K. Srinivasan  K. Vanitha Devi 《Crystal Research and Technology》2010,45(9):946-952

Single crystals of L‐ascorbic acid, popularly known as vitamin‐C, were grown from solutions with different solvents and solvent combinations by low temperature solution growth methods. The suitability of different solvents and solvent combinations such as acetone, ethanol, methanol, isopropyl alcohol, water, water + acetone (1:1), water + ethanol (3:1), water + isopropyl alcohol (3:1) and isopropyl alcohol + methanol (1:1) for crystal growth of L‐ascorbic acid was found out by assessing the solubility and crystallization behaviours. Solubility of L‐ascorbic acid in selected solvents and solvent combinations in a range of temperatures was determined by gravimetric method. Solution prepared with water, water + acetone (1:1), water + ethanol (3:1) and water + isopropyl alcohol (3:1) were yielded crystals with tabular, columnar and prismatic habits and their morphologies were evaluated by goniometry. Grown single crystals were characterized with various instrumental techniques such as powder X‐ray diffraction, Fourier infrared spectroscopy, optical transmittance study, differential scanning calorimetry and second harmonic generation studies. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献   

    

V. Rajnikant  V.K. Gupta  S. Shafi  E.H. Khan  J. Firoz  R. Gupta 《Crystal Research and Technology》2001,36(2):215-221

The crystal and molecular structure of 3 β ‐Acetoxy‐5 α ‐cholestan‐6‐one has been determined by X‐ray crystallographic techniques. The compound crystallizes in the space group P2₁ with cell parameters : a = 13.060(3), b=6.299(2), c=17.152(6)Å; β =96.47(3)o, V = 1402.02ų, Z = 2, R = 0.072 for 1921 observed reflections. The six‐membered rings (A, B and C) exist in the chair conformations while the five‐membered ring‐d assumes half‐chair. All rings of the steroid skeleton are trans connected.  相似文献   

    

Krishnamurthy Senthil Kumar  Sridharan Moorthy Babu  G. Bhagavannarayana 《Journal of Applied Crystallography》2011,44(2):313-318

Good quality and optically transparent single crystals of pure and doped glycine phosphite (GPI) were grown by both solvent‐evaporation and temperature‐cooling techniques. Dopants were chosen in different categories, namely transition metals (Cr, Mn, Co, Ni, Zn, Mg, Cd), rare‐earth metals (Ce, Nd, La), dyes (rhodamine B, malachite green, fluorescein) and an amino acid (l ‐proline). The concentration of dopants was chosen depending on the category of dopants and the quality of crystallization during the growth process. The crystalline perfection of the as‐grown pure and doped GPI crystals was investigated by high‐resolution X‐ray diffraction at room temperature. A multicrystal X‐ray diffractometer employing a well collimated and highly monochromated Mo Kα₁ beam and set in the (+, −, −, +) configuration was employed. Most of the crystal specimens show excellent crystalline perfection. However, grain boundaries, low‐angle tilt boundaries, and vacancy and interstitial point defects were observed in some crystal specimens.  相似文献   

    

K. Renuka Devi  K. Srinivasan 《Crystal Research and Technology》2015,50(2):171-178

Proton dissociation assisted negative polarity of malonic acid molecules admist glycine zwitterions leads to orgination of γ nucleation in the solution. Alteration in the nucleation behaviour and segregation of glycine polymorphs in the presence of malonic acid over a wide range of concentrations has been investigated both by experimental and analytical approaches. Complete changeover in the nucleation behaviour from 100% α to 100% γ is observed at the critical concentration of the additive. Shifting in the overall charge environment of the system towards cationic in the presence of malonic acid favours the nucleation of γ through induced charge compensation in the solution. Tuning of merohedral twinning in γ nucleation by the additive concentration has been well revealed in the present work. CNT based analytical approach employed elucidates well the experimental observations through the estimated interfacial energy, volume excess free energy, critical radius, activation energy barrier and nucleation rates of α and γ polymorphs. Structural affirmation of the nucleated polymorphs was carried out by powder x‐ray diffraction.  相似文献   

    

