XRD

Distribution by Scientific Domains
Distribution within Polymers and Materials Science

Kinds of XRD

  • powder xrd

  • Terms modified by XRD

  • xrd analysis
  • xrd data
  • xrd investigation
  • xrd measurement
  • xrd pattern
  • xrd result
  • xrd studies
  • xrd techniques

  • Selected Abstracts


    Synthesis and properties of ,-Fe2O3 nanorods

    CRYSTAL RESEARCH AND TECHNOLOGY, Issue 9 2010
    R. Ramesh
    Abstract We report synthesis of ,-Fe2O3 (hematite) nanorods by reverse micelles method using cetyltrimethyl ammonium bromide (CTAB) as surfactant and calcined at 300 C. The calcined ,-Fe2O3 nanorods were characterized by X-ray diffraction (XRD), high-resolution scanning electron microscopy (HRSEM), transmission electron microscopy (TEM), energy dispersive spectrometer (EDS), fourier transform infrared spectroscopy (FTIR) and vibrating sample magnetometer (VSM). The result showed that the ,-Fe2O3 nanorods were hexagonal structure. The nanorods have diameter of 30-50 nm and length of 120-150 nm. The weak ferromagnetic behavior was observed with saturation magnetization = 0.6 emu/g, coercive force = 25 Oe and remanant magnetization = 0.03 emu/g. ( 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]


    Transformation of a zinc inclusion complex to wurtzite ZnS microflowers under solvothermal conditions

    CRYSTAL RESEARCH AND TECHNOLOGY, Issue 9 2010
    Liwei Mi
    Abstract Wurtzite zinc sulfide (ZnS) microflowers were synthesized successfully by a convenient solvothermal route in ethylene glycol (EG) and ethylenediamine (EN) using thiourea and zinc inclusion complex as starting materials. The inclusion complex {[Zn(bipy)2(H2O)2](4-Cl-3-NH2 -C6H3SO3)2(bipy) (H2O)2}n was achieved by the reaction of zinc oxide (ZnO) and 4-Cl-3-NH2 -C6H3SO3 with the bridging ligand bipy under moderate conditions, in which bipy is 4,4,-bipyridine and 4-Cl-3-NH2C6H3SO3NH is 4-Chloro-3-aminobenzene sulfonic acid. The phase purity of bulk products was confirmed by powder X-ray diffraction and element analysis. The factors that might affect the purity of the ZnS product during the synthesis were discussed in detail. It was found that the products were significantly affected by the mixed solvents and the starting materials. X-ray single crystal diffraction, scanning electron microscopy (SEM), energy-dispersive X-ray spectrometry (EDS), and X-ray diffraction (XRD) were used to characterize the products. ( 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]


    Formation and ageing of L-glutamic acid spherulites

    CRYSTAL RESEARCH AND TECHNOLOGY, Issue 7 2010
    R. Beck
    Abstract Polycrystalline spherulites of L-glutamic acid have been crystallized by pH-shift precipitation from stirred aqueous solutions. The time dependent behaviour of the spherulites has been studied during the crystallization process and batch filtration tests have been performed. It has been shown that the FBRM mean chord length of the investigated spherulites decreases in the course of time. The fact that the size reduction progresses faster at higher temperature and the solubility of resuspended polycrystalline particles decreasing with time, implies an ageing mechanism to be responsible for the observed changes in the particle size. It has been shown that the surface area decreases with time, ruling out particle breakage as a possible explanation for the decrease in particle size. XRD and Raman studies of L-glutamic acid, however, show only marginal differences in the crystalline structure of particles obtained from different time stages. The ageing may occur due to several different mechanisms like phase transformation and Ostwald ripening. L-glutamic acid spherulites after 3 h exhibit a 3-fold higher value for the cake resistance as compared to particles after 0.5 h. However, particles obtained after 22 h exhibit an 8-fold lower cake resistance as compared to the initially obtained spherulites, The increase in the cake resistance is attributed to the appearance of small plate-like crystals and a change in the interaction between the crystal surface and the solution. ( 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]


