Browse
Submit Data
Databases
API
Help

Dataset Information

34 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

Two new glaserite-type orthovanadates: Rb₂KDy(VO₄)₂ and Cs_1.52K_1.48Gd(VO₄)₂.

ABSTRACT: The crystal structures of dirubidium potassium dysprosium bis-(vanadate), Rb₂KDy(VO₄)₂, and caesium potassium gadolinium bis-(vanadate), Cs_1.52K_1.48Gd(VO₄)₂, were solved from single-crystal X-ray diffraction data. Both compounds, synthesized by the reactive flux method, crystallize in the space group P m1 with the glaserite structure type. VO₄ tetra-hedra are linked to DyO₆ or GdO₆ octa-hedra by common vertices to form sheets stacking along the c axis. The large twelve-coordinate Cs⁺ or Rb⁺ cations are sandwiched between these layers in tunnels along the a and b axes, while the K⁺ cations, surrounded by ten oxygen atoms, are localized in cavities.

SUBMITTER: Rghioui L

PROVIDER: S-EPMC6659331 | biostudies-literature | 2019 Jul

REPOSITORIES: biostudies-literature

ACCESS DATA

Json Xml

Publications

Two new glaserite-type orthovanadates: Rb2KDy(VO4)2 and Cs1.52K1.48Gd(VO4)2.

Rghioui Lotfi L El Ammari Lahcen L Assani Abderrazzak A Saadi Mohamed M

Acta crystallographica. Section E, Crystallographic communications 20190621 Pt 7

The crystal structures of dirubidium potassium dysprosium bis-(vanadate), Rb2KDy(VO4)2, and caesium potassium gadolinium bis-(vanadate), Cs1.52K1.48Gd(VO4)2, were solved from single-crystal X-ray diffraction data. Both compounds, synthesized by the reactive flux method, crystallize in the space group P m1 with the glaserite structure type. VO4 tetra-hedra are linked to DyO6 or GdO<sub ...[more]

PMID: 31392021

Similar Datasets

MIn(HAsO4)2 (M = K, Rb, Cs): three new hydrogen-arsenates adopting two different structure types.

Project description:Potassium indium bis-[hydrogen arsenate(V)], KIn(HAsO4)2, rubidium indium bis-[hydrogen arsenate(V)], RbIn(HAsO4)2, and caesium indium bis-[hydrogen arsenate(V)], CsIn(HAsO4)2, were grown under mild hydro-thermal conditions (T = 493 K, 7-8 d). KIn(HAsO4)2 adopts the KSc(HAsO4)2 structure type (space group C2/c), while RbIn(HAsO4)2 and CsIn(HAsO4)2 crystallize in the space group R-3c and are the first arsenate representatives of the RbFe(HPO4)2 structure type. All three compounds have tetra-hedral-octa-hedral framework topologies. The M+ cations, located in voids of the respective framework, are slightly disordered in RbIn(HAsO4)2. In KIn(HAsO4)2, there is a second K-atom position with a very low occupancy, which may suggest that the K atom can easily move in the channels extending along [101].

| S-EPMC5730323 | biostudies-literature

Growth, Properties, and Theoretical Analysis of M2LiVO4 (M = Rb, Cs) Crystals: Two Potential Mid-Infrared Nonlinear Optical Materials.

Project description:Mid-Infrared nonlinear optical (Mid-IR NLO) crystals with excellent performances play a particularly important role for applications in areas such as telecommunications, laser guidance, and explosives detection. However, the design and growth of high performance Mid-IR NLO crystals with large NLO efficiency and high laser-damage threshold (LDT) still face numerous fundamental challenge. In this study, two potential Mid-IR NLO materials, Rb2LiVO4 (RLVO) and Cs2LiVO4 (CLVO) with noncentrosymmetric structures (Orthorhombic, Cmc21) were synthesized by high-temperature solution method. Thermal analysis and powder X-ray diffraction demonstrate that RLVO and CLVO melt congruently. Centimeter sized crystals of CLVO have been grown by the top-seeded solution growth method. RLVO and CLVO exhibit strong second harmonic generation (SHG) effects (about 4 and 5 times that of KH2PO4, respectively) with a phase-matching behavior at 1.064 μm, and a wide transparency range (0.33-6.0 μm for CLVO). More importantly, RLVO and CLVO possess a high LDT value (~28 × AgGaS2). In addition, the density functional theory (DFT) and dipole moments studies indicate that the VO4 anionic groups have a dominant contribution to the SHG effects in RLVO and CLVO. These results suggest that the title compounds are promising NLO candidate crystals applied in the Mid-IR region.

| S-EPMC5432528 | biostudies-literature

Order-disorder charge density wave instability in the kagome metal (Cs,Rb)V3Sb5.