V. Sagredo  L. M. de Chalbaud 《Crystal Research and Technology》2004,39(10):877-880

Single crystals of CdGa_2(1‐x)Cr_2xSe₄ compounds for 0 ≤ x ≤ 1 have been grown by using the chemical vapor transport technique in a closed system. The transporting agent was CdCl₂ in a proportion of 0.75 mg/cc of capsule. The starting material was previously synthetized. The structural characterization on the crystals were done by powder x‐ray diffraction studies. The results show three different phases for various Cr concentration ranges: spinel structure for x ≥ 0.7, rombohedral for 0.6 ≥ x ≥ 0.5 and tetragonal for 0.4 ≥ x ≥ 0. That is, the chromium dilution in the CdCr₂Se₄ compound by Ga atoms produces very significant changes in the structural atomic arrangement. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献   

    

《Crystal Research and Technology》2018,53(3)

Nucleation control, separation and crystal growth of polymorphic forms of the well‐known amino acid L‐histidine from pure aqueous solution is investigated by adopting the novel swift cooling crystallization process for the first time. The concomitant nucleation behavior of the stable orthorhombic and metastable monoclinic polymorphs of L‐histidine is investigated under different supersaturation conditions. While lower‐level of supersaturation favours the nucleation of stable polymorph, higher‐level supersaturation favours the nucleation of metastable polymorph of L‐histidine. By this way, the nucleated concomitant polymorphs of L‐histidine are separated successfully and grown as single crystals from pure aqueous solution without using any additives or anti‐solvents. Morphology of the nucleated polymorphs are identified through optical microscopy and confirmed by optical goniometry. Also, the morphological importance of different growth faces is evaluated. The distinction in the crystal system of the two polymorphs is identified by powder X‐ray diffraction (PXRD) and their crystallographic unit cell structure is refined by single crystal X‐ray diffraction (SCXRD) analyses. The thermal stability of the grown polymorphs is judged through differential scanning calorimetry (DSC). Results suggest that the supersaturation plays a key role in the nucleation and growth behaviour of the stable and metastable polymorphs of L‐histidine in aqueous solution.  相似文献   

    

K. Renuka Devi  K. Srinivasan 《Crystal Research and Technology》2011,46(12):1265-1272

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)  相似文献   

    

G. Anandha Babu  K. Thirupugalmani  P. Ramasamy 《Crystal Research and Technology》2009,44(6):675-681

Organic optical material 4‐Aminopyridinium‐4‐nitro phenolate (4AP4NP) has been synthesized, and single crystals of size 20 x 14 x 6 mm³ have been grown from acetone solvent at room temperature by solvent evaporation technique. The grown crystals have been characterized by X‐ray diffraction to determine the cell parameters, and by FT‐IR technique to confirm the formation of the expected compound. The crystal belongs to monoclinic crystal system with space group P2₁/a.The structural perfection of the grown crystals has been analyzed by high‐resolution X‐ray diffraction (HRXRD) rocking curve measurements. The thermal stability of the compound has been determined by TG‐DTA curves. The transmittance of 4AP4NP has been used to determine the refractive index n; the extinction coefficient K and both the real ε_r and imaginary ε_i components of the dielectric constant as functions of photon energy. The optical band gap of 4AP4NP is 2.4 eV. The dielectric and mechanical behavior of the specimen was also studied. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献   

    

P. Dhanasekaran  K. Srinivasan 《Crystal Research and Technology》2012,47(12):1217-1230

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.  相似文献   

    

N. Balamurugan  M. Lenin  G. Bhagavannarayana  P. Ramasamy 《Crystal Research and Technology》2007,42(2):151-156

The recently discovered crystal growth method called uniaxially solution‐crystallization method of Sankaranarayanan–Ramasamy (SR) is modified in some aspects and used for growth of triglycine sulphate (TGS) crystals. The modification leads to the simplicity, reduction of cost and avoided the temperature fluctuations. The 〈010〉 direction of TGS is very important and used for fabrication of infrared detectors. Using this method, the 〈001〉, 〈010〉 directional crystals of TGS were successfully grown in a glass crystallizer. The grown crystal was characterized by HRXRD, UV‐Visible and dielectric studies. The results prove the suitability of the modified SR method for oriented TGS crystal. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献   

    

S. A. Martin Britto Dhas  S. Natarajan 《Crystal Research and Technology》2008,43(8):869-873

L‐Valinium picrate (C₅H₁₂NO₂)⁺. (C₆H₂N₃O₇)^–, a non‐linear optical material from the amino acid family which has large second harmonic generation (SHG) efficiency, was grown by slow evaporation method. Characterization of the crystals was made using single crystal X‐ray diffraction. The functional groups and the modes of vibrations were found by using the Fourier transform infrared (FTIR) spectroscopy. The second harmonic generation (SHG) conversion efficiency was investigated using the Kurtz and Perry method. The SHG conversion efficiency is 60 times higher than that of the standard KDP and 8 times higher than that of the standard Urea and the optical transparency was analyzed using UV‐visible‐NIR absorption spectrum. The structural features of the material leading to the large SHG efficiency are discussed. Microhardness and dielectric studies were also carried out. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献   

