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Results in Journal Journal of Crystallization Process and Technology: 113

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Rui Zhang, Xuezhong Wang, Yang Zhang, Tao Liu, Zhang Rui, Wang Xuezhong, Zhang Yang, Liu Tao
Journal of Crystallization Process and Technology, Volume 9, pp 13-38; doi:10.4236/jcpt.2019.92002

Abstract:
Crystal shape distribution, i.e. the multidimensional size distribution of crystals, is of great importance to their down-stream processing such as in filtration as well as to the end-use properties including the dissolution rate and bioavailability for crystalline pharmaceuticals. Engineering crystal shape and shape distribution requires knowledge about the growth behavior of different crystal facets under varied operational conditions e.g. supersaturations. Measurement of the facet growth rates and growth kinetics of static crystals in a crystallizer without stirring has been reported previously. Here attention is given to study on real-time characterization of the 3D facet growth behavior of crystals in a stirred tank where crystals are constantly moving and rotating. The measurement technique is stereo imaging and the crystal shape reconstruction is based on a stereo imaging camera model. By reference to a case study on potash alum crystallization, it is demonstrated that the crystal size and shape distributions (CSSD) of moving and rotating potash alum crystals in the solution can be reconstructed. The moving window approach was used to correlate 3D face growth kinetics with supersaturation (in the range 0.04 - 0.12) given by an ATR FTIR probe. It revealed that {100} is the fastest growing face, leading to a rapid reduction of its area, while the {111} face has the slowest growth rate, reflected in its area continuously getting larger.
Nidhi Yaduvanshi, Deepak Kumar, Nikhil Rastogi, Ashok Kumar
Journal of Crystallization Process and Technology, Volume 9, pp 1-11; doi:10.4236/jcpt.2019.91001

S. Pekar Grygoriy, F. Singaеvsky Alexandr, M. Lokshin Myhailo, A. Vasin Ilya, V. Dubikovskyi Oleksandr, Grygoriy S. Pekar, Alexandr F. Singaеvsky, Myhailo M. Lokshin, Ilya A. Vasin, Oleksandr V. Dubikovskyi
Journal of Crystallization Process and Technology, Volume 9, pp 39-47; doi:10.4236/jcpt.2019.93003

Abstract:
Unconventional ways to improve the efficiency of purification of two different semiconductor materials of current interest, ZnO and Ge, are described. It is shown that, by using chemically assisted vapour transport of ZnO with carbon as a transporting agent, the degree of chemical purity of ZnO can be increased by more than an order of magnitude. It is also found that heating of the molten Ge in the experimentally determined narrow (about 20?C wide) temperature range in which an intense evaporation of certain substances is observed, leads to a significant reduction of germanium contamination. As a result, a subsequent deep purification of pre-heat treated germanium by zone refining can be achieved at twice reduced (as compared with “non-treated” Ge) number of passes of a boat with germanium through the melting zones. Thus, the Ge purification process becomes faster, cheaper and more efficient.
Metogbe B. Djihouessi, Sofiath Onifade, Martin P. Aïna, Hervé E. Labité, François De Paule Codo
Journal of Crystallization Process and Technology, Volume 8, pp 18-32; doi:10.4236/jcpt.2018.81002

Abstract:
This paper presented the first part of the studies about the development of a tool for groundwater contamination prediction, conducted by the Laboratory of Sciences and Technology of Water (UAC/Benin). The investigation made consisted in estimating the combined effect of retardation factor and biodegradation on migration processes of leachate, in the underlying soils of household waste dumpsites, without active safety barrier. Leachate infiltration tests for different initial conditions were made on soil columns and the breakthrough curves were traced for electrical conductivity, the 5 day biochemical oxygen demand (BOD5) and total kjeldahl nitrogen TKN. A mathematical migration model was developed and solved numerically by finite difference method and implemented with Matlab R2013a. Thus, the calibration of the model was made with electric conductivity data by determining the dispersion coefficient of the studied soils (D = 0.96 cm2/min). Simulations for model verification showed that the established model can perfectly predict the migration of biodegradable organic pollution (BOD5) but did not give conclusive results for the monitoring of nitrogenous organic matter (TKN). The influence of the retardation factor on the migration of biodegradable organic pollutants in soils was linear, while the biodegradation rate of the organic material on migration showed an exponential pattern.
Daniel Selzer, Burkard Spiegel,
Journal of Crystallization Process and Technology, Volume 8, pp 1-17; doi:10.4236/jcpt.2018.81001

Abstract:
Crystal nucleation is important to control the product properties in industrial crystallization processes. To investigate crystallization phenomena, methods which rely on microscopic volumes have gained relevance over the last decade. Microfluidic devices are suitable for carrying out crystallization experiments based on a large set of individual droplets in the nanoliter range. In this work, we propose a simple method to manufacture such devices from polycarbonate as an alternative to conventional chips made of poly (dimethylsiloxane). The microfluidic device consists of two main functional parts: A T-junction for droplet generation and a section for storage and observation of up to 400 individual droplets. Using these manufactured devices, it is easy to produce and store highly monodisperse droplets of substances that require either a hydrophilic or hydrophobic surface of the microchannel. Since crystal nucleation is a stochastic process which depends on the sample volume, a reproducible droplet volume is of great importance for crystallization experiments. The versatile applicability of the manufactured devices is demonstrated for substances which are used in different crystallization applications, for example, solution crystallization (aqueous potassium nitrate solution) and melt crystallization (ethylene glycol distearate). Finally, we demonstrate that the manufactured microfluidic devices in our experimental setup can be used to conduct crystal nucleation measurements. Based on these measurements we discuss our results with respect to state-of-the-art nucleation models.
Amel Adjimi, Meryem Lamri Zeggar, Nadhir Attaf, Mohammed Salah Aida
Journal of Crystallization Process and Technology, Volume 8, pp 89-106; doi:10.4236/jcpt.2018.84006

Abstract:
In the present work, undoped (SnO2) and fluorine-doped tin oxide (FTO) thin films were prepared by sol-gel process using a solution composed of (SnCl2, H2O), (NH4F), and ethanol mixture. The fluorine concentration effect on structural, optical and electrical properties of SnO2 films is investigated. The electrical properties of FTO films prepared by sol gel remain relatively lower than the ones deposited by other techniques. In present paper, we try to elucidate this difference. Films composition and the FTIR analysis, of films and formed precipitate during film growth, indicate that few amounts of fluorine are incorporated in SnO2 network, most of fluorine atoms remain in the solution. The films resistivity is reduced from 1.1 Ω·cm for undoped films to 3 × 10-2 Ω·cm for 50 wt.% doped FTO, but remains higher than the reported ones in the literature. This high resistivity is explained in terms of fluorine bonding affinity in the solution.
Noopur Rathi,
Journal of Crystallization Process and Technology, Volume 8, pp 73-87; doi:10.4236/jcpt.2018.83005

