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Incommensurate modulation and luminescence in the CaGd2(1-x)Eu-2x(MoO4)(4(1-y))(WO4)(4y) (0 <= x <= 1, 0 <= y <= 1) red phosphors

(2013) CHEMISTRY OF MATERIALS. 25(21). p.4387-4395
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Center for nano- and biophotonics (NB-Photonics)
Abstract
Scheelite related compounds (A',A '') [(B',B '')O-4], with B', B '' = W and/or Mo are promising new light-emitting materials for photonic applications, including phosphor converted LEDs (light-emitting diodes). In this paper, the creation and ordering of A-cation vacancies and the effect of cation substitutions in the scheelite-type framework are investigated as a factor for controlling the scheelite-type structure and luminescent properties. CaGd2(1-x)Eu2x(MoO4)(4(1-y))(WO4)(4y) (0 <= x <= 1, 0 <= y <= 1) solid solutions with scheelite-type structure were synthesized by a solid state method, and their structures were investigated using a combination of transmission electron microscopy techniques and powder X-ray diffraction. Within this series all complex molybdenum oxides have (3 + 2)D incommensurately modulated structures with superspace group I4(1)/a(alpha,beta,0)00(-beta,alpha,0)00, while the structures of all tungstates are (3 + 1)D incommensurately modulated with superspace group I2/b(alpha beta 0)00. In both cases the modulation arises because of cation-vacancy ordering at the A site. The prominent structural motif is formed by columns of A-site vacancies running along the c-axis. These vacant columns occur in rows of two or three aligned along the [110] direction of the scheelite subcell. The replacement of the smaller Gd3+ by the larger Eu3+ at the A-sublattice does not affect the nature of the incommensurate modulation, but an increasing replacement of Mo6+ by W6+ switches the modulation from (3 + 2)D to (3 + 1)D regime. Thus, these solid solutions can be considered as a model system where the incommensurate modulation can be monitored as a function of cation nature while the number of cation vacancies at the A sites remain constant upon the isovalent cation replacement. All compounds' luminescent properties were measured, and the optical properties were related to the structural properties of the materials. CaGd2(1-x)(MoO4)(4(1-y))(WO4)(4y) phosphors emit intense red light dominated by the D-5(0)-F-7(2) transition at 612 nm, along with other transitions from the D-5(1) and D-5(0) excited states. The intensity of the 5D0-7F2 transition reaches a maximum at x = 0.5 for y = 0 and 1.
Keywords
LIGHT-EMITTING-DIODES, luminescence, CRYSTAL-STRUCTURE, CONVERSION PHOSPHORS, SCHEELITE-TYPE, METAL OXIDES, EU3+, EMISSION, PHOTOLUMINESCENCE, FAMILY, SR, scheelites, structure, TEM, europium, modulation, rare earth

