STRUCTURE AND MORPHOLOGICAL STUDIES OF CdSe NANOCRYSTALS

2006 ◽  
Vol 05 (01) ◽  
pp. 109-117 ◽  
Author(s):  
S. N. SARANGI ◽  
S. N. SAHU ◽  
K. GOSWAMI
Keyword(s):  
Grazing Angle ◽  
Cdse Nanocrystals ◽  
Diffusion Limited Aggregation ◽  
Tem Analysis ◽  
X Ray ◽  
Cathodic Electrodeposition ◽  
Morphological Studies ◽  
Diffraction Patterns ◽  
Galvanostatic Condition ◽  
Microscopic Measurement

Nanocrystalline thin films of CdSe have been synthesized from an acidic solution containing CdSO 4 and SeO 2 by a cathodic electrodeposition technique under galvanostatic condition. The crystal structure and morphology have been investigated by Grazing angle X-Ray Diffraction (GXRD), Transmission Electron Microscopy (TEM) and optical microscopic measurement. The X-Ray and TEM diffraction patterns of the deposit reveal a bimodal size distribution with the presence of cubic (zinc blende) phase in the deposit. The particle sizes have been estimated from GXRD measurement found to be 4 nm to 6 nm, comparable to that obtained from TEM analysis. A Branched Fractal Pattern (BFP) in CdSe nanocrystals has been observed by optical microscopy, suggesting a diffusion-limited aggregation growth mechanism with fractal dimension 1.69 ± 0.04.

Synthesis, Structural, Morphological and I-V Characteristics of Polyaniline-MgCl Composite

2022 ◽  
Vol 1048 ◽  
pp. 141-146
Author(s):  
Madihally Nagaraja ◽  
Geetha Thippeswamy ◽  
Sushma Prashanth ◽  
Jayadev Pattar ◽  
Mahesh Hampapatna Mahesh
Keyword(s):  
Structural Analysis ◽  
Oxidative Polymerization ◽  
X Ray Diffraction ◽  
X Ray ◽  
Sem Micrographs ◽  
Morphological Studies ◽  
Current Voltage ◽  
Amorphous Nature ◽  
Diffraction Patterns ◽  
Polymerization Method

Composite of polyaniline-MgCl has been synthesized using oxidative polymerization method. Synthesized samples were characterized for structural analysis using FTIR and XRD. Morphological studies were carried by SEM micrographs. Current-Voltage (I-V) properties are obtained through Kiethly source meter. FTIR spectrum of polyaniline-MgCl composite indicates all the characteristic peaks of polyaniline. X-ray diffraction patterns represented the amorphous nature of polyaniline-MgCl composite. SEM micrographs confirmed the presence of MgCl particles in polyaniline matrix. I-V characteristics have shown the ohmic type behavior of polyaniline and polyaniline-MgCl composite.

scholarly journals Advances in Synchrotron X-ray Polycrystalline Diffraction

1988 ◽  
Vol 41 (2) ◽  
pp. 101 ◽  
Author(s):  
William Parrish
Keyword(s):  
High Resolution ◽  
Grazing Angle ◽  
Anomalous Scattering ◽  
Wavelength Selection ◽  
High Count ◽  
Instrument Function ◽  
X Ray ◽  
Depth Analysis ◽  
Diffraction Patterns ◽  
New Applications

The advantages of synchrotron radiation for X-ray polycrystalline diffraction are illustrated by a number of examples. The plane wave parallel-beam X-ray optics uses a Si(lll) channel monochromator for easy wavelength selection and a set of long parallel slits to define the diffracted beam. The constant simple instrument function and the high resolution symmetrical profiles (FWHM 0.05") greatly simplify the data analysis and add a new dimension to profile broadening studies. The geometry permits uncoupling the 6-26 sample-detector relationship without changing the profile shape and makes possible new applications such as grazing angle incidence depth analysis of thin films. The same instrumentation is used for high resolution energy dispersive diffraction (BOD) by step-scanning the monochromator. The resolution is two orders of magnitude better than conventional BOD and can be used at high count rates. The easy wavelength selection yields diffraction patterns with the highest PI B and permits anomalous scattering studies.