Abstract:
Batch crystallization studies of curcumin from hydrotropic solutions of sodium cumenesulphonate (NaCS) and of cinnamic acid from a photosensitive hydrotropic medium of sodium cinnamate (Na-CIN) were carried out, in an agitated reactor for the effect of alternate heating and cooling cycles on crystal morphology. The crystal characterization by Scanning electron microscopy (SEM) and crystal size distribution (CSD) showed formation of spheroidal curcumin crystals while cinnamic acid formed porous aggregates when subjected to thermal cycles. The UV irradiation of cinnamic acid however showed no formation of the aggregates. The type of hydrotrope used and the initial crystal morphologies of curcumin and cinnamic acid are shown to be important factors to result in a different behaviour of the crystal morphology upon thermal cycles. The CSD data were effectively used for estimation of nucleation and growth rate parameters.
, , Latif Fagbemi
Journal of Crystallization Process and Technology, Volume 8, pp 57-71; doi:10.4236/jcpt.2018.82004

Abstract:
An analytical investigation is conducted to study the effect of magnetic field on convection heat transfer through packed porous beds which consists of a horizontal fluid layer (river bed) and a porous zone with anisotropic permeability and underlined by a surface heated by a constant temperature T1. The free surface of the fluid layer overlying the horizontal porous layer receives solar rays to length of day and is then considered heated isothermally at temperature T2 such as T1 < T2. Flow in porous medium is assumed to be governed by the generalized Brinkman-extended Darcy law and in the fluid layer by the Navier-Stokes model. The Beavers-Joseph condition is applied at the interface between the two layers. The influence of Hartmann number and hydrodynamic anisotropy on the convective phenomenon is investigated analytically. It is found that the magnetic field, the anisotropic permeability and the thickness of the porous lining, ε, have a strong influence of the geothermal convective flow and the heat transfer rate.
Journal of Crystallization Process and Technology, Volume 8, pp 33-55; doi:10.4236/jcpt.2018.81003

Abstract:
Purification is a primary application of zone melting, in which the improvement of efficiency, production yield and minimum achievable impurity level are always the research focus due to the increasing demand for high purity metals. This paper has systematically outlined the whole development of related research on zone refining of metals including basic theories, variants of zone refining, parametric optimization, numerical models, and high purity analytical methods. The collection of this information could be of good value to improve the refining efficiency and the production of high purity metals by zone refining.
Galina A. Sycheva
Journal of Crystallization Process and Technology, Volume 7, pp 11-47; doi:10.4236/jcpt.2017.72002

Abstract:
Using differential thermal analysis, X-ray phase analysis, electron microscopy, and optical microscopy, the nucleation of crystals in glass obtained by blending metallurgical slag with silicon dioxide has been studied. The type of crystallization (homogeneous or heterogeneous, volume or surface) is revealed for each of nine compositions of synthesized glass. It is shown that the first crystalline phase in a volume crystallizing glass is perovskite (CaO·TiO2); in this phase a nucleation of the main phase occurs: melilite (solid solution of gehlenite 2CaO·Al2O3·SiO2 in akermanite 2CaO·MgO·2SiO2). The fundamental characteristics of homogeneous (for a catalizing phase, perovskite) and heterogeneous (for a catalyzed phase, melilite) of crystallization are determined: the steady state nucleation rate Ist, time of unsteady state nucleation τ, crystal growth rate U, and activation energy of frictional flow. The temperature dependences of Ist, τ, and U are obtained. The kinetics of the crystallization of glass is studied and the rates of the surface crystal growth are determined in the glass of nine compositions. The influence of grinding the particles of the original glass on the sequence of deposition of the crystalline phases was studied. Practical recommendations are presented for the use of blast-furnace slag as a raw material for the synthesis of glass and their further utilization.
Hiroaki Nishikawa, Takafumi Nishii
Journal of Crystallization Process and Technology, Volume 7, pp 48-53; doi:10.4236/jcpt.2017.72003

Abstract:
Freestanding membrane (FSM) of hydroxyapatite (HA) is a thin sheet of pure HA without any supporting substrates. Our original preparation process of FSM of HA had three steps: The first was the deposition of HA layer on sacrificial layer of solvent-soluble materials, the second was separation of FSM of HA by means of dissolution of sacrificial layer, and the third was post-annealing to crystallize FSM of HA. To date, the post-annealing process was a serious bottleneck of productivity owing to its too long time. In this short report, we proposed a novel sacrificial layer, heatproof and water-soluble Ba-compound, which makes the direct deposition of crystallized HA possible due to its heatproof property because the problem on the original process was that the previous sacrificial layers have no heatproof property and HA layer should be deposited as amorphous. We can deposit the Ba-compound sacrificial layer only in 1 hour followed with the direct deposition of crystallized HA layer, substituting the 20 hours of post-annealing. The FSM of HA was separated successfully from the substrate by means of dissolution of Ba-compound with water. Our novel process can shrink the process time by 19 hours.
Hiroaki Nishikawa, Ayaka Saito, Akiko Miyake, Yuichiro Tashiro, Yoshiya Hashimoto
Journal of Crystallization Process and Technology, Volume 7, pp 1-10; doi:10.4236/jcpt.2017.71001

Abstract:
To increase the biocompatibility of hydroxyapatite (HA), Ca10(PO4)6(OH)2, the Sr substitution of Ca into the HA structure was effected to yield Ca10-xSrx(PO4)6(OH)2(Sr-HA). For medical and dental applications, it is important that Sr-HA is prepared as a thin film so that the Sr fully substitutes the Ca sites in the HA structure and does not form segregated impurities consisting of Sr compounds. If the segregated Sr forms different amounts of different impurities, the dissolution of the Sr into the living body will not be reproducible across different samples. To confirm the Sr substitution into the Ca site in the HA structure, the systematic variation in the lattice constants of the Sr-HA with Sr content was evaluated as the first step. The a- and c-axis lengths were found to exhibit a linear relationship with the Sr content for six samples with different Sr contents, indicating that the prepared Sr-HA thin films likely possessed partial Sr substitution into the Ca sites of the HA structure. This result is an important first step in the accurate evaluation of the biological effects of Sr-HA thin films.
Journal of Crystallization Process and Technology, Volume 7, pp 55-63; doi:10.4236/jcpt.2017.73004

