Synthesis and characterization of a new nonlinear optical single crystal: L‐Lysinium trifluoroacetate

Single crystals of a new L‐Lysine salt: L‐Lysinium trifluoroacetate {abbreviated as LLyTFA; [(NH₂)‐(CH₂)₄‐CH‐(NH₃)‐(COOH)]⁺ CF₃COO^‐} were grown by slow evaporation of an aqueous solution at room temperature. The grown crystals were subjected to single crystal X‐ray diffraction, FTIR and UV‐Vis‐NIR spectrum analyses. The UV‐Vis‐NIR spectrum shows that the absorption is very less in the whole of the region from ultraviolet to near IR. The Kurtz‐Perry powder SHG measurement using a Nd:YAG laser of wavelength 1064nm confirms the frequency doubling of the crystal and its powder SHG efficiency was measured as d_eff = 0.96 d_eff (KDP). (© 2007 WILEY ‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Solution growth of new ferroelectric glycine phosphite unidirectional single crystals at room temperature

Glycine phosphite [NH₃CH₂COOH₃PO₃], abbreviated as GPI is the second hydrogen bonded ferroelectric crystal combination of phosphorous acid and amino acid following βnine phosphite crystals abbreviated as BPI. Sankaranarayanan and Ramasamy‐Technique was adopted to prepare the ferroelectric glycine phosphite unidirectional single crystal. The growth orientation was imposed by the pre‐grown 〈010〉 seed. As water was the solvent, transparent, colourless crystal with cylindrical shaped ingot of sized 20mm‐diameter was grown. Powder X‐ray diffraction, HRXRD, FTIR, dielectric and mechanical studies were carried out. The results are discussed in detail. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

The effect of metallic ions on tapering phenomenon of DKDP crystals and its elimination

The anomalous wedge‐like shape of KH₂PO₄‐type single crystal, also called tapering, is discussed in this paper. DKDP single crystals grew on seeds from the solutions containing high concentrations of Al³⁺, Fe³⁺ and Cr³⁺ impurities. The tapering phenomenon occurred on the prismatic {010} faces, and the tapering angle θ was nearly measured as 10°. We adjusted the pD value of the solution from 3.0 to 4.2 by adding K₂CO₃, the tapering angle of DKDP crystal grown from the same solution at same supercooling was reduced to 0°. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Synthesis,growth and characterization of single crystals of pure and thiourea doped L‐glutamic acid hydrochloride

L(+)Glutamic acid hydrochloride [HOOC (CH₂)₂CH(NH₂) COOH·HCl], a monoamino dicarboxylic acid salt of L‐Glutamic acid was synthesized and the synthesis was confirmed by FTIR analysis. Solubility of the material in water was determined. Pure and Thiourea doped L‐Glutamic acid hydrochloride crystals were grown by low temperature solution growth using solvent evaporation technique. XRD, UV‐Vis‐NIR analyses were carried out for both pure and thiourea doped crystals. The crystals were qualitatively analyzed by EDAX analysis and the presence of thiourea was confirmed. The cell parameters of L‐Glutamic acid hydrochloride have been determined as a = 5.151 Å, b = 11.79 Å, c = 13.35 Å by X‐ray diffraction analysis and it crystallizes in orthorhombic space group P2₁2₁2₁. UV‐Vis‐NIR spectra analysis showed good optical transmission in the entire visible region for both pure and doped crystals. Micro hardness of both pure and doped crystals has been determined using Vickers micro hardness tester. The SHG efficiencies of both pure and doped crystals were determined using Kurtz powder test and pure L‐Glutamic acid hydrochloride crystal was found to possess better efficiency than thiourea doped L‐Glutamic acid hydrochloride crystals. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Crystal structure of aluminum sulfate hexadecahydrate and its morphology

A single‐crystal structure of aluminum sulfate hexadecahydrate (Al₂(SO₄)₃·16H₂O) was captured with a polarizing microscope. The structure was similar to a hexagonal plate and consistent with the predicted morphology derived from the modified AE model. An octagonal plate morphology was first obtained in a vacuum but was transformed into hexagonal plate‐like when the effect of the solvent with two disappearing {1 1 0} and {1 0 −1} faces was considered.     