    Interdiffusion phenomena in InGaAs/GaAs superlattice structures

    CRYSTAL RESEARCH AND TECHNOLOGY, Issue 5 2010
    B. Sar, kavak
    Abstract We have studied structural properties of InGaAs/GaAs superlattice sample prepared by Molecular Beam Epitaxy (MBE) using high resolution X-ray diffractometer (HRXRD). Increasing strain relaxation and defect generations are observed with the increasing Rapid Thermal Annealing (RTA) temperature up to 775 C. The higher temperatures bring out relaxation mechanisms; interdiffusion and favored migration. The defect structure and the defects which are observed with the increasing annealing temperature were analyzed. Firstly, the in-plane and out-of-plane strains after the annealing of sample were found. Secondly, the structural defect properties such as the parallel X-ray strain, perpendicular X-ray strain, misfit, degree of relaxation, x composition, tilt angles and dislocation that are obtained from X-ray diffraction (XRD) analysis were carried out at every temperature. As a result, we observed that the asymmetric peaks especially in asymmetric (224) plane was affected more than symmetric and asymmetric planes with lower polar or inclination angles due to c-direction at low temperature. These structural properties exhibit different unfavorable behaviors for every reflection direction at the increasing temperatures. The reason is the relaxation which is caused by spatially inhomogeneous strain distribution with the increasing annealing temperature. In the InGaAs superlattice samples, this process enhances preferential migration of In atoms along the growth direction. Further increase in the annealing temperature leads to the deterioration of the abrupt interfaces in the superlattice and degradation in its structural properties. ( 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]


    Optical properties of 2-aminopyridinium nitrato silver

    CRYSTAL RESEARCH AND TECHNOLOGY, Issue 3 2010
    K. P. Bhuvana
    Abstract Crystals of 2-aminopyridinium nitrato silver have been synthesized by slow evaporation method. Grown crystals have been subjected to FTIR, Single crystal X-Ray diffraction and UV-Visible studies in order to investigate the structural and optical properties of the crystal. The FTIR spectrum reveals the presence of the functional group that corresponds to both 2-aminopyridine and silver nitrate, suggesting the formation of the compound, 2-aminopyridinium nitrato silver. From XRD it is observed that the crystal crystallizes in the structure of monoclinic with the space group of P21/c. The optical transmittance spectrum shows the maximum transparency of about 95% in the visible region is in consistent with the wide band gap, estimated as 4.738 eV. The optical constants n and k has also been determined from the transmittance data. The static dielectric constant is found to be 0.851. The wide band gap and the less dielectric constant suggest the suitability of this compound material for photoconductive applications. ( 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]


    Preparation of shuttle-like Sb2S3 nanorod-bundles via a solvothermal approach under alkaline condition

    CRYSTAL RESEARCH AND TECHNOLOGY, Issue 2 2010
    Ling Zhang
    Abstract Uniform shuttle-like Sb2S3 nanorod-bundles were synthesized via a polyvinylpyrrolidone (PVP) assisted solvothermal approach under alkaline condition, using antimony chloride (SbCl3) and thiourea (CH4N2S, Tu) as the starting materials in ethanol. The phase structure, composition and morphology of the product were characterized by means of X-ray diffraction (XRD), energy dispersive X-ray spectrometry (EDS), transmission electron microscopy (TEM), and high-resolution transmission electron microscopy (HRTEM). XRD and EDS results confirm that the synthesized Sb2S3 nanorod-bundles have an orthorhombic structure and an atomic ratio of 3:2 for S:Sb. TEM and HRTEM results show that the shuttle-like Sb2S3 bundles are composed of nanorods with a size distribution of 20-40 nm and growing along c-axis. Furthermore, experiments under different reaction conditions were carried out and the mechanism for the growth of nanorod-bundles was discussed ( 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]


    Synthesis and morphology of nanosized zeolite L

    CRYSTAL RESEARCH AND TECHNOLOGY, Issue 2 2010
    S. Sadegh Hassani
    Abstract AFM is a powerful tool for imaging nanoscale surface features; it provides two and three dimensional crystal structure images and other information about actual surface of zeolite crystallites. In this paper, nanosized zeolite L is synthesized in different crystallization times and a study of crystal growth of zeolite L is reported using atomic force microscopy (AFM). X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM) techniques are used for characterization of the as synthesized samples. TEM and two-dimensional AFM images indicate that the zeolite particles are in a nano-range and they have hexagonal structure. ( 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]


