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KEu(MoO₄)₂: polymorphism, structures, and luminescent properties

(2015) CHEMISTRY OF MATERIALS. 27(16). p.5519-5530
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Center for nano- and biophotonics (NB-Photonics)
Abstract
In this paper, with the example of two different polymorphs of KEu(MoO4)(2), the influence of the ordering of the A-cations on the luminescent properties in scheelite related compounds (A',A '') [(B',B '')O-4](m) is investigated. The polymorphs were synthesized using a solid state method. The study confirmed the existence of only two polymorphic forms at annealing temperature range 923-1203 K and ambient pressure: a low temperature anorthic alpha-phase and a monoclinic high temperature beta-phase with an incommensurately modulated structure. The structures of both polymorphs were solved using transmission electron microscopy and refined from synchrotron powder X-ray diffraction data. The monoclinic beta-KEu(MoO4)(2) has a (3+1)-dimensional incommensurately modulated structure (superspace group I2/b(alpha beta 0)00, a = 5.52645(4) angstrom, b = 5.28277(4) angstrom, c = 11.73797(8) angstrom, gamma = 91.2189(4)degrees, q = 0.56821(2)a*-0.12388(3)b*), whereas the anorthic alpha-phase is (3+1)-dimensional commensurately modulated (superspace group I (1) over bar(alpha beta gamma)0, a = 5.58727(22) angstrom, b = 5.29188(18)angstrom, c = 11.7120(4) angstrom, alpha = 90.485(3)degrees, beta = 88.074(3)degrees, gamma = 91.0270(23)degrees, q = 1/2a* + 1/2c*). In both cases the modulation arises due to Eu/K cation ordering at the A site: the formation of a 2-dimensional Eu3+ network is characteristic for the alpha-phase, while a 3-dimensional Eu3+-framework is observed for the beta-phase structure. The luminescent properties of KEu(MoO4)(2) samples prepared under different annealing conditions were measured, and the relation between their optical properties and their structures is discussed.
Keywords
DIFFRACTION, MOLYBDATES, TRANSITIONS, PHOTOLUMINESCENCE, GROWTH, RED PHOSPHORS, SINGLE-CRYSTALS, SOLID-STATE REACTION, CRYSTAL-STRUCTURE

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Chicago
Morozov, Vladimir A, Alla V Arakcheeva, Philip Pattison, Katrien Meert, Philippe Smet, Dirk Poelman, Nicolas Gauquelin, Johan Verbeeck, Artem M Abakumov, and Joke Hadermann. 2015. “KEu(MoO₄)₂: Polymorphism, Structures, and Luminescent Properties.” Chemistry of Materials 27 (16): 5519–5530.
APA
Morozov, V. A., Arakcheeva, A. V., Pattison, P., Meert, K., Smet, P., Poelman, D., Gauquelin, N., et al. (2015). KEu(MoO₄)₂: polymorphism, structures, and luminescent properties. CHEMISTRY OF MATERIALS, 27(16), 5519–5530.
Vancouver
1.
Morozov VA, Arakcheeva AV, Pattison P, Meert K, Smet P, Poelman D, et al. KEu(MoO₄)₂: polymorphism, structures, and luminescent properties. CHEMISTRY OF MATERIALS. 2015;27(16):5519–30.
MLA
Morozov, Vladimir A, Alla V Arakcheeva, Philip Pattison, et al. “KEu(MoO₄)₂: Polymorphism, Structures, and Luminescent Properties.” CHEMISTRY OF MATERIALS 27.16 (2015): 5519–5530. Print.
@article{7024975,
  abstract     = {In this paper, with the example of two different polymorphs of KEu(MoO4)(2), the influence of the ordering of the A-cations on the luminescent properties in scheelite related compounds (A',A '') [(B',B '')O-4](m) is investigated. The polymorphs were synthesized using a solid state method. The study confirmed the existence of only two polymorphic forms at annealing temperature range 923-1203 K and ambient pressure: a low temperature anorthic alpha-phase and a monoclinic high temperature beta-phase with an incommensurately modulated structure. The structures of both polymorphs were solved using transmission electron microscopy and refined from synchrotron powder X-ray diffraction data. The monoclinic beta-KEu(MoO4)(2) has a (3+1)-dimensional incommensurately modulated structure (superspace group I2/b(alpha beta 0)00, a = 5.52645(4) angstrom, b = 5.28277(4) angstrom, c = 11.73797(8) angstrom, gamma = 91.2189(4)degrees, q = 0.56821(2)a*-0.12388(3)b*), whereas the anorthic alpha-phase is (3+1)-dimensional commensurately modulated (superspace group I (1) over bar(alpha beta gamma)0, a = 5.58727(22) angstrom, b = 5.29188(18)angstrom, c = 11.7120(4) angstrom, alpha = 90.485(3)degrees, beta = 88.074(3)degrees, gamma = 91.0270(23)degrees, q = 1/2a* + 1/2c*). In both cases the modulation arises due to Eu/K cation ordering at the A site: the formation of a 2-dimensional Eu3+ network is characteristic for the alpha-phase, while a 3-dimensional Eu3+-framework is observed for the beta-phase structure. The luminescent properties of KEu(MoO4)(2) samples prepared under different annealing conditions were measured, and the relation between their optical properties and their structures is discussed.},
  author       = {Morozov, Vladimir A and Arakcheeva, Alla V and Pattison, Philip and Meert, Katrien and Smet, Philippe and Poelman, Dirk and Gauquelin, Nicolas and Verbeeck, Johan and Abakumov, Artem M and Hadermann, Joke},
  issn         = {0897-4756},
  journal      = {CHEMISTRY OF MATERIALS},
  keyword      = {DIFFRACTION,MOLYBDATES,TRANSITIONS,PHOTOLUMINESCENCE,GROWTH,RED PHOSPHORS,SINGLE-CRYSTALS,SOLID-STATE REACTION,CRYSTAL-STRUCTURE},
  language     = {eng},
  number       = {16},
  pages        = {5519--5530},
  title        = {KEu(MoO\unmatched{2084})\unmatched{2082}: polymorphism, structures, and luminescent properties},
  url          = {http://dx.doi.org/10.1021/acs.chemmater.5b01622},
  volume       = {27},
  year         = {2015},
}

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