Effects induced by chemical non‐stoichiometry and γ‐irradiation on the habit and unit cell parameters of ammonium tetrachlorozincate

The effect of chemical non‐stoichiometry and γ‐irradiation on the unit cell parameters of ammonium tetrachlorozincate (NH₄)₂ZnCl₄ (A₂ZC₄) has been studied. The unit cell parameters of crystal grown from solution with NH₄Cl/ZnCl₂ molar ratio 1:1, apparently non‐stoichiometrric, are nearly the same as those given for ammonium tetrachlorozincate in the literature. The 2:1 ratio is actually ‘pseudo‐stoichiometric’ due to the hygroscopic nature of ZnCl₂. The unit cell parameters of crystal grown from solution with molar ratio 2:1 match those of the structure (NH₄)₃ZnCl₅ (A₃ZC₅). The habit of the crystal grown in the former case, from solution with excess ZnCl₂, was different from that of the crystal grown in the later case, from solution with excess (NH₄)Cl. Between these two limits, a set of four samples were prepared from solutions with an excess of ZnCl₂ of 20, 30, 60 and 80 wt% in order to detect exact stoichiometric composition to grow A₂ZC₄. Analysis by X‐ray diffraction shows that the first two crystals out of this set are mixed from A₂ZC₄ and A₃ZC₅ The third and fourth crystals still contain traces of A₃ZC₅. Analysis of the X‐ray diffraction was then confirmed by DTA study. Irradiating A₂ZC₄ with γ‐dose of 250 kGy slightly increased the unit cell volume due to imperfections created by irradiation. Two computer programs were used to calculate the lattice constants and the results were compared. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Additive‐free solvothermal synthesis of peanut‐like BiVO4 powders with enhanced photocatalysis activity

Monoclinic peanut‐like BiVO₄ products have been successfully synthesized by a solvothermal method. The volume of CH₃COOH and the concentration of NH₃·H₂O were found to play important roles in the formation of this morphology. The optimal condition for preparation of highly active peanut‐like BiVO₄ samples are the volume of CH₃COOH, which was 5 ml, and the concentration of NH₃·H₂O, which was 2 mol/L. The as‐prepared samples were characterized by XRD, SEM, TEM, DRS, BET, and their photocatalytic activity was evaluated by photocatalytic decolorization of a Rhodamine B (RhB) aqueous solution under visible‐light irradiation. The results demonstrated that BiVO₄ with peanut‐like morphology was better than that of other BiVO₄ samples for photodegradation of RhB.     

Effect of Mn(II) ions on the growth of ammonium oxalate monohydrate crystals from aqueous solutions: I. Growth habit and surface morphology

The effect of concentration of Mn(II) ions on the growth habit and the surface micromorphology of different as‐grown faces of ammonium oxalate monohydrate (AO) single crystals grown from aqueous solutions was studied at a constant temperature of 30 °C and predefined supersaturations up to 20%. It was observed that the growth habit and the surface morphology of the crystals strongly depend on the supersaturation used for growth and the impurity concentration in the solution. The experimental results were analysed in terms of connected nets determined from different projections of the structure of AO crystals. Analysis of the observations revealed that: (1) the directions of connected nets corresponding to basic growth units composed of single (NH₄)₂C₂O₄ · H₂O molecules are in excellent agreement with the low‐index crystallographic directions of the orientations of growth layers, (2) all faces appearing in the growth morphology of AO crystals are F faces, and (3) the {001} face growing from pure aqueous solutions is essentially a kinetically rough face but the presence of Mn(II) impurity leads to their appearance in the morphology due to increase in the strength of bonds of the connected nets composing the surface graph.     

Synthesis,growth, morphology of the semiorganic nonlinear optical crystal L‐glutamic acid hydrochloride and its structural,thermal and SHG characterizations

One of the halide derivatives of L ‐glutamic acid which was identified as a semiorganic nonlinear optical material, L ‐glutamic acid hydrochloride [HOOC(CH₂)₂CH(NH₂)COOH.HCl], was grown as bulk single crystal and its significant properties were characterized. The stoichiometric title compound was synthesized and the solubility of its recrystallized form in DD water was determined in the temperature range 30–80 °C by gravimetric method. Structural confirmation was carried out by powder X ‐ray diffraction study through lattice parameter verification. Optical quality smaller dimension single crystals were grown from aqueous solution by self nucleation through slow evaporation of solvent method and a large dimension single crystal was grown by slow cooling method with reversible seed rotation technique. Morphological importances of different growth facets of the as grown crystals were studied through optical goniometry. Unit cell structure of the grown crystal was refined by single crystal X ‐ray diffraction analysis, functional groups present in the crystal responsible for various modes of vibrations were confirmed by FTIR spectroscopy analysis, thermal stability of the grown crytal was analysed by TG/DTA and DSC and second harmonic generation (SHG) of a fundamental Nd:YAG laser beam by Kurtz technique. Results indicate that the grown crystal is in stoichiometric composition and has significant improvement in its thermal and SHG properties when compared to pure L ‐glutamic acid polymorphs.     