    Hydrothermal synthesis of nano-crystalline BaMoO4 under mild conditions using simple additive

    CRYSTAL RESEARCH AND TECHNOLOGY, Issue 2 2010
    Guangru Tian
    Abstract Large-scale high-quality BaMoO4 nanocrystals have been synthesized in aqueous solutions under mild conditions with citrate as a simple additive. The crystals have bone-like, spindle-like and wheatear-like morphologies assembled from nanoparticles, nanofibers and have been characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) techniques. The results showed that experimental parameters had great influences on the shape evolution of products. The adjustment of these parameters such as room temperature stirring time, reaction temperature and reaction time of hydrothermal reaction, can lead to obvious morphology changes of products, and the growth mechanism has been proposed. Room-temperature photoluminescence indicated that the as-prepared BaMoO4 nanocrystals had a strong blue emission peak at 481.5 nm. This facile route could be employed to synthesize more promising nanomaterials with interesting self-assembly structures. ( 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]


    Influence of the substrate temperature on the structural, optical, and electrical properties of tin selenide thin films deposited by thermal evaporation method

    CRYSTAL RESEARCH AND TECHNOLOGY, Issue 1 2010
    N. Kumar
    Abstract Thin films of tin selenide (SnSe) were deposited on sodalime glass substrates, which were held at different temperatures in the range of 350-550 K, from the pulverized compound material using thermal evaporation method. The effect of substrate temperature (Ts) on the structural, morphological, optical, and electrical properties of the films were investigated using x-ray diffraction analysis (XRD), scanning electron microscopy (SEM), transmission measurements, and Hall-effect characterization techniques. The temperature dependence of the resistance of the films was also studied in the temperature range of 80-330 K. The XRD spectra and the SEM image analyses suggest that the polycrystalline thin films having uniform distribution of grains along the (111) diffraction plane was obtained at all Ts. With the increase of Ts the intensity of the diffraction peaks increased and well-resolved peaks at 550 K, substrate temperature, were obtained. The analysis of the data of the optical transmission spectra suggests that the films had energy band gap in the range of 1.38-1.18 eV. Hall-effect measurements revealed the resistivity of films in the range 112-20 , cm for films deposited at different Ts. The activation energy for films deposited at different Ts was in the range of 0.14 eV-0.28 eV as derived from the analysis of the data of low-temperature resistivity measurements. ( 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]


    Properties of InAs co-doped ZnO thin films prepared by pulsed laser deposition

    CRYSTAL RESEARCH AND TECHNOLOGY, Issue 12 2009
    J. Elanchezhiyan
    Abstract InAs co-doped ZnO films were grown on sapphire substrates by pulsed laser deposition. The grown films have been characterized using X-ray diffraction (XRD), Hall effect measurements, Atomic force microscope (AFM) and Field emission scanning electron microscope (FESEM) in order to investigate the structural, electrical, morphological and elemental properties of the films respectively. XRD analysis showed that all the films were highly orientated along the c-axis. It was observed from Hall effect measurements that InAs co-doped ZnO films were of n-type conductivity. In addition, the presence of In and As has been confirmed by Energy dispersive X-ray analysis. AFM images revealed that the surface roughness of the films was decreased upon the co-doping. ( 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]


    Vibrational, optical and microhardness studies of trimethoprim DL -malate

    CRYSTAL RESEARCH AND TECHNOLOGY, Issue 12 2009
    S. Franklin
    Abstract Trimethoprim malate, an organic crystal, has been synthesized using slow evaporation method from its aqueous solution. Structural, optical and the mechanical properties of the grown crystal have been investigated by various characterization techniques which include FTIR spectra, single crystal XRD, UV-Vis spectra and Vickers microhardness testing. The structure of the compound predicted by analysing the recorded FTIR spectrum compliments the structure determined using single crystal X-ray diffraction. Single crystal X-ray diffraction study reveals that the crystals are monoclinic [P21/c, a=12.9850 , b=9.3038 , c=15.6815 and ,=111.065]. The UV-Vis spectrum exhibits maximum transparency (98%) for a wide range suggesting the suitability of the title compound for optical applications. The optical constants have been calculated and illustrated graphically. Microhardness tests have been performed on the cystal under study and the Vicker hardness number has been calculated. The work hardening coefficient is found to be 2.85 which suggest that the crystal belongs to the family of soft materials. ( 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]


