Electronics structures of Rb,Cs and some of their metallic oxides studied by photoelectron spectroscopy

Photoemission measurements with He and Ne resonance lines and Al Kα radiation are reported on bulk samples of the alkali metals Rb, Cs, their suboxides Cs₇O, Cs₁₁O₃ and (Cs₁₁O₃)Rb₇. For comparison, the Hel spectrum of the “normal” oxide Cs₂O is added. The occurrence of ionic clusters in a metallic matrix is typical for the suboxides. Binding energies, Auger transitions, and electron concentrations are discussed. The spectra of the suboxides show a narrow non-bonding oxygen 2p band at 2.7 eV. Different binding energies are found for Cs atoms in the clusters and for the atoms in the metallic regions of (Cs₁₁O₃)Cs₁₀. The compound Cs₁₁O₃ consists of ionic [Cs₁₁O₃]^5? clusters, which are bound by 5 free electrons in accordance with the chemical bond model.     

Ionization energies of cesium and cesium oxide clusters

The vertical ionization potentials of 7 cesium and 86 oxidized cesium clusters were determined using the technique of photoionization mass spectrometry. The spectra were obtained using a tunablecw dye laser for clusters in a mass range 1 to 2024 amu. The vertical ionization potentials (IP) are presented as a function of size and composition. The ionization energies of cesium clusters, Cs_n, decrease with cluster size. Unusually low IP were observed for the enneamer, Cs₉, and for the cesium monoxide Cs₁₁ O. With increasing oxidation of the cesium metal clusters the IP decreases (suboxides) reaches a minimum at Cs(Cs₂O)_n and then increases (superoxides).     

Keggin-type cesium salt of first series transition metal-substituted phosphomolybdates: one-pot easy synthesis,structural, and spectral analysis

The Keggin-type cesium salt of transition metal-substituted phosphomolybdates, Cs₅[PCo(H₂O)Mo₁₁O₃₉]?·?6H₂O (1) and Cs₅[PMn(H₂O)Mo₁₁O₃₉]?·?6H₂O (2), were synthesized from commercially available H₃PMo₁₂O₄₀. The compounds were characterized by thermal, structural, and spectroscopic techniques. X-ray structural analysis reveals that, in these isostructural disordered compounds, the transition metal (Co/Mn) and Mo atoms are distributed over 12 positions. The presence of Co/Mn atoms was confirmed by powder XRD, FT-IR, DR-UV-Vis, ESR, and ³¹P NMR studies.     

Neue Elpasolithvertreter mit CoIII: Cs2KCoF6, Rb2KCoF6, Rb2NaCoF6 (mit einer Notiz über Cs2NaCoF6)

New Elpasolithes with Co^III: Cs₂KCoF₆, Rb₂KCoF₆, Rb₂NaCoF₆ (with a Notice on Cs₂NaCoF₆) New prepared are the compounds Cs₂KCoF₆ (a = 8.97₉ Å), Rb₂KCoF₆ (a = 8.80₉ Å), Rb₂NaCoF₆ (a = 8.42₁ Å), all cubic Elpasolithes, as well as Cs₂NaCoF₆ (Cs₂NaCrF₆?type, hexagonal with a = 6.23, c = 30.32 Å) all of light blue colour. Cs₂KCoF₆ (72.7–299.7 K) and Rb₂KCoF₆ (71.4–298.0 K) have been measured magnetically. The Madelung Part of Lattice Energy (MAPLE) is calculated and discussed.     

Crystal structure and some thermodynamic characteristics of cesium silicate Cs6Si10O23

Crystals of cesium silicate Cs₆Si₁₀O₂₃ were prepared upon the crystallization of glass Cs₂O · 4SiO₂. The crystal structure of Cs₆Si₁₀O₂₃ was determined by single-crystal X-ray diffraction (space group P $\bar 6$ 2m, a = 9.578(5) Å, c = 4.155(5) Å, Z = 0.5, 269 F(hkl), R = 0.0424). The three-dimensional tetrahedral silicate framework in Cs₆Si₁₀O₂₃ is similar to that in Rb₆Si₁₀O₂₃ (space group P $\bar 6$ 2m, a = 9.475(5) Å, c = 8.200(5) Å) in which layers formed by 12-membered rings of silicon-oxygen tetrahedra may be distinguished. However, while in the rubidium silicate structure the vertices of the tetrahedra neighboring in a layer point to opposite directions, in cesium silicate these tetrahedra are disordered as regards the arrangement of vertices either upward or downward relative to the layer plane. The random disorder results in a smaller unit cell parameter c in Cs₆Si₁₀O₂₃ compared to Rb₆Si₁₀O₂₃. The compound melts congruently; the melting temperature and the enthalpy of melting of the crystal are 1208 ± 1 K and 156.2 ± 15 kJ/mol, respectively.     

