Non-isothermal crystallization of K<Subscript>2</Subscript>O·TiO<Subscript>2</Subscript>·3GeO<Subscript>2</Subscript> glass

The crystallization of K₂O·TiO₂·3GeO₂ glass under non-isothermal condition was studied. In powdered glass with particle sizes less than 0.15 mm, surface crystallization was dominant and an activation energy of crystal growth of E _a,s=327±50 kJ mol⁻¹ was calculated. In the size range 0.15 to 0.45 mm, both surface and volume crystallization occurred. For particle sizes >0.45 mm, volume crystallization dominated with spherulitic morphology of the crystals growth and E _a,v=359±64 kJ mol⁻¹ was calculated.     

Crystal structure of glycine phosphite C<Subscript>2</Subscript>H<Subscript>5</Subscript>NO<Subscript>2</Subscript>·H<Subscript>3</Subscript>PO<Subscript>3</Subscript>

Single crystal X-ray diffraction study of glycine phosphite C₂H₅NO₂·H₃PO₃ was performed (monoclinic, space group P2₁/c, a = 7.401(3) Å, b = 8.465(3) Å, c = 9.737(3) Å; β = 100.73(5)°, Z = 4). It has been found that one of hydrogen atoms is located at the centre of symmetry forming two strong hydrogen bonds to yield H₄P₂O ₆ ^?2 dimers, while another hydrogen atom is statistically disordered over two positions and organizes the dimers into an infinite corrugated chain. The ordering of this hydrogen atom position and/or displacement of the other one from the centre of symmetry will lead to the loss of symmetry centre and lowering of the point group symmetry from C_2h to piezo-active group C₂ or C _s .     

Synthesis and thermal properties of Co<Subscript>2</Subscript>P<Subscript>2</Subscript>O<Subscript>7</Subscript> · 6H<Subscript>2</Subscript>O

The dependence of solid phase composition on the main parameters of the interaction in the CoSO₄-K₄P₂O₇-H₂O system was studied. The synthesis conditions were determined and a crystalline cobalt(II) diphosphat of the composition Co₂P₂O₇ · 6H₂O was synthesized. Its thermal properties were studied. The composition and the intervals, wherein the thermally stable products of partial and complete dehydration of Co₂P₂O₇ · 6H₂O are formed, were specified. The final heat treatment product, anhydrous α-Co₂P₂O₇, was identified and a sequence of the solid phase thermal transformations accompanying its formation was established.     

From Cs<Subscript>2</Subscript>Mo<Subscript>6</Subscript>Cl<Subscript>14</Subscript> to Cs<Subscript>2</Subscript>Mo<Subscript>6</Subscript>Cl<Subscript>14</Subscript>·H<Subscript>2</Subscript>O and Vice Versa: Crystal Chemistry Investigations

We report here the synthesis, the crystal structure and the luminescent properties of the new cluster compounds Cs₂Mo₆Cl₁₄·H₂O and Cs₂Mo₆Br₁₄·H₂O. Single-crystal X-ray diffraction performed on Cs₂Mo₆Cl₁₄·H₂O indicates that the compound crystallizes in the monoclinic space group C2/c with refined cell parameters a = 19.578 Å, b = 15.151 Å, c = 9.347 Å, and β = 115.64°. The structure can be described from discrete \(\left[ {{\text{Mo}}_{ 6} {\text{Cl}}^{\text{i}}_{ 8} {\text{Cl}}^{\text{a}}_{ 6} } \right]^{ 2- }\) anionic cluster units arranged in a “A–A’–A–A’” pseudo prismatic stacking parallel to (b, c) plane with both Cs⁺ cations and water molecules located between the layers. Moreover, the centric character of the trigonal structure of Cs₂Mo₆Cl₁₄ was also studied by combination of single-crystal X-ray diffraction and both X-ray and neutron powder diffraction. The results suggest an important influence of the sample preparation on the symmetry of the crystal structure. The crystal structure relationship between the \(\left[ {{\text{Mo}}_{ 6} {\text{Cl}}^{\text{i}}_{ 8} {\text{Cl}}^{\text{a}}_{ 6} } \right]^{ 2- }\) anionic cluster unit arrangements in Cs₂Mo₆Cl₁₄ and Cs₂Mo₆Cl₁₄·H₂O is discussed. Finally, the characterization of the luminescent properties of Cs₂Mo₆X₁₄ and Cs₂Mo₆X₁₄·H₂O (X = Cl, Br) indicates that emission profile is comparable regardless existence of water molecule in the crystal structure.     

