Z., Molokeev M. S., Liu Q.
Заглавие : Insights into Ba4Si6O16 structure and photoluminescence tuning of Ba4Si6O16:Ce3+,Eu2+ phosphors
Место публикации : J. Mater. Chem. C: Royal Society of Chemistry, 2015. - Vol. 3, Is. 48. - P.12477-12483. - ISSN 20507534 (ISSN), DOI 10.1039/c5tc03271g
Примечания : Cited References: 39. - This work was supported by the National Natural Science Foundations of China (Grant No. 51572023 and 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), 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: LIGHT-EMITTING-DIODES
ENERGY-TRANSFER
LUMINESCENCE PROPERTIES
WHITE-LIGHT
GLASS-CERAMICS
BA PHOSPHORS
EMISSION
GREEN
EU2+
FLUORESCENCE
Аннотация: The versatile polymorphism and chemical compositions of barium silicates have been studied for a long time and their crystal structures have been established. Herein, we focused on the understanding of the crystal structure of the Ba4Si6O16 phase and the structural correlation of Ba4Si6O16 and Ba2Si3O8; moreover, the luminescence properties of Ce3+,Eu2+-co-activated Ba4Si6O16 phosphors have been discussed. Ba4Si6O16:Ce3+,Eu2+ phosphors show tunable blue-green emission upon excitation with 365 nm ultraviolet (UV) light. The blue emission originates from Ce3+, whereas the bluish-green emission is ascribed to Eu2+, and variation in the emission peak wavelength from 442 to 497 nm can be achieved by properly tuning the Ce3+/Eu2+ ratio. Energy transfer from Ce3+ to Eu2+ in the Ba4Si6O16 host has been validated by the variation of emission spectra as well as the variation of Ce3+ decay lifetimes with increasing Eu2+ concentration, and the energy transfer mechanism is demonstrated to be a resonant type via a dipole-dipole process. The results suggest that Ba4Si6O16:Ce3+,Eu2+ phosphors are potential candidates as a blue-green component for UV-excited white light-emitting diodes. © 2015 The Royal Society of Chemistry.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Qiao, Jianwei, Ning, Lixin, Molokeev M. S., Chuang, Yu-Chun, Liu, Quanlin, Xia, Zhiguo
Заглавие : Eu2+ site preferences in the mixed cation K2BaCa(PO4)2 and thermally stable luminescence
Место публикации : J. Am. Chem. Soc. - 2018. - Vol. 140, Is. 30. - P.9730-9736. - ISSN 0002-7863, DOI 10.1021/jacs.8b06021
Примечания : Cited References: 40. - This work is supported by the National Natural Science Foundation of China (No. 51722202, 91622125, 51572023, and 11574003), Natural Science Foundations of Beijing (2172036) and M.M. acknowledges support of the Russian Foundation for Basic Research (17-52-53031).
Предметные рубрики: LIGHT-EMITTING-DIODES
SOLID-SOLUTION
PHOSPHORS
GREEN
BLUE
Аннотация: Site preferences of dopant Eu2+ on the locations of K+, Ba2+, and Ca2+ in the mixed cation phosphate K2BaCa(PO4)2 (KBCP) are quantitatively analyzed via a combined experimental and theoretical method to develop a blue-emitting phosphor with thermally stable luminescence. Eu2+ ions are located at K2 (M2) and K3 (M3) sites of KBCP, with the latter occupation relatively more stable than the former, corresponding to emissions at 438 and 465 nm, respectively. KBCP:Eu2+ phosphor exhibits highly thermal stable luminescence even up to 200 °C, which is interpreted as due to a balance between thermal ionization and recombination of Eu2+ 5d excited-state centers with the involvement of electrons trapped at crystal defect levels. Our results can initiate more exploration of activator site engineering in phosphors and therefore allow predictive control of photoluminescence tuning and thermally stable luminescence for emerging applications in white LEDs.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Altunin R. R., Moiseenko E. T., Zharkov S. M.
