The growth,spectral and thermal properties of the coordination compound crystal‐ strontium malate

Growth of single crystals of the title compound Sr(C₄H₄O₅).3H₂O is achieved using the gel diffusion technique. Multifaceted single crystals of size up to 4x3x3 mm³ are obtained. X‐Ray Diffraction (XRD) pattern of the grown crystal and the Fourier Transform Infra‐Red (FTIR) spectrum in the range 400‐4000 cm^‐1 are recorded. The vibrational bands corresponding to different functional groups are assigned. Thermal behavior of the material is investigated using Thermo Gravimetry (TG) and Differential Thermal Analysis (DTA). Thermal studies are indicative of a five‐stage decomposition scheme. © 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim     

Growth and characterization of L‐prolinium tartrate – A new organic NLO material

Single crystals of L‐Prolinium tartrate (C₅H₁₀NO₂)⁺ (C₄H₅O₆)^‐, a new organic non‐linear optical material of size: 15 × 10 × 10 mm³ were grown using submerged seed solution growth method. Characterization of the crystals was made using single crystal X‐ray diffraction and density determination. Spectroscopic, thermal, optical and mechanical studies were carried out. These studies show that the crystals are thermally stable upto 161°C, transparent for the fundamental and second harmonic generation of Nd: YAG (λ = 1064 nm) laser and possess good mechanical strength. Second harmonic generation (SHG) conversion efficiency was investigated to explore the NLO characteristics of this material using Kurtz and Perry method and it was found that the SHG conversion efficiency is about 90% of that of the standard KDP crystals. Laser damage threshold study was also carried out. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Spectroscopic properties of La3Ga5SiO14:Er3+ (1%) crystals

Single crystals of Erbium (Er) doped La₃Ga₅SiO₁₄ (LGS) have been grown along c‐axis by using the Czochralski method. The absorption and fluorescence spectra of LGS: Er³⁺ single crystals have been measured and analyzed according to the Judd‐Ofelt theory. When applied, the following spectral parameters have been obtained: intensity parameters Ω_t, Ω₂= 2.741674×10^‐20cm², Ω₄= 0.66934×10^‐20 cm² and Ω₆= 0.592591×10^‐20 cm², radiative transition probabilities A_J,J”, P_J,J”. The radiative lifetime of levels ⁴I_13/2, ⁴H_9/2, ⁴S_3/2 are 11.333ms, 0.447ms and 0.704ms, respectively. The fluorescence branching ratios and the integrated emission cross sections are also calculated. The results suggest that LGS: Er crystals have potential applications as a laser material. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Thermal,phase transition and FTIR spectroscopic studies in tetraethylammonium trichlorocadmiate crystals

Single crystals of tetraethylammonium trichlorocadmiate were grown by slow evaporation of aqueous solutions at room temperature. The bright and transparent crystals obtained were characterized through FTIR spectroscopy, thermo gravimetric (TG and DTA) and low temperature DSC analyses. A fitting decomposition pattern for the title compound was formulated based on the TG thermogram which shows a two‐stage weight loss between 300°C and 800°C. In this temperature range the DTA curve shows endothermic dips supporting the formulated decomposition pattern. The thermal anomalies observed in the low temperature DSC both during the heating and cooling cycles indicate the occurrence of the first and second order structural phase transitions in the compound. The FTIR and far IR spectra show characteristic vibration frequencies due to [N(C₂H₅)₄]⁺ and CdCl₃^‐ ions. Detailed structural analysis of the compound is under progress. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Growth and characterization of semi organic nonlinear optical LHPCL crystals

The growth of single crystals of L‐histidinium perchlorate (LHPCL), a semi organic nonlinear optical material with dimension upto 5 × 6 × 2.5 mm³ is reported. Good optical quality single crystals were grown from aqueous solution by slow solvent evaporation technique. The grown crystals were characterized by single crystal X‐ray diffraction (XRD), FT‐IR and optical transmission studies. Thermal studies confirm that LHPCL has a fairly high thermal stability (272°C) when compared with other members of histidine family. The scanning electron microscopy (SEM) provides information on the quality of the samples and grain distribution over the surface of the sample. The dielectric constant and dielectric loss of the compound were measured at different frequencies, and also at varying temperatures and the results of these experiments are discussed. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Single crystal growth and properties of semiorganic nonlinear optical L‐arginine hydrochloride monohydrate crystals