    Solvothermal production of CdS nanorods using polyvinylpyrrolidone as a template

    CRYSTAL RESEARCH AND TECHNOLOGY, Issue 8 2009
    Titipun Thongtem
    Abstract CdS nanorods were solvothermally produced using Cd(NO3)2 and S powder in ethylenediamine containing different amounts of polyvinylpyrrolidone (PVP). The phase with hexagonal structure was detected using X-ray diffraction (XRD) and selected area electron diffraction (SAED). Their SAED patterns were in accordance with those of the simulations. Scanning and transmission electron microscopies (SEM and TEM) revealed the presence of CdS nanorods with their lengths influenced by different amounts of PVP. The nanorods were also characterized using high resolution TEM (HRTEM). They grew in the [001] direction normal to the (002) parallel crystallographic planes composing the nanorods. Raman spectra showed the 1LO (first harmonic) and 2LO (second harmonic) modes at the same wavenumbers although the products were produced under different conditions. ( 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]


    Optical studies on ZnO films prepared by sol-gel method

    CRYSTAL RESEARCH AND TECHNOLOGY, Issue 8 2009
    T. Ghosh
    Abstract A standard sol-gel method was used to deposit ZnO thin films of suitable thickness on glass substrate. The optical characteristics of the visible to infrared range on thermal stress were critically observed. Morphological signature of the films was detected by X-ray diffraction (XRD) and the crystallite size determined by Scherrer method from XRD data were consistent with grain size estimated from spectroscopic data through Meulenkamp equation. The optical band gap value from the transmission spectrum was found to corroborate with the existing works. ( 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]


    Characterization of pure and doped potassium hydrogen tartrate single crystals grown in silica gel

    CRYSTAL RESEARCH AND TECHNOLOGY, Issue 5 2009
    I. Quasim
    Abstract Growth of pure-, sodium- and lithium- doped potassium hydrogen tartrate single crystals by gel technique is reported. Growth conditions conducive for the growth of single crystals are worked out. The crystals are characterized by using powder XRD, SEM, FTIR, AES, EDAX, CH analysis and thermoanalytical techniques. The stoichiometric composition for the grown crystals are established as KHC4H4O6.H2O, (K)0.98(Na)0.02.H2O and (K)0.94(Li)0.06HC4H4O6.H2O. Doping of sodium and lithium in the pure potassium hydrogen tartrate single crystals is found to influence the size, perfection, morphology, crystal structure and the thermal stability of crystals. ( 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]


    Effects of annealing on structural, electrical and optical properties of AgGa(Se0.5S0.5)2 thin films deposited by using sintered stoichometric powder

    CRYSTAL RESEARCH AND TECHNOLOGY, Issue 4 2009
    H. Karaagac
    Abstract The structural, electrical and optical properties of AgGa(Se0.5S0.5 )2 thin films deposited by using the thermal evaporation method have been investigated as a function of annealing in the temperature range of 450,600 C. X-ray diffraction (XRD) analysis showed that the structural transformation from amorphous to polycrystalline structure started at 450 oC with mixed binary phases of Ga2Se3, Ga2S3, ternary phase of AgGaS2 and single phase of S. The compositional analysis with the energy dispersive X-ray analysis (EDXA) revealed that the as-grown film has different elemental composition with the percentage values of Ag, Ga, Se and S being 5.58, 27.76, 13.84 and 52.82 % than the evaporation source powder, and the detailed information about the stoichometry and the segregation mechanisms of the constituent elements in the structure have been obtained. The optical band gap values as a function of annealing temperature were calculated as 2.68, 2.85, 2.82, 2.83, and 2.81 eV for as-grown, annealed at 450, 500, 550, and 600 C samples, respectively. It was determined that these changes in the band gap are related with the structural changes with annealing. The temperature dependent conductivity measurements were carried out in the temperature range of 250-430 K for all samples. The room temperature resistivity value of as-grown film was found to be 0.7x108 (,-cm) and reduced to 0.9x107 (,-cm) following to the annealing. From the variation of electrical conductivity as a function of the ambient temperature, the activation energies at specific temperature intervals for each sample were evaluated. ( 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]