Solubility in the systems Rb2SO4-H2SO4-H2O and Cs2SO4-H2SO4-H2O at 25°

Conclusions The solubility of rubidium and cesium sulfates in aqueous solutions of sulfuric acid was studied at 25°. Rubidium sulfate forms the compounds 3Rb₂SO₄· H₂SO₄, Rb₂SO₄ · H₂SO₄, Rb₂SO₄·3H₂SO₄ and Rb₂SO₄·7H₂SO₄ with sulfuric acid, while cesium sulfate forms the compounds Cs₂SO₄·H₂SO₄; Cs₂SO₄·3H₂SO₄ and Cs₂SO₄ · 7H₂SO₄.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 6, pp. 1166–1170, June, 1968.     

Synthese und Struktur eines Caesiumoxonitridomonowolframates(VI), Cs7[WN1,5O2,5]2

Synthesis and Crystal Structure of a Cesium Oxo Nitrido Monotungstate(VI), Cs₇[WN_1.5O_2.5]₂ Mixtures of tungsten powder and WO₃ react with an excess of CsNH₂ in autoclaves at 650 °C to yield hygroscopic yellow crystals of cesium oxo nitrido tungstate(VI) Cs₇[WN_1.5O_2.5]₂ besides Cs₆[W₂N₄O₃] [1]. After the reaction the crystals are embedded in cesium metal (from thermal decomposition of CsNH₂), which was washed out by liquid ammonia. The crystals allowed a successful X‐ray structure determination. Cs₇[WN_1.5O_2.5]₂ crystallizes in the space group P2₁/c with the lattice parameters a = 6.766(1) Å, b = 11.205(3) Å, c = 22.299(4) Å, β = 91.05(1)° and Z = 4. The crystal structure is built up by isolated tetrahedra [WX₄] with X = N, O, which are separeted by cesium cations.     

Über Hexafluoroferrate(III): Cs2TlFeF6, Cs2KFeF6, Rb2KFeF6, Rb2NaFeF6 und Cs2NaFeF6

On Hexafluoroferrates(III): Cs₂TlFeF₆, Cs₂KFeF₆, Rb₂KFeF₆, Rb₂NaFeF₆, and Cs₂NaFeF₆ New prepared are the compounds Cs₂TlFeF₆ (a = 9.21₁ Å), Cs₂KFeF₆ (a = 9.04₁ Å), Rb₂KFeF₆ (a = 8.86₈ Å) and Rb₂NaFeF₆ (a = 8.46 ₄Å) all cubic Elpasolithes as well as Cs₂NaFeF₆ (Cs₂NaCrF₆?type, hexagonal with a = 6.28₁, c = 30.53₂ Å), all colourless. Cs₂KFeF₆ was measured magnetically (70–297,2 K). The spectra of reflection were measured (9000–36000 cm^?1). The Madelung Part of Lattice Energy, MAPLE, is calculated and discussed.     

Quantum-Chemical Simulation of the Proton Transport in Mono- and Disubstituted Salts with Octahedral Anions

Salts Rb₂H₃IO₆, Rb₄H₆I₂O₁₂, and Rb₄H₂I₂O₁₀ and adducts CsHSO₄· H₆TeO₆ and Cs₂SO₄· H₆TeO₆ of the salt · acid type are calculated within density functional theory B3LYP. Calculations for Te, I, Rb, and Cs atoms make use of basis set LanL2DZ complemented by polarization d,p-functions and pseudopotential LanL2; for Li, O, and H atoms, basis set 6-31G** is used. The activation energy for the proton migration is commensurate with that for the water molecule abstraction in the salts and is smaller in rubidium salts than in cesium salts.     