Заглавие : Effect of the structural properties on the electrical resistivity of the Al/Ag thin films during the solid-state reaction
Коллективы : Russian Science FoundationRussian Science Foundation (RSF) [18-13-00080]
Место публикации : Phys. Solid State. - 2020. - Vol. 62, Is. 4. - P.708-713. - ISSN 1063-7834, DOI 10.1134/S1063783420040034. - ISSN 1090-6460(eISSN)
Примечания : Cited References: 43. - This study was supported by the Russian Science Foundation, project no. 18-13-00080.
Предметные рубрики: LIGHT-EMITTING-DIODES
PHASE-FORMATION
AG
AL
DIFFUSION
SUPPRESSION
INTERFACE
SURFACE
GROWTH
HEAT
Аннотация: Based on the results of in situ electron diffraction study of the solid-state reaction and electrical resistivity measurements on the Al/Ag thin films with an atomic ratio of Al : Ag = 1 : 3, the temperature of the reaction onset has been established and a model of the structural phase transitions has been proposed. The solid-state reaction begins at 70°C with the formation of the Al–Ag solid solution at the interface between the aluminum and silver nanolayers. It has been found that, in the course of the reaction, the intermetallic compounds γ-Ag2Al → μ-Ag3Al are successively formed. It is shown that the possibility of the formation of the μ‑Ag3Al phase during the solid-state reaction in the Al/Ag thin films depends on the aluminum-to-silver ratio, while the formation of the μ-Ag3Al phase begins only after all fcc aluminum has reacted.
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10.

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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11.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Ji, Haipeng, Huang, Zhaohui, Xia, Zhiguo, Molokeev M. S., Atuchin V. V., Fang, Minghao, Liu, Yangai
Заглавие : Discovery of new solid solution phosphors via cation substitution-dependent phase transition in M-3(PO4)2:Eu2+ (M =Ca/Sr/Ba) quasi-binary sets
Место публикации : J. Phys. Chem. C: American Chemical Society, 2015. - Vol. 119, Is. 4. - P.2038-2045. - ISSN 1932-7447, DOI 10.1021/jp509743r
Примечания : Cited References:48. - This work was supported by the National Natural Science Foundations ofChina (Grant Nos. 51032007, 51002146, and 51272242), the Research Fundfor 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 Ministryof Education of China (NCET-12-0950), the Beijing Nova Program(Z131103000413047), and Beijing Youth Excellent Talent Program(YETP0635). V.V.A. acknowledges the Ministry of Education and Science ofthe Russian Federation for financial support.
Предметные рубрики: LIGHT-EMITTING-DIODES
LUMINESCENCE PROPERTIES
ENERGY-TRANSFER
Аннотация: The cation substitution-dependent phase transition was used as a strategy to discover new solid solution phosphors and to efficiently tune the luminescence property of divalent europium (Eu2+) in the M3(PO4)2:Eu2+ (M = Ca/Sr/Ba) quasi-binary sets. Several new phosphors including the greenish-white SrCa2(PO4)2:Eu2+, the yellow Sr2Ca(PO4)2:Eu2+, and the cyan Ba2Ca(PO4)2:Eu2+ were reported, and the drastic red shift of the emission toward the phase transition point was discussed. Different behavior of luminescence evolution in response to structural variation was verified among the three M3(PO4)2:Eu2+ joins. Sr3(PO4)2 and Ba3(PO4)2 form a continuous isostructural solid solution set in which Eu2+ exhibits a similar symmetric narrow-band blue emission centered at 416 nm, whereas Sr2+ substituting Ca2+ in Ca3(PO4)2 induces a composition-dependent phase transition and the peaking emission gets red shifted to 527 nm approaching the phase transition point. In the Ca3?xBax(PO4)2:Eu2+ set, the validity of crystallochemical design of phosphor between the phase transition boundary was further verified. This cation substitution strategy may assist in developing new phosphors with controllably tuned optical properties based on the phase transition.
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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) : Guo Q. F., Ma B., Liao L. B., Molokeev M. S., Mei L. F., Liu H. K.
