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Title: Structure, luminescence and thermal quenching properties of Eu doped Sr{sub 2−x}Ba{sub x}Si{sub 5}N{sub 8} red phosphors

Abstract

Eu{sup 2+} doped Sr{sub 2-x}Ba{sub x}Si{sub 5}N{sub 8} phosphors were synthesized at 1610 ℃ for 4 h via the solid-state reaction method. The XRD results confirm that the complete solid solutions are formed. With the increase of x, the emission spectra show an obvious blue-shift from 610 nm to 585 nm under the excitation of 460 nm. The color tone can be tuned from yellow to red. The corresponding mechanism for the blue-shift of peak-wavelength is studied in detail. The results of decomposed Gaussian spectra and fluorescence lifetime show that the local coordination structure surrounding activator ions changes with increasing x value. It is found that the probability of Eu occupying Sr1 and Sr2 site is dependent on Ba/Sr ratio. The variation of thermal quenching properties and the corresponding mechanism is discussed in detail. The results indicate that Eu{sup 2+} doped Sr{sub 2-x}Ba{sub x}Si{sub 5}N{sub 8} is a promising orange red-emitting phosphor for near UV or blue light-pumped white light-emitting-diodes (wLEDs). - Graphical abstract: Eu{sup 2+} doped Sr{sub 2-x}Ba{sub x}Si{sub 5}N{sub 8} solid solutions were prepared by the solid-state reaction method. The structure, luminescence and thermal quenching properties with varying Ba/Sr ratio were investigated in detail. - Highlights: • Themore » stucture and luminescence properties of Eu doped Sr{sub 2-x}Ba{sub x}Si{sub 5}N{sub 8} phosphors were investigated. • The samples with the intermediate compositions(x=1.0,1.5) show better stability than the end members of both Sr{sub 2}Si{sub 5}N{sub 8}:Eu{sup 2+} and Ba{sub 2}Si{sub 5}N{sub 8}:Eu{sup 2+}. • The possible mechanism for the improvement of thermal quenching properties was proposed.« less

Authors:
; ; ; ;
Publication Date:
OSTI Identifier:
22658178
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Solid State Chemistry; Journal Volume: 246; Other Information: Copyright (c) 2016 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; CRYSTALS; DOPED MATERIALS; EMISSION SPECTRA; EUROPIUM IONS; EXPERIMENTAL DATA; LIGHT EMITTING DIODES; PHOSPHORS; QUENCHING; SOLID SOLUTIONS; X-RAY DIFFRACTION

