Crystal structure of Scheelite-type potassium cerium bis(tetraoxomolybdate( VI)), KCe(MoO4)2

Zhang, Hui-Ju; Fu, Li; Wang, Chaopeng; Fu, Hui-Feng; Xie, Wei-Gong

doi:10.1515/ncrs-2014-0105

Cited by 2 publications

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“…46 Like other NaR(MoO 4 ) 2 (R = rare earth elements) molybdenum oxides, NaEu(MoO 4 ) 2 47,48 has only the tetragonal scheelite-type structure with a statistical distribution of M + and R 3+ . KR(MoO 4 ) 2 (R = La3 30,31 -Ce 49 ) has similar statistical distribution of K + and R 3+ . Increasing the r(K)-r(R) difference from 0.367 Å (Ce) to 0.401 Å (Nd) turns the K + and R 3+ distribution into an ordered one, forming the incommensurately modulated structures (R = Nd−Eu).…”

Section: Resultsmentioning

confidence: 90%

KEu(MoO₄)₂: Polymorphism, Structures, and Luminescent Properties

et al. 2015

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In this paper, with the example of two different polymorphs of KEu(MoO 4 ) 2 , the influence of the ordering of the A-cations on the luminescent properties in scheelite related compounds (A′,A″) n [(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 α-phase and a monoclinic high temperature β-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 (23) o , 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 Eu 3+ network is characteristic for the α-phase, while a 3-dimensional Eu 3+-framework is observed for the β-phase structure. The luminescent properties of KEu(MoO 4 ) 2 samples prepared under different annealing conditions were measured, and the relation between their optical properties and their structures is discussed.

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Section: Resultsmentioning

confidence: 90%

KEu(MoO₄)₂: Polymorphism, Structures, and Luminescent Properties

et al. 2015

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“…The crystal structures of KR(MoO 4 ) 2 (R = rare earth elements) can be separated into two extensive groups: a scheelite-type group and a nonscheelite KY(MoO 4 ) 2 -type group. ,, Such a scheme was shown for the first time in ref . However, it was revised later. ,,, The following three groups of scheelite-type modifications can be distinguished: (1) tetragonal or monoclinic phases with random distribution of K + and R 3+ cations, ,− (2) triclinic α-phases (SG P 1̅) with a α-KEu(MoO 4 ) 2 -type structure and ordered K + and R 3+ up to R = Dy, ,− and (3) monoclinic incommensurately modulated β-phases with complete , or partial ordering of K + and R 3+ cations.…”

Section: Discussionmentioning

confidence: 99%

KTb(MoO₄)₂ Green Phosphor with K⁺-Ion Conductivity: Derived from Different Synthesis Routes

et al. 2021

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The influence of different synthesis routes on the structure and luminescent properties of KTb(MoO 4 ) 2 (KTMO) was studied. KTMO samples were prepared by solid-state, hydrothermal, and Czochralski techniques. These methods lead to the following different crystal structures: a triclinic scheelite-type α-phase is the result for the solid-state method, and an orthorhombic KY(MoO 4 ) 2 -type γ-phase is the result for the hydrothermal and Czochralski techniques. The triclinic α-KTMO phase transforms into the orthorhombic γ-phase when heated at 1273 K above the melting point, while KTMO prepared by the hydrothermal method does not show phase transitions. The influence of treatment conditions on the average crystallite size of orthorhombic KTMO was revealed by X-ray diffraction line broadening measurements. The electrical conductivity was measured on KTMO single crystals. The orthorhombic structure of KTMO that was prepared by the hydrothermal method was refined using synchrotron powder X-ray diffraction data. K + cations are located in extensive two-dimensional channels along the c-axis and the a-axis. The possibility of K + migration inside these channels was confirmed by electrical conductivity measurements, where strong anisotropy was observed in different crystallographic directions. The evolution of luminescent properties as a result of synthesis routes and heating and cooling conditions was studied and compared with data for the average crystallite size calculation and the grain size determination. All samples' emission spectra exhibit a strong green emission at 545 nm due to the 5 D 4 → 7 F 5 Tb 3+ transition. The maximum of the integral intensity emission for the 5 D 4 → 7 F 5 emission under λ ex = 380 nm excitation was found for the KTMO crashed single crystal.

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Crystal structure of Scheelite-type potassium cerium bis(tetraoxomolybdate( VI)), KCe(MoO4)2

Abstract: CeKMo 2 O 8 ,tetragonal, I4

Cited by 2 publications

References 5 publications

KEu(MoO₄)₂: Polymorphism, Structures, and Luminescent Properties

KEu(MoO₄)₂: Polymorphism, Structures, and Luminescent Properties

KTb(MoO₄)₂ Green Phosphor with K⁺-Ion Conductivity: Derived from Different Synthesis Routes

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Crystal structure of Scheelite-type potassium cerium bis(tetraoxomolybdate( VI)), KCe(MoO4)2

Abstract: CeKMo 2 O 8 ,tetragonal, I4

Cited by 2 publications

References 5 publications

KEu(MoO4)2: Polymorphism, Structures, and Luminescent Properties

KEu(MoO4)2: Polymorphism, Structures, and Luminescent Properties

KTb(MoO4)2 Green Phosphor with K+-Ion Conductivity: Derived from Different Synthesis Routes

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Product

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KEu(MoO₄)₂: Polymorphism, Structures, and Luminescent Properties

KEu(MoO₄)₂: Polymorphism, Structures, and Luminescent Properties

KTb(MoO₄)₂ Green Phosphor with K⁺-Ion Conductivity: Derived from Different Synthesis Routes