Identifying characteristics of the fibrous cesium titanate Cs2Ti5O11

Electron microscopic studies of the fibrous cesium titanate Cs₂Ti₅O₁₁ reveal characteristic features not readily apparent using standard methods of phase analysis (optical microscopy, X-ray diffraction). Its fibrous needle-like laths give characteristic diffuse scattering, complicating the indexing of electron diffraction patterns. The hydrated form Cs₂Ti₅O₁₁ · (1 + x)H₂O (0.5 < x < 1) is typically grossly distorted, resembling pyrolytic graphite. Cs₂Ti₅O₁₁ is unstable when stored under ambient conditions at room temperature for ∼1 year when disproportionation into Cs₂Ti₄O₉ and Cs₂Ti₆O₁₁ · nH₂O occurs. The structure of Cs₂Ti₅O₁₁ and intergrowth defects in the unstable forms have been studied by high-resolution electron microscopy. It is evident that these phases would be undesirable in titanate ceramics such as SYNROC, which are designed for immobilization of radioactive ¹³⁷C_s.     

Mobility of protons in 12-phosphotungstic acid and its acid and neutral salts

The proton mobility in 12-phosphotungstic heteropolyacid (PWA) and its salts (Cs₂HPW₁₂O₄₀·xH₂O, Cs₃PW₁₂O₄₀·xH₂O, (NH₄)₃PW₁₂O₄₀·xH₂O) was investigated by impedance spectroscopy and nuclear magnetic resonance with pulsed field gradient under wide range of relative humidity. Values of two diffusion components observed in PWA as well as in its acid cesium salt differ in one order of magnitude. Also there are two components in the impedance spectra of these compounds. Thus, we suggest, the proton transport take place both inside the grains and along its boundaries. Self-diffusion coefficients, observed in the neutral cesium and ammonium salts, are close to each other and equal to the fast diffusion coefficient in acid cesium salt. At the same time, there is the only relaxation component in the impedance spectra of neutral salts. Thus, it can be concluded, that in case of neutral salts of PWA, there is no proton transport inside the grains of these compounds, and their high proton conductivity caused by fast proton transport along the grain boundaries.     

Crystal growth,structural and electrical properties of rubidium and cesium vanadium oxide bronzes

Crystals of the following compounds were grown by cathodic reduction of CsV⁵⁺O or RbV⁵⁺O metls: Cs_0.3V₂O₅ (A), Cs₂V₅O₁₃ (B), CsV₂O₅ (C), Rb_0.4V₂O₅ (D), Rb_0.37V₂O_∼4.8 (E) (a new orthorhombic compound) and Rb_2−xV_3+2xO_8+2x (F). The crystal symmetry and cell parameters of the Rb compounds (which were known for F only) were determined, as well as those of Rb_0.3V₂O₅, which has the structure of A. Magnetic susceptibility and ESR measurements confirm the intermediate valence in E. A, C, and E are semiconductors with activation energies in the range 0.07–0.2 eV. Cs_0.3V₂O₅ (A), in which V⁴⁺ and V⁵⁺ do not occupy distinct crystallographic sites, has the highest electrical conductivity.     

Effect of the Support on the Nature of Metal-Promoter Interactions in Ru-Cs<Superscript>+</Superscript>/MgO and Ru-Cs<Superscript>+</Superscript>-Al<Subscript>2</Subscript>O<Subscript>3</Subscript> Catalysts for Ammonia Synthesis

The Ru-Cs⁺/MgO and Ru-Cs⁺/γ-Al₂O₃ catalysts, which were prepared by an impregnation method using RuOHCl₃ and Cs₂CO₃ as precursor compounds and reduced with H₂ at 450°C, are characterized by X-ray diffraction, high-resolution transmission electron microscopy (with X-ray microanalysis), and X-ray photoelectron spectroscopy (XPS). The Cs⁺/MgO(Al₂O₃) systems, Ru-Cs⁺ black, and model systems prepared by cesium sputtering onto polycrystalline ruthenium foil are studied as reference samples. It is found that, in the Ru-Cs⁺/MgO sample, cesium is present as a Cs_{2 + x}O cesium suboxide, which weakly interacts with the support, localized on the surface of Ru particles or near them. In the case of Ru-Cs⁺/γ-Al₂O₃, cesium occurs as a species that is tightly bound to the support; this is likely surface cesium aluminate, which prevents promoter migration to Ru particles. The Ru-Cs⁺/MgO sample exhibits a considerable shift of the Ru3d line in the XPS spectra toward lower binding energies, as compared to the bulk metal. It is hypothesized that this shift is due to a decrease in the electron work function from the surface of ruthenium because of the polarizing effect of Cs⁺ ions in contact with Ru particles. Based on the experimental results, the great difference between the catalytic activities of the Ru-Cs⁺/MgO and Ru-Cs⁺/γ-Al₂O₃ systems in ammonia synthesis at 250–400°C and atmospheric pressure is explained.     

