On the crystal structure type of 2 CsCl · CoCl2 · 2 H2O

The following three-component systems have been studied: CsCl MnCl₂ H₂O at 25 °C; 2 CsCl · CuCl₂ · 2 H₂O—2 CsCl · CoCl₂ H₂O at 10 °C and 2 CsCl · MnCl₂ · 2 H₂O—2 CsCl · CoCl₂ H₂O at 25 °C and 10 °C. It was established that Co²⁺-ions do not substitute isodimorphously the Cu²⁺-ions in the tetragonal salt 2 CsCl · CuCl₂ · 2 H₂O, whereas in the case of the triclinic salt 2 CsCl · MnCl₂ · 2 H₂O they can substitute isodimorphously the Mn²⁺-ions. The theoretical considerations supported by the results obtained allow to predict the existence of the double salt 2 CsCl · CoCl₂ · 2 H₂O as well as the type of its crystal structure — triclinic, space group P1 .     

Equilibrium coefficients of co‐crystallization of M2+ ions with MgSeO4·6H2O and their dependences on various physicochemical factors

Equilibrium co‐crystallization coefficients of low amounts of M²⁺ions (M²⁺ = {Ni²⁺, Cu²⁺, Co²⁺, Zn²⁺, Mn²⁺, Cd²⁺}) with MgSeO₄·6H₂O at 25 °C have been determined. Their values are comprised in the range: 0.058 (for Cd) < k_eq < 1.57 (for Co) and depend on some physicochemical and crystal chemical properties of both: co‐crystallizing salts (MSeO₄·nH₂O) and co‐crystallizing ions (M²⁺). These dependences are sometimes such strong, that they make it possible to derive simple formulae permitting estimation of k_eq coefficients at average error not exceeding 17%. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Über die Kristallstrukturdifferenzen der MeSO4 · nH2O-Salztypen

On the basis of the systematized data on the crystal structure of salts of the MeSO₄ · nH₂O type, where Me = Mg²⁺, Ni²⁺, Zn²⁺, Co²⁺, Fe²⁺, Cu²⁺ and n = 0–7, it is established that the differences in the structures of given chemical type metal sulphate crystal hydrates are determined by the nature of the metal ion. The differences in the crystal structure of the heptahydrate, as well as the existence or non-existence of crystal hydrates of some of the ions considered are explained with the electron configuration of the metal ions. The deformation trend of the octahedral coordination of the metal ions considered increases in the following way:      

The Double Salts Cd(C6H5COO)2 · CdCl2 and Cd(C6H5COO)2 · CdBr2

The systems Cd(C₆H₅COO)₂ CdCl₂ H₂O and Cd(C₆H₅COO) ₂ CdBr₂ H₂O have been studied at 25 °C. Formation of the double salts Cd(C₆H₅COO)₂ · CdCl₂ and Cd(C₆H₅COO)₂ · CdBr₂(1:1:0) has been established and their chemical individuality has been confirmed by chemical, X-ray, and DT-analyses. Proceeding from data on the structure of Cd(C₆H₅COO)₂ · 2 H₂O and the composition of the 1:1:0 double salts as well as using Pauling's rules for the most probable spacial disposition of the ions, the crystal structure type of the double salts obtained are predicted.     

Effect of Ca on HoPO4·nH2O (n = 1 and 2) crystallization from phosphoric acid solution

Ca‐substituted holmium phosphate, isomorphic with tetragonal form of HoPO₄·H₂O was synthesized by crystallization from boiling phosphoric acid (2 M H₃PO₄) solution containing 0.02M of Ho and 0–0.2 M of Ca. Calcium concentration, higher than 0.2 M Ca in solution resulted in biphasic solid crystallization: tetragonal HoPO₄·H₂O and orthorhombic HoPO₄·2H₂O. Ca incorporation in the solid according to substitution mechanism: Ca²⁺ + H⁺ ↔ Ho³⁺ was limited to ∼3 wt.% and was coupled with simultaneous incorporation of HPO₄²⁻. Ca for Ho substitution caused an expansion of the tetragonal unit cell of HoPO₄·H₂O, resulted from differences in the ionic radii (r_Ca > r_Ho). Effects of thermal treatment at 900 °C were as follows: (i) the orthorhombic admixture of HoPO₄·2H₂O re‐crystallized into tetragonal anhydrous HoPO₄, (ii) Ca–at first dissolved in crystal structure of HoPO₄·H₂O was expelled from it during re‐crystallization to form Ca(PO₃)₂, and that was associated with a contraction of the unit cell; a ‐ and c‐ axes went down to the level of Ca‐free anhydrous tetragonal form of HoPO₄. (iii) HPO₄²⁻ present in the solids as prepared underwent condensation according to reaction 2HPO₄²⁻ → P₂O₇⁴⁻ + H₂O. Scanning electron micrographs revealed significant changes in size and morphology of the crystals ranging from spherical globules of HoPO₄·H₂O formed in Ca‐free H₃PO₄ with increasing diameter in the presence of lower Ca concentration to rod‐like crystals organized in bundles resembling the “scheaf of wheat”, while crystallized from phosphoric acid solution with higher than 0.2 M Ca.     

