Showing papers in "Crystal Research and Technology in 2008"
TL;DR: In this paper, a ZSM-5 zeolite crystal with different Si/Al molar ratios in the range of 10-50 was synthesized using sodium silicate, aluminum sulfate and tetrapropylammonium bromide as the organic template.
Abstract: ZSM-5 zeolite crystal with different Si/Al molar ratios in the range of 10-50 was synthesized using sodium silicate, aluminum sulfate and tetrapropylammonium bromide (TPA-Br) as the organic template. The produced samples were characterized using XRD, FT-IR, SEM and EDX techniques. All synthesized samples were found to be ZSM-5 zeolite as confirmed by XRD and supported by FT-IR. SEM results showed that ZSM-5 synthesized with different Si/Al molar ratios had different morphologies and particle sizes. It was found that the average ZSM-5 crystal size increased as Si/Al molar ratio increased. Thermogravimetric-difference thermal analysis (TG-DTA) technique was also used to measure the amount of template occluded inside the crystal pore. The synthesized Na-ZSM-5 was transformed into its acidic form, i.e., H-ZSM-5 using ion exchange method with ammonium nitrate solution. The H-ZSM-5 acidity was determined by NH3-TPD. These results showed that different Si/Al molar ratios have effect on surface acidity of samples. The surface areas of the H-ZSM-5 were measured using BET method and the results showed that, decrease in Si/Al ratio, decreased the surface area. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
318 citations
TL;DR: In this paper, the authors show that L-arginine addition leads to reduction of electrical parameters of KDP and ADP single crystals which can be attributed mainly to the decrease of L-defects due to creation of additional hydrogen bonds by the impurity in random directions.
Abstract: Potassium dihydrogen orthophosphate (KDP) and ammonium dihydrogen orthophosphate (ADP) single crystals added with L-arginine have been grown by the solution methods. DC and AC electrical measurements were carried out at various temperatures along both a- and c- directions. Results indicate an increase of the electrical parameters with the increase of temperature which can be attributed mainly to the increase of thermally generated hydrogen bond vacancies (L. defects). Also, the present study indicates that L-arginine addition leads to reduction of electrical parameters of KDP and ADP single crystals which can be attributed mainly to the decrease of L-defects due to creation of additional hydrogen bonds by the impurity in random directions. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
132 citations
TL;DR: Czochralski growth of large metallic alloy single crystals of Al 13Co4 and Al13Fe4 from Al-rich solutions has been demonstrated for the first time in this article.
Abstract: Czochralski growth of large metallic alloy single crystals of Al 13Co4 and Al13Fe4 from Al-rich solutions has been demonstrated for the first time. A detailed description of all decisive steps of the growth procedure is given with particular emphasis to seeding from a native phase as well as spontaneous nucleation if no seed crystal from a preceding experiment is available. Czochralski growth in a high-temperature solution system requires much lower pulling rates compared to typical growth experiments from the melt and a time-dependent temperature program to compensate the change of the liquidus temperature that results from the permanently increasing Al content of the liquid phase. With a given amount of the initial melt, the size of the Al13Co4 crystals is limited by the rather narrow temperature range of the Al13Co 4 primary crystallization window, followed by Al9Co 2 phase crystallization. In the Al-Fe system, despite the huge temperature range of equilibrium between Al13Fe4 and its Al-rich melt, Czochralski growth of Al13Fe4 is restricted to higher temperatures due to the limited solubility that leads to mother liquid inclusions even at extremely low pulling rates.
78 citations
TL;DR: In this paper, single crystals of L-Tyrosine hydrochloride were grown by using the submerged seed solution method and characterized by using single crystal X-ray diffraction, functional groups and the modes of vibrations were identified by FTIR spectroscopy.
Abstract: School of Physics, Madurai Kamaraj University, Madurai – 625 021, India Received 17 September 2007, accepted 26 October 2007 Published online 16 November 2007 Key words L-tyrosine hydrochloride, XRD, NLO, FTIR, TGA/DTA, ,microhardness. PACS 61.10.-i, 78.30.-j, 65.40.-b, 62.20.-x, 42.70.mp Single crystals of L-Tyrosine hydrochloride were grown by using the submerged seed solution method. The grown crystals were characterized by using single crystal X-ray diffraction. Functional groups and the modes of vibrations were identified by FTIR spectroscopy. The TGA/DTA studies showed that the crystal is stable up to 232°C. Microhardness study revealed that the crystal is a hard material. It is transparent in the entire visible region. The SHG efficiency was determined by the Kurtz and Perry method.