Abstract:
It is known that the dense part of any liquid metal consists of ramified clusters of almost regular tetrahedrons (triangular pyramids with atoms in their vertexes) that are connected into chains by faces. Any metal additive as a second component of liquid alloy can be both beyond these clusters as separated atoms and into them as inherent clusters. The liquid-metal alloy transfers into the second state, at the first eutectic of the solvent. This polymorphic transition of liquid matrix is discovered in the systems, Pb-K and Na-Pb, by molecular-dynamic simulating their microstructure and in experiments on scattering slow neutrons by these alloys of different compositions. In the first system, the obtained results identify both the homogeneous alloy at low concentrations of potassium in liquid lead and the alloy clustering, (Pb4K)n, at potassium concentrations following the eutectic, Pb0.91K0.09. In the second one at the concentrations of lead more than 2%, just the second state is discovered with the clusters, (Na4Pb)n. One can expect the same polymorphic transition in the eutectic, Na0.93Tl0.07, with the micro-inhomogeneity, (Na6Tl)n, and with the melting point of 64 C. This eutectic maintained by the oxygen-free technology and enriched by the isotope, 205Tl, can become the best coolant for fast nuclear reactors due to the depressed chemical activity of sodium and composition stability.
S. Ramukutty, R. Jeyasudha, E. Ramachandran
Journal of Crystallization Process and Technology, Volume 7, pp 85-90; doi:10.4236/jcpt.2017.74006

Abstract:
The crystallization of ursodeoxycholic acid drug crystals in gel by reduction of solubility method is the first of its kind to be reported in literature. Monoclinic crystalline form of the structure was confirmed using single crystal X-ray diffraction analysis. This report deals with the kinetic analysis made from the thermogravimetric analysis/differential thermal analysis (TGA/DTA) data using Coats-Redfern (CR) relation. Thermodynamic parameters were also determined. Arrhenius equation for ursodeoxycholic acid was derived as k = 3.10 × 1010 e−172581/RT mol−1•s−1.
Danilo C. Curtolo, Semiramis Friedrich, Bernd Friedrich
Journal of Crystallization Process and Technology, Volume 7, pp 65-84; doi:10.4236/jcpt.2017.74005

Abstract:
Since the early 1950’s the use of Germanium has been continuously growing as new applications are being developed. Its first commercial usage as the main material, from which the semiconductors were made, was later replaced by Silicon. The applications were then shifted to a key component in fiber optics, infrared night vision devices and space solar cells, as well as a polymerization catalyst for polyethylene terephthalate (PET). With the advance development in new technologies, the attentions have been brought back to Germanium due to its excellent semiconductor properties. New applications on the field of high efficiency solar cells, SiGe based chips, LED technologies, etc., are being developed and show a great potential. According to DERA (Deutsche Rohstoffagentur/German Mineral Resources Agency), the demand for Ge will grow considerably by 2030, pushed mostly by the increase in the fiber optics market and advanced materials sector [1]. Therefore, this paper focuses on an overview of the production chain of Germanium, especially from its concentrate up to the single crystal growth of its valuable ultra-pure metallic form to be used in high technological applications.
Yuhua Ge, Tingting Li, Jingjing Cheng
Journal of Crystallization Process and Technology, Volume 6, pp 1-10; doi:10.4236/jcpt.2016.61001

Abstract:
Azilsartan (2-ethoxy-1-([2’-(5-oxo-4,5-dihydro-1,2,4-oxadiazol-3-yl)biphenyl-4-yl]methyl)-1H-benzimidazole-7-carboxylic acid) is a new angiotensin II receptor antagonist used in the treatment of hypertension. This paper describes the preparation of type I crystal and its single crystal diffraction data, the comparison of the powder diffraction data for both type I and II crystals as well as their stability and solubility in methanol.
Galina A. Sycheva
Journal of Crystallization Process and Technology, Volume 6, pp 29-55; doi:10.4236/jcpt.2016.64004

Abstract:
The crystal growth and nucleation in glasses in the lithium silicate system have been investigated. Phase separation in ultimately homogenized glasses of the lithium silicate system xLi2O·(100 ﹣ x)SiO2 (where x = 23.4, 26.0, 29.1, and 33.5 mol% Li2O) has been studied. The glasses of these compositions have been homogenized using the previously established special temperature-time conditions, which make it possible to provide a maximum dehydration and removal of bubbles from the glass melt. The parameters of nucleation and growth of phase separated in homogeneities and homogeneous crystal nucleation have been determined. The absolute values of the stationary nucleation rates Ist of lithium disilicate crystals in the 23.4Li2O·76.6SiO2, 26Li2O·74SiO2 and 29.1Li2O·70.9SiO2 glasses with the compositions lying in the metastable phase separation region have been compared with the corresponding rates Ist for the glass of the stoichiometric lithium disilicate composition 33.51Li2O·66.5SiO2. It has been found that the crystal growth rate has a tendency toward a monotonic increase with an increase in the temperature, whereas the dependences of the crystal growth rate on the time of low temperature heat treatment exhibit an oscillatory behavior with a monotonic decrease in the absolute value of oscillations. The character of crystallization in glasses with the compositions lying in the phase separation region of the Li2O-SiO2 system is compared with that in the glass of the stoichiometric lithium disilicate composition. The conclusion has been made that the phase separation weakly affects the nucleation parameters of the lithium disilicate and has a strong effect on the crystal growth.
F. Daisy Selasteen, S. Alfred Cecil Raj, A. Alagappa Moses, F. Emalda Prince, R. Esther Getsy, R. Elakkiya
Journal of Crystallization Process and Technology, Volume 6, pp 11-20; doi:10.4236/jcpt.2016.62002

Abstract:
The newly synthesized CdNa2?2C2O4?2H2O crystals having a size of 0.30 × 0.25 × 0.20 mm3 were grown by the single-diffusion reaction method in the silica gel medium at 28?C temperature. The crystalline nature of crystals was determined in 20 days by 1) varying the concentrations of the feed solutions and the gel pH level, 2) changing the specific gravity of the feed solution, and 3) changing the gel aging period. The crystals were characterized by using the methods such as powder X-ray diffraction, FTIR, UV, SEM-EDAX, TGA/DTA, and micro-hardness test. The structure of as-grown crystals was determined by the powder crystal XRD patterns. FTIR & SEM-EDAX spectral analyses were used to confirm the presence of the required functional groups of as grown crystals. UV absorption spectrum, the absorption peaks at 224.64 nanometer, determined the energy gap. TGA/DTA thermo gram was used to detect the thermal stability of sodium mixed cadmium oxalate dihydrate crystals. The present grown crystals were brittle and also plastic in nature was identified by Vickers micro-hardness test.
Jie Zhang, Xiaoshu Zhu
Journal of Crystallization Process and Technology, Volume 6, pp 21-28; doi:10.4236/jcpt.2016.63003