Fabrication of Mesoporous Cerium Dioxide Films by Cathodic Electrodeposition

2007 ◽  
Vol 7 (11) ◽  
pp. 4198-4201 ◽  
Author(s):  
Young-Soo Kim ◽  
Jin-Kyu Lee ◽  
Jae-Hoon Ahn ◽  
Eun-Kyung Park ◽  
Gil-Pyo Kim ◽  
...  
Keyword(s):  
Small Angle ◽  
Cerium Dioxide ◽  
Xrd Analysis ◽  
Sem Analysis ◽  
Cubic Phase ◽  
Tem Analysis ◽  
X Ray ◽  
Cathodic Electrodeposition ◽  
Glass Substrates ◽  
Transmission Electron

Mesoporous cerium dioxide (Ceria, CeO2) thin films have been successfully electrodeposited onto ITO-coated glass substrates from an aqueous solution of cerium nitrate using CTAB (Cetyltrimethylammonium Bromide) as a templatingagent. The synthesized films underwent detailed characterizations. The crystallinity of synthesized CeO2 film was confirmed by XRD analysis and HR-TEM analysis, and surface morphology was investigated by SEM analysis. The presence of mesoporosity in fabricated films was confirmed by TEM and small angle X-ray analysis. As-synthesized film was observed from XRD analysis and HR-TEM image to have well-crystallized structure of cubic phase CeO2. Transmission electron microscopy and small angle X-ray analysis revealed the presence of uniform mesoporosity with a well-ordered lamellar phase in the CeO2 films electrodeposited with CTAB templating.

Intra-layer ordering and inter-layer disordering of the Li2MnO3phase in Li1.07Mn1.93O4–δcathode materials: electron diffraction investigation andDIFFaXsimulation of X-ray diffraction patterns

2014 ◽  
Vol 47 (3) ◽  
pp. 879-886 ◽  
Author(s):  
He Zheng ◽  
Jianbo Wang ◽  
Zhongling Xu ◽  
Jianian Gui
Keyword(s):  
Electron Diffraction ◽  
Lithium Ion ◽  
X Ray Diffraction ◽  
Threefold Axis ◽  
Tem Analysis ◽  
Electron Diffraction Investigation ◽  
X Ray ◽  
Selected Area Electron Diffraction ◽  
Transmission Electron ◽  
Diffraction Patterns

A previous transmission electron microscopy (TEM) analysis revealed the existence of monoclinic Li2MnO3in the lithium-rich and oxygen-deficient Li1.07Mn1.93O4−δpowder. Interestingly, the monoclinic phase exhibits different nanoscale lamellar variants involving a rotation of the stacking direction by 120 or 240° along the pseudo-threefold axis,i.e.the [103]M//[111]C(M and C denote the monoclinic and cubic phases, respectively) zone axis. Here, a theoretical X-ray diffraction (XRD) study of Li2MnO3employing theDIFFaXprogram is presented. It is found that, with the occurrence of different stacking configurations, the characteristic superstructure reflections with 2θ between 20 and 35° (Cu Kα) in the XRD pattern become more and more broadened with the increasing degree of stacking disorder, indicating that XRD may fall short in detecting the presence of the monoclinic Li2MnO3phase. Moreover, selective peak asymmetry appears when the stacking sequence becomes extremely disordered. Further selected-area electron diffraction and theoretical neutron diffraction investigation may clarify the similar ambiguity concerning the crystal phases of other structurally related compound cathode materials for lithium-ion batteries (e.g.LiNi1/2Mn1/2O2, LiNi1/3Co1/3Mn1/3O2).

