H2O Crystals Research Articles

Doping effect of urea on growth, spectral, thermal, mechanical, electrical, nonlinear and optical studies of Sr(HCOO)2·2H2O crystal: enhanced third-order NLO properties with a high laser-induced damage threshold

Pure and urea doped (with 3 different concentrations, viz. 0.005, 0.05, and 0.1 M) strontium formate dihydrate (SFD, Sr(HCOO)2·2H2O) single crystals were grown from aqueous solutions by using slow solvent evaporation technique. In order to understand the effect of urea doping on the structural, chemical, thermal, morphological, optical properties of SFD crystals, the grown crystals were characterized by carrying out CHN analysis, powder X-ray diffraction, high resolution X-ray diffraction, Fourier transform infrared spectral, thermogravimetric, UV–Vis–NIR spectral, photoluminescence spectral, second harmonic generation efficiency, and Z-scan measurements. The results obtained indicate that the urea molecule have entered into the SFD crystal matrix and has improved the crystallinity. Also, the results indicate that urea doping significantly tunes the optical and thermal properties without significantly distorting the crystal structure of SFD crystal. The laser damage threshold (LDT) energy for the grown crystal has been measured by using a Q-switched Nd:YAG laser as a source in single-shot mode (1064 nm, 10 Hz, 420 mJ). The result of laser damage threshold (LDT) energy indicates that grown title crystal has excellent resistance to laser radiation than those of some known inorganic NLO materials. Its third-order nonlinear optical properties were investigated by Z-scan technique and proved that the grown crystal possesses two-photon absorptions (TPA) and the self-defocusing effect.

Effect of Ionic Liquid Additives on the Solubility Behavior and Morphology of Calcium Sulfate Dihydrate (Gypsum) in the Aqueous Sodium Chloride System and Physicochemical Solution Properties at 30 °C

We have investigated the solubility behavior of calcium sulfate dihydrate (gypsum, CaSO4·2H2O) in aqueous NaCl solutions upon the addition of ammonium- or imidazolium-based ionic liquids (ILs), viz., ethylammonium lactate (EAL), 1-ethyl-3-methyl imidazolium hydrogen sulfate ([C2mim]HSO4), and 1-butyl-3-methyl imidazolium hydrogen sulfate ([C4mim]HSO4) at 30 °C. The addition of ammonium lactate ILs increased solubility significantly, ∼500%, whereas the addition of imidazolium hydrogen sulfate ILs decreased the solubility by ∼60%. The addition of ILs shifted the solubility maximum of CaSO4·2H2O toward either higher or lower concentration of NaCl in solution depending on the nature of IL additive. Solution properties such as density (ρ) and speed of sound (u) have been measured for the quaternary systems (CaSO4·2H2O + NaCl + ILs + H2O) at 30 °C. Solution isentropic compressibility (κS) has been derived from measurements of u and ρ. Physical and derived properties have been fitted with suitable polynomial equations. Crystal growth formation and surface morphology of CaSO4·2H2O crystals recrystallized from different aqueous IL solutions have also been examined. IL additives have shown good potential for calcium sulfate scale removal and as calcium sulfate precipitation agent.

Conversion of Single Crystal (NH4)2Mo3S13·H2O to Isomorphic Pseudocrystals of MoS2 Nanoparticles

We have prepared nanocrystals of MoS2 across a range of length scales by heating single crystals of the molecular precursor (NH4)2Mo3S13·H2O. Rod-shaped crystals of the polysulfide precursor retain their original morphology after heating at temperatures up to 1000 °C and undergo complete conversion to MoS2 while acting as a template for the confined formation of MoS2 nanocrystals. This solid state transformation proceeds with the release of gaseous species without blowing the crystals apart and leads to formation of pores embedded into a nanocrystalline assembly of the templated nano-MoS2. The obtained assemblies of MoS2 nanocrystals have the exact same shape of the original rod-shaped (NH4)2Mo3S13·H2O crystals indicative of a pseudomorphic shape-retentive process. Such crystal-shaped nanocrystal assemblies show electrical conductivity values similar to a bulk MoS2 single crystal with electron carrier concentration of 1.5 × 1014 cm–3 and mobility of 7 cm2/(V s). The nanocrystals of MoS2 were grown at temp...

