Hydrothermal synthesis of germanium vanadate layered compounds

We measured nuclear forward scattering of synchrotron radiation by the 68.7 keV nuclear resonance of 73Ge with a half-life . The Debye temperatures of CaGeO3 in the wollastonite, garnet and perovskite phases were determined to be 386(20) K, 437(20) K and 507(20) K, respectively, and 309(20) K and 459(11) K for GeO2 in the quartz and rutile phases, respectively. The isomer shift is clearly dependent on the Ge valence but not directly on the coordination geometry. The so far unknown magnetic moment μe of the 68.7 keV excited state of 73Ge is determined to be . Time domain 73Ge Mössbauer spectroscopy with the 68.7 keV resonance is feasible for isomer shift and Debye temperature measurements but so far neither electric quadrupole nor magnetic hyperfine interactions could be observed.

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“…However, quadrupole hyperfine interactions might be observed in compounds with larger electric-field gradients, e.g. Ge-V layered compounds [16].…”

Section: Results and Discussion -mentioning

confidence: 99%

Nuclear forward scattering by the 68.7 keV state of ⁷³ Ge in CaGeO ₃ and GeO ₂

Simon

Sergueev

Perßon

et al. 2013

EPL

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“…Unlike the silicates, which exist exclusively in tetrahedral sites, germanates can adopt a variety of four-, five-, and six-coordinate environments. , They also have a tendency to form large multinuclear units with complex structures. Despite these interesting structural properties, they are relatively unexplored relative to the silicates, except as potential new open-framework analogues to zeolites. , Interestingly, vanadium germanates also form a series of unusual compounds whereby the vanadium and germanium ions can act as both building block and coordinated metal ion. − …”

Section: Introductionmentioning

confidence: 99%

Polar Materials with Isolated V⁴⁺ S = 1/2 Triangles: NaSr₂V₃O₃(Ge₄O₁₃)Cl and KSr₂V₃O₃(Ge₄O₁₃)Cl

et al. 2017

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Crystals of ASr 2 V 3 O 3 (Ge 4 O 13 )Cl, A = Na, K, were synthesized from high-temperature hydrothermal brines, and their structure and magnetic properties were investigated. These materials present a unique combination of a salt inclusion lattice, a polar crystal structure, and isolated V 4+ (S = 1/2) trimer magnetic clusters. The structures consist of a trimeric V 3 O 13 unit based on V 4+ (S = 1/2), having rigorous 3fold symmetry with a short V−V separation of 3.325(3) Å. The trinuclear V 4+ units are formed by three edge shared VO 6 octahedra sharing a central μ 3 -oxygen atom, which also imparts a polar sense on the structure. The V 3 O 13 units are isolated from one another by tetranuclear Ge 4 O 13 units, which are similarly arranged in a polar fashion, providing a unique opportunity to study the magnetic behavior of this triangular d 1 system as a discrete unit. Magnetization measurements indicate spin-1/2 per V atom at high temperature, and spin-1/2 per V 3 trimer at low temperature, where two V moments in each triangle are antiferromagnetically aligned and the third remains paramagnetic. The crossover between these two behaviors occurs between 20 and 100 K and is well-described by a model incorporating strong antiferromagnetic intra-trimer interactions and weak but nonzero inter-trimer interactions. More broadly, the study highlights the ability to obtain new materials with interesting structure−property relationships via chemistry involving unconventional solvents and reaction conditions.

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“…In the past few years, only four germanium vanadates were reported such as layered compounds (C 6 H 18 N 2 )Ge 2 V 4 O 12 (OH) 2 Á 2H 2 O and CsGeV 2 O 6 (OH) templated by cations [17], and discrete clusters of (pipH 2 ) 4 pipH) 4 [18]. We seek to incorporate the organic ligand into the germanium vanadate skeleton.…”

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confidence: 99%