Abstract:
Titania microspheres were synthesized using hydrothermal methods to exploit a new liquid chromatography stationary phase. The prepared titania microspheres were approximately 7 μm in diameter, and the particle size distribution was relatively narrow and uniform. Furthermore, the average specific surface area was 276.0 m2·g·1, the average pore volume was approximately 0.25 mL·g·1, and the pore diameter was approximately 35.9 nm for sintering titania microspheres. These parameters indicate that the titania microspheres prepared for this study have excellent surface properties for chromatography. Additionally, columns filled with the titania microspheres were able to separate basic compounds, including benzene, nitrobenzene and o-nitroanisole. It could be proposed that the titania microspheres prepared for this study would be a promising stationary phase for liquid chromatography.
, Kazuhiro Ishibashi, Sakura Hatakeyama
Journal of Crystallization Process and Technology, Volume 5, pp 24-30; doi:10.4236/jcpt.2015.51004

Abstract:
Poly-crystalline anatase TiO2 layer fabricated by LPCVD using titanium-tetra-iso-propoxide and NbF5 in H2-ambient was treated in conc.-HCl solution after thin layer of IIIb-group metal was deposited on the TiO2 layer. Resistivity of the as-deposited layer about 1 × 10-1 Ω·cm was drastically reduced to 3 × 10-3 Ω·cm by the wet-treatment using indium. Temperature dependence of the resistivity increased with temperature above 100 K for the wet-treated layer was quite different from that decreased above 100 K for the as-deposited layer, whereas the resistivity was saturated at lower temperatures. The resistivity at room-temperature was decreased with the thickness before the wet-treatment but independent on the thickness above 100 nm for the wet-treated layer. Indium was more effective for the resistivity reduction than gallium but aluminum was not useful for the treatment. As the results that the wet-treatment using indium was examined for the TiO2 layers deposited by various conditions, the optimum deposition condition to reduce the resistivity of the layer after the wet-treatment was clearly different from that for the as-deposited layer.
Ryosuke Nakata,
Journal of Crystallization Process and Technology, Volume 5, pp 9-14; doi:10.4236/jcpt.2015.51002

Abstract:
We studied chemical garden in order to investigate precipitation behavior for osmotic pressure under microwave irradiation. The salt concentration and microwave irradiation power were varied. Microwave irradiation induced release of osmotic pressure and change of precipitation pattern because polar molecules vibrate and rotate in an electromagnetic field. For example, the width of precipitation increased and the number of rapture of the membrane decreased due to the release of osmotic pressure by the irradiation. Accordingly, microwave irradiation accelerated the diffusion of ionic molecules through the membrane.
, Kazuhiro Ishibashi, Sakura Hatakeyama
Journal of Crystallization Process and Technology, Volume 5, pp 15-23; doi:10.4236/jcpt.2015.51003

Abstract:
Low resistive TiO2 layer was deposited by low pressure chemical vapor deposition (LPCVD) at pressure around 0.25 Pa using titanium-tetra-iso-propoxide (TTIP) and NbF5 in H2-ambient. Acti-vation energy for the deposition rate on the temperature was significantly decreased to 120 kJ/mol as compared with 228 kJ/mol for the deposition in H2 without NbF5. The deposition rate linearly increased with NbF5 supply rate but gradually decreased with H2 supply rate indicated that F on the deposition surface acts as catalyst for TTIP-dissociation but is non-activated by hydrogen. Resistivity of the layer was decreased by NbF5 supply depending on the deposition temperature with the activation energy of 319 kJ/mol, whereas the energy was 244 kJ/mol for the layer deposited in H2 without NbF5. The dependence of resistivity on NbF5. and H2 supply rates suggested that the doping should be performed by sufficient NbF5 and H2 supply rate to improve the crystallinity. As a result of the optimization, the resistivity was successfully reduced to 5 × 10-2 Ω·cm. Optical transmission spectra in UV-Vis region indicated that significant absorption observed for the layer deposited in H2 was notably decreased by using NbF5. The improved optical property was better than that for the layer deposited in O2-ambient.
, Yuya Yamada
Journal of Crystallization Process and Technology, Volume 5, pp 43-47; doi:10.4236/jcpt.2015.53006

Abstract:
Contact angle of ethylene glycol and formamide on (100) faces of NaCl, KCl, and KBr single crystal was measured, and the specific surface free energy (SSFE) was calculated. Dispersion component of the SSFE was 90.57, 93.78, and 99.52 mN·m-1 for NaCl, KCl, and KBr, respectively. Polar component of the SSFE was 1.05, 0.65, and 0.45 mN·m-1 for NaCl, KCl, and KBr. Such a large ratio of dispersion component of SSFE results from the neutrality of the crystal surface of alkali halide. Lattice component of alkali halide is 780, 717 and 689 kJ·mol-1 for NaCl, KCl, and KBr. The larger lattice enthalpy decreases dispersion component, and increases polar component of the SSFE. The larger lattice enthalpy is considered to enhance the rumpling of the crystal surface more strongly, and such rumpling is considered to decrease the neutrality of the crystal surface.
Journal of Crystallization Process and Technology, Volume 5, pp 1-8; doi:10.4236/jcpt.2015.51001

Abstract:
Dissolution of the (100) face of octacalcium phosphate (OCP) single crystal in weak acidic solutions (pH = 6.5; 25°C) was observed in situ using atomic force microscopy. Monomolecular steps (2.0 nm high) were observed; they originated from etch pits or crystal edges. Advancement of the dissolution process led to precipitation of nanoparticles as small as ~10 nm even though the solution was undersaturated with respect to OCP. This precipitation of nanoparticles was accompanied by a drastic decrease in the dissolution rate; however, the substrate OCP continued to dissolve, indicating that dissolution and growth occurred simultaneously on the same surface. The precipitated nanoparticles coalesced and eventually covered the entire surface without changing the surface morphology of the substrate crystal. The step height after complete coverage was ~2.0 nm, the same as that observed on the dissolving OCP surface. These findings indicate that the precipitated phase was a pseudomorph of OCP crystal.
M. A. Rahman
Journal of Crystallization Process and Technology, Volume 5, pp 31-42; doi:10.4236/jcpt.2015.52005