Заглавие : Crystal structure and luminescence properties of novel Sr10−x(SiO4)3(SO4)3O:xEu2+ phosphor with apatite structure
Место публикации : Ceram. Int.: Elsevier Science, 2016. - Vol. 42, Is. 10. - P.11687-11691. - ISSN 0272-8842, DOI 10.1016/j.ceramint.2016.04.086. - ISSN 1873-3956(eISSN)
Примечания : Cited References:26. - This present work is supported by the National Natural Science Foundation of China (Grant no. 41172053).
Предметные рубрики: Light-Emitting-Diodes
Energy-transfer
Tunable phosphor
LEDs
Eu-2+
Ions
Ce3+
Ключевые слова (''Своб.индексиров.''): crystal structure--apatite--phosphor
Аннотация: In this paper, a series of novel luminescent Sr10−x(SiO4)3(SO4)3O:xEu2+ phosphors with apatite structure were synthesized by a high temperature solid-state reaction. The phase structure, photoluminescence (PL) properties, as well as the PL thermal stability were investigated. Sr9.92(SiO4)3(SO4)3O:0.08Eu2+ phosphor exhibits better thermal quenching resistance, retaining the luminance of 66.55% at 150 °C compared with that at 25 °C. The quenching concentration of Eu2+ in Sr10(SiO4)3(SO4)3O was about 0.08 (mol) with the dipole–quadrupole interaction. The Sr10−x(SiO4)3(SO4)3O:xEu2+ phosphors exhibited a broad-band green emission at 538 nm upon excitation at 396 nm. The results indicate that Sr10−x(SiO4)3(SO4)3O:xEu2+ phosphors have potential applications as near UV-convertible phosphors for white-light UV LEDs.
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14.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Liang S. S., Dang P. P., Li G. G., Molokeev M. S., Wei Y., Lian H. Z., Shang M. M., Al Kheraiff A. A., Lin J.
Заглавие : Controllable two-dimensional luminescence tuning in Eu2+,Mn2+ doped (Ca,Sr)9Sc(PO4)7 based on crystal field regulation and energy transfer
Место публикации : J. Mater. Chem. C. - 2018. - Vol. 6, Is. 25. - P.6714-6725. - ISSN 2050-7526, DOI 10.1039/c8tc01825a. - ISSN 2050-7534(eISSN)
Примечания : Cited References: 63. - This work was financially supported by the National Natural Science Foundation of China (NSFC No. 51672265, 51672266, 21521092, 51750110511, 51672257, and 51672259), the Key Research Program of Frontier Sciences of CAS (Grant No. YZDY-SSW-JSC018), the National Basic Research Program of China (2014CB643803), the Scientific and Technological Department of Jilin Province (Grant No. 20150520029JH and 20170414003GH), Jiangmen Innovative Research Team Program (2017) and Major Program of Basic Research and Applied Research of Guangdong Province (2017KZDXM083), the Russian Science Foundation (Grant No. 17-12-01047), and the Distinguished Scientist Fellowship Program of King Saud University, as well as the Deanship of Scientific Research at King Saud University through research group no. (RG-1939-038).
