Defect Scheelite-Type Lanthanoid(III) Ortho-Oxomolybdates(VI) Ln0.667[MoO4] (Ln = Ce, Pr, Nd, and Sm) and Their Relationship to Zircon and the NaTl-Type Structure

Schustereit, Tanja; Müller, S.; Schleid, Thomas; Hartenbach, Ingo

doi:10.3390/cryst1040244

Cited by 17 publications

(10 citation statements)

References 21 publications

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“…Redox processes between Ce 3+ and Mo 6+ were never observed, neither in syntheses of chloride derivatives of cerium oxidomolybdates4 nor in cerium oxidomolybdates of various compositions, e.g. Ce 2 Mo 2 O 9 14. Bond valence calculations15,16 for the title compounds support this statement providing values of +3 (±0.1) and +6 (±0.1) for the valences of the cerium and the molybdenum cations, respectively.…”

Section: Methodsmentioning

confidence: 97%

Syntheses, Crystal Structures, and Twinning of the Isotypic Rare‐Earth Metal Bromide Ortho‐Oxidomolybdates LaBrMoO₄ and CeBrMoO₄

Hartenbach

Henning

Schleid

et al. 2012

Zeitschrift anorg allge chemie

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Solid‐state reactions of La2O3, LaBr3, and MoO3 in molar ratios of 1:1:3 lead to single crystals of LaBrMoO4 among a few by‐products, which emerge from redox reactions of Br– with hexavalent molybdenum. To obtain the analogous cerium compound, Ce2O3 was synthesized in situ by using CeO2 and Ce in a 3:1 molar ratio. The two rare‐earth metal bromide ortho‐oxidomolybdates(VI) REBrMoO4 (RE = La and Ce) crystallize isotypically in the monoclinic space group Pc (a = 982 – 977 pm, b ≈ 581 pm, c = 810 – 803 pm, β ≈ 90°, Z = 4). In the crystal structure, two crystallographically unique RE3+ cations are present, both with similar coordination environments of three plus one Br– and six O2– anions in the shape of distorted tetracapped trigonal prisms. The two distinguishable Br– anions both display coordination spheres of three plus one RE3+ cations each, building up distorted tetrahedra. These are fused together via four common edges to form anti‐PbO‐type 2∞{[BrRE$\rm^{e}_{4/4}$]2+} layers (e = edge‐connecting) parallel to the (100) plane. Two crystallographically different oxidomolybdate(VI) units are also found in the structure, which can be best described as strands of apically vertex‐shared [MoO5]4– trigonal bipyramids along [001] represented by the formula 1∞{[MoO$\rm^{e}_{4/4}$O$\rm^{e}_{4/4}$]2–} (v = vertex‐connecting, t = terminal). The aforementioned 2∞{[BrRE$\rm^{e}_{4/4}$]2+} layers and the 1∞ {[MoO$\rm^{e}_{4/4}$O$\rm^{e}_{4/4}$]2–} chains are alternately stacked along the a axis. The peculiarity of this structure is expressed by the position of the Mo6+ cations, which are not situated in the center of the bipyramids, but reside offset in a trigonal pyramid. Since both the (Mo1)6+ and the (Mo2)6+ cations are located in the same partial tetrahedron, relative to the triangular plane of the trigonal bipyramid, a structure description in a non‐centrosymmetric space group is immanent. Both title compounds display a twinned crystal structure with strong similarities to those of the chloride homologues REClMoO4 (RE = La – Pr) and LaClWO4.

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Section: Methodsmentioning

confidence: 97%

Syntheses, Crystal Structures, and Twinning of the Isotypic Rare‐Earth Metal Bromide Ortho‐Oxidomolybdates LaBrMoO₄ and CeBrMoO₄

Hartenbach

Henning

Schleid

et al. 2012

Zeitschrift anorg allge chemie

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“…16 For either application, as a dielectric material or for the immobilization of nuclear waste, the efficacy of the material will depend on its stability. Material stability is again related to material properties such as crystallinity, phase purity, and distribution of the luminescent probe, 9 or radionuclide, respectively.…”

Section: Introductionmentioning

confidence: 99%

Characterization of powellite-based solid solutions by site-selective time resolved laser fluorescence spectroscopy

et al. 2013

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We present a comprehensive study of the solid solution system Ca 2 (MoO 4 ) 2 -NaGd(MoO 4 ) 2 on the molecular scale, by means of site-selective time resolved laser fluorescence spectroscopy (TRLFS). Eu 3+ is used as a trace fluorescent probe, homogeneously substituting for Gd 3+ in the solid solution crystal structure. Site-selective TRLFS of a series of polycrystalline samples covering the whole composition range of the solid solution series from 10% substitution of Ca 2+ to the NaGd end-member reveals it to be homogeneous throughout the whole range. The trivalent ions are incorporated into the powellite structure in only one coordination environment, which exhibits a very strong ligand-metal interaction. Polarizationdependent measurements of a single crystal of NaGd(Eu)(MoO 4 ) 2 identify the coordination geometry to be of C 2v point symmetry. The S 4 symmetry of the Ca site within the powellite lattice can be transformed into C 2v assuming minor motion in the first coordination sphere.