75 citations
TL;DR: The long chain imidazolium halides [Cnmim]Br·xH2O (n = 10, 12; x = 0, 1) have been synthesized and their structural and thermal behaviour together with their photophysical properties characterized as mentioned in this paper.
Abstract: The long chain imidazolium halides [Cnmim]Br·xH2O (n = 10, 12; x = 0, 1) have been synthesized and their structural and thermal behaviour together with their photophysical properties characterized. X-ray structure analyses of the monohydrates ([C12mim]Br·H2O: triclinic, P1, no. 2, Z = 2, Pearson code aP112, a = 550.0(5) pm, b = 779.4(5) pm, c = 2296.1(5) pm, α = 81.89(5)°, β = 83.76(5)°, γ = 78.102(5)°, 3523 unique reflections with Io > 2σ(Io), R1 = 0.0263, wR2 = 0.0652, GooF = 1.037, T = 263(2) K; [C14mim]Br•H2O: triclinic, P1, no. 2, Z = 12, Pearson code aP11, a = 549.86(8) pm, 782.09(13) pm, c = 2511.3(4) pm, α = 94.86(2)°, β = 94.39(2)°, γ = 101.83(2)°, 2063 unique reflections with Io > 2σ(Io), R1 = 0.0429, wR2 = 0.0690, GooF = 0.770, T = 293(2) K) show for both compounds similar bilayered structures. Sheets composed of hydrophilic structure regions constituted by positively charged imidazolium head groups, bromide anions and hydrogen bonded water alternate with hydrophobic areas formed by interdigitated long alkyl chains belonging to imidazolium cations with different orientation. Combined differential scanning calorimetry and polarizing optical microscopy shows that the monohydrates as well as the anhydrous imidazolium salts are thermotropic liquid crystals which adopt smectic mesophases. The mesophase region is larger in case of the monohydrates when compared to the anhydrous compounds indicating that water obviously stabilizes the mesophase. All compounds show an intense whitish photoluminescence with short lived (1π←1π*) and long lived (1π←3π*) transitions. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
70 citations
TL;DR: In this paper, the crystallization of Mefenamic acid (MA) was investigated and the crystal size distribution of MA was determined using Focused Beam Reflectance Measurement (FBRM) technique.
Abstract: The crystallization of Mefenamic Acid, (MA), which has a prevalent usage in drug formulation, was investigated MA is a high-dose, anti-inflammatory, analgesic agent used for pain in menstrual disorders Some negative properties of MA are a high hydrophobicity and propensity to stick to surfaces, which cause great problems during granulation and tabletting To facilitate tabletability, enhance dissolution rates, and develop a stable and reproducible dosage form, investigation of the physicochemical properties of mefenamic acid is necessary Pharmaceutical drugs are commonly crystalline materials and are therefore subject to polymorphism Polymorphism, the ability of a substance to exist in more than one crystalline form, is a significant phenomenon in the field of chemical engineering sciences, including pharmaceutical development Establishing the polymorphic behaviour of a drug molecule early in development minimizes the number of unsuitable candidates developed and reduces the risk of encountering issues later which may have a major financial and time impact Mefenamic acid crystals were recrystallized from five different solvents of N, N-dimethylformamide (DMF), acetone, N, N-dimethylacetamide (DMA), Dimethylsulfoxide (DMS) and Ethyl Acetate (EA) In order to characterize the Mefenamic Acid crystal structure and the polymorphic forms of the crystals obtained by recrystallization, the scanning electron microscopy (SEM), Raman diffractometry and X-ray pattern were used From the industrial crystallization point of view, the crystal size distribution (CSD), the crystal shape, the polymorphic form and the crystallization steps are important factors that affect the quality and bioavailability of a drug For the determination of crystal size distribution of MA, The Focused Beam Reflectance Measurement (FBRM) technique was practiced and CSD profiles were obtained (© 2008 WILEY-VCH Verlag GmbH & Co KGaA, Weinheim)
50 citations
TL;DR: In this paper, the organic NLO material 2-nitro aniline and picric acid (2NAP) was synthesized, needle shaped single crystals of dimension 10 × 1 × 0.8 mm-3 were grown by slow evaporation solution growth technique from the saturated solution of the title compound in chloroform at ambient temperature.