Предметные рубрики: SOLID-SOLUTION PHOSPHORS
LIGHT-EMITTING-DIODES
CATION SUBSTITUTION
Аннотация: Currently, controllable luminescence tuning and the generation of single component white emission are viable strategies to modify and optimize the luminescence performances of phosphors, which offer appealing prospects for the w-LED lighting industry. In this paper, we designed two-dimensional (2D) tunable color coordinates on the CIE diagram in the Eu2+,Mn2+ doped (Ca,Sr)9xSc(PO4)7 system by a combination of crystal field regulation and the energy transfer method. X-ray powder diffraction (XRD) and Rietveld refinement were utilized to analyze the phase composition and structural variation of the studied phosphors. The transmission electron microscopy (TEM) and photoluminescence spectra were exploited to analyze the generation of nanosegregation. The effects of the schedule of cation substitutions and energy transfer on the photoluminescence properties were investigated in detail. The corresponding luminescence mechanisms of the red-shifted emission with Sr2+ → Ca2+ substitution and Eu2+ → Mn2+ energy transfer were deeply discussed and proposed. In addition, the temperature-dependent thermal quenching behavior and the electroluminescence (EL) performance of the fabricated w-LED devices were also investigated to characterize the prepared Ca9(1−0.03−x−y)Sr9xSc(PO4)7:0.27Eu2+,9yMn2+. Finally, a representative w-LED device composed of a 369 nm UV chip and Ca9(1−0.03−0.02−0.5)Sr4.5Sc(PO4)7:0.27Eu2+,0.18Mn2+ could present excellent EL performance with the parameters CRI = 88, CCT = 3122 K and color coordinate (0.45, 0.44), which could well meet the commercial standard of warm white light. Therefore, our results suggest that this two-step luminescence tuning method is feasible to be applied in other phosphor systems for obtaining efficient white emitting phosphors.
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15.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Ji, Haipeng, Huang, Zhaohui, Xia, Zhiguo, Molokeev M. S., Jiang, Xingxing, Lin, Zheshuai, Atuchin V. V.
Заглавие : Comparative investigations of the crystal structure and photoluminescence property of eulytite-type Ba3Eu(PO4)3 and Sr3Eu(PO4)3
Место публикации : Dalton Trans.: Royal Society of Chemistry, 2015. - Vol. 44, Is. 16. - P.7679-7686. - ISSN 1477, DOI 10.1039/c4dt03887h. - ISSN 14779234(eISSN)
Примечания : Cited References:65. - This work was supported by the National Natural Science Foundations of China (grant no. 51032007, no. 51002146, no. 51272242), the Research Fund for the Doctoral Program of Higher Education of China (grant no. 20130022110006), Natural Science Foundations of Beijing (2132050), and the Program for New Century Excellent Talents in the University of the Ministry of Education of China (NCET-12-0950), Beijing Nova Program (Z131103000413047) and Beijing Youth Excellent Talent Program (YETP0635). VVA is partly supported by the Ministry of Education and Science of the Russian Federation.
Предметные рубрики: LIGHT-EMITTING-DIODES
DOPED Sr3Gd(PO4(3 PHOSPHOR
EFFICIENT
Аннотация: In this study, the Ba3Eu(PO4)3 and Sr3Eu(PO4)3 compounds were synthesized and the crystal structures were determined for the first time by Rietveld refinement using powder X-ray diffraction (XRD) patterns. Ba3Eu(PO4)3 crystallizes in cubic space group I3d, with cell parameters of a = 10.47996(9) Å, V = 1151.01(3) Å3 and Z = 4; Ba2+ and Eu3+ occupy the same site with partial occupancies of 3/4 and 1/4, respectively. Besides, in this structure, there exists two distorted kinds of the PO4 polyhedra orientation. Sr3Eu(PO4)3 is isostructural to Ba3Eu(PO4)3 and has much smaller cell parameters of a = 10.1203(2) Å, V = 1036.52(5) Å3. The bandgaps of Ba3Eu(PO4)3 and Sr3Eu(PO4)3 are determined to be 4.091 eV and 3.987 eV, respectively, based on the UV–Vis diffuse reflectance spectra. The photoluminescence measurements reveal that, upon 396 nm n-UV light excitation, Ba3Eu(PO4)3 and Sr3Eu(PO4)3 exhibit orange-red emission with two main peaks at 596 nm and prevailing 613 nm, corresponding to the 5D0 → 7F1 and 5D0 → 7F2 transitions of Eu3+, respectively. The dynamic disordering in the crystal structures contributes to the broadening of the luminescence spectra. The electronic structure of the phosphates was calculated by the first-principles method. The analysis elucidats that the band structures are mainly governed by the orbits of phosphorus, oxygen and europium, and the sharp peaks of the europium f-orbit occur at the top of the valence bands.
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16.

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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17.

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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