L‐arginine hydrochloride monohydrate (LAHCl.H₂O) has been synthesized and single crystals have been grown from its aqueous solution by slow evaporation and slow cooling methods. The solubility of the material was measured at various temperatures and bulk crystals of size 26×13×11 mm³ have been grown by optimizing the growth parameters. The grown crystals have been subjected to single crystal XRD studies to confirm the structure and to estimate the lattice parameters. FTIR analysis indicate the mode of vibrations of different molecular groups present in LAHCl and confirm the protonation of guanidyl, amino groups and deprotonation of COO^‐ groups. UV‐Vis transmission spectrum revealed the linear optical properties of the grown crystals with a transparency of 65% over the entire visible range upto 300 nm. Thermal behavior of the grown crystal was investigated from DTA and TGA measurements. Dielectric studies have been carried out on the grown crystals. Kurtz and Perry powder SHG technique confirms the NLO property of the grown crystal. The SHG efficiency of LAHCl was found to be 0.38 with respect to KDP. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Synthesis,growth, morphology and characterization of ferroelectric glycine phosphite single crystals

Glycine phosphite (NH₃CH₂COO.H₃PO₃), a potential ferroelectric material, was grown as single crystals from aqueous solutions by slow evaporation and slow cooling methods. Laboratory synthesized title compound was purified by recrystallization method and confirmed by Fourier transform infrared and Laser Raman studies. Temperature dependent solubility in double distilled water in the range between 288 and 328 K was determined by gravimetric method. Morphological importance of various growth faces were studied by optical goniometry. Powder x‐ray diffraction study performed on the grown crystals confirms the crystal system and lattice parameters of the unit cell. Optical transparency of the grown crystals in the ultraviolet–visible ‐near infrared region was studied by spectroscopic method. Thermal stability of the grown crystals in the temperature region above ambient until melting was studied using differential scanning calorimetry. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Microhardness studies on as‐grown (111) faces of some alkaline earth nitrates

Single crystals of Sr(NO₃)₂, Ba(NO₃)₂ and Pb(NO₃)₂ are grown from their aqueous solutions at a constant temperature of 35 °C by slow evaporation technique. Crystals of size 8 to 10 mm along one edge are obtained in a period of 10 days. Chemical etching technique has been employed to study the dislocations in these crystals. The dislocations are randomly distributed and the dislocation density is about 10⁴ to 10⁵ /cm². Microhardness studies are made on as–grown (111) faces of these crystals upto a load of 100 g. The hardness of the crystals increases with an increase in load and thereafter it becomes independent of the applied load. These results are discussed on the basis of reverse indentation size effect. Meyer index number n for these crystals is estimated at both low and high load regions. An analysis of hardness data of these crystals as well as some other cubic crystals like alums and alkali halates are discussed using Gilman–Chin parameter H_v/C₄₄, where H_v is the microhardness and C₄₄ is the shear constant. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Synthesis,growth and characterization of L‐histidinium acetate dihydrate single crystals

L‐histidinium acetate dihydrate {abbreviated as LHAc; [C₆H₁₀ N₃O₂⁺ C₂H₃O₂^‐ 2H₂O], a new nonlinear optical (NLO) material has been grown from aqueous solution. The grown crystals were subjected to X‐ray diffraction, Fourier transform infrared (FTIR) and FT‐Raman analyses. Thermal studies have been carried out for its thermal stability. Optical behaviour such as UV‐Vis‐NIR spectrum and second harmonic generation (SHG) were also investigated. Its SHG efficiency was found as d_eff = 2.2 d_eff (KDP). (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Synthesis and thermal,phase transition and FTIR spectral characterization of tetraethylammonium tetrachlorocuprate (II) crystals

Single crystals of tetraethylammonium tetrachlorocuprate (II), [N(C₂H₅)₄]₂CuCl₄, were grown by slow evaporation method at room temperature. The crystals were characterized through powder XRD, thermogravimetric (TG‐DTA), low temperature differential scanning calorimetric (DSC) studies and FTIR spectroscopy. While the powder XRD pattern of the compound shows sharp Bragg peaks confirming the crystallinity of the compound, the TG‐DTA studies confirm formation of the compound in the stoichiometric ratio. The thermal anomalies observed in DSC curve at ‐120°C in the heating cycle and around ‐30°C in the cooling cycle indicate a first order phase transition. The phase transition was predicted to be associated with the ordering of CuCl₄^2‐ and successive long range orientation of [N(C₂H₅)₄]⁺ ions which are disordered at high temperatures. The cationic [N(C₂H₅)₄]⁺ plays a role in phase transitions at low temperatures. The sharp exothermic peak observed in high temperature DSC indicates a structural phase transition when [N(C₂H₅)₄]CuCl₃ is formed on heating the compound. The FTIR spectra of the compound characterize the various chemical bonding and water molecules adsorbed in the compound. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Crystal growth and magnetic properties of the copper coordination polymer [Cu(µ ‐C2O4)(4‐aminopyridine)2(H2O)]n