Thermodynamic properties and NMR study of tetragonal tetrahalogen-metallate dihydrate crystals of Rb2[CuX4]·2H2O (X = Cl− and Br−)

The thermodynamic properties and phase transitions in Rb2[CuBr4]·2H2O are studied through differential scanning calorimetry (DSC), thermogravimetric analysis, and nuclear magnetic resonance (NMR) experiments. The DSC endothermic peaks near 337 and 353 K are accompanied by the partial escape of H2O. The temperature dependence of the NMR resonance frequency, line width, and spin–lattice relaxation time near the transition temperatures are related to variations in the symmetry of the environments of Rb(I) ions. The DSC peaks seem to correspond to a chemical change caused by thermal decomposition, rather than a physical change such as a structural phase transition. The results obtained here are compared to those of Rb2[CuCl4]·2H2O crystal from our previous study.

Investigation of Polymorphism and Vibrational Properties of MnMoO4Microcrystals Prepared by a Hydrothermal Process

MnMoO4 microcrystals were synthesized by hydrothermal methods, and their structural, morphological, and vibrational properties were investigated. Conventional reactors and microwave-heated hydrothermal vessels were used to synthesize micrometer-sized MnMoO4 polymorphs at different temperature and time conditions. MnMoO4·H2O crystals were obtained in both reactors at temperatures below 200 °C, for times up to 24 h. These microcrystals belong to the triclinic P1 space group, and their 26 characteristic Raman bands were identified. A monoclinic MnMoO4 polymorph belonging to the P2/c structure was synthesized at temperatures higher than 200 °C only into conventional hydrothermal reactors. Polarized micro-Raman analyses have evidenced and allowed the assignment of 18 phonon modes predicted by group-theory calculations for this polymorph. Another MnMoO4 polymorph, within the monoclinic C2/m space group, was obtained by two processing routes: (i) heating the P2/c microcrystals at 600 °C; or (ii) heating the MnM...

Effects of anions on calcium arsenate crystalline structure and arsenic stability

Based on the crystallization reaction between calcium and arsenate, three anions, namely, chloride (Cl−), sulfate (SO42−), and carbonate (CO32−), were introduced during the formation of calcium arsenate in this study. The effects of these anions on arsenic stability and calcium arsenate crystalline properties were characterized using TCLP, XRF, XRD, SEM-EDS, TEM and particle size distribution (PSD). The results show that these anions significantly affect the calcium arsenate crystalline structure and arsenic-leachate concentration. The effect of chloride on arsenic stabilization was mainly a result of the formation and growth of calcium arsenate apatite (Ca5(AsO4)3OH and Ca5(AsO4)3Cl) crystal. Sulfate is propitious to improve the formation of Ca4(OH)2(AsO4)2·4H2O crystals and enhance their stability effectively under corresponding sulfate concentration treatments. A small amount of carbonate is beneficial to the formation and growth of Ca4(OH)2(AsO4)2·4H2O crystals. However, when the CO32– concentration was higher than 0.5 mol/L, Ca-As compounds were not precipitated. Instead, CaCO3 and Na3Ca(CO3)2·5H2O were generated successively, inhibiting calcium-arsenate crystallization and thus releasing more arsenic into aqueous solution. The trends of grain size are opposite to that of arsenic-leachate concentration, indicating that larger calcium arsenate crystals are more stable in the TCLP test. The internal structure of different Ca-As compounds can be changed and transformed by adding the three anions within a certain range. In summary, the results of this paper provide some meaningful information for the treatment of arsenic-containing wastewater or arsenic-bearing sludges using lime precipitation.

