Studies on the preparation and characterization of the Ce2(SO4)3 · 8(H,D)2O

Cerium Sulfate octohydrate crystals were crystallized from aqueous solutions under controlled conditions. The solubility measurements were carried out on temperatures between 10 and 80°. Thermoanalytical methods were applied for the study of the thermal behaviour of this compound. Raman spectra of polycrystalline Ce₂(SO₄)₃ · 8H₂O and Ce₂(SO₄)₃ · 8D₂O recorded at 80 K are reported. The vibrational modes have been assigned by comparing the spectrum of both compounds and using structural considerations.     

Preparation and studies of new crystals in the K3H(SO4)2-(NH4)3H(SO4)2-H2O system

To elucidate the effect of isomorphic substitution on the kinetics of phase transitions, single crystals of (K _x (NH₄)_1?x ) _m H _n (SO₄)_{(m + n)/2} · yH₂O solid solutions are grown from the K₃H(SO₄)₂-(NH₄)₃H(SO₄)₂-H₂O system, whose end members are known to undergo superprotonic phase transitions of fundamentally different kinetics. The chemical composition of the single crystals grown is determined by energy dispersive X-ray microanalysis. The thermal and optical behavior of (K,NH₄)₉H₇(SO₄)₈ · H₂O single crystals is studied in the temperature range 295–420 K and the crystal structure at 295 K is determined. A comparison of the results of the studies with data for crystal K₉H₇(SO₄)₈ · H₂O published earlier shows that the substitution of ammonium for potassium atoms lowers the temperature of the structural phase transition by 8 K.     

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.     

Crystal structure of octapotassium octasulfatodiceriate pentahydrate

Single crystals without Co and Ni have been crystallized by the substitution method in the K₂Ni(SO₄)₂-Ce(SO₄)₂-H₂SO₄-H₂O system using K₂Co(SO₄)₂ · 6H₂O, K₂ (Co,Ni)(SO₄)₂ · 6H₂O, or K₂Ni(SO₄)₂ · 6H₂O as protocrystals. The structure of the single crystals obtained has been established by X-ray diffraction analysis. The crystal structure contains dimer complex anions [Ce₂(μ-SO₄)₂(SO₄)₆]⁸⁻, K⁺ cations, and crystallization water molecules.     

Optical properties of non‐centrosymmetric mixed crystals K2(La1‐x Cex)(NO3)5 · 2 H2O (x = 0.0 – 1.0)

Large single crystals of optical quality of the non‐centrosymmetric orthorhombic potassium rare earth nitrate mixed crystals K₂(La_1–x Ce_x)(NO₃)₅ · 2 H₂O were grown at 38 °C from diluted HNO₃. For crystals with x = 0.0, 0.19, 0.38 and 0.66 refractive indices and their dispersion were determined with an error less than 1 · 10^–4 in the wavelength range 0.404 – 1.083 μm by the prism method. Phase matching conditions for collinear SHG frequency conversion were analysed in detail, including calculation of the effective nonlinear optical susceptibility. By an appropriate choice of the fraction x of cerium the mixed crystals K₂(La_1–x Ce_x)(NO₃)₅ · 2 H₂O allow an adjustment of non‐critical type I phase matching conditions to a desired wavelength of the fundamental wave within the range 1.055(4) – 1.107(6) μm. Non‐critical type II phase matching can be tuned in the wavelength range 0.949(2) – 0.931(2) μm. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Mosaic microinhomogeneity in crystals of (Co,Ni)K2(SO4)2 · 6H2O solid solutions

The mosaic microinhomogeneity in mixed crystals of the isomorphic series (Co,Ni)K₂(SO₄)₂ · 6H₂O has been studied. The growth processes have been observed in situ in optical and confocal microscopes and the distribution of composition components has been studied by the energy-dispersive method. The results make it possible to develop model concepts about the formation of composition microinhomogeneity in solid solutions.     

Growth of Er2(SO4)3 ⋅ 8H2O crystals and study of their structure and properties

New crystals of the composition Er₂(SO₄)₃ ? 8H₂O have been synthesized by the method similar to that used for synthesis of (CH₃)₂NH₂Al(SO₄)₂ ? 6H₂O. The synthesized crystals were studied by the X-ray diffraction method. The crystals are monoclinic C2/c) and contain no (CH₃)₂NH₂ ions. It is established that, contrary to DMAAS crystals, Er₂(SO₄)₃ ? 8H₂O crystals undergo no phase transitions and possess neither ferroelectric nor ferroelastic properties.     