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Citation

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Chicago
Morozov, Vladimir A, Anne Bertha, Katrien Meert, Senne Van Rompaey, Dmitry Batuk, Gerardo T Martinez, Sandra Van Aert, et al. 2013. “Incommensurate Modulation and Luminescence in the CaGd2(1-x)Eu-2x(MoO4)(4(1-y))(WO4)(4y) (0 <= x <= 1, 0 <= y <= 1) Red Phosphors.” Chemistry of Materials 25 (21): 4387–4395.
APA
Morozov, V. A., Bertha, A., Meert, K., Van Rompaey, S., Batuk, D., Martinez, G. T., Van Aert, S., et al. (2013). Incommensurate modulation and luminescence in the CaGd2(1-x)Eu-2x(MoO4)(4(1-y))(WO4)(4y) (0 <= x <= 1, 0 <= y <= 1) red phosphors. CHEMISTRY OF MATERIALS, 25(21), 4387–4395.
Vancouver
1.
Morozov VA, Bertha A, Meert K, Van Rompaey S, Batuk D, Martinez GT, et al. Incommensurate modulation and luminescence in the CaGd2(1-x)Eu-2x(MoO4)(4(1-y))(WO4)(4y) (0 <= x <= 1, 0 <= y <= 1) red phosphors. CHEMISTRY OF MATERIALS. 2013;25(21):4387–95.
MLA
Morozov, Vladimir A, Anne Bertha, Katrien Meert, et al. “Incommensurate Modulation and Luminescence in the CaGd2(1-x)Eu-2x(MoO4)(4(1-y))(WO4)(4y) (0 <= x <= 1, 0 <= y <= 1) Red Phosphors.” CHEMISTRY OF MATERIALS 25.21 (2013): 4387–4395. Print.
@article{4212392,
  abstract     = {Scheelite related compounds (A',A '') [(B',B '')O-4], with B', B '' = W and/or Mo are promising new light-emitting materials for photonic applications, including phosphor converted LEDs (light-emitting diodes). In this paper, the creation and ordering of A-cation vacancies and the effect of cation substitutions in the scheelite-type framework are investigated as a factor for controlling the scheelite-type structure and luminescent properties. CaGd2(1-x)Eu2x(MoO4)(4(1-y))(WO4)(4y) (0 {\textlangle}= x {\textlangle}= 1, 0 {\textlangle}= y {\textlangle}= 1) solid solutions with scheelite-type structure were synthesized by a solid state method, and their structures were investigated using a combination of transmission electron microscopy techniques and powder X-ray diffraction. Within this series all complex molybdenum oxides have (3 + 2)D incommensurately modulated structures with superspace group I4(1)/a(alpha,beta,0)00(-beta,alpha,0)00, while the structures of all tungstates are (3 + 1)D incommensurately modulated with superspace group I2/b(alpha beta 0)00. In both cases the modulation arises because of cation-vacancy ordering at the A site. The prominent structural motif is formed by columns of A-site vacancies running along the c-axis. These vacant columns occur in rows of two or three aligned along the [110] direction of the scheelite subcell. The replacement of the smaller Gd3+ by the larger Eu3+ at the A-sublattice does not affect the nature of the incommensurate modulation, but an increasing replacement of Mo6+ by W6+ switches the modulation from (3 + 2)D to (3 + 1)D regime. Thus, these solid solutions can be considered as a model system where the incommensurate modulation can be monitored as a function of cation nature while the number of cation vacancies at the A sites remain constant upon the isovalent cation replacement. All compounds' luminescent properties were measured, and the optical properties were related to the structural properties of the materials. CaGd2(1-x)(MoO4)(4(1-y))(WO4)(4y) phosphors emit intense red light dominated by the D-5(0)-F-7(2) transition at 612 nm, along with other transitions from the D-5(1) and D-5(0) excited states. The intensity of the 5D0-7F2 transition reaches a maximum at x = 0.5 for y = 0 and 1.},
  author       = {Morozov, Vladimir A and Bertha, Anne and Meert, Katrien and Van Rompaey, Senne and Batuk, Dmitry and Martinez, Gerardo T and Van Aert, Sandra and Smet, Philippe and Raskina, Maria V and Poelman, Dirk and Abakumov, Artem M and Hadermann, Joke},
  issn         = {0897-4756},
  journal      = {CHEMISTRY OF MATERIALS},
  keyword      = {LIGHT-EMITTING-DIODES,luminescence,CRYSTAL-STRUCTURE,CONVERSION PHOSPHORS,SCHEELITE-TYPE,METAL OXIDES,EU3+,EMISSION,PHOTOLUMINESCENCE,FAMILY,SR,scheelites,structure,TEM,europium,modulation,rare earth},
  language     = {eng},
  number       = {21},
  pages        = {4387--4395},
  title        = {Incommensurate modulation and luminescence in the CaGd2(1-x)Eu-2x(MoO4)(4(1-y))(WO4)(4y) (0 {\textlangle}= x {\textlangle}= 1, 0 {\textlangle}= y {\textlangle}= 1) red phosphors},
  url          = {http://dx.doi.org/10.1021/cm402729r},
  volume       = {25},
  year         = {2013},
}

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