Project description:The origin of the charge density wave phases in the kagome metal compound AV3Sb5 is still under great scrutiny. Here, we combine diffuse and inelastic x-ray scattering to identify a 3-dimensional precursor of the charge order at the L point that condenses into a CDW through a first order phase transition. The quasi-elastic critical scattering indicates that the dominant contribution to the diffuse precursor is the elastic central peak without phonon softening. However, the inelastic spectra show a small broadening of the Einstein-type phonon mode on approaching TCDW. Our results point to the situation where the Fermi surface instability at the L point is of order-disorder type with critical growth of quasi-static domains. The experimental data indicate that the CDW consists on an alternating Star of David and trihexagonal distortions and its dynamics goes beyond the classical weak-coupling scenario and is discussed within strong-electron phonon coupling and non-adiabatic models.

| S-EPMC9950456 | biostudies-literature

Rb/Cs-Modified P2 Na0.7Mn0.8Mg0.2O2: Application in Sodium-Ion Batteries.

Project description:To meet the growing energy demands, sodium-ion batteries can be a potential substitute for lithium-ion batteries. Here, we report the solid-state synthesized alkali Rb- and Cs-modified Na0.7Mn0.8Mg0.2O2, which adopts hexagonal P63/mmc symmetry. The second charge/discharge capacity for the as-synthesized Rb- and Cs-modified P2 Na0.7Mn0.8Mg0.2O2 are 118/114 and 130/125 mA h g-1, which reduces to 62/62 and 77/76 mA h g-1, respectively, after 100 cycles. In situ synchrotron X-ray diffraction data illustrate that a solid solution reaction occurs for most of the charge/discharge process in both cases. Rb-modified P2 Na0.7Mn0.8Mg0.2O2 shows multiple phases near the charged state, whereas Cs-modified P2 Na0.7Mn0.8Mg0.2O2 shows the formation of a new phase (P2new) at about 2.5 V and multiple phases below 1.7 V. The P2new phase is found to evolve in conjunction with the original P2 phase until about 1.7 V, where the P2 reflection appears to split into multiple reflections and a single P2 phase is recovered at 2.7 V on the second charge. The Cs-modified P2 Na0.7Mn0.8Mg0.2O2 shows better energy density in comparison with the K- and Rb-modified P2 Na0.7Mn0.8Mg0.2O2 and comparable to the parent P2 Na0.7Mn0.8Mg0.2O2. Ex situ scanning electron microscopy images show no noticeable change in surface morphology of the Cs-modified Na0.7Mn0.8Mg0.2O2, whereas in the case of Rb-modified P2 Na0.7Mn0.8Mg0.2O2, rods and irregular-shaped particles are observed after the 100th cycle. The solid-state 23Na NMR shows a distinct shift in the peak position in comparison with the parent P2 Na0.7Mn0.8Mg0.2O2, and two Na environments are observed with no local disordering in Rb- and Cs-modified P2 Na0.7Mn0.8Mg0.2O2 samples. Overall, this article illustrates the influence of using larger alkali ions to modify P2 Na0.7Mn0.8Mg0.2O2 and compares this scheme in terms of phase transitions and electrochemical performance.

| S-EPMC6648630 | biostudies-literature

Cs3VO(O2)2CO3: an exceptionally thermostable carbonatoperoxovanadate with an extremely large second-harmonic generation response.

Project description:A novel nonlinear optical (NLO) carbonatoperoxovanadate, Cs3VO(O2)2CO3, with an exceptionally high thermostability was successfully synthesized by introducing highly polarizable Cs+ cations and inorganic polydentate carbonate anions into asymmetric peroxovanadates. The structure of Cs3VO(O2)2CO3 is composed of distorted [VO(O2)2CO3]3- units and charge balancing Cs+ cations. The title compound exhibits the largest NLO intensity ever found in the current carbonate NLO materials, i.e., 23.0 times that of KH2PO4 (KDP). The remarkably strong second-harmonic generation (SHG) response originates from the synergistic effect of the exceedingly polarizable Cs+ cations, distortive polyhedra of the V5+ cation, delocalized π orbitals in CO3 groups, and distorted localized π orbitals in O2 groups. First-principles calculations indicated that introducing the polarizable cations into peroxovanadates not only induces the enhancement of the SHG response but also improves the thermal stability of the framework.

| S-EPMC6301201 | biostudies-literature

Two new Rb-Ga arsenates: RbGa(HAsO4)2 and RbGa2As(HAsO4)6.

Project description:The crystal structures of hydro-thermally synthesized (T = 493 K, 7-9 d) rubidium gallium bis-[hydrogenarsenate(V)], RbGa(HAsO4)2, and rubidium digallium arsenic(V) hexa-[hydrogenarsenate(V)], RbGa2As(HAsO4)6, were solved by single-crystal X-ray diffraction. Both compounds have tetra-hedral-octa-hedral framework topologies. The M+ cations are located in channels of the respective framework. RbGa(HAsO4)2 crystallizes in the RbFe(HPO4)2 structure type (Rc), while RbGa2As(HAsO4)6 adopts the structure type of RbAl2As(HAsO4)6 (Rc), which represents a modification of the RbFe(HPO4)2 structure type. In this modification, one third of the M3+O6 octa-hedra are replaced by AsO6 octa-hedra, and two thirds of the voids in the structure, which are usually filled by M+ cations, remain empty to achieve charge balance.

| S-EPMC6127722 | biostudies-literature

Syntheses and crystal structures of a new family of hybrid perovskites: C5H14N2·ABr3·0.5H2O (A = K, Rb, Cs).