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“…Although dipolar interactions appear to be more classical than their exchange-coupled counterparts, it has been shown that on a square or diamond lattice, quantum fluctuations can map long-ranged dipolar interactions to a two-dimensional Ising model [5][6][7]. The LiRF 4 family is special as the rare-earth ions are arranged in a slightly distorted diamond-like structure making them intriguing to study in relation to order by disorder phenomena [8].For the case of a dipolar-coupled Ising ferromagnet, the theoretical upper critical dimension D * = 3 and the mean-field calculations actually apply quite well as shown, for instance, in LiHoF 4 [9]. This is despite the significant role of hyperfine interactions around the quantum phase transition [10,11].…”

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confidence: 99%

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confidence: 99%

Dimensional Reduction in Quantum Dipolar Antiferromagnets

et al. 2016

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We report ac susceptibility, specific heat, and neutron scattering measurements on a dipolar-coupled antiferromagnet LiYbF 4 . For the thermal transition, the order-parameter critical exponent is found to be 0.20(1) and the specific-heat critical exponent −0.25ð1Þ. The exponents agree with the 2D XY=h 4 universality class despite the lack of apparent two-dimensionality in the structure. The order-parameter exponent for the quantum phase transitions is found to be 0.35(1) corresponding to ð2 þ 1ÞD. These results are in line with those found for LiErF 4 which has the same crystal structure, but largely different T N , crystal field environment and hyperfine interactions. Our results therefore experimentally establish that the dimensional reduction is universal to quantum dipolar antiferromagnets on a distorted diamond lattice. DOI: 10.1103/PhysRevLett.116.197202 Critical phenomena near continuous phase transitions do not depend on the microscopic details of systems but only on the symmetry of the order parameter and interactions and the spatial dimensionality [1]. Such universality for classical thermal transitions has been thoroughly demonstrated with various physical systems over decades while nowadays a similar line of effort is actively pursued for zero-temperature quantum transitions [2][3][4]. Comparing experimental observations with theoretical models has been particularly successful for magnetic insulators that could be simply modeled by short-ranged, exchange-coupled spins on a lattice. Although dipolar interactions appear to be more classical than their exchange-coupled counterparts, it has been shown that on a square or diamond lattice, quantum fluctuations can map long-ranged dipolar interactions to a two-dimensional Ising model [5][6][7]. The LiRF 4 family is special as the rare-earth ions are arranged in a slightly distorted diamondlike structure making them intriguing to study in relation to order by disorder phenomena [8].For the case of a dipolar-coupled Ising ferromagnet, the theoretical upper critical dimension D Ã ¼ 3 and the meanfield calculations actually apply quite well as shown, for instance, in LiHoF 4 [9]. This is despite the significant role of hyperfine interactions around the quantum phase transition [10,11]. Recently, quantum and classical critical properties of a long-range, dipolar-coupled antiferromagnet could be investigated for the first time with LiErF 4 [12]. It was discovered that the specific-heat and order-parameter critical exponents, α ¼ −0.28ð4Þ and β T ¼ 0.15ð2Þ, for the thermal transition are totally different from the mean-field predictions of α ¼ 0 and β T ¼ 0.5. Instead, these exponent values suggest a 2D XY=h 4 universality class, despite the absence of any apparent two dimensionality in the structure of the system. This intriguing dimensional reduction was further corroborated by the β H ¼ 0.31ð2Þ for the quantum transition induced by applying a longitudinal magnetic field, which corresponds to ð2 þ 1ÞD, as expected from quantum-classical mapping [4]. Whether t...

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Defect Scheelite-Type Lanthanoid(III) Ortho-Oxomolybdates(VI) Ln0.667[MoO4] (Ln = Ce, Pr, Nd, and Sm) and Their Relationship to Zircon and the NaTl-Type Structure

Cited by 17 publications

References 21 publications

Syntheses, Crystal Structures, and Twinning of the Isotypic Rare‐Earth Metal Bromide Ortho‐Oxidomolybdates LaBrMoO₄ and CeBrMoO₄

Syntheses, Crystal Structures, and Twinning of the Isotypic Rare‐Earth Metal Bromide Ortho‐Oxidomolybdates LaBrMoO₄ and CeBrMoO₄

Characterization of powellite-based solid solutions by site-selective time resolved laser fluorescence spectroscopy

Dimensional Reduction in Quantum Dipolar Antiferromagnets

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Defect Scheelite-Type Lanthanoid(III) Ortho-Oxomolybdates(VI) Ln0.667[MoO4] (Ln = Ce, Pr, Nd, and Sm) and Their Relationship to Zircon and the NaTl-Type Structure

Cited by 17 publications

References 21 publications

Syntheses, Crystal Structures, and Twinning of the Isotypic Rare‐Earth Metal Bromide Ortho‐Oxidomolybdates LaBrMoO4 and CeBrMoO4

Syntheses, Crystal Structures, and Twinning of the Isotypic Rare‐Earth Metal Bromide Ortho‐Oxidomolybdates LaBrMoO4 and CeBrMoO4

Characterization of powellite-based solid solutions by site-selective time resolved laser fluorescence spectroscopy

Dimensional Reduction in Quantum Dipolar Antiferromagnets

Contact Info

Product

Resources

About

Syntheses, Crystal Structures, and Twinning of the Isotypic Rare‐Earth Metal Bromide Ortho‐Oxidomolybdates LaBrMoO₄ and CeBrMoO₄

Syntheses, Crystal Structures, and Twinning of the Isotypic Rare‐Earth Metal Bromide Ortho‐Oxidomolybdates LaBrMoO₄ and CeBrMoO₄