Abstract:
Slow evaporation method was used to grow pure and KCl (10 mol%) doped KAP single crystal. The solubility and metastable zone width of aqueous solutions of pure and KCl (10 mol%) doped KAP crystal were evaluated to analyze the crystallization process. Measuring the induction period τ, the critical nucleation parameters like interfacial energy (σ), energy of formation of the critical nucleus (ΔG*) were determined using the classical theory of nucleation. The structural properties and optical constants of the grown crystals have been put to test and observed that the addition of KCl results in an enhancement of properties of the crystal. Grown crystals were characterized by powder X-ray diffraction. FTIR spectra confirmed the presence of KCl in pure KAP crystal. UV- Visible spectroscopic studies revealed that addition of KCl in pure KAP crystal increased transparency from 75% to 80%. The analysis of the optical absorption data revealed the presence of both indirect and direct transitions and both of these band gaps increased with the addition of KCl. The transmittance data was analyzed to calculate the refractive index, oscillator energy, dispersion energy, electric susceptibility, zero-frequency dielectric constant and both the real and imaginary parts of the dielectric permittivity as a function of photon energy. The moments of ε(E) were also determined. The dispersion i.e. spectral dependence of the refractive index was discussed according to the single-effective oscillator model proposed by Wemple and DiDomenico.
Journal of Crystallization Process and Technology, Volume 5, pp 49-57; doi:10.4236/jcpt.2015.54007

Abstract:
Ferroelectric SrBi2Ta2O9-(Bi4Ti3)1-xNbxO12 (x = 0.02) (SBT-BTN) multilayer thin films with various stacking periodicity have been synthesized on Ir/Ti/SiO2/Si substrate by metal organic chemical vapor deposition technique (MOCVD). Tributylbismuth [Bi(C4H9)3], Strontium-bis[Tantal(pentanethoxy)(2-methoxyethoxid)] [Sr[Ta(OEt)5(OC2H4OMe)]2], Titanium Bis(isopropoxy)bis(1-methoxy-2-methyl-2-propoxide) [Ti(OiPr)2(mmp)2] and Niob-ethoxide [Nb(OC2H5)5] were selected as precursors. X-ray diffraction patterns show that the multilayer films annealed at 800oC consist of fully formed perovskite phase with polycrystalline structure and plate-like grains with no crack. The remanent polarization () and coercive field (Ec) are 16.2 μC/cm2 and 230 kV/cm, respectively, which is much higher, compared to pure SBT film ( = 6.4 μC/cm2, Ec = 154 kV/cm). In the films prepared above 700oC, postannealing increased the capacitor shorting rate; this was attributed to oxidizing of the top iridium layer. In this paper, the dependence of composition variation around stoichiometric on ferroelectric properties in SBT-BTN multilayer films is studied.
, Shouta Saiki, Kazuhiro Ishibashi, Akie Nakagawa, Sakura Hatakeyama
Journal of Crystallization Process and Technology, Volume 4, pp 79-88; doi:10.4236/jcpt.2014.42011

Abstract:
Nb and F co-doped anatase TiO2 layers were deposited by low pressure chemical vapor deposition (LPCVD) at pressure of 3 mtorr using titanium-tetra-iso-propoxide (TTIP), O2 and NbF5 as precursor, oxidant and dopant respectively. Resistivity beyond 100 Ωcm for undoped layer was decreased with increasing supply of the dopant and dependent on the supply ratio of O2 to TTIP and decreased to 0.2 Ωcm by the optimization. X-ray fluorescent spectroscopy showed Nb-content in the layer was decreased with the O2-supply ratio. X-ray photo-spectroscopy indicated that F substituted O-site in TiO2 by O2-supply but carbon-contamination and F missing substitution in the O-site were significantly increased by excess O2-supply. Further, it was suggested that the substituted F played an important role to reduce resistivity without significant contribution of O-vacancies. XRD spectra showed F missing substitution in the O-site degraded the crystallinity.
Journal of Crystallization Process and Technology, Volume 4, pp 89-98; doi:10.4236/jcpt.2014.42012

Abstract:
We discuss crystal formation in supersaturated suspensions of monodisperse hard spheres with a concentration of hard spheres randomly pinned in space and time. The pinning procedure introduces an external length scale and an external time scale that restrict the accessible number of configureurations and ultimately the number of pathways leading to crystallization. We observe a significant drop in the nucleation rate density at a characteristic pinning concentration that can be directly related to the structure of the critical nucleus and the dynamics of its formation in the unpinned system.
Journal of Crystallization Process and Technology, Volume 4, pp 111-120; doi:10.4236/jcpt.2014.42014

Abstract:
Crystallization and glass transition kinetics of Se90-xZn10Sbx (x = 0, 2, 4, 6) chalcogenide glasses prepared by conventional melt-quenching technique were studied under non-isothermal condition using a differential scanning Calorimeter (DSC) measurement at different heating rates 5, 7, 10 and 12°C/min. The glass transition temperatures Tg, the crystallization temperatures Tc and the peak temperatures of crystallization Tp were found to be dependent on the compositions and the heating rates. From the dependence on the heating rates of Tg and Tp, the activation energy for glass transition, Eg, and the activation energy for crystallization, Ec, are calculated and their composition dependence is discussed. The activation energy of glass transition Eg, Avrami index n, dimensionality of growth m and activation energy of crystallization Ec have been determined from different models.
, Bikshandarkoil R. Srinivasan, Kalimuthu Moovendaran
Journal of Crystallization Process and Technology, Volume 4, pp 121-125; doi:10.4236/jcpt.2014.42015

Abstract:
Reinvestigation of the growth of L-proline succinate (1) (Paramasivam and Ramachandra Raja, Journal of Crystallization Process and Technology, 2 (2012) 21 - 24; Balamurugaraj et al., Journal of Material Physics and Chemistry 1 (2013) 4 - 8) and L-threonine zinc acetate (2) (Puhal Raj and Ramachandra Raja, Photonics and Optoelectronics, 2 (2013) 56 - 64) is reported. Slow evaporation of an aqueous solution containing equimolar quantities of L-proline and succinic acid (for 1) and L-threonine and zinc acetate (for 2) results in the fractional crystallization of succinic acid (in the first case) and L-threonine (in the second case) and not any novel organic non-linear optical (NLO) crystals. In this paper, the usefulness of infrared spectra for correct product characterization is demonstrated.
, Marcin Jewartowski, Tomasz Aleksander Kowalewski
Journal of Crystallization Process and Technology, Volume 4, pp 46-59; doi:10.4236/jcpt.2014.41007