Crystal structure of Na<Subscript>4</Subscript>[Na<Subscript>2</Subscript>Cr<Subscript>2</Subscript>(C<Subscript>2</Subscript>O<Subscript>4</Subscript>)<Subscript>6</Subscript>] · 10H<Subscript>2</Subscript>O

Single crystals of the Na₄[Na₂Cr₂(C₂O₄)₆] · 10H₂O complex were synthesized for the first time. The structure of the complex was determined by X-ray diffraction analysis. The compound crystallizes in the monoclinic crystal system with the unit cell parameters a = 17.290(4) Å, b = 12.521(3) Å, c = 15.149(3) Å, β = 100.45(3)°, Z = 4, space group Cc. Anionic layers [NaCr(C₂O₄)₃] _2n ^4n? can be distinguished in the crystal structure of the complex. The Na⁺ cations and water molecules, involved in the formation of a hydrogen bond network, are located between the anionic layers.     

Crystal structure of Ba<Subscript>3</Subscript>[UO<Subscript>2</Subscript>(C<Subscript>2</Subscript>O<Subscript>4</Subscript>)<Subscript>2</Subscript>(NCS)]<Subscript>2</Subscript> · 9H<Subscript>2</Subscript>O

Single crystals of Ba₃[UO₂(C₂O₄)₂(NCS)]₂ · 9H₂O are synthesized and studied by X-ray diffraction. The crystals are orthorhombic, space group Fddd, Z = 16, and the unit cell parameters are a = 16.253(3) Å, b = 22.245(3) Å, c = 39.031(6) Å. The main crystal structural units are mononuclear complex groups [UO₂(C₂O₄)₂NCS]^3? of the crystal-chemical family (AB ₂ ⁰¹ M¹ (A = UO ₂ ²⁺ , B⁰¹ = C₂O ₄ ^2? , M¹ = NCS^?) of the uranyl complexes linked into a three-dimensional framework by electrostatic interactions and hydrogen bonds involving oxalate ions and water molecules.     

Neutron diffraction study of Rb<Subscript>2</Subscript>UO<Subscript>2</Subscript>(SeO<Subscript>4</Subscript>)<Subscript>2</Subscript> · 2D<Subscript>2</Subscript>O

A powder of deuterated rubidium diselenatouranylate dihydrate Rb₂UO₂(SeO₄)₂ · 2D₂O has been studied by neutron diffraction. The compound is orthorhombic, space group Pna2₁, with the following unit cell parameters: a = 13.654(2) Å, b = 11.863(2) Å, c = 7.625(1) Å, Z = 4, R _F = 3.77, R _I = 6.12, and χ² = 2.21. Basic structure units are [UO₂(SeO₄)₂ · D₂O]^2? layers belonging to the AB ₂ ² M¹ crystal-chemical group (A = UO ₂ ²⁺ , B² = SeO ₄ ^2? , M¹ = D₂O) of uranyl complexes. The hydrogen atoms if the water molecules involved in the layer form intralayer hydrogen bonds with the terminal oxygen atoms of selenate ions. The outer-sphere water molecules are coordinated to the rubidium ions and are involved in hydrogen bonding with oxygen atoms of neighboring [UO₂(SeO₄)₂ · D₂O]^2? layers.     

V<Subscript>3</Subscript>O<Subscript>7</Subscript> · H<Subscript>2</Subscript>O oxide nanostructures: Synthesis and study

Nanorods of orthorhombic V₃O₇ · H₂O with the parameters a = 16.805 Å, b = 9.428 Å, and c = 3.660 Å are prepared under hydrothermal conditions (T = 180–190°C, τ = 30–40 h) from the V₂O₅ · nH₂O/H₂C₂O₄ · 2H₂O composite. The particle diameter is 40–70 nm, and the length is several micrometers. The IR spectra, electric conductivity, and thermal properties of the nanorod powder are studied. In air V₃O₇ · H₂O begins to decompose at temperatures above 150°C, and at 350°C nanobelts V₂O₅ 40–100 nm wide and 40 µm long are formed. A mechanism of nanostructure formation is suggested.     