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.     

Synthesis,Crystal Structure and Spectroscopic Characterization of {6-[2-(2-chlorophenyl)-1,3-thiazol-4-yl]-2-oxo-1,3-benzothiazol-3(2<Emphasis Type="Italic">H</Emphasis>)-yl}acetic acid

Abstract  

The title compound {6-[2-(2-chlorophenyl)-1,3-thiazol-4-yl]-2-oxo-1,3-benzothiazol-3(2H)-yl}acetic acid was prepared and characterized by elemental analyses, FT-IR, ¹H NMR spectroscopy, X-ray diffraction. A quantum-chemical calculation was performed using the CNDO method. In the title compound, C₁₈H₁₁ClN₂O₃S₂, the crystal structure is stabilized by intermolecular hydrogen bonds (C–H···O=C) to form centrosymmetric R₂² R_{2}^{2} (16) dimers and the C–H···O, O–H···N, and C–H···N interactions generating the graph set motifs R₂² R_{2}^{2} (9) and R₂² R_{2}^{2} (22).     

Synthesis of stoichiometric LiNbO3 nanopowder through a wet chemical method

Stoichiometric lithium niobate powder which are used as feeding material in near stoichometric LiNbO₃ crystal growth have been successfully prepared from commercial niobium hydroxide [Nb(OH)₅] and nontoxic DL‐malic acid by a wet chemical method. The synthesis temperature was pre‐determined by the results from thermogravimetric and differential thermal analysis. The structure and morphology of the as‐prepared samples were observed by using the infrared spectroscopy and the scanning electron microscopy. The X‐ray diffraction experiment showed that lithium niobate powder had an ilmenite structure, and its unit cell parameters were calculated to be a = b = 0.5140 nm, c = 1.3738 nm, and V = 0.3144 nm³. The melting point of the synthesized powder is 1239 °C and Curie temperature T_c is 1122 °C. This synthesis method would be helpful to grow the near‐stoichiometric LiNbO₃ crystal with double crucible techniques. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Synthesis and structure of (NH4)4[(DMF)2Mo8O26]· 2CH3CH2OH·2H2O (DMF= N , N -dimethylformamide)

A new organic-inorganic hybrid γ-octamolybdate complex, (NH₄)₄[(C₃H₇NO)₂Mo₈O₂₆]·2CH₃CH₂OH·2H₂O was synthesized from the mixture of ethanol, DMF, 4-aminobenzoic acid, (NH₄)₆Mo₇O₂₄·4H₂O, HCl and H₂O. The structure was determined by X-ray crystallography. It crystallizes in monoclinic P2₁/n space group with the crystal cell parameters of a = 8.8825(4), b = 21.1608(10), c = 11.1343(6) ?, β = 104.7720(10)°, V = 2023.64(17) ?³ and Z = 2. The crystal X-ray analysis shows that two DMF molecules are bound to γ-octamolybdate anion. The molecular structure is stabilized by the complex hydrogen bonding.     

Synthesis, Spectroscopic Characterization and Crystal Structure of a New Acetyl phosphorylamidate P(O)[NHC(O)C6H4(4-NO2)][N(CH(CH3)2)(CH2C6H5)]2

Abstract  

A new acetyl phosphorylamidate P(O)[NHC(O)C₆H₄(4-NO₂)][N(CH(CH₃)₂)(CH₂C₆H₅)]₂ has been synthesized and characterized by elemental analysis, ¹H, ¹³C and ³¹P NMR, IR and single crystal X-ray diffraction. Single crystal X-ray analysis shows that it belongs to triclinic system, space group P[`1] P\bar{1} , with a = 10.5868(16) Å, b = 11.8058(18) Å, c = 12.4364(19) Å, α = 65.410(3)°, β = 67.492(4)°, γ = 85.879(3)°, V = 1,298.6(3) Å³, and Z = 2. The intermolecular PO···HN hydrogen bond makes H-bonded dimer of molecule with Ci symmetry. In the crystal network, the dimers are aggregated in the chain arrays through π-stacking between p-NO₂–C₆H₄–C(O)–NH– moieties. Moreover, weak C–H···O and C–H···π interactions exist in the crystal network.     