Citation Formats

Liu, Y.H., Chen, L., Zhou, X.F., Liu, R.H., E-mail: griremlrh@126.com, and Zhuang, W.D. Structure, luminescence and thermal quenching properties of Eu doped Sr{sub 2−x}Ba{sub x}Si{sub 5}N{sub 8} red phosphors. United States: N. p., 2017. Web. doi:10.1016/J.JSSC.2016.11.009.
Liu, Y.H., Chen, L., Zhou, X.F., Liu, R.H., E-mail: griremlrh@126.com, & Zhuang, W.D. Structure, luminescence and thermal quenching properties of Eu doped Sr{sub 2−x}Ba{sub x}Si{sub 5}N{sub 8} red phosphors. United States. doi:10.1016/J.JSSC.2016.11.009.
Liu, Y.H., Chen, L., Zhou, X.F., Liu, R.H., E-mail: griremlrh@126.com, and Zhuang, W.D. Wed . "Structure, luminescence and thermal quenching properties of Eu doped Sr{sub 2−x}Ba{sub x}Si{sub 5}N{sub 8} red phosphors". United States. doi:10.1016/J.JSSC.2016.11.009.
@article{osti_22658178,
title = {Structure, luminescence and thermal quenching properties of Eu doped Sr{sub 2−x}Ba{sub x}Si{sub 5}N{sub 8} red phosphors},
author = {Liu, Y.H. and Chen, L. and Zhou, X.F. and Liu, R.H., E-mail: griremlrh@126.com and Zhuang, W.D.},
abstractNote = {Eu{sup 2+} doped Sr{sub 2-x}Ba{sub x}Si{sub 5}N{sub 8} phosphors were synthesized at 1610 ℃ for 4 h via the solid-state reaction method. The XRD results confirm that the complete solid solutions are formed. With the increase of x, the emission spectra show an obvious blue-shift from 610 nm to 585 nm under the excitation of 460 nm. The color tone can be tuned from yellow to red. The corresponding mechanism for the blue-shift of peak-wavelength is studied in detail. The results of decomposed Gaussian spectra and fluorescence lifetime show that the local coordination structure surrounding activator ions changes with increasing x value. It is found that the probability of Eu occupying Sr1 and Sr2 site is dependent on Ba/Sr ratio. The variation of thermal quenching properties and the corresponding mechanism is discussed in detail. The results indicate that Eu{sup 2+} doped Sr{sub 2-x}Ba{sub x}Si{sub 5}N{sub 8} is a promising orange red-emitting phosphor for near UV or blue light-pumped white light-emitting-diodes (wLEDs). - Graphical abstract: Eu{sup 2+} doped Sr{sub 2-x}Ba{sub x}Si{sub 5}N{sub 8} solid solutions were prepared by the solid-state reaction method. The structure, luminescence and thermal quenching properties with varying Ba/Sr ratio were investigated in detail. - Highlights: • The stucture and luminescence properties of Eu doped Sr{sub 2-x}Ba{sub x}Si{sub 5}N{sub 8} phosphors were investigated. • The samples with the intermediate compositions(x=1.0,1.5) show better stability than the end members of both Sr{sub 2}Si{sub 5}N{sub 8}:Eu{sup 2+} and Ba{sub 2}Si{sub 5}N{sub 8}:Eu{sup 2+}. • The possible mechanism for the improvement of thermal quenching properties was proposed.},
doi = {10.1016/J.JSSC.2016.11.009},
journal = {Journal of Solid State Chemistry},
number = ,
volume = 246,
place = {United States},
year = {Wed Feb 15 00:00:00 EST 2017},
month = {Wed Feb 15 00:00:00 EST 2017}
}
  • The crystal structure, electronic structure, and photoluminescence properties of Eu{sub x}Si{sub 6-z}Al{sub z-x}O{sub z+x}N{sub 8-z-x} (x=0-0.1, 0<z<1) and Eu{sub x}M{sub y}Si{sub 6-z}Al{sub z-x-y}O{sub z+x+y}N{sub 8-z-x-y} (M=2Li, Mg, Ca, Sr, Ba) have been studied. Single-phase Eu{sub x}Si{sub 6-z}Al{sub z-x}O{sub z+x}N{sub 8-z-x} can be obtained in very narrow ranges of x{<=}0.06 (z=0.15) and z<0.5 (x=0.3), indicating that limited Eu{sup 2+} ions can be incorporated into nitrogen-rich Si{sub 6-z}Al{sub z}O{sub z}N{sub 8-z}. The Eu{sup 2+} ion is found to occupy the 2b site in a hexagonal unit cell (P6{sub 3}/m) and directly connected by six adjacent nitrogen/oxygen atoms ranging 2.4850-2.5089 A. The calculatedmore » host band gaps by the relativistic DV-X{alpha} method are about 5.55 and 5.45 eV (without Eu{sup 2+} 4f5d levels) for x=0 and 0.013 in Eu{sub x}Si{sub 6-z}Al{sub z-x}O{sub z+x}N{sub 8-z-x} (z=0.15), in which the top of the 5d orbitals overlap with the Si-3s3p and N-2p orbitals within the bottom of the conduction band of the host. Eu{sub x}Si{sub 6-z}Al{sub z-x}O{sub z+x}N{sub 8-z-x} shows a strong green emission with a broad Eu{sup 2+} band centered at about 530 nm under UV to near-UV excitation range. The excitation and emission spectra are hardly modified by Eu concentration and dual-doping ions of Li and other alkaline-earth ions with Eu. Higher Eu concentrations can significantly quench the luminescence of Eu{sup 2+} and decrease the thermal quenching temperature. In addition, the emission spectrum can only be slightly tuned to the longer wavelengths ({approx}529-545 nm) by increasing z within the solid solution range of z<0.5. Furthermore, the luminescence intensity of Eu{sub x}Si{sub 6-z}Al{sub z-x}O{sub z+x}N{sub 8-z-x} can be improved by increasing z and the dual-doping of Li and Ba. - Graphical abstract: Excitation and emission spectra of Eu{sub x}Si{sub 6-z}Al{sub z-x}O{sub z+x}N{sub 8-z-x} with the project of a 2x2x2 supercell crystal structure viewed along (001), in which red spheres are the Eu atoms.« less