Abstract:
Thermochromic liquid crystals (TLC) and true-colour digital image processing have been successfully used in non-intrusive technical, industrial and biomedical studies and applications. Thin coatings of TLC at surfaces are utilized to obtain detailed temperature distributions and heat transfer rates for steady or transient processes. Liquid crystals also can be used to make the temperature and velocity fields in liquids visible by the simple expedient of directly mixing the liquid crystal material into the liquid (water, glycerol, glycol, and silicone oils) in very small quantities to use as thermal and hydrodynamic tracers. In biomedical situations, e.g., skin diseases, breast cancer, blood circulation and other medical application, TLC and image processing are successfully used as an additional non-invasive diagnostic method especially useful for screening large groups of potential patients. The history of this technique is reviewed, principal methods and tools are described and some examples are presented. Also steady-state and transient liquid crystal thermography (LCT) is used to measure local heat transfer on a plate equipped with transverse vortex generators. Automated evaluation allows determining the heat transfer coefficient without arbitrary influence of human interpretation.
Journal of Crystallization Process and Technology, Volume 4, pp 145-155; doi:10.4236/jcpt.2014.43019

Abstract:
Previously we derived equations determining line broadening in ax-ray diffraction profile due to stacking faults. Here, we will consider line broadening due to particle size and strain which are the other factors affecting line broadening in a diffraction profile. When line broadening in a diffraction profile is due to particle size and strain, the theoretical model of the sample under study is either a Gaussian or a Cauchy function or a combination of these functions, e.g. Voigt and Pseudovoigt functions. Although the overall nature of these functions can be determined by Mitra’s R(x) test and the Pearson and Hartley x test, details of a predicted model will be lacking. Development of a mathematical model to predict various parameters before embarking upon the actual experiment would enable correction of significant sources of error prior to calculations. Therefore, in this study, predictors of integral width, Fourier Transform, Second and Fourth Moment and Fourth Cumulant of samples represented by Gauss, Cauchy, Voigt and Pseudovoigt functions have been worked out. An additional parameter, the coefficient of excess, which is the ratio of the Fourth Moment to three times the square of the Second Moment, has been proposed. For a Gaussian profile the coefficient of excess is one, whereas for Cauchy distributions, it is a function of the lattice variable. This parameter can also be used for determining the type of distribution present in aggregates of distorted crystallites. Programs used to define the crystal structure of materials need to take this parameter into consideration.
, , Hiroshi Abe, Shintaro Kobayashi,
Journal of Crystallization Process and Technology, Volume 4, pp 193-205; doi:10.4236/jcpt.2014.44024

Abstract:
By direct observations of transmission electron microscopy (TEM), irreversible morphological transformations of as-deposited amorphous Au/Si multilayer (a-Au/a-Si) were observed on heating. The well arrayed sequence of the multilayer changed to zigzag layered structure at 478 K (=Tzig). Finally, the zigzag structure transformed to Au nanoparticles at 508 K. The distribution of the Au nanoparticles was random within the thin film. In situ X-ray diffraction during heating can clarify partial crystallization Si (c-Si) in the multilayer at 450 K (= ), which corresponds to metal induced crystallization (MIC) from amorphous Si (a-Si) accompanying by Au diffusion. On further heating, a-Au started to crystallize at around 480 K (=Tc) and gradually grew up to 3.2 nm in radius, although the volume of c-Si was almost constant. Continuous heating caused crystal Au (c-Au) melting into liquid AuSi (l-AuSi) at 600 K (= ), which was lower than bulk eutectic temperature ( ). Due to the AuSi eutectic effect, reversible phase transition between liquid and solid occurred once temperature is larger than . Proportionally to the maximum temperatures at each cycles (673, 873 and 1073 K), both and Au crystallization temperature approaches to . Using a thermodynamic theory of the nanoparticle formation in the eutectic system, the relationship between and the nanoparticle size is explained.
, Hiromi Suzuki, Risa Akutsu
Journal of Crystallization Process and Technology, Volume 4, pp 20-26; doi:10.4236/jcpt.2014.41003

Abstract:
Plasma-assisted chemical vapor deposition (PCVD) at pressure as low as 3 mtorr using titanium-tetra-isopropoxide (TTIP) and oxygen mixed gas plasma generated by 13.56 MHz radio frequency power (RF-power) below 70 W were applied to deposit titanium-oxide layer at temperature under 40°C. Plasma optical emission spectroscopy and FTIR indicated that density of OH group in the amorphous layer was related to the density of OH or H2O in the plasma and the species was formed on electrode to induce the RF-power. Hydrophilicity on the layer was dependent on the density of chemisorbed OH, but was degraded by the excess OH. The PCVD-TiOx coating was demonstrated on polyethylene terephthalate and showed good hydrophilic property with the contact angle of water about 5°.
, , V I Dimov, B. Kostova, Svilen M Gechev
Journal of Crystallization Process and Technology, Volume 4, pp 156-167; doi:10.4236/jcpt.2014.43020

Abstract:
Complex crystal aggregates from fluorspar vapor phase were grown at specific low-pressure/high-temperature conditions. The quasi-equilibrium of initiated crystal-chemical reactions at the proceeding vapour-crystal phase transformation was strongly dependent on the mass-transport inside an originally designed multicameral crucible, loaded by several portions of natural fluorite. By changing the temperature pressure over the already molten fluorspar portions as well as the gas-permeability of the channels connecting different sections in crucible interior to vacuum ambient, one may control the rate of gaseous-vapour diffusion and the degree of supper-saturation inside the peripheral crucible compartment wherein nucleation and crystal growing occurred. In this way, grown aggregates revealed a complicated habit formed during three-stage growing process provided by relevant thermodynamic and phase. Residual stresses were not observed in the aggregates whereas those in simultaneously grown boules from the non-vaporized melts in crucible cameras were clearly distinguished. The optical transmittance spectra of the boules were obtained considerably better, especially in the UV, comparing to those for crystal aggregates, both showing several peaks of specific light-absorption due to enhanced presence of rare-earth (RE) impurities. The aggregates manifest nearly full reflectivity from Vis to near IR region. The vapor phase growth mechanisms, when natural fluorite with some RE contents has been used, were explained on thermodynamic grounds that shown the manner of reliable control on the phenomenon. The results were anticipated to help for developing new perspective techniques for growth from vapor of several fluoride compounds with complex structure and composition and wide application. It was speculated that similar growth mechanisms of CaF2 crystals were possible on the moon in its very early period of formation.
Sundaram Ramukutty,
Journal of Crystallization Process and Technology, Volume 4, pp 71-78; doi:10.4236/jcpt.2014.42010

Abstract:
Kinetics of the decomposition of racemic ibuprofen crystals were studied by non-isothermal analysis. Thermogravimetric analysis revealed that ibuprofen is thermally stable up to 152.6°C and the initial loss of mass was due to evaporation only. Activation energy, pre-exponential factor, activation entropy and Gibbs free energy for the decomposition of ibuprofen were determined using the integral method of Coats-Redfern (CR). Geometrical contraction models were found to be the best fits. The Arrheinus equation for the thermal decomposition of ibuprofen is k = (1.1 × 107) e–79125/RT sec–1.
, Keiko Takahashi, Masayuki Kawasaki, Toshihiko Kagami
Journal of Crystallization Process and Technology, Volume 4, pp 177-184; doi:10.4236/jcpt.2014.44022