Abstract: The organic NLO material 2-nitro aniline and picric acid (2NAP) was synthesized, needle shaped single crystals of dimension 10 × 1 × 0.8 mm-3 were grown by slow evaporation solution growth technique from the saturated solution of the title compound in chloroform at ambient temperature. The material was characterized through elemental analysis, powder XRD, 1H NMR, 13C NMR and FTIR techniques. The various planes of reflection have been identified from the XRD powder pattern. The formation of the charge transfer complex was confirmed by UV-VIS spectroscopy. The thermal stability of the crystals was investigated using TG/DTA analyses techniques. The second harmonic generation (SHG) efficiency of the material was estimated using Nd: YAG laser as source. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
43 citations
TL;DR: In this article, Larginine hydrochloride monohydrate (LAHCl) has been synthesized and single crystals have been grown from its aqueous solution by slow evaporation and slow cooling methods.
Abstract: 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)
43 citations
TL;DR: In this paper, the positions of borates with the non-linear optical properties were determined including complicate cases using topology and symmetry analysis of anionic radicals with the separation of blocks, typical for borate groups.
Abstract: New borates with the non-linear optical properties, obtained and investigated in Moscow State University in the last years, are reviewed. The positions of compounds in systematic were determined including complicate cases using topology and symmetry analysis of anionic radicals with the separation of blocks, typical for borate groups. Such approach revealed structural correlations between borates and silicates and led to prediction of new structures, two of which are realized. The origin of properties is connected with the highly polarizable electron density on lone pair or asymmetric bonds, presented in the structures. Experimental observation electron density distrubution has been made for Pb-hilgardite, a crystal with the high optical non-linearity. Different approaches to the structure-properties relation are discussed. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
41 citations
TL;DR: In this paper, a semi-organic nonlinear optical (NLO) material of L-Proline cadmium chloride monohydrate (L-PCCM) single crystal was grown and the metastable zone width and induction period were determined experimentally in order to optimize the growth parameters.
Abstract: Nucleation parameters such as solubility, induction period, interfacial energy and metastable zone width have been investigated for the aqueous solution growth of a semi-organic nonlinear optical (NLO) material of L-Proline cadmium chloride monohydrate (L-PCCM) single crystal. Metastable zone width and induction period values were determined experimentally in order to optimize the growth parameters. The grown crystals are transparent (dimensions: 16 x 8 x 5 mm3) and characterized by powder X-Ray Diffraction and dielectric studies. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
37 citations
TL;DR: In this paper, single crystals of potassium acid phthalate (KAP) and amino acid (DL-Alanine, L-Methionine) doped KAP were grown from aqueous solutions by slow cooling method using powder X Ray diffraction (XRD) and Fourier Transform Infrared (FTIR) analysis.
Abstract: Single crystals of potassium acid phthalate (KAP) and amino acid (DL-Alanine, L-Methionine) doped KAP were grown from aqueous solutions by slow cooling method. The grown crystals were characterized using powder X Ray diffraction (XRD) and Fourier Transform Infrared (FTIR) analysis. The thermal stability of KAP in the presence of dopants was analysed using Thermogravimetric and Differential Scanning caloriemetric (TGA/ DSC) studies and the maximum temperature for non linear optical application of this compound in the presence of dopants was found out. The transmittance of KAP was found to increase in the presence of dopants. Etch pits were observed for all the crystals using different etchants. Vickers microhardness tests were performed to study the mechanical stability of the crystals. The hardness of DL-alanine doped KAP is more than that of L-alanine doped KAP crystal. The dielectric constant and loss were determined as a function of temperature. Frequency response of the dielectric constant and dielectric loss factor have been studied over the frequency range of 50Hz – 5MHz. Second harmonic generation (SHG) was confirmed in all the crystals using the Kurtz and Perry powder technique. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
TL;DR: In this paper, the authors measured the optical absorption in photonic crystals of potassium acid phthalate and calculated the optical band gap by using the absorption spectrum, which revealed a direct band gap of 3.70 eV.