Crystal Structure of Tetra- and Pentasodium Salts of Nitrilotris(methylenephosphonic Acid)

Tetra- and pentasodium salts of nitrilotris(methylenephosphonic acid) N(CH2PO3)3H6 (NTP) have been studied by single-crystal X-ray diffraction and spectroscopy. [Na8(H2O)12{NH(CH2PO3)3H}2] · H2O crystallizes in triclinic system, space group P1, Z = 1, a = 7.1515(2) A, b = 11.1590(3) A, c = 12.0583(3) A; α = 92.077(2)°, β = 106.145(2)°, γ = 5.628(2)°, CCDC No. 1432091. The crystal structure comprises two-dimensional layers lying along planes (011), where dimeric molecules are linked by bridges each comprising four Na hydration octahedra. The [Na5(H2O)11{NH(CH2PO3)3}] · 2H2O crystals are monoclinic, space group P21/n, Z = 4, a = 6.3024(2) A, b = 21.5639(7) A, c = 18.1608(6) A; β = 91.261(3)°, CCDC No. 1497161. The crystal packing comprises alternating layers in planes [020] made of two-dimensional nets of Na hydration polyhedra, and columns of Na hydration octahedra lying in planes [040], with acid moieties in between.

Raman spectra of lithium compounds

The paper is devoted to the results of investigating the spontaneous Raman scattering spectra in the lithium compounds crystals in a wide spectral range by the fibre-optic spectroscopy method. We also present the stimulated Raman scattering spectra in the lithium hydroxide and lithium deuteride crystals obtained with the use of powerful laser source. The symmetry properties of the lithium hydroxide, lithium hydroxide monohydrate and lithium deuteride crystals optical modes were analyzed by means of the irreducible representations of the point symmetry groups. We have established the selection rules in the Raman and infrared absorption spectra of LiOH, LiOH·H2O and LiD crystals.

Recovery of lithium from salt-brine eluates by direct crystallization as lithium sulfate

Brine from natural salt lakes (salt brine) is an important source of lithium; consequently the recovery of lithium from brine eluates prepared through Li+ adsorption-desorption is economically important. The present paper describes a study on the direct crystallization of Li2SO4·H2O from synthetic and real salt-brine eluates.Thermal evaporation of a sulfate-type synthetic eluate (1400mM Li+, 61mM Na+, 6.7mM K+, 16.7mM Mg2+, and 10.0mM Mn2+), to a degree of concentration (Dcon) in excess of 13, produced high purity (97%) Li2SO4·H2O crystals in 54% yield. The addition of ethanol to the eluate resulted in an increased yield of Li2SO4·H2O crystals, but these crystals were of lower purity due to the co-precipitation of other metal sulfates.Two types of eluate were prepared by the batchwise adsorption of Li+ from brine followed by desorption with 2M sulfuric acid. Evaporation of an eluate with a Li+ concentration of 1370mM to a Dcon of 8.6 at 323K produced high-purity (97%) Li2SO4·H2O crystals in 43% yield after the CaSO4·2H2O had been removed at a Dcon of around 3. The evaporation of the eluate to dryness at 323K followed by rinsing with water afforded Li2SO4·H2O crystals in 83% yield and in 84% purity. This simple evaporation method can be applied to lithium extraction from salt lakes in arid areas.

Comparative study of the phase transitions and spectral properties of NH2(CH3)2Me1-хСrx(SO4)2×6H2O (Me = Al, Ga) ferroelectrics

This article is devoted to study of Cr3+ ion complexes in NH2(CH3)2Me1-xCrx(SO4)2 × 6H2O, Me = Al, Ga (DMAMe1-xCrxS) crystals. On the basis of spectroscopic data the energy diagram and the parameters of the crystal field corresponding to the above mentioned complexes were specified. It was shown that isomorphous substitution of the metal ion practically does not affect the temperature of ferroelectric-ferroelastic phase transition in NH2(CH3)2Ga1-xCrx(SO4)2 × 6H2O contrary to the case of NH2(CH3)2Al1-xCrx(SO4)2 × 6H2O crystal. The structure and temperature changes of the absorption spectra of the above mentioned solid solutions are explained in terms of the internal electronic transitions in [Сr(H2O)6]3+ octahedral complexes. The symmetry and distortion of the complexes within the structure of all investigated crystals were analyzed on the basis of the Raman spectroscopy data.