    Low temperature hydrothermal growth and optical properties of ZnO nanorods

    CRYSTAL RESEARCH AND TECHNOLOGY, Issue 1 2009
    J. H. Yang
    Abstract Well-faceted hexagonal ZnO nanorods have been synthesized by a simple hydrothermal method at relative low temperature (90C) without any catalysts or templates. Zinc oxide (ZnO) nanorods were grown in an aqueous solution that contained Zinc chloride (ZnCl2, Aldrich, purity 98%) and ammonia (25%). Most of the ZnO nanorods show the perfect hexagonal cross section and well-faceted top and side surfaces. The diameter of ZnO nanorods decreased with the reaction time prolonging. The samples have been characterized by X-ray powder diffraction (XRD) and scanning electron microscopy (SEM) measurement. XRD pattern confirmed that the as-prepared ZnO was the single-phase wurtzite structure formation. SEM results showed that the samples were rod textures. The surface-related optical properties have been investigated by photoluminescence (PL) spectrum and Raman spectrum. Photoluminescence measurements showed each spectrum consists of a weak band ultraviolet (UV) band and a relatively broad visible light emission peak for the samples grown at different time. It has been found that the green emission in Raman measurement may be related to surface states. ( 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]


    Growth and characterization of strontium tartrate pentahydrate crystals

    CRYSTAL RESEARCH AND TECHNOLOGY, Issue 10 2008
    A. Firdous
    Abstract Silica gel impregnated with L-tartaric acid and using strontium nitrate as the second reactant leads to the growth of well faceted strontium tartrate pentahydrate single crystals. The morphological developmen and internal cell dimensions are observed to be different from the ones reported in the literature for strontium tartrate trihydrate crystals. The crystals are characterized using XRD, CH analysis, SEM, FTIR spectroscopy and thermoanalytical techniques. The crystals are observed to be thermally stable upto about 105C but thereafter start decomposing and ejecting water of hydration at various stages, finally reducing to strontium oxide. ( 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]


    Characterization of reactive DC magnetron sputtered TiAlN thin films

    CRYSTAL RESEARCH AND TECHNOLOGY, Issue 10 2008
    B. Subramanian
    Abstract Thin films of about 1,m Titanium Aluminum Nitride (TiAlN) were deposited onto mild steel substrates by reactive direct current (DC) magnetron sputtering using a target consisting of equal segments of titanium and aluminum. X-ray diffraction (XRD) analysis showed that the TiAlN phase had preferred orientations along 111 and 200 with the face-centered cubic structure. Scanning Electron Microscope (SEM) and Atomic Force Microscope (AFM) analyses indicated that the films were uniform and compact. Photoluminescence (PL) spectra reveal that TiAlN thin films are of good optical quality. Laser Raman studies revealed the presence of characteristic peaks of TiAlN at 312.5, 675, and 1187.5 cm,1. ( 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]


    Growth of YCOB single crystals by flux technique and their characterization

    CRYSTAL RESEARCH AND TECHNOLOGY, Issue 5 2008
    R. Arun Kumar
    Abstract Nonlinear optical single crystals of YCOB with good optical quality were grown by the flux technique for the first time. Polycrystalline YCOB samples were synthesized by solid state reaction method. The thermal analysis of the sample was performed with lithium carbonate flux in different weight proportions and the growth temperature was optimised. Single crystals of YCOB with dimensions 3 3 5 mm3 were obtained by the method of ,slow-cooling'. The grown crystals were characterized by XRD, UV-VIS-NIR, EDAX, FTIR and etching studies. The powder XRD pattern revealed the formation of YCOB compound. The lattice parameters were identified through single crystal XRD studies. The UV-VIS-NIR results showed that the crystal has a sharp cutoff at 220 nm and is nearly 55% transparent over a wide wavelength range enabling applications in the UV region. The EDAX measurement revealed the ,flux-free' crystal formation. The presence of the functional groups belonging to the YCOB crystals was identified by the FTIR results. ,Hillock-like' patterns are observed in the etching studies. The primary emphasis in this study is laid to describe ,flux technique' as an alternative method to grow YCOB crystals. The results are presented and discussed. ( 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]