Abstract: Optical absorption in photonic crystals of potassium acid phthalate has been measured at room temperature, from which the band gap has been determined and the optical band gap was calculated by using absorption spectrum. The analysis of absorption coefficient in the absorption region reveals a direct band gap of 3.70 eV. Further this study includes the theoretical calculations to determine the optical constant of the material and a technique for photonic band gap tuning which is minimally required to develop the optoelectronic device. It was confirmed that potassium acid phthalate crystal has maximum transparency in the entire visible region and hence it exhibits industrial application oriented properties. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
TL;DR: In this paper, single crystals of REE, Al borates, new and known representatives of huntite family are obtained by annealing REEBO3 on Al2O3 surface at 1100°C.
Abstract: Single crystals of REE, Al borates, new and known representatives of huntite family are obtained by annealing of REEBO3 on Al2O3 surface at 1100°C. Phase identification for REE=Pr, Eu, Tb, Tm, Ho, Yb has been carried out using unit cell parameter determination on single crystals. Crystal structures of C 2/c (PrAl3(BO3)4) and C 2 (EuAl3(BO3)4) - two polytypic modifications, previously determined for other REE's have been studied. Formation of one or another polytype in similar thermodynamic conditions is probably dependent on electronic structure of rare earth ion. Crystal field stabilization energy in crystal fields of different symmetry is a possible factor of polytype stability (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
TL;DR: In this paper, the optical transmittance data in a wavelength range between 300 and 1600 nm was analyzed and the optical band gap was found to be 2.58 eV for film thickness 300 nm.
Abstract: Thermally processed lead iodide (PbI2) thin films were prepared by the vacuum evaporation method in a constant ambient. Measured thickness of the film was verified analytically from the optical transmittance data in a wavelength range between 300 and 1600 nm. From the Tauc relation for the non-direct inter band transition, the optical band gap of the film was found to be 2.58 eV for film thickness 300 nm. X-ray diffraction analysis confirmed that PbI2 films are polycrystalline, having hexagonal structure. The low fluctuation in Urbach energy indicates that the grain size is quite small. The present findings are in agreement with the other results. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
TL;DR: The effect of lithium dopant on crystal properties has been studied in this paper, where single crystals of pure and lithium substituted L-alanine are successfully grown by slow evaporation method at constant temperature of 32°C.
Abstract: Single crystals of pure and lithium substituted L-alanine are successfully grown by slow evaporation method at constant temperature of 32°C. The effect of lithium dopant on crystal properties has been studied. Powder and single crystal XRD analysis confirms the structure and change in lattice parameter values for the doped crystals. The crystals were characterized by solubility studies, density, melting point measurements, FTIR and UV-Vis-NIR techniques. Thermal and mechanical stability of crystals were tested by TGA/DTA and micro hardness analysis. NLO activity of the crystals is found to be increased in the presence of lithium ions. The dielectric constant and dielectric loss of the crystals were studied as a function of frequency. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
TL;DR: In this paper, the transport properties of ternary mixed WSxSe2-x single crystals have been studied by measuring the thermo power, electrical conductivities and Hall parameters in a small temperature range 303-423 K.
Abstract: The transport properties of ternary mixed WSxSe2-x single crystals have been studied by measuring the thermo power, electrical conductivities and Hall parameters in a small temperature range 303-423 K. The electrical conductivity was highest for selenium rich WSe2 and lowest for sulphur rich WS2 crystals. All the crystals showed semiconducting behaviour from the temperature dependence of ‘ρ’, ‘RH’ and ‘S’. The Hall coefficients showed that the samples are p-type conducting. The temperature dependence of resistivity, Hall coefficients, carrier concentration showed that all of them are thermally activated. The values of activation energies, pre-exponential factors and the scattering parameters have been determined. The dominant scattering mechanism for the charge carriers has been explained. The relation between the TEP and the concentration of charge carriers and electrical conductivity was studied. The effective masses of holes and the effective density of states have been determined. These parameters show an increase with increase in sulphur content. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
TL;DR: In this paper, the nucleation of protein crystals by gold nanoparticles was observed, and the effect was established both with uncoated and coated gold particles with 16-mercaptodecanoic acid.