    

P. Shenoy  K. V. Bangera  G. K. Shivakumar 《Crystal Research and Technology》2010,45(8):825-829

The investigations on the formation of mixed crystals of ammonium dihydrogen orthophosphate (ADP) and potassium dihydrogen orthophosphate (KDP) i.e. potassium ammonium dihydrogen phosphate, K_1‐x(NH₄)_xH₂PO₄ have been presented in this paper. Pure and mixed crystals of ADP and KDP have been grown by slow evaporation technique from the supersaturated solution at an ambient temperature 26±1 °C for ammonium concentration x in the range 0.0 ≤ x ≤ 1.0 in the case of mixed crystals. Crystal compositions were determined by flame atomic absorption spectroscopy and chemical analysis. The results of the X‐ray analysis of the grown crystals are also reported. Thermogravimetric analysis (TGA) and differential thermal analysis (DTA) were used to study the kinetic process of dehydration and the high temperature phase behaviour. DTA showed the distinct thermal events attributed to dehydration of ADP, KDP and K_1‐x(NH₄)_xH₂PO₄. The results of thermal analysis and chemical analysis are consistent with each other. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献   

    

Z. H. Sun  D. Xu  X. Q. Wang  X. J. Liu  G. Yu  G. H. Zhang  L.Y. Zhu  H. L. Fan 《Crystal Research and Technology》2007,42(8):812-816

Single crystal growth of the organic nonlinear optical crystal, L‐arginine trifluoroacetate (L‐Arg·CF₃COOH, abbreviated as LATF) is reported. Low temperature solution growth method is employed for the growth of bulk single crystals. The cell parameters are verified by single crystal diffraction. Fourier transform infrared (FT‐IR) and Fourier transform Raman analysis are used to confirm the presence of various functional groups in the grown crystal. The thermal properties of the grown crystals are studied by thermogravimetric analysis and differential scanning calorinetry analysis (TGA/DSC). Second harmonic generation (SHG) measurement confirms the NLO properties of the grown crystal. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献   

    

O. Ye. Zhbankov  I. D. Olekseyuk  O. M. Yurchenko  V. Z. Pankevich 《Crystal Research and Technology》2006,41(9):843-847

The phase diagrams of the CuInS₂‐Sb₂S₃ and CuInS₂‐Bi₂S₃ systems were investigated using X‐ray powder diffraction and differential thermal analysis. Based on these results, the compositions for the growth of the CuInS₂ single crystals from CuInS₂‐Sb₂S₃ and CuInS₂‐Bi₂S₃ melts were selected and Bridgman crystal growth process was performed. The investigation of the obtained single crystals using X‐ray powder diffraction and optical absorption spectra indicates that the incorporation of the solvent atoms into the crystal lattice is absent. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献   

    

N. Vijayan  G. Bhagavannarayana  K. K. Maurya  S. Pal  S. N. Datta  R. Gopalakrishnan  P. Ramasamy 《Crystal Research and Technology》2007,42(2):195-200

Single crystal of 8‐hydroxyquinoline (8HQ) having chemical formula C₉H₇NO, an organic nonlinear optical (NLO) material has been successfully grown by slow evaporation solution growth technique at room temperature. The crystal system has been confirmed from the powder X‐ray diffraction (PXRD) analysis. The crystalline perfection was evaluated by high resolution X‐ray diffractometry (HRXRD). From this analysis we found that the quality of the crystal is quite good. However, a very low angle (tilt angle 14 arc sec) boundary was observed which might be due to entrapping of solvent molecules in the crystal during growth. Its optical behavior has been examined by UV‐Vis. analysis, which shows the absence of absorbance between the wavelengths ranging from 400 to 1200 nm. From the thermal analysis it was observed that the material exhibits single sharp weight loss starting at 113°C without any degradation. The laser damage threshold was measured at single shot mode and the SHG behavior has been tested using Nd:YAG laser as a source. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献   

    