Project description:The syntheses and crystal structures of three hybrid perovskites, viz. poly[1-methyl-piperizine-1,4-diium [tri-μ-bromido-potassium] hemihydrate], {(C5H14N2)[KBr3]·0.5H2O} n , (I), poly[1-methyl-piperizine-1,4-diium [tri-μ-bromido-rubidium] hemihydrate], {(C5H14N2)[RbBr3]·0.5H2O} n , (II), and poly[1-methyl-piperizine-1,4-diium [tri-μ-bromido-caesium] hemihydrate], {(C5H14N2)[CsBr3]·0.5H2O} n , (III), are described. These isostructural (space group Amm2) phases contain a three-dimensional, corner-sharing network of distorted ABr6 octa-hedra (A = K, Rb, Cs) with the same topology as the classical perovskite structure. The doubly protonated C5H14N2 2+ cations occupy inter-stices bounded by eight octa-hedra and the water mol-ecules lie in square sites bounded by four octa-hedra. N-H⋯Br, N-H⋯(Br,Br), N-H⋯O and O-H⋯Br hydrogen bonds consolidate the structures.

| S-EPMC6690442 | biostudies-literature

Unveiling the Origin of Alkali Metal (Na, K, Rb, and Cs) Promotion in CO2 Dissociation over Mo2C Catalysts.

Project description:Molybdenum carbide (Mo2C) is a promising and low-cost catalyst for the reverse water-gas shift (RWGS) reaction. Doping the Mo2C surface with alkali metals can improve the activity of CO2 conversion, but the effect of these metals on CO2 conversion to CO remains poorly understood. In this study, the energies of CO2 dissociation and CO desorption on the Mo2C surface in the presence of different alkali metals (Na, K, Rb, and Cs) are calculated using density functional theory (DFT). Alkali metal doping results in increasing electron density on the Mo atoms and promotes the adsorption and activation of CO2 on Mo2C; the dissociation barrier of CO2 is decreased from 12.51 on Mo2C surfaces to 9.51-11.21 Kcal/mol on alkali metal-modified Mo2C surfaces. Energetic and electronic analyses reveal that although the alkali metals directly bond with oxygen atoms of the oxides, the reduction in the energy of CO2 dissociation can be attributed to the increased interaction between CO/O fragments and Mo in the transition states. The abilities of four alkali metals (Na, K, Rb, and Cs) to promote CO2 dissociation increase in the order Na (11.21 Kcal/mol) < Rb (10.54 Kcal/mol) < Cs (10.41 Kcal/mol) < K (9.51 Kcal/mol). Through electronic analysis, it is found that the increased electron density on the Mo atoms is a result of the alkali metal, and a greater negative charge on Mo results in a lower energy barrier for CO2 dissociation.

| S-EPMC9181518 | biostudies-literature

Phase Segregation in Cs-, Rb- and K-Doped Mixed-Cation (MA)x(FA)1-xPbI3 Hybrid Perovskites from Solid-State NMR.

Project description:Hybrid (organic-inorganic) multication lead halide perovskites hold promise for a new generation of easily processable solar cells. Best performing compositions to date are multiple-cation solid alloys of formamidinium (FA), methylammonium (MA), cesium, and rubidium lead halides which provide power conversion efficiencies up to around 22%. Here, we elucidate the atomic-level nature of Cs and Rb incorporation into the perovskite lattice of FA-based materials. We use 133Cs, 87Rb, 39K, 13C, and 14N solid-state MAS NMR to probe microscopic composition of Cs-, Rb-, K-, MA-, and FA-containing phases in double-, triple-, and quadruple-cation lead halides in bulk and in a thin film. Contrary to previous reports, we have found no proof of Rb or K incorporation into the 3D perovskite lattice in these systems. We also show that the structure of bulk mechanochemical perovskites bears close resemblance to that of thin films, making them a good benchmark for structural studies. These findings provide fundamental understanding of previously reported excellent photovoltaic parameters in these systems and their superior stability.

| S-EPMC5719467 | biostudies-literature

Tunable resistivity of correlated VO2(A) and VO2(B) via tungsten doping.

Project description:Applications of correlated vanadium dioxides VO2(A) and VO2(B) in electrical devices are limited due to the lack of effective methods for tuning their fundamental properties. We find that the resistivity of VO2(A) and VO2(B) is widely tunable by doping them with tungsten ions. When x < 0.1 in V1-xWxO2(A), the resistivity decreases drastically by four orders of magnitude with increasing x, while that of V1-xWxO2(B) shows the opposite behaviour. Using spectroscopic ellipsometry and X-ray photoemission spectroscopy, we propose that correlation effects are modulated by either chemical-strain-induced redistribution of V-V distances or electron-doping-induced band filling in V1-xWxO2(A), while electron scattering induced by disorder plays a more dominant role in V1-xWxO2(B). The tunable resistivity makes correlated VO2(A) and VO2(B) appealing for next-generation electronic devices.

| S-EPMC7297976 | biostudies-literature