Synthese und Struktur von Cs11[(WN2,5O1,5)2](N3)2, ein Caesiumoxonitridomonowolframat(VI)-azid

Synthesis and Structure of Cs₁₁[(WN_2,5O_1,5)₂](N₃)₂, a Cesium Oxo Nitrido Monotungstate(VI) Azide Cs₁₁[(WN_2,5O_1,5)₂](N₃)₂ results from the reaction of a mixture of CsNH₂, W and WO₃ at 620 °C in autoclaves. It crystallizes monoclinic in the space group C2/m with the lattice parameters a = 12.421(4) Å, b = 11.568(6) Å, c = 10.516(4) Å, β = 118.71(3)° and Z = 4. The crystal structure is built up by isolated tetrahedra [WX₄] with X = N, O, which are connected by cesium cations. Between the cesium ions lie azide ions separated from the anions [WX₄]. The tungsten atoms and azide ions together build up the motif of a distorted arrangement of the CsCl structure type.     

New cesium titanate layer structures

A phase study of the Cs₂OTiO₂ system in the composition range 75–100 mole% TiO₂ and the temperature range 850–1200°C revealed the existence of two new cesium titanates, with compositions Cs₂Ti₅O₁₁ and Cs₂Ti₆O₁₃. The former compound undergoes a reversible hydration reaction below 200°C to form Cs₂Ti₅O₁₁ · (1 + x)H₂O, 0.5 < x < 1. The structures of the three phases have been determined. They are based on corrugated layers of edge-shared octahedra, with cesium ions (and H₂O) packing between the layers. In Cs₂Ti₆O₁₃, the layers are continuous in two dimensions, whereas in Cs₂Ti₅O₁₁ and Cs₂Ti₅O₁₁ · (1 + x)H₂O, the layers are periodically stepped to give 5-octahedra wide, corner-linked ribbons.     

Über Hexafluorovanadate(III). Cs2MVF6 und Rb2MVF6 (MTl,K und Na); mit einer Bemerkung über Na3VF6

On Hexafluorovanadates(III). Cs₂MVF₆ and Rb₂MVF₆ (M?Tl, K. and Na); with a Remark on Na₃VF₆ By heating the binary fluorides in a closed system we obtained Cs₂TlVF₆ (a = 9.23₄ Å), Cs₂KVF₆ (a = 9.04₇ Å), Rb₂KVF₆ (a = 8.85₅ Å) and Rb₂NaVF₆ (a = 8.46₈ Å), all cubic Elpasolithes of soft green colour as well as Cs₂NaVF₆ (hexagonal a = 6.24 Å, c = 30.58 Å, isotypic with Cs₂NaCrF₆) and Na₃VF₆ (monoclinic a = 5.51₃ Å, b = 5.72₁ Å, c = 7.96₃ Å, β = 90.4₇°, isotypic with Na₃AlF₆). VF₃ (3.0–296.2°K), Cs₂TlVF₆, Cs₂KVF₆ and Rb₂KVF₆ (all from 70–299°K) have been measured magnetically. The spectra of reflection in the range of 9 000 to 33 000 cm^?1 of VF₃ and the new quaternary fluorides are measured and discussed. The Madelung Part of Lattice Energy (MAPLE) is calculated and discussed.     

Röntgenographische Untersuchungen in den Systemen GeO2-{K2O,Rb2O,Cs2O}

Zusammenfassung Folgende GeO₂-reiche Alkaligermanate wurden aufgefunden und röntgenographisch hinsichtlich der Gitterparameter charakterisiert: K₂Ge₈O₁₇ und Rb₂Ge₈O₁₇ (isotyp), Rb₂Ge₇O₁₅ und Cs₂Ge₅O₁₁. Die Existenz der seinerzeit als Pentagermanate beschriebenen isotypen Verbindungen von K, Rb, Cs und Tl sowie deren Gitterparameter werden bestätigt, doch ergab eine ausführliche Prüfung an gut kristallisierten Produkten zusammen mit den genau bestimmten Dichtewerten eine geringfügige Verschiebung im Verhältnis Me₂O/GeO₂, entsprechend einer Formel Me₂Ge₆O₁₃.

