Physics

Lead Sulphide (PbS) thin film was deposit by chemical bath deposition (CBD) process on the glass substrate at room temperature for various time intervals. The precursors used for this deposition are lead acetate since as a supply of lead ions (Pb2+) and thiourea the same as the supply of sulfide ions (S2-) with 0.1M concentration. The pH of the mixed precursors solution was maintained at 9.5-10 by addition of drop by drop ammonia very slowly. The cause of deposition time for different hours studied. The influence of deposition time on properties of PbS film was investigated. The color of films appears black-gray after taking out of the bath. The thickness of the film is increased with increase in deposition time. The electrical resistance and resistivity were 500MΩ and 18.75 MΩ-cm and band gap measured as a function of temperature using D.C. four probe methods was 0.3742 eV. The Cyclic Voltammetry (CV), Linear Sweep Voltammetry (LSV), Chronoamperometry were studied by using potentio...

Thermoelectric (TE) materials are possible solutions of the current problems in the energy sector to overcome environmental pollution, increasing energy demand and the decline of natural resources. Thermoelectric materials are a promising alternative for the conversion of waste heat to electricity. Nanocrystalline PbTe powder was synthesized by a simple chemical method at room temperature and systematically investigated at various durations as samples A1–A5. Fourier Transform infrared spectroscopy (FTIR), x-ray diffraction (XRD), microstructural analysis by scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS) confirmed the composition of the samples. TE parameters as thermo-emf of samples A1–A5 and electrical conductivity were measured. The cyclic voltammetry gives a band gap of 0.25 eV, which is in agreement with the optical band gap of the material. The A4 sample has an average crystal size of 36 nm with preferred orientation in (200) verifying the cubic mo...

Lead Sulphide (PbS) thin film was deposit by chemical bath deposition (CBD) process on the glass substrate at room temperature for various time intervals. The precursors used for this deposition are lead acetate since as a supply of lead ions (Pb2+) and thiourea the same as the supply of sulfide ions (S2-) with 0.1M concentration. The pH of the mixed precursor's solution was maintained at 9.5-10 by addition of drop by drop ammonia very slowly. The cause of deposition time for different hours studied. The influence of deposition time on properties of PbS film was investigated. The color of films appears black-gray after taking out of the bath. The thickness of the film is increased with increase in deposition time. The electrical resistance and resistivity were 500MΩ and 18.75 MΩ-cm and band gap measured as a function of temperature using D.C. four probe methods was 0.3742 eV. The Cyclic Voltammetry (CV), Linear Sweep Voltammetry (LSV), Chronoamperometry were studied by using potentiostat.

Bismuth Telluride (Bi 2 Te 3) dendritic nanostructures were prepared on stainless steel substrate by electrochemical deposition from an aqueous solution of bismuth nitrate and tellurium dioxide in the presence of nitric acid. The structural and morphological properties of the deposited films were investigated as a function of applied deposition voltage. X-ray diffractometric studies confirmed the rhombohedral phase of Bi 2 Te 3 crystals in the deposited films. The deposition potential apparently was found to be playing a significant role in controlling the reaction rate resulting in the evolution of dendritic Bi 2 Te 3 crystals with preferred orientation along (0 0 15) hkl plane. These Bi 2 Te 3 nanocrystals can be used effectively in variety of applications such as thermoelectric refrigeration, thermoelectric generator (TEG), thermoelectric cooling (TEC), thermal sensor etc.

Present work deals with the temporal electrodeposition of Bi2Te3 thin films. Structural, elemental and surface morphological analysis of deposited films has been caused out using XRD and SEM with EDXs techniques. XRD contributes the formation of Bi2Te3 crystals with crystalline size in the range of 3 nm to 9 nm. EDXS is in agreement with X-ray diffractometer and confirms the qualitative formation of Bi2Te3 in the stoichiometry of 2:3. Scanning electron microscope reveals the influence of the deposition time over the evolution of spherical morphology with increasing diameters of the Bi2Te3 particles in the deposited films.