On the (MgxNi1–x)SeO4 · 6 H2O and (MgxCu1–x)SeO4 · 5 H2O mixed crystal formation

Mixed crystals (Mg_xNi_1–x)SeO₄ · 6 H₂O and (Mg_xCu_1–x)SeO₄ · 5 H₂O have been prepared studying the solubility in the MgSeO₄–NiSeO₄–H₂O and MgSeO₄–CuSeO₄–H_2O systems at 25 °C. It has been shown that the monoclinic structure of MgSeO₄ · 6 H₂O is unstable and undergoes a change into tetragonal structure due to the included nickel ions (about 4 at %). The lattice parameters of (Mg_{xNi 1–x})SeO₄ 6 H₂O have been calculated. It has been established that the magnesium ions incorporate isodimorphously in the crystal structure of CuSeO₄ · 5 H₂O which could be an indication of the existence of MgSeO₄ · 5 H₂O isostructural with the triclinic CuSeO₄ 5 H₂O. The distribution coefficients of the salt components between the liquid and solid phases have been calculated.     

Synthesis and characterization of (NH4)2CuBr2Cl2·2H2O crystals

Single crystals of a new compound, (NH₄)₂CuBr₂Cl₂.2H₂O, were grown from saturated aqueous solution at room temperature by slow evaporation method. The grown crystals were characterized through elemental, powder XRD, thermal and DSC analyses and FTIR and far IR spectra. The elemental analysis and the decomposition pattern formulated using the TG‐DTG studies confirm the stoichiometry of the compound. The crystallinity of the compound is confirmed from the powder XRD pattern. A preliminary single crystal X‐ray diffraction structural analysis reveals that the title compound belongs to the orthorhombic system with a = 7.7466 Å, b = 7.783 Å and c = 8.1211 Å. The low temperature DSC shows thermal anomalies at –161.1, –156.5, –152.4, –145.2, –134, –18.5, and 1.4°C during the heating run and at –4.3, –54.8, –66.1, –90.6, –109.7 and –147.2 °C during the cooling run. The thermal hysterses indicate first order phase transitions in the title compound at these temperatures. The FTIR spectra were used to assign the characteristic vibrational frequencies due to NH₄⁺, CuX₄^2– ions and other chemical bonds. The effect of substitution of two bromine atoms on the phase transitions of a closely related crystal, diammonium tetrachloro cuprate dihydrate is also discussed. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Thermal expansion,pyroelectricity and linear optical properties of Li2SeO4·H2O and Li2SO4·H2O

Large single crystals of polar Li₂SeO₄·H₂O were grown at 343 K from aqueous solution. Temperature dependent thermal expansion coefficients of Li₂SeO₄·H₂O and Li₂SO₄·H₂O were determined within the temperature range 133 K–313 K and coefficients of the pyroelectric effect within the temperature range 183–343 K. Refractive indices between 365 nm and 1530 nm as well as unpolarized absorption spectra of Li₂SeO₄·H₂O and Li₂SO₄·H₂O were measured and phase‐matching curves for second harmonic generation were calculated. Both compounds allow type I and type II phase‐matching at wavelengths from about 650 nm to the near infrared region. (© 2003 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Electron Paramagnetic Resonance of VO2+ in M2Zn(SeO4)2 · 6H2O(M=K,Rb) Single Crystals

The EPR spectrum of VO²⁺ has been studied in single crystals of K₂Zn(SeO₄)₂ · 6H₂O and Rb₂Zn(SeO₄)₂ ∼ 6H₂O at ∼9.45 GHz. VO²⁺ substitutes for Zn²⁺ have preferential orientations in the lattice. The V = O of the intense vanadyl center is nearly along the longest Zn H₂O direction. Spin-Hamiltonian parameters have been evaluated from single crystal as well as from powder spectra.     