In this paper, we consider various ways of crystal growth of the polymer [Cu(µ ‐C₂O₄)(4‐aminopyridine)₂(H₂O)]_n. Single crystals of the size of 1.5×1.5×0.2 mm³ have been grown by a slow diffusion technique from solutions of the monoammine copper complex and of the mixture of potassium oxalate and aminopyridine with the stoichiometric ratio. Magnetic susceptibility and ESR measurements have been performed on single crystals large enough for investigating anisotropic properties. The susceptibility can be well described within the model of a Heisenberg antiferromagnetic spin chain. The magnetic measurements reveal a small concentration of paramagnetic moments reflecting the high quality of the single crystals. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

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)     

Growth,structure, and superconducting properties of Bi2Sr2Ca2Cu3O10 and (Bi,Pb)2Sr2Ca2Cu3O10‐y crystals

Large and high‐quality single crystals of both Pb‐free and Pb‐doped high temperature superconducting compounds (Bi_1‐xPb_x)₂Sr₂Ca₂Cu₃O_10‐y (x = 0 and 0.3) were grown by means of a newly developed “Vapour‐Assisted Travelling Floating Zone” technique (VA‐TSFZ). This modified zone‐melting technique was realised in an image furnace and allowed for the first time to grow Pb‐doped crystals by compensating for the Pb losses occurring at high temperature. Crystals up to 3×2×0.1 mm³ were successfully grown. Post‐annealing under high pressure of O₂ (up to 10 MPa at T = 500°C) was undertaken to enhance T_c and improve the homogeneity of the crystals. Structural characterisation was performed by single‐crystal X‐ray diffraction (XRD) and the structure of the 3‐layer Bi‐based superconducting compound was refined for the first time. Structure refinement showed an incommensurate superlattice in the Pb‐free crystals. The space group is orthorhombic, A2aa, with cell parameters a = 27.105(4) Å, b = 5.4133(6) Å and c = 37.009(7) Å. Superconducting studies were carried out by A.C. and D.C. magnetic measurements. Very sharp superconducting transitions were obtained in both kinds of crystals (ΔT_c ≤ 1 K). In optimally doped Pb‐free crystals, critical temperatures up to 111 K were measured. Magnetic critical current densities of 2�10⁵ A/cm² were measured at T = 30 K and μ₀H = 0 T. A weak second peak in the magnetisation loops was observed in the temperature range 40‐50 K above which the vortex lattice becomes entangled. We have measured a portion of the irreversibility line (0.1‐5 Tesla) and fitted the expression for the melting of a vortex glass in a 2D fluctuation regime to the experimental data. Measurements of the lower critical field allowed to obtain the dependence of the penetration depth on temperature: the linear dependence of λ(T) for T < 30 K is consistent with d‐wave superconductivity in Bi‐2223. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

X‐Ray Powder Diffraction,DTA and Vibrational Studies of CdNH4PO4.6H2O Crystals

Cadmium Ammonium Phosphate Hexahydrate (CAPH) is analogous to naturally occurring struvite. CAPH crystals are grown by slow evaporation technique. These crystals are characterised by X‐ray, TG‐DTA and Infra‐red studies. Powder X‐ray pattern indicates the orthorhombic crystal structure analogous to struvite. TG‐DTA analysis suggests loss of water of hydration (6H₂O) between 113 and 391°C. Later the substance melts and only Cd remains around 780 °C. Infra Red spectrum is characteristic of H₂O, PO₄^3‐ and NH₄⁺ radicals.     