Structure and thermal decomposition of Cs<Subscript>2</Subscript>HPO<Subscript>4</Subscript> · 2H<Subscript>2</Subscript>O

The thermal transformations of disubstituted cesium orthophosphate crystal hydrate under heating in air up to 400°C have been studied. The dehydration process occurs in two stages with the loss of 0.6 water molecules at 60?100°C and 1.4 water molecules at 100?160°C. Anhydrous Cs₂HPO₄ is stable up to 300°C and is completely converted into cesium pyrophosphate Cs₄P₂O₇ at 330°C. The structure of Cs₂HPO₄ · 2H₂O has been determined. The compound crystallizes in monoclinic space group P2₁/c and has the unit cell parameters a = 7.4761(5) Å, b = 14.2125(8) Å, c = 7.9603(6) Å, β = 116.914(5)°, V = 754.20(9) ų, and Z = 4 at?123°C. An earlier unknown polymorph of Cs₄P₂O₇ has been found. According to X-ray powder diffraction data, hexagonal space group Р6₃ has been proposed for the formed pyrophosphate.     

Effects of acid treatment on electrochemical properties of Li<Subscript>2</Subscript>MnO<Subscript>3</Subscript>·LiNi<Subscript>0.5</Subscript>Co<Subscript>0.45</Subscript>Fe<Subscript>0.05</Subscript>O<Subscript>2</Subscript> cathode materials

A new composite, Li₂MnO₃·LiNi_0.5Co_0.45Fe_0.05O₂, can be synthesized by a solid-state method and preconditioned with 5 wt% HCl, H₂SO₄, or H₃PO₄ solution to achieve H⁺/Li⁺ exchange. The effects of acid treatment on the structure, morphology, and electrochemical properties of Li₂MnO₃·LiNi_0.5Co_0.45Fe_0.05O₂ cathode materials are analyzed. The X-ray powder diffraction patterns imply that the hexagonal α-NaFeO₂ structure (space group R\(\bar{3}\)m) of the materials is not changed by the acid treatment. The scanning electron microscope images show that particles become spherical with smooth surfaces after acid treatment, and the Brunauer–Emmett–Teller analysis reveals that the specific surface area increases. The charge–discharge test demonstrates that acid-treated Li₂MnO₃·LiNi_0.5Co_0.45Fe_0.05O₂ cathode materials deliver higher initial coulombic efficiencies than untreated material, owing to the improvement of the catalytic reduction activity of oxygen released during the initial charge process. Furthermore, Li₂MnO₃·LiNi_0.5Co_0.45Fe_0.05O₂ treated with HCl displays the best electrochemical performance, with the acid treatment improving the initial coulombic efficiency from 66.0 to 82.2%. Thus, acid treatment can effectively improve the electrochemical performance of electrode materials in Li-ion batteries.     

Synthesis and crystal structure of [UO<Subscript>2</Subscript>CrO<Subscript>4</Subscript>(C<Subscript>5</Subscript>NH<Subscript>5</Subscript>COO)] · H<Subscript>2</Subscript>O

Synthesis and X-ray diffraction study of [UO₂CrO₄(C₅NH₅COO)] · H₂O crystals were performed. The compound crystallizes in the monoclinic system with the unit cell parameters a = 7.5025(3) Å, b = 11.5188(6) Å, c = 13.0518(6) Å, β = 97.877(4)°, V = 1117.29(9) ų, space group P2₁/n, Z = 4, R = 0.0263. The structure is formed by three [UO₂CrO₄(C₅NH₅COO)] layers parallel to (10\(\bar 1\)). The coordination polyhedron of uranium atoms is a pentagonal bipyramid, whose apices are occupied by oxygen atoms of uranyl, three chromate groups, and two molecules of isonicotinic acid. Crystal chemical formula of the [UO₂CrO₄(C₅NH₅COO)] layer can be represented as AT³B², where A = UO ₂ ²⁺ , T³ = CrO ₄ ^2? , and B² = C₅NH₅COO molecules. The isonicotinic acid molecules are in the form of zwitterions.     