Growth and characterization of a new langasite‐type single crystal Sr3NbAl1.5Ga1.5Si2O14

Single crystals of Sr₃NbAl_1.5Ga_1.5Si₂O₁₄ (SNAGS) with langasite structure have been successfully grown by Czochralski method. The X‐ray diffraction (XRD) verified that the as‐grown crystal was isostructural with A₃BC₃D₂O₁₄ structure and the lattice parameters were calculated as follows: a = 8.242 Å, c = 5.041 Å, V = 296.6 ų. The piezoelectric coefficient d₁₁ was 5.7pC/N, which was 2.47 times of α‐quartz (d₁₁=2.31pC/N). The electric resistivity was up to 3.04×10⁶ Ωcm at 700 °C for X‐cut sample. In addition, the transmission spectrum of the SNAGS crystal showed that it had a high transmittance (>80%) in the range of 350‐800 nm and exceeded 90% above 520 nm. These results suggest that the SNAGS crystals have potential applications in high‐temperature piezoelectric sensors and optical techniques. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Kinetically controlled synthesis of hollow Cu2O nanocubes under solvothermal condition

Hollow Cu₂O nanocubes have been fabricated under solvothermal condition using N,N ‐dimethylformamide (DMF) as solvent at 120 °C for 12 h. The products were characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), X‐ray powder diffraction (XRD) and high‐resolution transmission electron microscopy (HRTEM). Series of experiment confirmed that the amount of water, the reaction time and temperature played important roles in the morphology evolution of hollow Cu₂O nanocubes. DMF is a relatively weak alkali solvent and could release a certain amount of OH^– under the given conditions. As the release speed of OH^– from DMF became substantially slow, the nucleation and growth of Cu₂O nanocubes turned into kinetically controlled process. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Synthesis and thermal characterization of methylammonium tetrachloro zincate (II) monohydrate crystals

Single crystals of methylammonium tetrachloro zincate (II) monohydrate were grown by slow evaporation of saturated aqueous solutions at room temperature. The grown crystals were colourless, bright and transparent. The crystals were characterized through elemental analysis, powder X‐ray diffraction, thermogravimetric (TG‐DTA) and low temperature differential scanning calorimetric (DSC) techniques. While the powder XRD pattern shows the crystallinity of the compound, the elemental analysis and the TG‐DTA confirm the stoichiometry of the compound. The low temperature DSC indicates first order structural phase transition at ‐8°C during heating cycle. The FTIR and far IR spectra of the compound show characteristic vibrational frequencies due to CH₃NH₃ and ZnCl₄^2‐ ions and other chemical bonds. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Ferrous Tartrate recognition of sodium chloride {111} and its effect on crystal growth

The surface morphology and growth pattern of some molecules could be altered by the recognition of ferrous tartrate (FeC₄H₄O₆, FeTA). We have explored this phenomenon in the aspect of growth rate and morphology alteration of sodium chloride crystals where few researches have been done. In this paper, the crystallization behavior of NaCl with added FeTA was studied by supersaturation test, conductivity, scanning electron microscopy (SEM), and X‐ray diffraction (XRD). The results showed that the supersaturation of NaCl solution could be increased to about 5.5 % in presence of FeTA prior to the onset of crystallization. Furthermore, SEM images and XRD results indicated that the addition of FeTA could change the morphology of NaCl crystal from cubic to octahedron by impeding the growth of {111} and {110} faces. Besides, the interaction between NaCl {111} face and FeTA was discussed and the possible spatial structure of FeTA was speculated through the lattice parameters of NaCl.     

Cuprous oxide microcrystals via hydrothermal approach: morphology evolution and photocatalytic properties

Cuprous oxide (Cu₂O) microcrystals with various morphologies were prepared under mild hydrothermal condition. The samples were characterized by means of XRD, SEM, and UV/DRS. The morphology of the as‐prepared Cu₂O microcrystals typically had cubic symmetry and the morphology evolution from radial, six hollow branches to truncated octahedra (again cubic) were realized by adding acetic acid. The peak relative intensity of XRD pattern shows that the exposed planes of samples is consistent with their morphology. A possible growth mechanism of Cu₂O microcrystals is also proposed. The behavior of adsorption and photocatalysis of Cu₂O microcrystals was investigated by degrading methyl orange (MO) in aqueous solution. The results show that the as‐prepared Cu₂O radial six hollow branches microcrystals with exposed {110} planes have higher degradation efficiency to methyl orange (MO) than cubic ones with exposed {100} planes and truncated octahedral with exposed {111} planes microcrystals.     

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)