  • The influence of the replacement of Sr by Ca on structural and luminescence properties of Eu{sup 2+}-doped Sr{sub 2}Si{sub 5}N{sub 8} is reported. The Rietveld refinement of the powder X-ray diffraction data shows that the Ca{sup 2+} ion preferentially occupies the larger Sr site in Sr{sub 2}Si{sub 5}N{sub 8}:Eu{sup 2+}. Although the excitation spectrum is hardly modified, the position of the emission band of Eu{sup 2+} can be tailored through partial replacement of Sr by Ca in Sr{sub 2}Si{sub 5}N{sub 8}:Eu{sup 2+}, resulting in red-emission shifting from 620 to 643 nm. Furthermore, (Sr, Ca){sub 2}Si{sub 5}N{sub 8}:Eu{sup 2+} shows highmore » potential as a conversion phosphor for white-light LED applications due to similar absorption, conversion efficiency and thermal quenching behaviour for 465 nm excitation after the introduction of the Ca ion. - Graphical abstract: The temperature dependence of the luminescence efficiency of M{sub 1.9}Eu{sub 0.1}Si{sub 5}N{sub 8} (M=Ca, Sr, Ba) and Sr{sub 1.3}Ca{sub 0.6}Eu{sub 0.1}Si{sub 5}N{sub 8} ({lambda}{sub exc}=465 nm)« less
  • Host lattice Ba{sub 3}Si{sub 5}O{sub 13-{delta}}N{sub {delta}} oxonitridosilicates have been synthesized by the traditional solid state reaction method. The lattice structure is based on layers of vertex-linked SiO{sub 4} tetrahedrons and Ba{sup 2+} ions, where each Ba{sup 2+} ion is coordinated by eight oxygen atoms forming distorted square antiprisms. Under an excitation wavelength of 365 nm, Ba{sub 3}Si{sub 5}O{sub 13-{delta}}N{sub {delta}}:Eu{sup 2+} and Ba{sub 3}Si{sub 5}O{sub 13-{delta}}N{sub {delta}}:Eu{sup 2+},Ce{sup 3+} show broad emission bands from about 400-620 nm, with maxima at about 480 nm and half-peak width of around 130 nm. The emission intensity is strongly enhanced by co-doping Ce{supmore » 3+} ions into the Ba{sub 3}Si{sub 5}O{sub 13-{delta}}N{sub {delta}}:Eu{sup 2+} phosphor, which could be explained by energy transfer. The excitation band from the near UV to the blue light region confirms the possibility that Ba{sub 3}Si{sub 5}O{sub 13-{delta}}N{sub {delta}}:Eu{sup 2+}, Ce{sup 3+} could be used as a phosphor for white LEDs. - Graphical abstract: Emission spectra for Ba{sub 3(1-x-y)}Si{sub 5}O{sub 13-{delta}}N{sub {delta}}/xEu{sup 2+},yCe{sup 3+} (0<=x<=2%,0<=y<=2%) under the excitation wavelength of 365 nm.« less
  • Mn{sup 2+}-doped M{sub 2}Si{sub 5}N{sub 8} (M=Ca, Sr, Ba) phosphors have been prepared by a solid-state reaction method at high temperature and their photoluminescence properties were investigated. The Mn{sup 2+}-activated M{sub 2}Si{sub 5}N{sub 8} phosphors exhibit narrow emission bands in the wavelength range of 500-700 nm with peak center at about 599, 606 and 567 nm for M=Ca, Sr, Ba, respectively, due to the {sup 4}T{sub 1}({sup 4}G){yields}{sup 6}A{sub 1}({sup 6}S) transition of Mn{sup 2+}. The long-wavelength emission of Mn{sup 2+} ion in the host of M{sub 2}Si{sub 5}N{sub 8} is attributed to the effect of a strong crystal-field ofmore » Mn{sup 2+} in the nitrogen coordination environment. Also it is observed that there exists energy transfer between M{sub 2}Si{sub 5}N{sub 8} host lattice and activator (Mn{sup 2+}). The potential applications of these phosphors have been pointed out. - Graphical abstract: The luminescence properties of Mn{sup 2+} in M{sub 2}Si{sub 5}N{sub 8} (M=Ca, Sr, Ba) have been investigated. All M{sub 2}Si{sub 5}N{sub 8}:Mn{sup 2+} phosphors show narrow symmetric bands in the wavelength range of 500-700 nm with peak center at about 599, 606 and 567 nm for M=Ca, Sr, Ba, respectively. The observed band emission is ascribed to the {sup 4}T{sub 1}({sup 4}G){yields}{sup 6}A{sub 1}({sup 6}S) transition of Mn{sup 2+} in M{sub 2}Si{sub 5}N{sub 8} host lattice.« less
  • The preparation of Eu 2+-substituted barium aluminum silicates is achieved using a rapid microwave-assisted preparation. The phase evolution of two BaAl 2Si 2O 8:Eu 2+ polymorphs, the higher temperature hexagonal phase (hexacelsian), and the lower temperature monoclinic phase (celsian), is explored by varying the ramp time and soak time. This preparation method significantly reduces the reaction time needed to form these phases compared to conventional solid state routes. The luminescent properties of the two phases are identified under UV excitation with the hexagonal phase emitting in the UV region (λ em = 372 nm) and the monoclinic phase emitting inmore » the blue region (λ em = 438 nm). The differences in optical properties of the two polymorphs are correlated to the coordination number and arrangement of the alkali earth site. The optical properties of the monoclinic phase can be further tuned through the substitution of Sr 2+, forming the solid solution (Ba 1–xSr x)Al 2Si 2O 8:Eu 2+. Changes in the crystal structure due to Sr 2+ substitution produce a surprising blue-shift in the emission spectrum, which is explained by a greater dispersion of bond lengths in the (Ba/Sr)–O polyhedra. The entire monoclinic solid solution exhibits excellent quantum yields of nearly 90 %, owing to the structural rigidity provided by the highly connected tetrahedral network.« less