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Photoconductive studies on electron beam evaporated CdSe films
No full textThin CdSe films were electron beam evaporated. The CdSe powder synthesized in thel aboratory by a chemical method was used as source for the deposition of films. Clean glass and titanium substrates were used as substrates. The substrate temperature was varied in the range of 30–250 1C. X-ray diffraction studies indicated polycrystalline hexagonal structure. The band gap was 1.65eV. The grain
size was15–30nm with increase of substrate temperature. Photoconductive cells fabricated with the doped and undoped films have exhibited high photosensitivity and high signal to noiseratio. The current voltage characteristics were linear
Influence of CH3SO3H and AlCl3 in direct and pulse current electrodeposition of trivalent chromium
No full textComparison of direct and pulse current electrodeposition of the trivalent chromium from urea
formic acid as a complexing agent was studied in detail. The influences of CH3SO3H and AlCl3 on
the properties of the deposit were also studied. The presence of CH3SO3H exhibits higher current
efficiency and better corrosion resistance because of its higher hydrogen overpotential. The pulse
current electrodeposition leads to growth of b-Cr. The corrosion studies were conducted by
potentiodynamic polarisation and electrochemical impedance spectroscopy. The morphology of
the deposits was characterised by scanning electron microscopy (SEM) and X-ray diffraction
Evaluation of corrosion and wear resistance titanium nitride (TiN) coated on mild steel (MS) with brush plated nickel interlayer
No full textTitanium nitride (TiN) coatings were deposited onmild steel (MS) by direct current reactivemagnetron
sputtering. With the aim of improving the corrosion resistance of TiN, an additional nickel interlayer
was brush plated on the steel substrates before TiN film formation. The phases have been identified
with X-ray diffraction analysis. The hardness values of TiN layers were found to increase with the
increase in thickness of the Ni interlayer. The wear track investigations of TiN layers showed that the
TiN/MS system was worn out by abrasive wear mechanism while on the film with Ni interlayer is by
adhesive wear. It was found that the TiN/Ni/MS stack had a weaker tendency towards corrosion and
higher corrosion resistance in 3?5%NaCl than the bare MS substrate, Ni/MS and TiN/MS specimen
Structural analysis of phosphatidyl choline lipids and glycerol precursors
No full textThe structures and stabilities of the glycerol (G) and glycerol 3-phosphae (G3P) isomers have been calculated in the gas phase, using an ab initio density functional theory (DFT) method. The different conformational structures are shown to be at the origin of the various phospholipid conformers, except, obviously, for the alkyl chain torsions. The G3P conformations have been examined taking into account the experiemntal structures of the complexation sites in the glycerol kinase (GK) and glycerol 3-phosphate acyl transferase (G3PAT) enzymes, which correspond to the first nd second steps of the "de novo" phospholipid biogenesis, respectively. The conformational analysis of the glycerophosphate skeleton is shown to determine most of the structural characteristics of the phosphatidyl choline lipids, which differ by the length of their diacyl chains, i.e. dilauroyl (DL), dimyristoyl (DM) and dipalmitoyl (DP) phosphatidylcholines (PC). Higher energy conformers with kinks in the acyl chains have been found, in preparation for molecular dynamics studies of the chain melting phase transformation
Deposition of Cd-xZn1-xSe films by brush electrodeposition and their characteristics
No full textCdxZn1-xSe films(0≤x≤1) were deposited for the first time by the brush plating technique at
room temperature from an aqueous bath containing zinc sulphate, cadmium sulphate and
selenium oxide. The deposition current density was varied in the range of 50 – 250 mA
cm-2. The as deposited films exhibited cubic structure. Composition of the films was
estimated by EDAX studies. Optical band gap of the films varied from 1.72 eV to 2.70 eV
as the composition varied from CdSe to ZnSe side. Electrical properties of the films were
determined at room temperature. The room temperature resistivity, carrier density and
mobility varied in the range of 9.0 ohm cm – 200 ohm cm,10 – 2 cm2V-1s-1 and 6.94 x
1016 – 1.56 x 1016 cm-3 respectively as the composition changed from CdSe to ZnSe side
Corrosion behavior of Cr electrodeposited from Cr(VI) and Cr(III)-baths using direct (DCD) and pulse electrodeposition (PED) techniques
No full textA comparison was made between the electrochemical corrosion behaviors of chromium deposited from
hexavalent [Cr(VI)] and trivalent [Cr(III)] chromium baths using direct current (DCD) and pulse electro
deposited (PED) techniques. Chromium coatings were deposited on mild-steel (MS) substrate. The corrosion
behavior of both DCD and PED chromium from Cr(VI) and Cr(III)-baths in 3.5%NaCl solution was
studied using potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). The
results indicated that PED chromium from Cr(VI) and Cr(III)-baths have higher charge-transfer resistance
Rct and very low Icorr than that of DCD chromium on mild-steel substrate
Microstructural and spectroscopic investigations into the effect of CeO2 additions on the performance of a MnO2 aqueous rechargeable battery
No full textThe influence of CeO2 additions on the electrochemical behaviour of the MnO2 cathode in a Zn–MnO2
battery using lithium hydroxide (LiOH) as an electrolyte is investigated using microscopy and spectroscopic
techniques. The results showed that such additions greatly improve the discharge capacity of
the battery (from 155 to 190mAhg−1) but only from the second discharge cycle onwards. Capacity fade
with subsequent cycling is also greatly reduced. With an aim to understand the role of CeO2 on the
discharge–charge characteristics of MnO2 and its mechanism, we have used a range of microscopy, spectroscopy
and diffraction-based techniques to study the process. The CeO2 is not modified by multiple
discharged and charged cycles. The CeO2 may enhance the discharge–charge performance of the battery
by raising the oxygen evolution potential during charging but does not take part directly in the redox
reaction
Electrochemical properties of MmNi3.03Si0.85Co0.60Mn0.31Al0.08 hydrogen storage alloys in alkaline electrolytes—A cyclic voltammetric study at different temperatures
No full textThe cyclic voltammetric behavior of MmNi3.03Si0.85Co0.60Mn0.31Al0.08-based metal hydride electrode was
studied in alkaline electrolytes at various temperatures (303, 308, 318 and 328 K). Electrochemical parameters
such as limiting current density and corrosion potential were determined at these temperatures.
The corrosion potential became more negative with increasing temperature. Hydrogen diffusivity was
also found to increase with increasing temperature. From electrochemical discharge experiments, it was
concluded that the charge transfer process was the rate-determining step
Synthesis of Nanocrystalline Boron Nitride by Combustion Process
No full textNanocrystalline boron nitride powders were synthesized by combustion process using urea as a
fuel. Experiments were carried out by heating boric acid and urea in an N
2
atmosphere at 850
°
C. Boric acid was
used as a source of boron while urea, as a source of nitrogen. The reactions were carried out in an autoclave
with provisions for purging with nitrogen gas. The samples were characterized by powder X-ray diffraction,
Fourier transform IR spectroscopy (FT-IR), FT-Raman spectroscopy, UV-VIS spectroscopy, and SEM
Predictive modeling of deposition rate in electro-deposition of copper–tin using regression and artificial neural network
No full textThe aim of this paper is to develop a model using artificial neural network for the electro-deposition of
copper–tin alloy (bronze) based on the experimentally obtained data. Copper–tin alloy was electrodeposited
from a cyanide bath. The coating composition was determined using X-ray fluorescence spectroscopy.
The deposition rate was calculated from the mass, composition and area of the deposit and its
approximate density. The results were used to create a model for the plating characteristics using
ANN. The ANN model was compared with the regression model for analysis