Abstract:
Contact angles of water droplet on as-grown Z, +X, –X, and m faces of synthetic quartz crystals with growth term of 20 and 48 days, and polished Z, +X, –X, Y, and 45˚ cut faces of synthetic quartz crystal were observed. The average of the contact angles on as-grown Z, +X, and –X faces increased with the growth term, and they were larger than that on polished Z, +X, and –X faces. On the other hand, the average of the contact angles of water on m face decreased with the growth term, and they were smaller than that on polished Y cut face. Growth rate of the faces of synthetic crystals was measured and the order of growth rate was, m < –X < +X < Z. Specific surface free energy (SSFE) was calculated using Neumann’s equation. The SSFE of polished face was in the order of, m < –X < +X < Z, which corresponds to the order of the growth rate. The SSFE was larger for the face with larger growth rate.
, Kazuhiro Ishibashi, Sakura Hatakeyama
Journal of Crystallization Process and Technology, Volume 4, pp 185-192; doi:10.4236/jcpt.2014.44023

Abstract:
Low pressure chemical vapor deposition (LPCVD) of anatase TiO2 as a reduction gas was demonstrated at pres- sure of 3 mtorr in comparison to that using TTIP and O2 with study for the property of the layers. Dissociation energy of TTIP in H2 was higher than that in O2 but resistivity of the layer deposited in H2 was significantly decreased to 0.2 Ω cm in contrast to the high resistivity beyond 100 Ω cm of the layer deposited in O2. UV-Vis optical transmission spectra showed absorption around 2.2 eV was increased in the layer deposited by TTIP + H2 in addition to decrease of forbidden energy gap due to increase of Urbach tail. Resistivity at low temperature below 100 K indicating the layer deposited in H2-ambient was degenerated by the high electron density but the resistivity was decreased with temperature above 100 K with the activation energy about 100 meV. A possible electronic conduction model based on kernel, grain boundary and surface trap to clarify the temperature dependent resistivity suggesting resistivity of the layer was limited by depletion region in the grain-boundary extended from the surface and the kernel with significantly low resistivity in 10-3 Ω cm order was formed in the layer.
, Ravindranath Teniram Chaudhari
Journal of Crystallization Process and Technology, Volume 4, pp 212-224; doi:10.4236/jcpt.2014.44026

Abstract:
The phosphate mineral struvite is basically formed in urinary tracks and kidney. One of the analogous compounds of struvite is potassium magnesium phosphate hexahydrate (KMgPO4·6H2O), known as struvite-k crystal and found in animal urinary calculi. In the present investigation, struvite-k crystals were grown by single diffusion and double diffusion techniques in agar gelmedium. The grown crystals were analyzed by optical microscopy, scanning electron microscopy (SEM), fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), energy dispersive X-ray analysis (EDXA) and thermogravimetric analysis (TGA). Optical microscopy and SEM exhibited the different morphologies. The FTIR spectra revealed the presence of water molecules, stretching and bending vibrations of phosphate (PO4) ions. However the powder XRD results from the crystalline nature. Elemental composition in the crystal was obtained by EDXA, while 36.89% weight loss of water molecules is observed in TGA study.
Mallikharjuna Rao Darla, Sriharsha Hegde,
Journal of Crystallization Process and Technology, Volume 4, pp 60-63; doi:10.4236/jcpt.2014.41008

Abstract:
Ferro nematic suspensions are the prominent materials to enhance the electro optical performance of liquid crystal displays. Electro optical properties of polymer dispersed liquid crystal (PDLC) display with the introduction of Barium Titanate nanoparticles have been investigated in this article and it is shown that there is a considerable enhancement in electro-optical response of the displays. The nanoparticles lower the switch-on electric field and thereby increase the optical transmission at certain voltages of the displays. The electro-optical characteristics of the PDLC cells were investigated with a He-Ne laser followed by MatLab calculations.
, Naoki Furubayashi, Fujiko Shibata, Yoshiko Kobayashi, Sachiko Kaito, Yuki Ohnishi, Koji Inaka
Journal of Crystallization Process and Technology, Volume 4, pp 1-13; doi:10.4236/jcpt.2014.41001

Abstract:
Crystallization of enzymes in presence of impurities is important for clarifying the role of enzymes in natural world. Although it is proposed that impurities inhibit nucleation of enzyme crystallization, details are unclear. In this study, crystallization of cellobiohydrolase from Aspergillus niger was investigated by dynamic and time-resolved static light scattering using cellobiose as an impurity. We aimed to clarify how cellobiose inhibits cellobiohydrolase crystallization and to crystallize cellobiohydrolase in concentrated cellobiose without using seeds. The contribution of attractive forces to total intermolecular interactions of cellobiohydrolase monomers increased with the molar ratio of cellobiose/cellobiohydrolase (R(cb/ce)). Association dynamics of cellobiohydrolase using lithium sulfate, however, showed that the initial aggregation rate decreased with an increase in R(cb/ce). Because binding sites of cellobioses to cellobiohydrolase molecules differed from those for the growth of protein crystals, the binding of cellobioses would increase the chemical potential of the cellobiohydrolase monomers, which gradually reduced supersaturation for growth as the aggregate size increased. This result was in contrast with the conventional idea that cellobiose inhibits the nucleation of cellobiohydrolase crystals. Gentle agitation of cellobiose-containing cellobiohydrolase solutions during sitting-drop vapor-diffusion growth resulted in the growth of cellobiohydrolase single crystals for all R(cb/ce) conditions without using seeds.
, Takatoshi Minakuchi, Miyuki Onodera
Journal of Crystallization Process and Technology, Volume 4, pp 14-19; doi:10.4236/jcpt.2014.41002

Abstract:
Pentacene thin layers were deposited on Si with the native oxide at 80°C by remote-plasma-assisted deposition (RPAD) using hydrogen-plasma cell to supply atomic hydrogen radicals. The deposition rate was increased by RPAD comparing to that by non-excited hydrogen gas supply whereas thermal evaporation rate of pentacene from crucible was same in the both process. DFM and XRD studies showed the grain laterally grew in the thin film phase with the size above 10 μm by RPAD. First-principles molecular orbital calculations suggested pentacene is evaporated from crucible as the trimer or larger cluster but atomic hydrogen penetrated into the cluster enhances cracking of pentacene clusters to the monomer.
Journal of Crystallization Process and Technology, Volume 4, pp 31-38; doi:10.4236/jcpt.2014.41005