    PSSS-controlled synthesis of CaCO3 superstructures

    CRYSTAL RESEARCH AND TECHNOLOGY, Issue 9 2007
    Hua Tang
    Abstract Complex CaCO3 superstructure can be easily synthesized by using poly (sodium 4-styrenesulfonate) (PSSS) as a structure directing agent to direct the controlled precipitation of calcium carbonate from aqueous solution. The products were characterized by scanning electron microscopy (SEM), and powder X-ray diffraction (XRD) analysis. The results revealed that the morphology of the products changed significantly with the increasing of the concentration of PSSS in solution, from rhombohedral particles to plate-packed aggregates to spheres with smooth surface, to sponge-like spheres and finally to complex spherical superstructure consisted of plate-like sub-units. We hypothesize that the observed sequential changes in morphology of CaCO3 particles with added PSSS concentration may be due to the influence of PSSS on nucleation, growth and aggregation of CaCO3 crystals. The formation mechanisms of CaCO3 crystals with different morphologies were discussed. ( 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]


    Photostimulated changes of properties of CdTe films

    CRYSTAL RESEARCH AND TECHNOLOGY, Issue 8 2007
    T. D. Dzhafarov
    Abstract The effect of illumination during the close-spaced sublimation (CSS) growth on composition, structural, electrical, optical and photovoltaic properties of CdTe films and CdTe/CdS solar cells were investigated. Data on comparative study by using X-ray diffraction (XRD), scanning electron microscopy (SEM), absorption spectra and conductivity-temperature measurements of CdTe films prepared by CSS method in dark (CSSD) and under illumination (CSSI) were presented. It is shown that the growth rate and the grain size of CdTe films grown under illumination is higher (by factor about of 1.5 and 3 respectively) than those for films prepared without illumination. The energy band gap of CdTe films fabricated by both technology, determined from absorption spectra, is same (about of 1.50 eV), however conductivity of the CdTe films produced by CSSI is considerably greater (by factor of 107) than that of films prepared by CSSD. The photovoltaic parameters of pCdTe/nCdS solar cells fabricated by photostimulated CSSI technology (Jsc = 28 mA/cm2, Voc =0.63 V) are considerably larger than those for cells prepared by CSSD method (Jsc = 22 mA/cm2, Voc = 0.52 V). A mechanism of photostimulated changes of properties of CdTe films and improvement of photovoltaic parameters of CdTe/CdS solar cells is suggested. ( 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]


    Effect of different metal ions on structural, thermal, spectroscopic and optical properties of ATCC and ATMC single crystals

    CRYSTAL RESEARCH AND TECHNOLOGY, Issue 8 2007
    R. Perumal
    Abstract A novel metal-organic coordination complex nonlinear optical crystals, tri-allylthiourea cadmium chloride [(CdCl2(AT)3] and tri-allylthiourea mercury chloride [(HgCl2(AT)3] abbreviated as ATCC, ATMC (AT is Allylthiourea i.e.,CH2=CHCH2NHCSNH2) has been synthesized and grown as single crystals. It was synthesized in deionised water and further recrystallized to improve its purity. Single crystals of the allylthiourea co-ordination complex nonlinear optical crystals tri allylthiourea cadmium chloride (ATCC) with dimensions of 14x14x10 mm3 and tri allylthiourea mercury chloride (ATMC) with dimensions of 15x15x12 mm3 were grown successfully from aqueous solution by solvent evaporation as well as by temperature lowering method. It exhibits powder SHG efficiencies higher than that of a well known organic NLO crystal Urea. The solubility of the as grown crystals was estimated from the aqueous solution and the effect of different metal ions on the grown crystals, structural, thermal, spectral and optical properties were analyzed. XRD studies the reveals the same structure of both materials. Influence of the different central metal (Cd and Hg) atoms, changing the thermal properties of the materials when NLO complexes formed with the common ligand allylthiourea. The metal co-ordination was confirmed form the spectroscopic analysis. From the UV transmittance studies, red shift was from the transparency cut-off wavelengths. The value is 285nm for ATCC is and is 335nm ATMC, Non-linear an optical study confirms the suitabilities of the as grown crystals for the non linear optical applications. ( 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]