Hydrothermal synthesis and formation of 4ZnO·B2O3·H2O whiskers via a new route

4ZnO·B₂O₃·H₂O whiskers were prepared from 2ZnO·3B₂O₃·3.5H₂O under hydrothermal process at 160 °C for 10 h. The synthesized product was characterized by XRD, SEM, TG‐DSC and FT‐IR. SEM results showed that the synthesized 4ZnO·B₂O₃·H₂O whiskers' length was about 3–10 μm and the diameter was 0.2–0.3 μm. Further study on the whiskers' growth process and mechanism showed that the formation of the whiskers went through three stages and the morphology of 4ZnO·B₂O₃·H₂O changed from irregular particles to rod‐like structures and finally to whiskers. The variation of the morphology of the 4ZnO·B₂O₃·H₂O whisker with the concentration of the starting material was investigated. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Photoacoustic Spectroscopical Studies on L-Tyrosine and Pd(Tyr)2Cl · H2O Complex Crystal

The complex crystal of Pd(Tyr)₂Cl · H₂O was synthesized and its PA spectra (with L-tyrosine) were determined and explained. A method used to resolve the PA amplitude spectrum was suggested. With the phase spectrum of the complex, the PA absorption peaks were resolved by this method, and the non-radiative relaxation time of all absorption bands were calculated.     

Crystal Structure Study of Co(II) Complexes with 2,2′-(1,4-Ethylenedioxyl) Dibenzoic Acid-[Co · L · (H2O)3]n · nH2O· 0.2 nH2O

The structure ofS the title complex [Co. L. (H₂O)₃]_n. nH₂O. 0.2 nH₂O has been established by single crystal X-ray diffraction. Crystals of the complex are monoclinic, space group C2/c with cell constants α = 45.29(4), b=10.631(6), c = 8.015(6) Å, β = 90.65(8)°, Z = 8, D_c = 1.489 g. cm⁻³ The structure was solved and refined to R =0.0478 (wR = 0.0577). In the chain structure, Co(II) ions are hexacoordinated by 0 atoms in an octahedral arrangement. CoO₆ octahedra share corners (bridged) through O atoms of water, with each L^2--ligand binding two adjacent Co atoms.     

Crystal structure of chloro[1-hydroxyethane-1,1-diphosphonato(3−)]ditin(II) monohydrate Sn2(HL)Cl · H2O

The synthesis and X-ray structure analysis of Sn₂(HL)Cl · H₂O, where HL ^3? is the anion of 1-hydroxyethane-1,1-diphosphonic acid, are reported. The coordination polyhedra of two independent tin(II) atoms are the Sn(1)O₂Cl and Sn(2)O₃ trigonal pyramids, in which one of the vertices is occupied by a lone electron pair (Sn-O, 2.144–2.218 Å and Sn-Cl, 2.573 Å). The pyramids are complemented by weaker Sn?O and Sn?Cl contacts to form severely distorted (3 + 3) octahedra. The SnO₂Cl and SnO₃ pyramids are linked by the HL ^3? bridging ligands into the [Sn₂(HL)Cl]₆ cyclic molecules, which, in turn, are joined by additional Sn?O, Sn?Cl, O(H₂O)?O(L), and O(H₂O)?Cl contacts with each other and with crystallization water molecules into a three-dimensional framework.     

Crystalloluminescence and Mechanoluminescence Spectra of Ba(ClO3)2 · H2O and 2 K2SO4 · Na2SO4 Crystals

Crystalloluminescence and mechanoluminescence of Ba(ClO₃)₂ · H₂O and 2 K₂SO₄ · Na₂SO₄ crystals are investigated. The crystalloluminescence spectra are almost similar to the photoluminescence spectra; however, they differ completely from the mechanoluminescence spectra. The crystalloluminescence excitations may take place due to the various processes: (i) the recombination of ions, (ii) from amorphous to crystalline transition, (iii) from the phase change during the crystallization, and (iv) from the dielectric breakdown by the electric field produced due to the creation of microfracture during the crystal growth. It is concluded that the crystalloluminescence excitation in Ba(ClO₃)₂ · H₂O and 2K₂SO₄ · Na₂SO₄ crystals may be chemical in origin.     