Separating NaCl and AlCl3·6H2O Crystals from Acidic Solution Assisted by the Non-Equilibrium Phase Diagram of AlCl3-NaCl-H2O(-HCl) Salt-Water System at 353.15 K

Extracting AlCl3·6H2O from acid leaching solution through crystallization is one of the key processes to extracting aluminum from fly ash, coal gangue and other industrial solid wastes. However, the obtained products usually have low purity and a key problem is the lack of accurate data for phase equilibrium. This paper presented the non-equilibrium phase diagrams of AlCl3-NaCl-H2O (HCl) salt-water systems under continuous heating and evaporation conditions, which were the main components of the acid leaching solution obtained through a sodium-assisted activation hydrochloric acid leaching process. The ternary system was of a simple eutonic type under different acidities. There were three crystalline regions; the crystalline regions of AlCl3·6H2O, NaCl and the mixture AlCl3·6H2O/NaCl, respectively. The phase diagram was used to optimize the crystallization process of AlCl3·6H2O and NaCl. A process was designed to evaporate and remove NaCl at the first stage of the evaporation process, and then continue to evaporate and crystallize AlCl3·6H2O after solid-liquid separation. The purities of the final salt products were 99.12% for NaCl and up to 97.35% for AlCl3·6H2O, respectively.

Double-Four-Ring [Si8O12][OH]8 Cyclosilicate and Functionalized Spherosilicate Synthesis from [N(n-C4H9)4]H7[Si8O20]·5.33H2O Cyclosilicate Hydrate Crystals

A new synthesis method for preparing spherosilicates with a double-four-ring (D4R) silicate core (Si8O12) and functional siloxy substituents such as (OSi(CH3)2Cl) on the vertices was discovered. Key to this achievement was the synthesis of [N(n-C4H9)4]H7[Si8O20]·5.33H2O D4R cyclosilicate hydrate precursor crystals having only 5.33 water molecules per D4R unit, which is much smaller than the number in the state-of-the-art tetramethylammonium- and choline-containing cyclosilicate hydrate crystals that have up to 65 water molecules per D4R. The low water content allows the use of bifunctional silylating agents such as dichlorodimethylsilane that lose their chloride functionality upon reaction with water molecules. Dissolution of [N(n-C4H9)4]H7[Si8O20]·5.33H2O crystals in acidified tetrahydrofuran liberates uncharged D4R [Si8O12][OH]8 cyclosilicate molecules, as shown by small angle X-ray scattering and 29Si nuclear magnetic resonance. A concentrated stable solution of [Si8O12][OSi(CH3)2Cl]8 spherosilicate co...

Growth and Characterization of Tetraphenylphosphonium Bromide Crystal

Multiple-phenyl phosphorous compounds are a group of chemical materials that have been used as reactants, pharmaceutical intermediates, extractants, and catalysts in organic synthetic reactions. However, the crystal growth of bulk crystals of multiple-phenyl phosphorous compounds, which may expand their applications in photonics technology, have been largely overlooked. In this article, the crystal growth of tetraphenylphosphonium bromide (TPPB) has been studied in organic solvents and water. The crystal structures and crystallization features are analyzed by X-ray diffraction data. By a slow temperature-lowering method, a single-crystal of TPPB (2H2O) with the size of 27 × 20 × 20 mm3 has been obtained in water. The basic thermal and optical properties were characterized. We find that the TPPB (2H2O) crystal shows excellent transparent property in the near-IR region. Large Raman shifts and strong Raman scattering intensity indicate that TPPB is a potential candidate in Raman-scattering-based nonlinearity applications.