    Synthesis and characterization of fine lithium niobate powders by sol- gel method

    CRYSTAL RESEARCH AND TECHNOLOGY, Issue 4 2007
    L. H. Wang
    Abstract Lithium niobate (LN) nanocrystal powders were prepared by low-temperature sol-gel method. Dihydrate lithium acetate as lithium source, and niobium chloride as niobium source were used as starting materials. The gel and powders were characterized by thermogravimetry and differential scanning calorimetry (TG/DSC), X-ray diffraction (XRD), transmission electronmicroscopy (TEM) and Fourier transform infrared (FTIR) spectra. The results show that when the gel was heat-treated at 600C, the fine LN nanocrystals with the size of 40-60 nm were obtained, and the size of the powders become larger with the heat-treated temperature increasing. ( 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]


    Effect of NaCl filler on ferroelectric phase and polaron configurations of PVDF films

    CRYSTAL RESEARCH AND TECHNOLOGY, Issue 4 2007
    I. S. ElashmawiArticle first published online: 8 MAR 200
    Abstract Polyvinyldene fluoride (PVDF) films filled with NaCl of mass fraction range 1 , W , 6 % were prepared by casting technique. Their crystalline structure, thermal, optical properties and Electron spin resonance (ESR) were examined. X-ray diffraction (XRD) and differential thermal analysis (DTA) measurements indicated a maximum ferroelectric ,-phase increment at 4%. DTA was used to identify the phase transition temperatures, the order of reaction and the activation energy of melting. The UV-Visible optical absorption implied a minimum value of the estimated optical energy gap at W = 4%. ESR spectra contained a Lorentizian signal exhibiting a minimum value of the symmetry factor at W = 4%. The energy levels of the optical gap boundaries were though to contribute to ESR transitions. ( 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]


    Solvothermal growth of single-crystal hexagonal prismatic SrCO3 microrods

    CRYSTAL RESEARCH AND TECHNOLOGY, Issue 3 2007
    Fanglin Du
    Abstract Single-crystal hexagonal prism SrCO3 microrods have been prepared by a simple solvothermal route. The effects of the reaction time, the content of 1,2-propanediol and the reactants mass on the products have been investigated, respectively. The as-synthesized microrods were characterized by X-ray powder diffraction (XRD), field-emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM). The results reveal that the products have uniform shape and excellent monodispersity. ( 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]


    XRD, thermal, FTIR and SEM studies on gel grown ,-glycine crystals

    CRYSTAL RESEARCH AND TECHNOLOGY, Issue 1 2007
    E. Ramachandran
    Abstract Glycine is the smallest among amino acids. The polymorphs, ,- and ,-forms of glycine were crystallized in silica gel by reduction of solubility method. The grown crystals were characterized by single crystal X-ray diffraction studies and density determination. Fourier transform infrared spectroscopic studies and thermogravimetric analysis of ,-glycine were also conducted. Morphological and scanning electron microscopic (SEM) studies were also made and compared with the crystal packing. ( 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]


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

    CRYSTAL RESEARCH AND TECHNOLOGY, Issue 1 2007
    R. Sathyalakshmi
    Abstract L(+)Glutamic acid hydrochloride [HOOC (CH2)2CH(NH2) COOHHCl], a monoamino dicarboxylic acid salt of L-Glutamic acid was synthesized and the synthesis was confirmed by FTIR analysis. Solubility of the material in water was determined. Pure and Thiourea doped L-Glutamic acid hydrochloride crystals were grown by low temperature solution growth using solvent evaporation technique. XRD, UV-Vis-NIR analyses were carried out for both pure and thiourea doped crystals. The crystals were qualitatively analyzed by EDAX analysis and the presence of thiourea was confirmed. The cell parameters of L-Glutamic acid hydrochloride have been determined as a = 5.151 , b = 11.79 , c = 13.35 by X-ray diffraction analysis and it crystallizes in orthorhombic space group P212121. UV-Vis-NIR spectra analysis showed good optical transmission in the entire visible region for both pure and doped crystals. Micro hardness of both pure and doped crystals has been determined using Vickers micro hardness tester. The SHG efficiencies of both pure and doped crystals were determined using Kurtz powder test and pure L-Glutamic acid hydrochloride crystal was found to possess better efficiency than thiourea doped L-Glutamic acid hydrochloride crystals. ( 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]