Electron paramagnetic resonance of Gd3+ in Eu2Zn3(NO3)12·24H2O single crystals

Electron paramagnetic resonance of Gd³⁺ in Eu₂Zn₃(NO₃)₁₂·24H₂O single crystals is studied at ≈9.45 GHz and at 298 and 77 K. Gd³⁺ substitutes for the Eu³⁺ site. In addition to the allowed fine structure lines, forbidden transitions (ΔM = ±2,±3,±4,±5) are observed. The superposition model is applied to the zero‐field splitting parameter b₂⁰. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

The Thermal Decomposition of Polyhalite K2SO4 · MgSO4 · 2 CaSO4 · 2 H2O

The thermal decomposition of polyhalite (K₂SO₄ · MgSO₄ · 2 CaSO₄ · 2H₂O) was investigated by DSC/TG and X-ray powder diffraction. The decomposition of the polyhalite starts at 285 °C in releasing the crystal water within one step. Simultaneously the decomposition of the polyhalite into anhydrite and two solid solutions of the compositions K₂SO₄ · 1.76 MgSO₄ · 0.24 CaSO₄ and K₂SO₄ · 0.64 MgSO₄ · 1.36 CaSO₄ is taking place. The mechanism of decomposition runs through K₂SO₄ · MgSO₄ CaSO₄. This phase reacts immediately to the solid solutions, mentioned above.     

Structural features of a new [Fe(nicotinamide)2(H2O)4]·[Fe(H2O)6]·(SO4)2·2H2O complex

A new nicotinamide complex of Fe(II) cation was prepared by reaction between ferrous sulfate and nicotinamide in aqueous solution. The complex was characterized on the basis of elemental analysis, FT IR and UV–VIS spectroscopy, electrochemistry (cyclic voltammetry) and X–ray crystallography. The complex consists of the molecular composition of [Fe(nicotinamide)₂(H₂O)₄]· [Fe(H₂O)₆]·(SO₄)₂·2H₂O. The complex crystallizes in the monoclinic space group P 2₁/c [a = 12.862(3), b = 7.110(3), c = 16.382(3) Å; β = 95.79(2)°]. It has been proven that nicotinamide is coordinated to Fe(II) through the nitrogen atom of its heterocyclic ring. © 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim     

Growth of R 2 Me(SO4)2 · 6H2O single crystals with due regard for solubility diagrams of the R 2SO4-MeSO4-H2O systems (R = K, NH4; Me = Ni, Co)

The optimum conditions for growing R ₂ Me(SO₄)₂ · 6H₂O crystals are found from the analysis of the _{R 2} ⁺ SO₄-Me ²⁺SO₄-H₂O systems (R = K, NH₄; Me = Ni, Co) in the temperature range from 55 to 25°C. A new economical technology for growth of single crystals of double sulfate hexahydrates is developed, which allows the use of starting presynthesized solutions of hydrated or anhydrous K, Ni, Co, and (NH₄) sulfates. Transparent K₂Ni(SO₄)₂ · 6H₂O, K₂Co(SO₄)₂ · 6H₂O, and (NH₄)₂Ni(SO₄)₂ · 6H₂O crystals (35–55) × (25–40) × 10 mm in size are grown on seeds by the method of slow cooling.     

Synthesis and crystal structure of [CuCl(phen)2]3H3V10O28 · 7 H2O

The new compound, [CuCl(phen)₂]₃H₃V₁₀O₂₈ · 7 H₂O, was prepared by reaction of an aqueous KVO₃ solution (pH 3) with an aqueous solution of CuSO₄ · 5 H₂O in which 1,10‐phenanthroline (phen) and KCl were added. The crystal structure of the compound was determined, and the proton position in H₃V₁₀O₂₈^3– were calculated by the bond length/bond number method and also determined from difference electron density map. The protons are bound to colinearly arranged μ–OV₂ and μ–OV₃ groups which is the common protonation type in trihydrogen decavanadates. The structure crystallizes in P1 space group symmetry. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Growth kinetics and micromorphology of NH4Cl:Mn2+ crystals formed in the NH4Cl-MnCl2-H2O-CONH3 system

The growth kinetics and elementary growth processes on the surface of NH₄Cl:Mn²⁺ heterogeneous crystals formed in the NH₄Cl-MnCl₂-H₂O-CONH₃ system are experimentally studied. It is found that a change in the composition of complexes in an NH₄Cl crystal from Mn(NH₄)₂Cl₄ · 2H₂O to MnCl₂ · 2CONH₃ leads to the occurrence of a local maximum in the kinetic curve and a change in the shape of dislocation growth centers from flat to conical. The growth kinetics of {100} faces of heterogeneous NH₄Cl:Mn²⁺ crystals is described within the Bliznakov model using the Fowler-Guggenheim adsorption isotherm, which takes into account the lateral interaction of adsorbed particles.