X-Ray Studies on Phospholipid Bilayers. XII. Interactions of Pentachlorophenol with Myelin

1992 ◽  
Vol 47 (7-8) ◽  
pp. 601-607 ◽  
Author(s):  
M. Suwalsky ◽  
F. Villena ◽  
G. Montoya ◽  
C. Garrido ◽  
I. Sánchez ◽  
...  
Keyword(s):  
Chronic Administration ◽  
Nerve Fibers ◽  
Phospholipid Bilayers ◽  
X Ray Diffraction ◽  
X Ray ◽  
Morphological Studies ◽  
Vital Functions ◽  
Sciatic Nerves ◽  
Diffraction Patterns

Pentachlorophenol (PCP) is a widely used pesticide, particularly for the preservation of wood. Given its high toxicity and resistance to degradation it has become a dangerous environmental pollulant. Due to its high lipophilicity, PCP is able to partition into the lipid bilayer of cell membranes disrupting several vital functions. The present research was concerned with the effects that the chronic administration of PCP could produce in vivo to the sciatic nerve of rats. X-ray diffraction patterns obtained from freshly dissected and dried sciatic nerves of PCP treated rats did not show significant differences in their reflections with respect to those present in the patterns from untreated animals. However, morphological studies performed by optical and electron microscopy showed degenerative changes in about 10% of the A and B type of nerve fibers.

Evaluation of Freezing Methods by Low Temperature X-Ray Diffraction

1977 ◽  
Vol 35 ◽  
pp. 330-333
Author(s):  
T. Gulik-Krzywicki ◽  
M.J. Costello
Keyword(s):  
Biological Materials ◽  
Molecular Organization ◽  
X Ray Diffraction ◽  
Glass Capillary ◽  
X Ray ◽  
Rate Dependent ◽  
Before And After ◽  
Freeze Etching ◽  
Diffraction Patterns ◽  
Set Up

Freeze-etching electron microscopy is currently one of the best methods for studying molecular organization of biological materials. Its application, however, is still limited by our imprecise knowledge about the perturbations of the original organization which may occur during quenching and fracturing of the samples and during the replication of fractured surfaces. Although it is well known that the preservation of the molecular organization of biological materials is critically dependent on the rate of freezing of the samples, little information is presently available concerning the nature and the extent of freezing-rate dependent perturbations of the original organizations. In order to obtain this information, we have developed a method based on the comparison of x-ray diffraction patterns of samples before and after freezing, prior to fracturing and replication.Our experimental set-up is shown in Fig. 1. The sample to be quenched is placed on its holder which is then mounted on a small metal holder (O) fixed on a glass capillary (p), whose position is controlled by a micromanipulator.

Examination of Rabbit Fc Crystals

1968 ◽  
Vol 26 ◽  
pp. 140-141
Author(s):  
J. P. Robinson ◽  
P. G. Lenhert
Keyword(s):  
Molecular Weight ◽  
Flat Plate ◽  
Phosphate Buffer ◽  
Asymmetric Unit ◽  
X Ray Diffraction ◽  
X Ray ◽  
Neutral Ph ◽  
Small Crystals ◽  
Carbon Coated ◽  
Diffraction Patterns

Crystallographic studies of rabbit Fc using X-ray diffraction patterns were recently reported. The unit cell constants were reported to be a = 69. 2 A°, b = 73. 1 A°, c = 60. 6 A°, B = 104° 30', space group P21, monoclinic, volume of asymmetric unit V = 148, 000 A°3. The molecular weight of the fragment was determined to be 55, 000 ± 2000 which is in agreement with earlier determinations by other methods.Fc crystals were formed in water or dilute phosphate buffer at neutral pH. The resulting crystal was a flat plate as previously described. Preparations of small crystals were negatively stained by mixing the suspension with equal volumes of 2% silicotungstate at neutral pH. A drop of the mixture was placed on a carbon coated grid and allowed to stand for a few minutes. The excess liquid was removed and the grid was immediately put in the microscope.