We report the studies related to the growth of crystalline AlN in a DC thermal plasma reactor, operated
by a transferred arc plasma torch. The reactor is capable of producing the nanoparticles of Al and AlN
depending on the composition of the reacting gas. Al and AlN micro crystals are formed at the anode
placed on the graphite and nano crystalline Al and AlN gets deposited on the inner surface of the
plasma reactor. X-ray diffraction, Raman spectroscopy analysis, single crystal X-ray diffraction and
TGA-DTA techniques are used to infer the purity of post process crystals as a hexagonal AlN. The
average particle size using SEM was found to be around 30 mm. The morphology of nanoparticles of Al
and AlN, nucleated by gas phase condensation in a homogeneous medium were studied by transmis-
sion electron microscopy analysis. The particle ranged in size between 15 and 80 nm in diameter. The
possible growth mechanism of crystalline AlN at the anode has been explained on the basis of non-
equilibrium processes in the core of the plasma and steep temperature gradient near its periphery. The
gas phase species of AlN and various constituent were computed using Murphy code based on
minimization of free energy. The process provides 50% yield of microcrystalline AlN and remaining of Al
at anode and that of nanocrystalline h-AlN and c-Al collected from the walls of the chamber is about
33% and 67%, respectively.

The present work reports the application of
micron-particulate crystalline hexagonal aluminium
nitride/aluminium as a novel, mild acidic and reusable
solid heterogeneous catalyst in organic synthesis. The
catalyst was synthesized by thermal plasma technique and
characterized using X-ray diffractometer and scanning
electron microscopy. It catalyzes efficiently many organic
transformations such as the synthesis of heterocyclic
compounds 2,4,5-triaryl-substituted imidazoles and 2-aryl
benzimidazoles.

We report the mass production of Ni metal nanoparticles using dc transferred arc thermal plasma reactor by
homogeneous gas phase condensation process. To increase the evaporation rate and purity of Ni nanoparticles small
amount of hydrogen added along with argon in the plasma. Crystal structure analysis was done by using X-ray
diffraction technique. The morphology of as synthesized nanoparticles was carried out using FESEM images. The
magnetic properties were measured by using vibrating sample magnetometer at room temperature.

This paper for the first time reports the (200) oriented growth of hexagonal Aluminum nitride crystals during
synthesis of aluminum nanoparticles in dc transferred arc thermal plasma reactor by gas phase condensation in nitrogen
plasma. The structural and morphological study of as synthesized AlN crystal and aluminium nanoparticles was done by
using the x-ray diffraction method, scanning electron microscopy and transmission electron microscopy.

Synthetic graphite is one of the best thermal shock resistant materials and generally believed to remain unaffected by a thermal shock alone. However, subject to a cold thermal shock, under a pool-boiling heat transfer process, micron size synthetic graphite may become noticeably fragile and can convert into rotationally misoriented few-layer graphene (FLG) near the Leidenfrost point. Such FLG is of immense technological and fundamental interest. Here we show how such FLG, with precisely controlled number of layers, can readily be obtained from an isostatically compacted synthetic graphite and discovered the mechanism behind such transformation by a theoretical modeling.

A rapid synthesis method is reported for magnetic nanoparticles of nickel ferrite involving thermal plasma assisted vapor phase condensation process. The as-synthesized samples were characterized by X-ray Diffraction, Transmission Electron Microscopy, Vibrating Sample Magnetometer and X-ray Photoelectron Spectroscopy techniques. The average particle size was determined from the TEM micrographs and found to be around 30 nm. The effects of reactor parameters on the magnetic and structural properties have been evaluated, to find the optimized parameters so as to achieve the highest values of saturation magnetization and coercivity. Reasonably high saturation magnetization (48 emu/g) has been assigned to the high degree of crystallinity, achieved on account of high temperature during the growth, and the cation redistribution. The high value of coercivity (115 Oe) is explained on the basis of possible lattice defects arising from the cation redistribution. Detailed analysis of cation distribution using the XRD line intensity data leads to the conclusion that these samples are iron deficit and nickel rich.

The present work reports the application of micron-particulate crystalline hexagonal aluminium nitride/aluminium as a novel, mild acidic and reusable solid heterogeneous catalyst in organic synthesis. The catalyst was synthesized by thermal plasma technique and characterized using X-ray diffractometer and scanning electron microscopy. It catalyzes efficiently many organic transformations such as the synthesis of heterocyclic compounds 2,4,5-triaryl-substituted imidazoles and 2-aryl benzimidazoles.