Abstract: Nucleation of protein crystals by gold nanoparticles was observed. Lysozyme and ferritin were used as model proteins. The effect was established with uncoated gold nanoparticles and with gold nanoparticles coated by 16-mercaptodecanoic acid. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
TL;DR: In this paper, a semiorganic crystal, L-glutamic acid hydrobromide, C5H10NO4Br (GHB), has been grown from aqueous solution, which belongs to the non-centrosymmetric P212121 space group with protonated glutamic acid as cation and bromine as anion.
Abstract: A new semiorganic crystal, L-glutamic acid hydrobromide, C5H10NO4Br (GHB) has been grown from aqueous solution. The single crystal X-ray analysis of the crystal showed that it belongs to the non-centrosymmetric P212121 space group with protonated glutamic acid as cation and bromine as anion. The back-bone conformations of the amino acid are in cis and trans form. The side-chain conformations are observed to be in gauche I / trans / cis / trans forms. The characteristic ‘head-to-tail’ hydrogen bonding interaction is observed through a chain C(5) motif. Further, the crystal structure is stabilized by an intricate three-dimensional hydrogen bonding network. TGA/DTA showed that the grown crystals are thermally stable upto 219 °C without any phase transition. The functional groups responsible for the various modes of vibrations were identified by using FTIR spectroscopy. UV-Vis-NIR spectra showed that the crystals have excellent transparency in the visible and infrared regions. The second harmonic generation (SHG) conversion efficiency was investigated to explore the NLO characteristics of the material. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
TL;DR: In this article, the crystalline material of acenaphthene picrate (ACP) was synthesized and the single crystals of the title compound were grown by slow evaporation solution growth technique.
Abstract: The crystalline material of acenaphthene picrate (ACP) was synthesized and the single crystals of the title compound grown by slow evaporation solution growth technique. The solubility of the complex compound was estimated using different solvents as chloroform, ethanol, (1:1) chloroform - acetone mixture. The material was characterized through elemental analysis; powder XRD, NMR and FTIR techniques. The various planes of reflection have been identified from the XRD powder pattern. The formation of the charge transfer complex was confirmed by UV-VIS spectroscopy. The thermal stability of the crystals was studied using TG/DTA analyses techniques. The second harmonic generation (SHG) of the material was confirmed by using Nd: YAG laser. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
TL;DR: In this paper, a Ferroelectric Glycine Phosphite (GPI) crystal has been grown from aqueous solution employing the slow cooling technique, where the same procedure was used to grow single crystals of 10 wt% of Thiourea doped GPI.
Abstract: Ferroelectric Glycine Phosphite (GPI) crystal have been grown from aqueous solution employing the slow cooling technique. As the crystal solubility in water depends on temperature, single crystals were grown. Transparent, colourless crystals with habit morphology weighing about 8g were obtained with in a month. The same procedure was used to grow single crystals of 10 wt% of Thiourea doped GPI (TUGPI). Formation of a new crystal was confirmed by Powder X-ray diffraction studies as well as FTIR studies. Crystalline quality were found using rocking curve for both the crystals. Due to the presence of Thiourea in TUGPI, it improves the crystalline perfection and also enhances the growth rate. The variation of hardness on (010) faces of monoclinic GPI and TUGPI crystals, with load were studied.Vickers hardness numbers, Hv were found to decrease with the increase in load. The value of Mayer's index, ‘n ’ was found to be greater than 1.6 for GPI and TUGPI showing soft-material category. The results are discussed in detail. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
TL;DR: In this article, the effect of RPI antiscalant on homogeneous nucleation and growth of gypsum was examined under conditions of supersaturation and temperature, simulating a brackish water desalination unit using solar energy.
Abstract: Calcium sulphate dihydrate (gypsum) crystallization was studied under conditions, of supersaturation and temperature, simulating a brackish water desalination unit using solar energy. The effect of an commercial sodium salt of poly(acrylic acid), based compound known as RPI, on homogeneous nucleation and growth of gypsum was also examined. Gypsum was precipitated by mixing aqueous CaCl2 and Na2SO4 solutions. It was found that, with increasing temperature or supersaturation, the induction time decreases and the growth rate increases. By using classical nucleation theory, the interfacial tension and the nucleation rate values were estimated. It was shown that the interfacial tension is temperature dependent. The addition of increasing quantities of RPI, in the same conditions of temperature and supersaturation, prolongs the induction time, decreases the nucleation rate and increases the interfacial tension. The addition mode of RPI (in calcium or in sulphate solution) was found as an important parameter in controlling the inhibition process of gypsum crystallization. XRD and SEM analysis showed that RPI antiscalant strongly affected the texture and the morphology of the deposit gypsum. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
TL;DR: In this article, an optically transparent crystal of potassium dihydrogen phosphate (KDP) has been grown from aqueous solution along (001) plane with the aid of modified growth assembly of Sankaranarayanan-Ramasamy (SR) Method.