    Structural, electrical and optical properties of Ge implanted GaSe single crystals grown by Bridgman technique

    CRYSTAL RESEARCH AND TECHNOLOGY, Issue 12 2006
    H. Karaa
    Abstract Structural, optical and electrical properties of Ge implanted GaSe single crystal have been studied by means of X-Ray Diffraction (XRD), temperature dependent conductivity and photoconductivity (PC) measurements for different annealing temperatures. It was observed that upon implanting GaSe with Ge and applying annealing process, the resistivity is reduced from 2.1 109 to 6.5 105 ,-cm. From the temperature dependent conductivities, the activation energies have been found to be 4, 34, and 314 meV for as-grown, 36 and 472 meV for as-implanted and 39 and 647 meV for implanted and annealed GaSe single crystals at 500C. Calculated activation energies from the conductivity measurements indicated that the transport mechanisms are dominated by thermal excitation at different temperature intervals in the implanted and unimplanted samples. By measuring photoconductivity (PC) measurement as a function of temperature and illumination intensity, the relation between photocurrent (IPC) and illumination intensity (,) was studied and it was observed that the relation obeys the power law, IPC ,,n with n between 1 and 2, which is indication of behaving as a supralinear character and existing continuous distribution of localized states in the band gap. As a result of transmission measurements, it was observed that there is almost no considerable change in optical band gap of samples with increasing annealing temperatures for as-grown GaSe; however, a slight shift of optical band gap toward higher energies for Ge-implanted sample was observed with increasing annealing temperatures. ( 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]


    Growth and photorefractive properties of Mg:Ce:Cu:LiNbO3 crystals grown by Czochralski method

    CRYSTAL RESEARCH AND TECHNOLOGY, Issue 8 2006
    Y. X. Fan
    Abstract In this paper, photorefractive properties of Mg:Ce:Cu:LiNbO3 crystals were studied. The crystals doped with different concentration of Mg ions have been grown by the Czochralski method. Mg concentrations in grown crystals were analyzed by an inductively coupled plasma optical emission spectrometry (ICP-OE/MS). The crystal structures were analyzed by the X-ray powder diffraction (XRD), ultraviolet-visible (UV-Vis) absorption spectra and infrared (IR) transmitatance spectra. The photorefractive properties of crystals were experimentally studied by using two-beam coupling. In this experiment we determined the writing time, maximum diffraction efficiency and the erasure time of crystals samples with He-Ne laser. The results showed that the dynamic range (M/#), sensitivity (S) and diffraction efficiency (,) were dependent on the Mg doping concentration, and the Mg(4.58mol%):Ce:Cu:LiNbO3 crystal was the most proper holographic recording media material among the six crystals studied in the paper. ( 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]


    Habit modification and improvement in properties of potassium hydrogen phthalate (KAP) crystals doped with metal ions

    CRYSTAL RESEARCH AND TECHNOLOGY, Issue 3 2006
    S. K. Geetha
    Abstract Potassium hydrogen phthalate (KAP) single crystals were grown by slow evaporation and slow cooling techniques. The growth procedure like temperature cooling rate, evaporation rate, solution pH, concentration of the solute, supersaturation ratio etc., has been varied to have optically transparent crystals. Efforts were made to dope the KAP crystals with rubidium, sodium and lithium ions. The dopant concentration has been varied from 0.01 to 10 mole percent. Good quality single crystals were grown with different concentrations of dopants in the mother phase. Depending on the concentration of the dopants and the solution pH value, there is modification of habit. Rubidium ions very much improve the growth on the prismatic faces. The transparency of the crystals is improved with rubidium and sodium doping. The role of the dopants on the non-linear optical performance of KAP indicates better efficiency for doped crystals. The grown crystals were characterized with XRD, FT-IR, chemical etching, Vickers microhardness and SHG measurements. The influence of the dopants on the optical, chemical, structural, mechanical and other properties of the KAP crystals was analysed. 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim [source]