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Title: First-principles calculation on electronic structure and optical property of BaSi{sub 2}O{sub 2}N{sub 2}:Eu{sup 2+} phosphor

Abstract

The crystal structure, electronic structure and optical properties of BaSi{sub 2}O{sub 2}N{sub 2}:Eu{sup 2+} with varying Eu doping concentrations are computed by the density functional theory (DFT) and compared with experimental results. The results show that the lattice parameters of primitive cells of Ba{sub 1−x}Si{sub 2}O{sub 2}N{sub 2}:Eu{sub x} become smaller and Eu–N bond length shortens as Eu concentration increases. The band structure of Ba{sub 1−x}Si{sub 2}O{sub 2}N{sub 2}:Eu{sub x} exhibits a direct optical band gap and it's propitious to luminescence. The energy differences from the lowest Eu 5d state to the lowest Eu 4f state decrease with increasing Eu concentrations. The analysis of simulative absorption spectra indicates that the electron transition from Eu 4f states to 5d states of both Eu and Ba atoms contributes to the absorption of Ba{sub 1−x}Si{sub 2}O{sub 2}N{sub 2}:Eu{sub x}. Under the coupling effect between Eu and Ba, Ba in BaSi{sub 2}O{sub 2}N{sub 2} exhibits longer wavelength absorption and increases absorption efficiency. The emission wavelength is deduced by measuring energy differences from the lowest Eu 5d state to the lowest Eu 4f state, and the result is in good agreement with experimental value within experimental Eu{sup 2+} doping range. - Graphical abstract: The structuremore » and optical property of BaSi{sub 2}O{sub 2}N{sub 2}:Eu{sup 2+} are computed by DFT and its absorption mechanism is analysed. Results show that absorption peak α is from the host lattice absorption. The absorption peaks β, γ and δ are from Eu 4f to Eu 5d and Ba 6s 5d states. The absorption is attributed to the coupling effect of Eu and Ba atom. - Highlights: • The crystal, electronic structure and optical properties of BaSi{sub 2}O{sub 2}N{sub 2}:Eu{sup 2+} are computed by DFT. • The lattice parameters of primitive cells reduces and Eu–N bond length shortens as Eu{sup 2+} increases. • The energy gap from Eu 5d state to Eu 4f state decrease with increasing Eu concentrations. • Both Eu and Ba atoms contributes to the absorption of Ba{sub 1−x}Si{sub 2}O{sub 2}N{sub 2}:Eu{sub x}. • The deduced emission wavelength is in good agreement with experimental value.« less

Authors:
; ;
Publication Date:
OSTI Identifier:
22658240
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Solid State Chemistry; Journal Volume: 248; Other Information: Copyright (c) 2017 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; ABSORPTION SPECTRA; ABUNDANCE; BARIUM COMPOUNDS; BOND LENGTHS; CONCENTRATION RATIO; CRYSTAL STRUCTURE; DENSITY FUNCTIONAL METHOD; DOPED MATERIALS; ELECTRONIC STRUCTURE; EUROPIUM IONS; EXPERIMENTAL DATA; LATTICE PARAMETERS; OPTICAL PROPERTIES; WAVELENGTHS