Crystal structure of Na<Subscript>3</Subscript>(NH<Subscript>4</Subscript>)<Subscript>2</Subscript>[Ir(SO<Subscript>3</Subscript>)<Subscript>2</Subscript>Cl<Subscript>4</Subscript>]·4H<Subscript>2</Subscript>O

The complex Na₃(NH₄)₂[Ir(SO₃)₂Cl₄]·4H₂O was examined with single crystal X-ray diffraction and IR spectroscopy. Crystal data: a = 7.3144(4) Å, b = 10.0698(5) Å, c = 12.3748(6) Å, β = 106.203(1)°, V = 875.26(8) ų, space group P2₁/c, Z = 2, d _calc = 2.547 g/cm³. In the complex anion two trans SO ₃ ^2? groups are coordinated to iridium through the S atom. The splitting of O-H bending vibrations of crystallization water molecules and N-H ones of the ammonium cation is considered in the context of different types of interactions with the closest neighbors in the structure.     

Crystal structure of [(C<Subscript>6</Subscript>H<Subscript>5</Subscript>)<Subscript>4</Subscript>P][Ni(B<Subscript>9</Subscript>C<Subscript>2</Subscript>H<Subscript>11</Subscript>)<Subscript>2</Subscript>]·CCl<Subscript>4</Subscript>

A new compound containing the tetraphenylphosphonium cation and the nickel(III) bisdicarbollyl anion, [(C₆H₅)₄P][Ni(B₉C₂H₁₁)₂]·CCl₄, was synthesized and investigated by XRD at room temperature (295 K). Crystal data: C₂₉H₄₂B₁₈PCl₄Ni, M = 816.69, monoclinic, space group P2/c; unit cell parameters a = 13.5873(6) Å, b = 7.1475(2) Å, c = 20.7829(8) Å, β = 94.4595(13)°, V = 2012.2(2) ų, Z = 2, d _calc = 1.348 g/cm³. The structure was solved by direct and Fourier methods and refined by the full-matrix least squares method in an anisotropic (isotropic for H) approximation to the final R ₁ = 0.0466 for 3055 I _hkl ≥ 2σ _I of 23,655 reflections collected and 5618 independent I _hkl (Bruker X8 APEX diffractometer, λMoK _α).     

Crystal structure of Cs[(UO<Subscript>2</Subscript>)<Subscript>2</Subscript>(C<Subscript>2</Subscript>O<Subscript>4</Subscript>)<Subscript>2</Subscript>(OH)] · H<Subscript>2</Subscript>O

Single crystals of Cs[(UO₂)₂(C₂O₄)₂(OH)] · H₂O were synthesized and structurally studied using X-ray diffraction. The compound crystallizes in monoclinic space group P2₁/m, Z = 2, with the unit cell parameters a = 5.5032(4) Å, b = 13.5577(8) Å, c = 9.5859(8) Å, β = 97.012(3)°, V = 709.86(9) ų, R = 0.0444. The main building units of crystals are [(UO₂)₂(C₂O₄)₂(OH)]^? layers of the A₂K ₂ ⁰² M² (A = UO ₂ ²⁺ , K⁰² = C₂O ₄ ^2? , and M² = OH^?) crystal-chemical family. Uranium-containing layers are linked into a three-dimensional framework via electrostatic interactions with outer-sphere cations and hydrogen bonds with water molecules.     