Oxidation of Molybdenum Disulfide Sheet in Water under in Situ Atomic Force Microscopy Observation

In situ observation of molybdenum disulfide (MoS2) sheet exposed to water was performed using atomic force microscopy (AFM) to obtain a better understanding for the preparation and application of two-dimensional molybdenum disulfide. It was found that the MoS2 sheet underwent chemical reactions in water, leading to the partial etching of the surface layer and the formation of needlelike protrusions on the surfaces. X-ray photoelectron spectroscopy (XPS) and atomic absorption spectroscopy (AAS) analyses showed that this behavior might arise from the oxidation of MoS2 into Mo(VI) and SO42–. The oxidative product Mo(VI) was present in the form of either MoO3·H2O crystals on the MoS2 surface or molybdate ions in aqueous solution, whereas SO42– was present in the solution, resulting in the etching of the surface layer and the formation of needlelike protrusions. These findings might be significant in terms of applications of two-dimensional MoS2 and the concentration of molybdenite.

Effect of cellulose triacetate membrane thickness on forward‐osmosis performance and application for spent electroless nickel plating baths

ABSTRACTCellulose triacetate (CTA) forward‐osmosis (FO) membranes were prepared via the phase inversion method. The influence of thickness on the performance and morphology of CTA FO membranes was discussed in detail. When the thickness of the membrane was 50.0 ± 0.5 μm (CTA4), the prototype CTA membranes displayed a water flux of 20.2 L m−2 h−1 and a reverse salt transport of 14.6 g m−2 h−1 using 1 mol/L NaCl as the draw solution and deionized water as the feed solution during the FO process at 25 °C. In addition, the high‐performance CTA4 FO membranes have been used to process spent electroless nickel plating baths where the water flux could reach 13 L m−2 h−1 and NiSO4·6H2O crystals occurred in the feed solution of the spent electroless nickel plating baths. The recovery rates of NiSO4·6H2O and water from the spent electroless nickel plating baths were 44.54% and 53.53%, respectively. This study focused on improving membrane design for the FO process and finding a new method of waste liquor or wastewater treatment. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45049.

Proton conducting system (ImH2)2SeO4·2H2O investigated with vibrational spectroscopy

Imidazolium selenate dihydrate (ImH2)2SeO4·2H2O crystals have been investigated using Raman and IR spectroscopy. Experimental data were supported by the quantum-chemical calculations (DFT), Hirshfield surfaces and fingerprint plots analysis, and Bader theory calculations. The imidazolium selenate dihydrate crystal exhibits high proton conductivity of the order of ~10−1S/m at T=333K. The spectra of this compound are dominated by bands related to the lattice modes, the internal vibrations of the protonated imidazole cation, selenate anion, water molecules, and hydrogen bonds network. For the imidazolium selenate dihydrate crystal, the formal classification of the fundamental modes has been carried out.

Ti-doped Fe1−xTixF3·0.33H2O/C nanocomposite as an ultrahigh rate capability cathode materials of lithium ion batteries

The conductivity problem of FeF3·0.33H2O is the main constraint on development and application of this next-generation cathode material for lithium/sodium ion batteries. It has been found in our previous theoretical calculation that Ti-doping can dramatically improve the conductivity FeF3·0.33H2O, and thus improving its electrochemical performance. Herein, Ti-doped Fe1−xTixF3·0.33H2O (x = 0, 0.06, 0.08, 0.10) compounds have been successfully synthesized via a liquid-phase method. Subsequently, a ball milling process with acetylene black (AB) has been used to form Fe1−xTixF3·0.33H2O/C (x = 0, 0.06, 0.08, 0.10) nanocomposite. The chemical composition and elemental distribution of the Ti-doped FeF3·0.33H2O samples were investigated by X-ray diffraction (XRD) and energy-dispersive X-ray spectroscopy (EDXs). The results show that Ti can effectively dope into the samples, and replace partially Fe3+ ions in the FeF3·0.33H2O crystal. Especially the Fe0.92Ti0.08F3·0.33H2O/C nanocomposite achieves an initial capacity of 460.15 mAh g−1 and retains a discharge capacity of 294.86 mAh g−1 after 40 cycles in the voltage range of 1.5–4.5 V. Besides, the as-prepared material shows excellent rate capability, it can deliver a discharge capacity of 146.06 mAh g−1 even at 2 C.