Synthesis and characterization of 1‐phenyl‐3‐(propan‐2‐yl)‐1H‐pyrazol‐5‐ol single crystals

The synthesis of pyrazoles and its derivatives remains of great interest due to their wide applications in pharmaceutical and agrochemical industry. The 1‐phenyl‐3‐(propan‐2‐yl)‐1H‐pyrazol‐5‐ol was synthesized. The 1‐phenyl‐3‐(propan‐2‐yl)‐1H‐pyrazol‐5‐ol single crystals were grown by slow solvent evaporation technique using mixture of chloroform and methanol as a solvent. Yellowish and transparent crystals having maximum dimensions of 0.005 m × 0.004 m × 0.002 m were grown. The crystals were characterized by powder XRD, FT–IR, TG–DTA–DSC and dielectric study. The crystals remained stable up to 160 °C and then start decomposing. The DSC suggested both endothermic and exothermic reactions. One broad exothermic peak was observed at 558.1 °C due to complete decomposition of the sample into the gaseous phase and reaction within the products. Thermodynamic and Kinetic parameters of decomposition were calculated by Coats–Redfern formula. The dielectric study was carried out in the frequency range from 50 Hz to 5 MHz at room temperature. The dielectric constant decreased as the frequency of the applied field increased. The variations of dielectric loss, a.c. conductivity and a.c. resistivity also studied with the frequency of the applied field. Jonscher's power law was verified for a.c. conductivity.     

Growth of α-NiSO<Subscript>4</Subscript> · 6H<Subscript>2</Subscript>O crystals at high rates

The high-rate growth of nickel sulfate hexahydrate NiSO₄ · 6H₂O (α-NSH) crystals up to 120 × 120 × 65 mm³ in size is described for the first time. The data on the distribution of related impurities in the {011} and {001} growth sectors of α-NSH crystals grown at different rates are reported. The transmission spectra of both growth sectors of these crystals are obtained. The structural quality and the optical properties of rapidly and slowly grown α-NSH crystals are compared. It is established that the {011} growth sector of crystals grown at rates exceeding 5 mm/day shows the best characteristics for application in UV filters.     

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)     

Crystal data and some physical properties of Tl2InGaTe4 crystals

The room temperature crystal data, Debye temperature, dark and photoelectrical properties of the Bridgman method grown Tl₂InGaTe₄ crystals are reported for the first time. The X‐ray diffraction technique has revealed that Tl₂InGaTe₄ is a single phase crystal of tetragonal body‐centered structure belonging to the space group. A Debye temperature of 124 K is calculated from the results of the X‐ray data. The current‐voltage measurements have shown the existence of the switching property of the crystals at a critical voltage of 80 V. The dark electrical resistivity and Hall effect measurements indicated the n ‐type conduction with an electrical resistivity, electron density and Hall mobility of 2.49×10³ Ω cm, 4.76×10¹² cm^–3 and 527 cm²V^–1s^–1, respectively. The photosensitivity measurements on the crystal revealed that, the variation of photocurrent with illumination intensity is linear, indicating the domination of monomolecular recombination at room temperature. Moreover, the spectral distribution of the photocurrent allowed the determination of the energy band gap of the crystal studied as 0.88 eV. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Crystal Structure of Diethyl 2‐[2,2,2‐ trifluoro‐1‐(indole‐3‐yl)‐ethyl]‐2‐acetamidomalonate

The title compound (C₁₉H₂₁F₃N₂O₅) has been determined from three dimensional X‐ray diffraction data. The crystals are monoclinic, a = 7.626(4)Å, b = 17.515(4)Å, c = 15.066(3)Å, β = 101.02(3)°, V = 1975(1)ų, Z = 4, D_calc = 1.393g cm^‐3, space group P2₁/c. The structure was solved by direct methods and refined by full‐matrix least‐squares method (R = 0.039).     

Synthesis and characterization of dihydroxylammonium tetrachlorocuprate dihydrate crystals

A new hydroxylammonium compound, [(NH₃OH)₂CuCl₄], was synthesized and its crystals were grown at room temperature by slow evaporation of aqueous solutions. The crystals were characterized through powder XRD, thermogravimetry (TG), differential thermal analysis (DTA), low temperature differential scanning calorimetric (DSC) and FTIR spectra. The X‐ray powder diffraction confirms the crystallinity of the compound. A fitting decomposition pattern of the compound was formulated based on the TG and thereby confirming the formation of the compound in the stoichiometric ratio. The thermal anomalies occurring in the low temperature DSC indicate successive phase transitions. The low temperature phase transitions are attributed to the ordering of [NH₃OH]⁺ ions. While most of the phase transitions are of first order type, the one occurring at –126 °C is of second order. Two glass transitions occur when the compound was cooled between –157.9 and –136.9 °C. The characteristic vibration bands due to [NH₃OH]⁺ and CuClequation/tex2gif-stack-1.gif ions are observed in the IR spectra. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)