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The GeO₂-rich regions of alkaline germanate systems have been examined by X-rays. The compounds K₂Ge₈O₁₇ and Rb₂Ge₈O₁₇ (isostructural), Rb₂Ge₇O₁₅ and Cs₂Ge₅O₁₁ have been detected and characterized by their lattice parameters. The existence as well as the cell dimensions of the isotypic compounds previously described as pentagermanates have been corroborated; a detailed investigation of completely crystallized material gives strong evidence for a lower Me₂O/GeO₂-ratio, in accordance with precise density measurements. Thus a formulaMe ₂Ge₆O₁₃ (Me=K, Rb, Cs, Tl) has to be assumed.

     

Physical chemistry of rubidium uranomolybdates in the Rb<Subscript>2</Subscript>O-UO<Subscript>3</Subscript>-MoO<Subscript>3</Subscript> system

Rubidium uranomolybdates Rb₂UMo₂O₁₀ · 3H₂O, Rb₂UMo₂O₁₀, Rb₆UMo₄O₁₈, Rb₆U₂Mo₄O₂₁, Rb₂U₂MoO₁₀, Rb₂U₂Mo₃O₁₆, and Rb₂U₆Mo₇O₄₀ · 2H₂O have been synthesized and characterized by reaction calorimetry. The calorimetric data have been used to calculate the standard enthalpies of formation for the these compounds.     

Über quaternäre Oxoplumbate(IV). Zur Kenntnis von Rb2Li14[Pb3O14] und Cs2Li14[Pb3O14]

On Quaternary Oxoplumbates(IV). On the Knowledge of Rb₂Li₁₄[Pb₃O₁₄] and Cs₂Li₁₄[Pb₃O₁₄] For the first time, Rb₂Li₁₄[Pb₃O₁₄] and Cs₂Li₁₄[Pb₃O₁₄] have been prepared by heating of mixtures of Li₂O, β-?PbO₂”? and Rb₂PbO₃, Cs₂PbO₃ respectively with Li:Pb:A = 14:3:2, (A = Rb, Cs). [Ag-cylinders, sealed under vacuum in Duran-glass ampoule, 590 and 550°C, 40 d, powder (650°C, 200 d, single crystals of Rb₂Li₁₄[Pb₃O₁₄])]. Rb₂Li₁₄[Pb₃O₁₄] is nearly colourless with ivory nuance, Cs₂Li₁₄[Pb₃O₁₄] is pale yellow. According to powder and single crystal investigations, both are isotypic with K₂Li₁₄[Pb₃O₁₄]. Structure refinement of Rb₂Li₁₄[Pb₃O₁₄]: 1015 symmetry independent reflexions, four-circle-diffraktometer PW 1100 (Fa. Philips), ω-scan, MoKα, R = 5.73%, R_W = 5.33%, absorption not considered, space group Immm with a = 1284.71(9), b = 793.90(4), c = 727,35(5) pm, d_x-ray = 4.99 g · cm^?3, d_pyc = 5.01 g · cm^?3, Z = 2. Cs₂Li₁₄[Pb₃O₁₄]: a = 1295.28(12), b = 796.69(8), c = 732.44(7) pm, d_x-ray = 5.31 g · cm^?3, d_pyc = 5.28 g · cm^?3, Z = 2. The Madelung Part of Lattice Energy, MAPLE, Effective Coordination Numbers, ECoN, these via Mean Effective Ionic Radii, MEFIR, are calculated.     

Two Pyrophosphates with Large Birefringences and Second-Harmonic Responses as Ultraviolet Nonlinear Optical Materials

Two new pyrophosphates nonlinear optical (NLO) materials, Rb₃PbBi(P₂O₇)₂ ( I ) and Cs₃PbBi(P₂O₇)₂ ( II ), were successfully designed and synthesized. Both compounds exhibit large NLO effects and birefringences. Material I presents the scarce case of possessing the coexistence of large birefringence (0.031 at 1064 nm and 0.037 at 532 nm) and second harmonic generation (SHG) response (2.8× potassium dihydrogen phosphate (KDP)) in ultraviolet NLO phosphates and its SHG is the largest in the phase-matching (PM) pyrophosphates. Both I and II have three-dimensional (3D) crystal structures composed of corner-shared RbO₁₂ (CsO₁₁), RbO₁₀ (CsO₁₀), BiO₆, PbO₇ (PbO₆) and P₂O₇ groups, in which P₂O₇ and PbO₇ (PbO₆) units form an alveolate [PbPO]_∞ skeleton frame. Theoretical calculations reveal that the P−O, Bi−O and Pb−O units are mainly responsible for the moderate birefringence and large SHG efficiency of I .