Citation Formats

Tong, Zhi-Fang, E-mail: tongzhifang1998@126.com, Wei, Zhan-Long, and Xiao, Cheng. First-principles calculation on electronic structure and optical property of BaSi{sub 2}O{sub 2}N{sub 2}:Eu{sup 2+} phosphor. United States: N. p., 2017. Web. doi:10.1016/J.JSSC.2017.01.021.
Tong, Zhi-Fang, E-mail: tongzhifang1998@126.com, Wei, Zhan-Long, & Xiao, Cheng. First-principles calculation on electronic structure and optical property of BaSi{sub 2}O{sub 2}N{sub 2}:Eu{sup 2+} phosphor. United States. doi:10.1016/J.JSSC.2017.01.021.
Tong, Zhi-Fang, E-mail: tongzhifang1998@126.com, Wei, Zhan-Long, and Xiao, Cheng. Sat . "First-principles calculation on electronic structure and optical property of BaSi{sub 2}O{sub 2}N{sub 2}:Eu{sup 2+} phosphor". United States. doi:10.1016/J.JSSC.2017.01.021.
@article{osti_22658240,
title = {First-principles calculation on electronic structure and optical property of BaSi{sub 2}O{sub 2}N{sub 2}:Eu{sup 2+} phosphor},
author = {Tong, Zhi-Fang, E-mail: tongzhifang1998@126.com and Wei, Zhan-Long and Xiao, Cheng},
abstractNote = {The crystal structure, electronic structure and optical properties of BaSi{sub 2}O{sub 2}N{sub 2}:Eu{sup 2+} with varying Eu doping concentrations are computed by the density functional theory (DFT) and compared with experimental results. The results show that the lattice parameters of primitive cells of Ba{sub 1−x}Si{sub 2}O{sub 2}N{sub 2}:Eu{sub x} become smaller and Eu–N bond length shortens as Eu concentration increases. The band structure of Ba{sub 1−x}Si{sub 2}O{sub 2}N{sub 2}:Eu{sub x} exhibits a direct optical band gap and it's propitious to luminescence. The energy differences from the lowest Eu 5d state to the lowest Eu 4f state decrease with increasing Eu concentrations. The analysis of simulative absorption spectra indicates that the electron transition from Eu 4f states to 5d states of both Eu and Ba atoms contributes to the absorption of Ba{sub 1−x}Si{sub 2}O{sub 2}N{sub 2}:Eu{sub x}. Under the coupling effect between Eu and Ba, Ba in BaSi{sub 2}O{sub 2}N{sub 2} exhibits longer wavelength absorption and increases absorption efficiency. The emission wavelength is deduced by measuring energy differences from the lowest Eu 5d state to the lowest Eu 4f state, and the result is in good agreement with experimental value within experimental Eu{sup 2+} doping range. - Graphical abstract: The structure and optical property of BaSi{sub 2}O{sub 2}N{sub 2}:Eu{sup 2+} are computed by DFT and its absorption mechanism is analysed. Results show that absorption peak α is from the host lattice absorption. The absorption peaks β, γ and δ are from Eu 4f to Eu 5d and Ba 6s 5d states. The absorption is attributed to the coupling effect of Eu and Ba atom. - Highlights: • The crystal, electronic structure and optical properties of BaSi{sub 2}O{sub 2}N{sub 2}:Eu{sup 2+} are computed by DFT. • The lattice parameters of primitive cells reduces and Eu–N bond length shortens as Eu{sup 2+} increases. • The energy gap from Eu 5d state to Eu 4f state decrease with increasing Eu concentrations. • Both Eu and Ba atoms contributes to the absorption of Ba{sub 1−x}Si{sub 2}O{sub 2}N{sub 2}:Eu{sub x}. • The deduced emission wavelength is in good agreement with experimental value.},
doi = {10.1016/J.JSSC.2017.01.021},
journal = {Journal of Solid State Chemistry},
number = ,
volume = 248,
place = {United States},
year = {Sat Apr 15 00:00:00 EDT 2017},
month = {Sat Apr 15 00:00:00 EDT 2017}
}
  • Polarized emission and absorption spectroscopy of 4f{sup 6} Eu{sup 3+} in Na{sub 3}[Yb{sub 0.95}Eu{sub 0.05}(dpa){sub 3}]{center_dot}NaClO{sub 4}{center_dot}10H{sub 2}O (dpa = dipicolinate) is reported with the objective of characterizing the crystal-field energy levels. Empirical and theoretical studies were compared by fitting a parameterized Hamiltonian to the data.