Solubility phase diagrams of Me 2SO4-NiSO4-H2O systems and the growth of Me 2Ni(SO4)2 · n H2O crystals [ Me = Na, Rb, Cs; n = 4, 6]

On the basis of the physicochemical analysis of the solubility phase diagrams for the Me ₂SO₄-NiSO₄-H₂O ternary systems (Me = Na, Rb, or Cs), the optimum concentration and temperature conditions for the crystallization of the Me ₂Ni(SO₄)₂ · nH₂O solid phases were found. Techniques for growth of single crystals of these binary salts have been developed. Such techniques allow application of mother liquors containing hydrates or anhydrous sulfates of Na, Rb, Cs, and Ni as raw materials. Na₂Ni(SO₄)₂ · 4H₂O, Rb₂Ni(SO₄)₂ · 6H₂O, and Cs₂Ni(SO₄)₂ · 6H₂O single crystals (28–34) × (8–13) × (5–10) mm³ in size have been grown from aqueous solutions in the dynamic regime. Original Russian Text ? L.V. Soboleva, 2007, published in Kristallografiya, 2007, Vol. 52, No. 6, pp. 1141–1144.     

Synthesis,Crystal Growth,Structural and Physical Properties of bis(thallium) bis(nitrilotriacetato) zirconate dihydrate,Tl2Zr(N[CH2COO]3)2 · 2H2O

Single crystals of Tl₂Zr(N[CH₂COO]₃)₂ · 2H₂O having optical quality and dimensions up to 30 × 25 × 12 mm have been grown from aqueous solutions by controlled lowering of temperature. The raw material was synthesized as the first fraction of crystallization during evaporation of an aqueous solution of (CH₃NH₃)₂Zr(N[CH₂COO]₃)₂ · 2H₂O and TlNH₂SO₃. A crystal structure analysis revealed an isotypy to the K₂Zr(N[CH₂COO]₃)₂ · 2H₂O family, space group Ccc2, a₁ = 14.780(2)Å, a₂ = 14.933(2)Å, a₃ = 8.901(1)Å, Z = 4, ρ_calc. = 3.145 gcm^‐3. Thermal stability, thermal expansion and pyroelectric, dielectric, piezoelectric, elastic and thermoelastic properties have been determined. All properties are closely related to those of Rb₂Zr(N[CH₂COO]₃)₂ · 2H₂O.     

Growth and properties of mixed K2Ni x Co1−x (SO4)2 · 6H2O crystals

Optically homogeneous mixed K₂Ni _x Co_{(1 ? x)}(SO₄)₂ · 6H₂O crystals are grown from solutions of different compositions by the temperature-reduction technique in static and dynamic regimes. The optical characteristics of the grown crystals are measured: transmittance reaches 80% in the wavelength range of 240–290 nm and no more than 9% in the visible spectral range. The thermal stability of the crystals is studied. It is established that the thermal stability of mixed K₂Ni _x Co_{1 ? x} (SO₄)₂ · 6H₂O crystals is higher than that of K₂Co(SO₄)₂ · 6H₂O crystal. The defects of the mixed crystals grown in static and dynamic regimes are investigated by X-ray topography.     

Growth and Physical Characterization of Double Cation Hydrogen Double Sulphate System Li2NaH(SO4)2 · H2O

Single crystals of Li₂NaH(SO₄)₂ H₂O are grown from aqueous solution, containing equimolar amounts of Li₂SO₄ H₂O and NaHSO₄ from 80°C down to 30°C over a period of 15 days, resulting in large good quality crystals. The as-grown crystals are verified by using XRD powder technique. The local structure is discussed in the light of vibrational spectroscopy. Water of crystallization is evidenced from both IR and Raman spectra. Several endothermic and an exothermic phase transition anomalies have been observed from DTA scan. Considerable weight loss is observed at 108°C from thermogravimetric study (TGA). The melting point of the material is found to be 450 °C. The density of the compound is measured to be 2.5217 g/cm³.     

Single crystal growth of La2(SO4)3 · 9 D2O

Single crystals of La₂(SO₄)₃ · 9 D₂O were grown from saturated D₂O solutions. According to X-ray diffraction measurements, the crystals have a hexagonal structure with unit cell parameters a = 10.996 Å and c = 8.077 Å (space group C–P6₃/m). Several physical properties were also determined (density, refractive indices, dielectric constants, specific heat, coefficient of linear expansion, microhardness).     

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.     

Phase transitions in Cs5(HSO4)2(H2PO4)3 crystal

The symmetry (sp. gr.I $\bar 4$ 3d) and lattice parameters have been determined for the first time for Cs₅(H₂SO₄)₂(H₂PO₄)₃ crystals in the temperature range from 172 to 390 K. The thermal and optical properties of crystals, as well as their conductivity, have been investigated at elevated temperatures. It is shown that a crystal heated to T = 365 K undergoes a phase transition with symmetry lowering to the tetragonal phase (with the parameters a = 4.965(1) Å and c = 5.016(1) Å), while at T ≈ 390 K a phase transition to the cubic phase is presumably observed. With a decrease in temperature, a phase transition without a change in symmetry occurs at T = 240 K.     