Effect of conductive copolymers on scale formation of gypsum

Abstract The crystallization of scale forming minerals is an important problem in a number of processes. Calcium sulfate dihydrate (CaSO4·2H2O, gypsum) is the most unwelcome deposit in the production of oil and gas, in water cooling systems and in hydrometallurgical processes. Additives have been used in these processes to prevent the formation and deposition of scaling salts. In this study, the effects of additives on the spontaneuos precipitation of CaSO4·2H2O were investigated in aqueous solutions at 30°C. Conductive copolymers with different vinylphosphonic acid (VPA) contents were used as additives. The degree of inhibition of cystallization was measured as an increase in induction time and the reduction in crystallization rate. The crystallization reactions were interpreted in terms of the Langmuir adsorption isotherm. The cystals were characterized by scanning electron microscope (SEM) and Fourier Transform Infrared Spectroscopy (FT-IR). The VPA content of the copolymer and the supersaturation of the solution were found to be effective parameters on CaSO4·2H2O crystallization.

Synthesis and crystal structure of trans-[Ru(NO)(NH3)4SO4]ClO4 and [Ru(NO)(NH3)4SO4][Ru(NO)(NH3)3Cl(SO4)]HSO4•H2O

After the addition of the saturated NaClO4 solution to a solution of trans-[Ru(NO)(NH3)4SO4]HSO4•H2O, trans-[Ru(NO)(NH3)4SO4]ClO4 perchlorate salt (I) is obtained with the yield of ~80%. The heating of trans-[Ru(NO)(NH3)4(H2O)](HSO4)SO4 at a temperature of ~220 °C results in a complete removal of coordination water and a partial removal of ammonia molecules. Successive treatment of the thermolysis product with sulfuric and hydrochloric acids yields [Ru(NO)(NH3)4SO4][Ru(NO)(NH3)3Cl(SO4)]HSO4•H2O crystals (II). The single crystal X-ray diffraction method is used to determine the structure of the compounds obtained. For I: space group P21/c, a = 6.6949(9) A, b = 13.7049(19) A, c = 12.8641(17) A, β = 101.028(4)°; for II: space group Р21/c, a = 14.1304(4) A, b = 12.4908(3) A,, c = 11.6264(3) A, β = 94.1980(10)°.

Mass production of two-dimensional oxides by rapid heating of hydrous chlorides.

Two-dimensional (2D) nanoscale oxides have attracted research interest owing to their electronic, magnetic optical and catalytic properties. If they could be manufactured on a large scale, 2D oxides would be attractive for applications ranging from electronics to energy conversion and storage. Herein, we report facile fabrication of oxide nanosheets by rapid thermal annealing of corresponding hydrous-chloride compounds. By heating CrCl3·6H2O, ZrOCl2·8H2O, AlCl3·6H2O and YCl3·6H2O crystals as precursors, we immediately collect large quantities of ultrathin Cr2O3, ZrO2, Al2O3 and Y2O3 nanosheets, respectively. The formation of layered nanosheets relies on exfoliation driven by rapid evaporation of water and/or other gas molecules generated under annealing. Our route allows simple, efficient and inexpensive production of 2D oxides. As a demonstration, we evaluate Cr2O3 nanosheets prepared by our method as anodes in lithium-ion batteries and find superior performance in comparison with their microcrystalline counterparts.