Abstract: Growth of bulk nonlinear optical (NLO) single crystals gained new significance with the advent of solid-state laser sources for opto-electronic applications. An optically transparent crystal of potassium dihydrogen phosphate (KDP) has been grown from aqueous solution along (001) plane with the aid of modified growth assembly of Sankaranarayanan-Ramasamy (SR) Method. The evaporation rate was controlled and single crystals of 5 mm diameter and 60 mm length with a growth rate 5 mm per day have been grown successfully. The improved transparency of grown crystal was investigated using DRS UV transmittance spectral analysis and the presence of functional groups in the grown crystal is confirmed using FTIR analysis. (© 2007 WILEY -VCH Verlag GmbH & Co. KGaA, Weinheim)
TL;DR: In this article, the ionic liquid (IL) 1-butyl-3methylimidizolium tetrafluoroborate ([BMIm][BF4]) with different buffer/IL proportions was used for lysozyme crystallization.
Abstract: Lysozyme crystallization was conducted in the ionic liquid (IL) 1-butyl-3-methylimidizolium tetrafluoroborate ([BMIm][BF4]) with different buffer/IL proportions. It was found that the addition of [BMIm][BF4] could promote the crystallization process, during which more lager single crystals with controllable morphologies could be obtained due to the manageable crystal growth velocity. A probable explanation was proposed based on the influence of the ionic polarization and kinetics in the lysozyme crystallization. Moreover, the transform in coordination number and the relative growth rate of different crystal faces were discussed. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
TL;DR: In this article, the gelatine-gel diffusion technique was used to determine the structure of the orthorhombic struvite [NH4[Mg(H2O)6](PO4)] structure in space group Pmn 21.
Abstract: Phases with composition M [Mg(H2O)6](X O4), where M = Rb, Tl and X = P, As, were obtained by means of the gelatine-gel diffusion technique from Mg-EDTA and corresponding metal phosphate/arsenate solutions at pH > 9. The crystal structures were determined from single crystal X-ray diffractometer data sets. All compounds crystallize isotypically with two formula units in the orthorhombic struvite [NH4[Mg(H2O)6](PO4)] structure type in space group Pmn 21 and with lattice parameters of a ≈ 6.88, b ≈ 6.16, c ≈ 11.34 A. The structures consist of slightly distorted [Mg(OH2)6] octahedra (m symmetry), X O4 tetrahedra (m symmetry) and [M O10] polyhedra (m symmetry) as single building units, held together by an intricate hydrogen bonding network. The structure can also be described as made up of closed packed pseudo -hexagonal layers of [Mg(OH2)6] units stacked along [010] with the X O4 tetrahedra and the M atoms in the voids of this arrangement. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
TL;DR: In this paper, single crystals of amino acid doped (L-citrulline, L-ascorbic acid) triglycine sulphate were grown by slow evaporation technique.
Abstract: Single crystals of amino acid doped (L–citrulline, L-ascorbic acid) triglycine sulphate were grown by slow evaporation technique. The lattice parameters and crystalline quality were confirmed by powder X-ray diffraction studies. The presence of functional groups in the grown crystals was confirmed by Fourier transform infrared spectrum analysis. The dielectric studies were carried out to identify the phase transition temperature and the dielectric constant was found to be less for both the doped crystals than pure triglycine sulphate crystal. Micro hardness studies were carried out using Vickers pyramidal indentation technique at room temperature showed a decrease in hardness due to doping. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
TL;DR: In this paper, large single crystals of the polar (point group mm 2) compound tris(glycine) zinc chloride, (NH3CH2COO)3 · ZnCl2, were grown from aqueous solutions.