Synthesis and properties of (VO)<Subscript>0.09</Subscript>V<Subscript>0.18</Subscript>Mo<Subscript>0.82</Subscript>O<Subscript>3</Subscript> · 0.54H<Subscript>2</Subscript>O microrods

The (VO)_0.09V_0.18Mo_0.82O₃ · 0.54H₂O microrods of hexagonal symmetry system with the unit cell parameters a = 10.586 Å and c = 3.698 Å were obtained for the first time under hydrothermal conditions (T = 160°C, τ = 30?50 h). Particles were 1–2 μm in diameter and up to 45 μm in length. The compound is thermally stable up to 469°C. The core-electron Mo3d, V2p, and O1s and valence-band X-ray photoelectron spectra and IR spectra of the samples were studied. The molybdenum atoms in the complex oxide have the oxidation state Mo⁶⁺. The vanadium atoms introduced into the h-MoO₃ lattice in molybdenum positions have the oxidation state V⁵⁺. Approximately one-third of vanadium atoms as vanadyl ions (VO)²⁺ are located in the channels of h-MoO₃ lattice, thus stabilizing the latter.     

Proton conductivity and spectral data of Cs<Subscript>2</Subscript>HPO<Subscript>4</Subscript> · 2H<Subscript>2</Subscript>O

The Cs₂HPO₄ · 2H₂O single crystals synthesized from an aqueous solution containing equimolar amounts of H₃PO₄ and Cs₂CO₃ were studied by impedance and IR spectroscopy, X-ray diffraction analysis, and differential scanning calorimetry (DSC). The IR spectra were analyzed in accordance with the structural data, and the absorption bands were assigned. The proton conductivity was studied at temperatures in the range 20–250°C. The conductivity of dehydrated Cs₂HPO₄ was low, ~10^–5–10^–9 S cm^–1 at 90–250°C with an activation energy of conductivity E _a = 1.1 eV at 130–250°C. The processes determining the character of the temperature dependence of conductivity were consistent with the DSC and thermogravimetry data. According to these data, dehydration of the crystalline hydrate Cs₂HPO₄ · 2H₂O starts at 60°C and occurs in three stages, forming Cs₂HPO₄ · 1.5H₂O below 100°C; anhydrous Cs₂HPO₄ at t > 160°C, which is stable up to 300°C; and Cs₄P₂O₇ above 330°C.     

Study of the kinetic aspects of formation of calcium monosilicate in the model system CaSO<Subscript>4</Subscript>·2H<Subscript>2</Subscript>O-Na<Subscript>2</Subscript>O·SiO<Subscript>2</Subscript>

The possibility and kinetic aspects of formation of X-ray amorphous calcium monosilicate in the model system CaSO₄·2H₂O-Na₂O·SiO₂ at room temperature were studied.     

<Superscript>35</Superscript>Cl NQR for the SbCl<Subscript>3</Subscript> complex with aniline,SbCl<Subscript>3</Subscript>·NH<Subscript>2</Subscript>C<Subscript>6</Subscript>H<Subscript>5</Subscript>

The temperature dependence of the ³⁵Cl NQR frequencies and spin-lattice relaxation times has been investigated for a trigonal-bipyramidal vn complex SbCl₃·NH₂C₆H₅. Thermally activated motion of chlorine atoms (pseudorotation) was not revealed in the complex, in contrast to the vπ complexes of SbCl₃ with related molecular structures. The high potential barrier of pseudorotation in the aniline complex is likely to be due to the unusually high nonequivalence of Sb-Cl chemical bonds.     

[Ca(OPPh<Subscript>3</Subscript>)<Subscript>5</Subscript>][Mo<Subscript>6</Subscript>(μ<Subscript>3</Subscript>-Cl)<Subscript>8</Subscript>Cl<Subscript>6</Subscript>] · OPPh<Subscript>3</Subscript>: Synthesis and crystal structure

A solvatothermal reaction of the octahedral cluster molybdenum complex (H₃O)₂[Mo₆(μ₃-Cl)₈Cl₆] · 6H₂O with CaCl₂ · 6H₂O and OPPh₃ in acetonitrile gave the known polymeric complex trans-[{Ca(OPPh₃)₄}{Mo₆(μ₃-Cl)₈Cl₆}]_∞. However, a closer examination revealed that this system also produces a novel cluster complex, [Ca(OPPh₃)₅][Mo₆(μ₃-Cl)₈Cl₆] · OPPh₃, which was isolated and characterized by X-ray diffraction.