  • Pb{sub 4}O(BO{sub 3}){sub 2} has a layered-type arrangement with optimally aligned BO{sub 3} triangles. The optical band gap is 3.317 eV obtained via the extrapolation method from the UV-vis-IR optical diffuse reflectance spectrum, consequently the absorption edge is about 374 nm. Density functional calculations using a generalized gradient approximation were utilized to investigate the electronic structures and optical properties of Pb{sub 4}O(BO{sub 3}){sub 2}. The calculated band structures show a direct gap of 2.608 eV, which is in agreement with the experimental optical band gap. A delocalized {pi} bonding of BO{sub 3} triangles and the stereo-effect of the lone pairmore » 6s{sup 2} of lead cations are studied in electron densities. The birefringence is about 0.039-0.061 with the wavelength larger than about 375 nm. The calculated second-order susceptibility d{sub 24}=3.5 d{sub 36} (KDP) which is well consistent with the powder SHG intensity. - Graphical abstract: The density of state (DOS) show that the bottom of the valence bands is mainly derived from of the lone pair 6s{sup 2} of Pb{sup 2+}, and the top of the valence band is attributed to the hybridization orbitals from B-O groups. Calculated electronic structures indicate that the BO{sub 3} group with typical delocalization {pi} orbitals and strongly distorted lead oxygen polyhedra with highly asymmetric lobes on lead cations make a large SHG effect in Pb{sub 4}O(BO{sub 3}){sub 2}. Highlights: Black-Right-Pointing-Pointer Lone pair effect on Pb{sup 2+} and delocalization {pi} orbital in BO{sub 3} group is studied. Black-Right-Pointing-Pointer The combination of PbO{sub n} (n=3,4,5) and BO{sub 3} group makes Pb{sub 4}O(BO{sub 3}){sub 2} a large SHG effect. Black-Right-Pointing-Pointer Pb{sub 4}O(BO{sub 3}){sub 2} is a direct gap material with the gap 2.608 eV by the ab initio method. Black-Right-Pointing-Pointer The calculated birefringence is about 0.039-0.061 with the wavelength of about 375 nm. Black-Right-Pointing-Pointer The second-order susceptibility d{sub 24}=3.5d{sub 36} (KDP) in accordance with the experimental result.« less
  • The electronic structure, the linear optical properties, and the structural properties of [alpha]-Al[sub 2]O[sub 3] in the corundum structure are studied by means of first-principles local density calculations. An indirect band gap of 6.29 eV is obtained, which is almost the same as the direct band gap of 6.31 eV at [Gamma]. The calculated density of states are compared with X-ray photoemission and photoabsorption measurements. Real space charge density analysis shows Al[sub 2]O[sub 3] to be highly ionic with an effective charge formula of Al[sub 2][sup +2.75]O[sub 3][sup [minus]1.83]. The calculated dielectric function is in general agreement with the experimentalmore » vacuum ultraviolet data. It is shown that the component with c-direction polarization is in better agreement with the experimental data because it is less affected by the exciton formation near the absorption edge. Various careful test calculations indicate that the remaining discrepancy in the optical spectra may be in the LDA approximation of the electronic structure theory. The total energy calculation for the ground-state structural properties of [alpha]-Al[sub 2]O[sub 3] shows excellent agreement with experimental data: the calculated equilibrium volume, c/A ratio, bulk modulus, and internal parameters for Al and O atoms differ from measured values by 0.0, [minus]4.3, [minus]4.0[minus], 0.85, and 1.96 percent, respectively. The calculations for the electronic structure and the optical properties are repeated with crystal parameters obtained at 2000 C.« less
  • Ta{sub 2}O{sub 5}:Eu{sup 3+}: Mg{sup 2+} or Ca{sup 2+} phosphor materials were prepared by molten salt method using KCl as flux. The X-ray diffraction (XRD) patterns illustrated that the well crystallized Ta{sub 2}O{sub 5}:Eu{sup 3+}: Mg{sup 2+} or Ca{sup 2+} were formed in the presence of flux under reduced temperature (800 °C) in contrast to conventional solid state method (1200-1500 °C). Scanning electron microscope (SEM) images indicate the achievement of well dispersed particles (hexagonal tablet and rod-like structures). Meanwhile, the photo-luminescent studies demonstrated that Ta{sub 2}O{sub 5} is an efficient host to sensitize europium red emissions. The addition of Mg{supmore » 2+} or Ca{sup 2+} as co-dopant enhanced the luminescent intensity of Ta{sub 2}O{sub 5}: Eu{sup 3+} compound.« less
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