Abstract:
Various characteristics of mesomorphism can be explained using intermolecular interactions between a pair of liquid crystalline molecules. The intermolecular interactions have been calculated considering multipole-multicentere expansion method and modified by second order perturbation treatments. For calculation of multipole i.e. charge, dipole, etc. at each atomic center of molecules, para-butyl-p’-cyano-biphenyl, GAMESS, an ab initio program, with 6-31G* basis set has been used. The stacking, in-plane and terminal interaction energies explain the liquid crystalline behaviour of the system.
Muthaiyan Rajalakshmi, Ravanan Indirajith, Rengasamy Gopalakrishnan
Journal of Crystallization Process and Technology, Volume 4, pp 39-45; doi:10.4236/jcpt.2014.41006

Abstract:
Single crystals of La4Mo7O27 have been successfully grown by the flux growth method H3BO3 as the flux in a plantium crucible using the starting materials of La2O3, H3BO3 and MoO3 in a molar ratio of 0.16:0.16:0.68, in which H3BO3 acted as a flux. Transparent colorless crystals were obtained with size of 0.8 × 0.3 × 0.2 mm3 under the optimized crystal growth conditions: growth temperature of 727°C, growth time of 95 h and cooling rate of 0.5°C/hr. A well-developed morphology of the crystals was observed and analyzed. The preparation process of starting materials on crystal growth was investigated. The grown crystals were characterized by powder X-ray diffraction (PXRD), EDAX, SEM, UV-Vis, photoluminescence studies, thermal analysis, dielectric studies and second harmonic generation (SHG). The results are presented and discussed.
Yuqing Huang, , Lin Luo, Hui Yang, Chunmei Tong, Wenfei Chen, Tingyu Huang, Ruiling Liu
Journal of Crystallization Process and Technology, Volume 4, pp 27-30; doi:10.4236/jcpt.2014.41004

Abstract:
Objective: To determine the transformation between two known crystal forms of the title compound (C18H23NO3, Mr = 301.37). Methods: To recrystallize or heat the crystals and determine the crystal form by testing the melting points. Results: Both the two known crystal forms of the title compound can be changed by dissolving into different organic solvents such as acetone and ethyl acetate. Crystal form I was not influenced by heating while crystal form II can be transformed to crystal form I through melting method. Conclusion: Organic solvents have significant influences on the two crystal forms of title compound. Crystal form I shows a better thermal stability than crystal form II.
, Priya Murugasen
Journal of Crystallization Process and Technology, Volume 4, pp 99-110; doi:10.4236/jcpt.2014.42013

Abstract:
The optically transparent and bulk single crystal of p-Toluidine p-Toluenesulfonate (PTPT) was grown by slow evaporation technique. The lattice parameters and crystallinity of the grown crystal were estimated by single crystal XRD. The optical absorption of the crystal was recorded using the UV-Vis-NIR spectrophotometer. The optical bandgap and optical constants of the material were determined by using absorption spectrum. The refractive index of the grown crystal has been determined using the Brewster angle method. The dielectric constant and dielectric loss were measured as a function of frequency and temperature for the grown crystal. Nonlinear optical properties were performed to confirm the SHG efficiency of the grown crystal. Hence, PTPT is an excellent NLO material with enhanced SHG efficiency required for important applications in the field of optoelectronic and photonics. This material exhibits NLO behaviour remarkably due to its better optical and dielectric properties.
Yushin Kanazawa,
Journal of Crystallization Process and Technology, Volume 4, pp 65-70; doi:10.4236/jcpt.2014.42009

Abstract:
We studied precipitation patterns in a Liesegang system under microwave irradiation in order to investigate metal salt diffusion in an electrolyte gel. The salt species and microwave irradiation power were varied. Microwave irradiation induced periodic patterns of precipitation because polar molecules vibrate and rotate in an electromagnetic field. For example, the number of patterns increased with the irradiation power. Accordingly, microwave irradiation nonlinearly accelerated the diffusion of ionic molecules.
Anitha S. Nair, Vinila V. S., Sheelakumari Issac, Reenu Jacob, Anusha Mony, Harikrishnan G. Nair, Sam Rajan, Satheesh D. J., Jayakumari Isac
Journal of Crystallization Process and Technology, Volume 4, pp 126-133; doi:10.4236/jcpt.2014.42016

V. S. Vinila, Reenu Jacob, Anusha Mony, Harikrishnan G. Nair, Sheelakumari Issac, Sam Rajan, Anitha S. Nair, D. J. Satheesh, Jayakumari Isac
Journal of Crystallization Process and Technology, Volume 4, pp 168-176; doi:10.4236/jcpt.2014.43021

Abstract:
With the discovery of high-TC superconducting materials like Yttrium Barium Cupric Oxide, Bismuth Strontium Calcium Copper Oxide and Thallium Calcium Barium Copper Oxide, tremendous interest has developed over the past two years in understanding these materials as well as utilizing them in a variety of applications. The thin films of these materials are expected to play an important role in the area of microelectronics, especially for interconnects in integrated circuits, Josephson junctions, magnetic field sensors and optical detectors. Here, the authors designed a new nanocrystalline ceramic type II high-TC superconductor, Gadolinium Barium Copper Oxide (GdBaCuO/GBCO). The GBCO perovskite phase structure was prepared by the conventional solid state thermochemical reaction technique involving mixing, milling, calcination and sintering. In GBCO system, the method for controlling microstructure and superconducting state is related to oxygen content consideration because small changes in oxygen concentration can often lead to huge change in Tc. In order to show the viability of the proposed method, super-conducting powder was prepared in special furnace. The sample was analyzed by X-Ray Diffraction (XRD), an indispensible non-destructive tool for structural materials characterization and quality control which makes use of the Debye-Scherrer method. The comparison of XRD results with JCPDS files confirmed the orthorhombic structure of the sample. Micro-structural features are studied using Scanning Electron Microscopy (SEM) which revealed that its particle size is in the nanometer range. It also confirmed the calculated value of particle size from Debye Scherrer’s formula. EDX plot shows the presence of all the constituents. X-ray instrumental peak broadening analysis was used to evaluate the size and lattice strain by the Williamson-Hall Plot method.
Yulong Lei, , Yang Liu, Guanghui Tian, Hongguang Ge
Journal of Crystallization Process and Technology, Volume 4, pp 135-139; doi:10.4236/jcpt.2014.43017

Abstract:
A pair of new anticancer nucleosides based on 1,2,4-triazole nucleosides and 1-((2-hydroxyethoxy) methyl)-5-(phenylthio)-1H-1,2,4-triazole-3-carboxamide have been synthesized, and have given the corresponding products in excellent yields. Its structures and conformations were confirmed by single crystal X-ray diffraction.
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