Effect of growth conditions on the functional properties of K2Co(SO4)2·6H2O crystals

K₂Co(SO₄)₂ · 6H₂O single crystals of optical quality have been grown and the effect of solution pH on their solubility and transmission spectra has been investigated. A kinetic growth curve is obtained for the (110) face and the onset temperature of dehydration is established for single-crystal samples. The structural quality of single crystals grown at different supersaturations is analyzed.     

Crystal growth,structure, crystalline perfection and characterization of zinc magnesium ammonium sulfate hexahydrate mixed crystals ZnxMg(1−x)(NH4)2(SO4)2·6H2O

Mixed crystals Zn_xMg_(1?x)(NH₄)₂(SO₄)₂·6H₂O of the two well-known Tutton's salts Zn(NH₄)₂(SO₄)₂·6H₂O and Mg(NH₄)₂(SO₄)₂·6H₂O were grown with varying molar proportions (x=0.10–0.90) by slow evaporation solution growth technique. The mixed crystal Zn_0.54Mg_0.46(NH₄)₂(SO₄)₂·6H₂O is crystallizing in monoclinic system with space group P2₁/c and cell parameters a=6.2217(4) Å, b=12.5343(7) Å, c=9.2557(6) Å, β=106.912(3)°. The coexistence of zinc and magnesium ions in the mixed crystal was confirmed by inductively coupled plasma (ICP), atomic absorption spectroscopy (AAS) and energy dispersive X-ray spectroscopy (EDS). Compositional dependence of lattice parameters follows Vegard's relations. Slight variations are observed in FT-IR and XRD of pure and mixed crystals. Comparison of crystalline perfection as evaluated by high-resolution X-ray diffraction (HRXRD) for mixed crystals of various proportions reveals a reasonably good crystalline perfection for the mixed crystal with nearly equimolar ratio of Zn and Mg. The surface morphology of the mixed crystals changing with composition was studied by scanning electron microscopy (SEM). UV–vis studies reveal that the transparency of the mixed crystals was not much affected.     

Investigation of the structure and properties of (K x (NH4)1 − x )3H(SO4)2 single crystals

The influence of isomorphous replacement in the cation sublattice on the kinetics of the phase transition in single crystals of the solid solutions (K _x (NH₄)_{1 ? x} ) _m H _n (SO₄)_{(m + n)/2} · yH₂O belonging to the K₃H(SO₄)₂-(NH₄)₃H(SO₄)₂-H₂O salt system was studied. Superproton phase transitions for the end compositions of this system have been found earlier. The optical and thermal properties of crystals with the composition (K,NH₄)₃H(SO₄)₂ in the temperature range from 295 to 500 K were investigated, and the crystal structure was determined at 295 K. The results of the study and the comparison with the literature data show that the replacement of potassium atoms with ammonia leads to a fundamental change in the kinetics of the phase transition, the phase-transition temperature remaining virtually unchanged.     

Cs2Ni(SO4)2 · 6H2O (CNSH) crystal: Growth and some properties

Large single crystals of cesium-nickel sulfate hexahydrate Cs₂Ni(SO₄)₂ · 6H₂O of optical quality were grown for the first time. The crystal structure and the optical and thermogravimetric properties of this compound were investigated.     

Growth of single crystals of NaH2PO4 (NaDP), NaH2PO4 · H2O (NaDP · H2O), and NaH2PO4 · 2H2O (NaDP · 2H2O) sodium dihydrogenphosphate based on the analysis of the Na2O-P2O5-H2O phase diagram

The crystallization conditions for the NaH₂PO₄, NaH₂PO₄ · H₂O, and NaH₂PO₄ · 2H₂O solid phases have been established from the analysis of the phase diagram of solubility of the ternary Na₂O-P₂O₅-H₂O system in the temperature range from 0 to 100°C. Based on these data, the methods for growing sodium dihydrogenphosphate single crystals of the above compositions are developed. The initial components for preparing mother solutions were H₃PO₄ and NaOH solutions taken in certain weight ratios. For the first time, NaDP, NaDP · H₂O, and NaDP · 2H₂O single crystals were grown on a seed by the method of temperature decrease. The habits of the NaDP and NaDP · H₂O single crystals are determined. __________ Translated from Kristallografiya, Vol. 47, No. 5, 2002, pp. 937–944. Original Russian Text Copyright ? 2002 by Soboleva, Voloshin.     

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)