Electron diffraction studies of amorphous and polycrystalline thin films

1990 ◽  
Vol 48 (4) ◽  
pp. 118-119
Author(s):  
D J H Cockayne ◽  
D R McKenzie
Keyword(s):  
Thin Films ◽  
Electron Diffraction ◽  
Polycrystalline Materials ◽  
Good Resolution ◽  
Scattered Intensity ◽  
Radial Density ◽  
X Ray ◽  
Polycrystalline Thin Films ◽  
Nitrogen Ion ◽  
Diffraction Patterns

The study of amorphous and polycrystalline materials by obtaining radial density functions G(r) from X-ray or neutron diffraction patterns is a well-developed technique. We have developed a method for carrying out the same technique using electron diffraction in a standard TEM. It has the advantage that studies can be made of thin films, and on regions of specimen too small for X-ray and neutron studies. As well, it can be used to obtain nearest neighbour distances and coordination numbers from the same region of specimen from which HREM, EDS and EELS data is obtained.The reduction of the scattered intensity I(s) (s = 2sinθ/λ ) to the radial density function, G(r), assumes single and elastic scattering. For good resolution in r, data must be collected to high s. Previous work in this field includes pioneering experiments by Grigson and by Graczyk and Moss. In our work, the electron diffraction pattern from an amorphous or polycrystalline thin film is scanned across the entrance aperture to a PEELS fitted to a conventional TEM, using a ramp applied to the post specimen scan coils. The elastically scattered intensity I(s) is obtained by selecting the elastically scattered electrons with the PEELS, and collecting directly into the MCA. Figure 1 shows examples of I(s) collected from two thin ZrN films, one polycrystalline and one amorphous, prepared by evaporation while under nitrogen ion bombardment.

Electron diffraction detection of ordliking in annealed PbTe thin film

1990 ◽  
Vol 48 (4) ◽  
pp. 1018-1019
Author(s):  
Karimat El-Sayed
Keyword(s):  
Thin Film ◽  
Electron Diffraction ◽  
Lead Telluride ◽  
Structural Basis ◽  
Face Centered Cubic ◽  
X Ray ◽  
Polycrystalline Thin Films ◽  
Stage Process ◽  
Diffraction Patterns ◽  
Face Centered

Lead telluride is an important semiconductor of many applications. Many Investigators showed that there are anamolous descripancies in most of the electrophysical properties of PbTe polycrystalline thin films on annealing. X-Ray and electron diffraction studies are being undertaken in the present work in order to explain the cause of this anamolous behaviour.Figures 1-3 show the electron diffraction of the unheated, heated in air at 100°C and heated in air at 250°C respectively of a 300°A polycrystalline PbTe thin film. It can be seen that Fig. 1 is a typical [100] projection of a face centered cubic with unmixed (hkl) indices. Fig. 2 shows the appearance of faint superlattice reflections having mixed (hkl) indices. Fig. 3 shows the disappearance of thf superlattice reflections and the appearance of polycrystalline PbO phase superimposed on the [l00] PbTe diffraction patterns. The mechanism of this three stage process can be explained on structural basis as follows :

Dynamical Scattering in Electron Diffraction of wet Protein Crystals

1980 ◽  
Vol 38 ◽  
pp. 42-43
Author(s):  
B. B. Chang ◽  
D. F. Parsons
Keyword(s):  
Electron Diffraction ◽  
Scattering Theory ◽  
Protein Crystals ◽  
Electron Diffraction Data ◽  
Specimen Thickness ◽  
Major Question ◽  
X Ray ◽  
Scattering Effects ◽  
Diffraction Patterns ◽  
Acceleration Voltage

The significance of dynamical scattering effects remains the major question in the structural analysis by electron diffraction of protein crystals preserved in the hydrated state. In the few cases (single layers of purple membrane and 400-600 Å thick catalase crystals examined at 100 kV acceleration voltage) where electron-diffraction patterns were used quantitatively, dynamical scattering effects were considered unimportant on the basis of a comparison with x-ray intensities. The kinematical treatment is usually justified by the thinness of the crystal. A theoretical investigation by Ho et al. using Cowley-Moodie multislice formulation of dynamical scattering theory and cytochrome b5as the test object2 suggests that kinematical analysis of electron diffraction data with 100-keV electrons would not likely be valid for specimen thickness of 300 Å or more. We have chosen to work with electron diffraction patterns obtained from actual wet protein crystals (rat hemoglobin crystals of thickness range 1000 to 2500 Å) at 200 and 1000 kV and to analyze these for dynamical effects.

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