Abstract: Large single crystals of the polar (point group mm 2) compound tris(glycine) zinc chloride, (NH3CH2COO)3 · ZnCl2, were grown from aqueous solutions. The refractive indices were measured in the wavelength region from 365 nm to 1083 nm and an unpolarised absorption spectrum was recorded (transparency range from 260 to 1550nm). The phase matching conditions for second harmonic generation were analysed: both, type I (ss-f) and type II (sf-f) are possible in the red and near IR region. All five components of the piezoelectric tensor [dijk ] were determined; the maximum values of longitudinal and transverse piezoelectric effects are less than one half of d111 of α-quartz. In addition, a redetermination of the crystal structure (including location of H atoms) is presented. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
TL;DR: In this article, the structural and optical properties of ZnO nanostructures strongly depended on the supply time of Ar. The Raman spectroscopy revealed the low level of oxygen vacancies and Zn interstitials in samples.
Abstract: ZnO nanostructures were grown on Au-coated Si (100) substrates by carbonthermal reduction method with the help of Ar at the beginning of growth. The structural and optical properties of ZnO nanostructures strongly depended on the supply time of Ar. When the given time of Ar gas current was 90s, sample was ZnO nanowires with hexagonal morphology. The Raman spectroscopy revealed the low level of oxygen vacancies and Zn interstitials in samples. Room temperature photoluminescence (PL) spectra exhibited the intensity of green emission increased on the condition of rich oxygen (decrease given time of Ar) and the nanowire had strongest intensity of UV emission compared with other nanostructures. Green emission is ascribed to the electron transition from the bottom of the conduction band to the antisite defect O-Zn level. (C) 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
TL;DR: The quasi-binary phase diagram of lithium oxide was investigated by differential scanning calorimetry and X-ray diffraction in this article, and the system was shown to have one eutectic point at 50.5 mol% MoO3 and 49.5 Mol% LiO0.5 with a temperature of 524.6°C. At this point the melt is in equilibrium with Li2MoO4 and Li4Mo5O17.
Abstract: The quasi-binary phase diagram lithium oxide – molybdenum(VI) oxide was investigated by differential scanning calorimetry and X-ray diffraction. The four intermediate phases Li4MoO5, Li2MoO4, Li4Mo5O17, and Li2Mo4O13 show incongruent melting. The system has one eutectic point at 50.5 mol% MoO3 and 49.5 mol% LiO0.5 with a eutectic temperature of 524.6°C. At this point the melt is in equilibrium with Li2MoO4 and Li4Mo5O17. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
TL;DR: In this paper, single crystal growth experiments were conducted to investigate the growth rate of acetaminophen (paracetamol) crystals under carefully controlled conditions of temperature, supersaturation and pH value.
Abstract: Single crystal growth experiments were conducted to investigate the growth rate of acetaminophen (paracetamol) crystals under carefully controlled conditions of temperature, supersaturation and pH value. The relative growth rate of the different faces was studied. Growth Rate Dispersion (GRD) was observed by studying the effect of supersaturation and temperature on the growth rate. The growth rate in all directions was found to be temperature dependant. Elongation of the crystals was measured due to the faster growth in the Y- direction and Xa direction compared to in the Xb direction. Dissolution of the crystals was observed at pH values greater than 8.5, and a growth rate retardation was observed when increasing the pH from 5.6, which is the normal value without additions, to higher values in both acidic and basic mediums up to 8.5. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
TL;DR: The reproducibility of biomacromolecular crystallization (tetragonal and orthorhombic lysozyme crystals) was studied by monitoring the evolution of protein concentration during the crystallization process using Mach-Zehnder interferometer.
Abstract: The reproducibility of biomacromolecular crystallization (tetragonal and orthorhombic lysozyme crystals) was studied by monitoring the evolution of protein concentration during the crystallization process using Mach-Zehnder interferometer. It was found that formation of both tetragonal and orthorhombic crystals exhibited poor reproducibility. When the crystallization occurred under isothermal conditions, the protein concentration in the solution varied differently in different experiments under identical conditions (for both types of crystals). Moreover, in the case of orthorhombic lysozyme crystallization (under either isothermal or thermal gradient conditions), it is clear that the crystals could not be always readily formed. When formation of tetragonal lysozyme crystals was conducted at a temperature gradient condition, however, the evolution of concentration was reproducible. The phenomena found in this study revealed that biomacromolecular crystallization can be uncertain, which is probably caused by the process of nucleation. Such uncertainties will be harmful for the efforts of screening crystallization conditions for biomacromolecules. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)