M. S. Goorsky  B. K. Tanner 《Crystal Research and Technology》2002,37(7):645-653

The in‐plane mosaic structure of Au/Fe and GaN‐based epitaxial layers has been determined directly by laboratory‐based grazing incidence in‐plane x‐ray diffraction in which Bragg reflections normal to the plane of the wafer are probed. High intensity and acceptable signal‐to‐noise can be obtained with no modifications to commercially available equipment. Excellent agreement is obtained between measurements of the same Au/Fe multilayer samples at the European Synchrotron Radiation Facility in Grenoble and with the laboratory system employing a focused x‐ray beam from a microfocus generator. The technique is particularly important for the GaN‐based systems as it uniquely provides a measure of the so‐called twist mosaic independent of the out‐of plane (tilt) mosaic.  相似文献   

    

K. Srinivasan  S. Kanimozhi 《Crystal Research and Technology》2010,45(6):611-618

The habit of the organic non‐linear optical material meta‐nitroaniline (mNA) crystallized from different organic solvents such as acetone, benzene, ethyl acetate, n‐hexane, methanol and toluene were studied. Solubility of mNA in these solvents at various temperatures in the range between 288 and 323 K was determined by gravimetric method. Crystals were grown by restricted evaporation of solvents method. Solutions with different solvents having different chemical nature and polarity yielded crystals with different habits: one‐dimensional needles, two‐dimensional rhombic platelets and three‐dimensional octahedral. In addition, the mNA crystals show unidirectional growth behaviour along its polar [001] direction irrespective of the solvents used. All the grown crystals were found to be orthorhombic system with point group mm2 and space group Pbc2₁ which was confirmed by powder X‐ray diffraction study. Optical transmittance study showed that the grown mNA single crystals have optical transparency in the wavelength range between 430 and 1550 nm. SHG efficiency of the grown mNA crystal was 3 times grater than KDP. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献   

    

Lei Wang  Guanghui Zhang  Xitao Liu  Xinqiang Wang  Luning Wang  Luyi Zhu  Dong Xu 《Crystal Research and Technology》2013,48(12):1087-1096

A novel organic crystal, L‐lysine p‐nitrophenolate monohydrate (LLNP) has been grown successfully from an aqueous solution by the slow cooling method. Transparent single crystal of dimensions 22 × 12 × 12 mm³ has been obtained. The single crystal X‐ray diffraction has shown that LLNP belongs to the orthorhombic crystallographic system with space group P2₁2₁2₁. The functional groups and vibrational frequencies of the crystal have been identified using IR and Raman spectra. The proton and carbon configurations have been confirmed through ¹H‐NMR and ¹³C‐NMR spectra analyses. The UV‐Vis‐NIR transmittance spectrum for LLNP crystal has been recorded in the range from 200 to 2500 nm. The second harmonic generation (SHG) intensity of LLNP has been measured by powder SHG method and found to be as 4.2 times as that of KDP. The thermal properties have been studied by using thermo gravimetric (TG) and differential thermal analysis (DTA).  相似文献   

    

R. Khler  P. Schfer 《Crystal Research and Technology》2002,37(7):734-746

Usually about one micrometer is considered the lower limit of spatial resolution (in direct space) of x‐ray diffraction. This is due as well to diffraction as to image detection. The latter problem can be addressed by image magnification. There are several efforts to achieve image magnification. One is magnification by asymmetric Bragg reflection. This is well known for many years. In the present paper the implications regarding experimental set‐up, resolution and efficiency will be considered from the experimental point of view. High magnification at good spatial resolution requires synchrotron radiation. Experiments were performed at beamlines ID19 and ID11 of the European Synchrotron Radiation Facility (ESRF). It is shown that actually a spatial resolution considerable better than one micrometer can be achieved. There are, however, some drawbacks which are related to source characteristics, synchrotron beam optics, Fresnel and Bragg diffraction.  相似文献   

    

A. Aravindan  P. Srinivasan  N. Vijayan  R. Gopalakrishnan  P. Ramasamy 《Crystal Research and Technology》2007,42(11):1097-1103

Amino acid family crystals exhibit excellent nonlinear and electro‐optical properties. L‐alanine alaninium nitrate (LAAN) single crystal belonging to the amino acid group was grown by slow cooling solution growth technique. The High resolution X‐ray diffraction (HRXRD), Fourier transform infrared (FTIR) spectroscopy, Raman spectroscopy, UV‐Vis., Photoluminescence (PL) and Factor group analyses were carried out. The factor group analysis reveals 183 internal vibrations for the title compound. The second harmonic generation property was tested by Kurtz‐Perry powder technique. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献