M. P. Deshpande

SnS thin films deposited by chemical bath deposition, dip coating and SILAR techniques

The SnS thin films were synthesized by chemical bath deposition (CBD), dip coating and successive ionic layer adsorption and reaction (SILAR) techniques. In them, the CBD thin films were deposited at two temperatures: ambient and 70 °C. The energy dispersive analysis of X-rays (EDAX), X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM) and optical spectroscopy techniques were used to characterize the thin films. The electrical transport properties studies on the as-deposited thin films were done by measuring the I–V characteristics, DC electrical resistivity variation with temperature and the room temperature Hall effect. The obtained results are deliberated in this paper.

Magnetite Fe3O4 nanoparticles synthesis by wet chemical reduction and their characterization

The authors report the synthesis of Fe3O4 nanoparticles by wet chemical reduction technique at ambient temperature and its characterization. Ferric chloride hexa-hydrate (FeCl3 6H2O) and sodium boro-hydrate (NaBH4) were used for synthesis of Fe3O4 nanoparticles at ambient temperature. The elemental composition of the synthesized Fe3O4 nanoparticles was determined by energy dispersive analysis of x-rays technique. The x-ray diffraction (XRD) technique was used for structural characterization of the nanoparticles. The crystallite size of the nanoparticles was determined using XRD data employing Scherrers formula and Hall–Williamsons plot. Surface morphology of as-synthesized Fe3O4 nanoparticles was studied by scanning electron microscopy. High resolution transmission electron microscopy analysis of the as-synthesized Fe3O4 nanoparticles showed narrow range of particles size distribution. The optical absorption of the synthesized Fe3O4 nanoparticles was studied by UV–vis–NIR spectroscopy. The as-synthesized nanoparticles were analyzed by Fourier transform infrared spectroscopy technique for absorption band study in the infrared region. The magnetic properties of the as-synthesized Fe3O4 nanoparticles were evaluated by vibrating sample magnetometer technique. The thermal stability of the as-synthesized Fe3O4 nanoparticles was studied by thermogravimetric technique. The obtained results are elaborated and discussed in details in this paper.

Synthesis and characterization of different morphological SnS nanomaterials

SnS in three nano forms possessing different morphologies such as particles, whiskers and ribbons were synthesised by chemical route. The morphology variation was brought about in the chemical route synthesis by varying a synthesis parameter such as temperature and influencing the synthesis by use of surfactant. The elemental composition determination by energy dispersive analysis of x-rays (EDAX) showed that all three synthesized SnS nanomaterials were tin deficient. The x-ray diffraction (XRD) study of the three SnS nanomaterials showed that all of them possess orthorhombic structure. The Raman spectra of the three SnS nanomaterials showed that all three samples possess three common distinguishable peaks. In them two peaks lying at 98 ± 1 cm−1 and 224 ± 4 cm−1 are the characteristic Ag mode of SnS. The third peak lying at 302 ± 1 cm−1 is associated with secondary Sn2S3 phase. The transmission electron microscopy (TEM) confirmed the respective morphologies. The optical analysis showed that they possess direct as well as indirect optical bandgap. The electrical transport properties study on the pellets prepared from the different nanomaterials of SnS showed them to be semiconducting and p-type in nature. The current–voltage (I–V) plots of the silver (Ag)/SnS nanomaterials pellets for dark and incandescent illumination showed that all configurations showed good ohmic behaviour except Ag/SnS nanoribbons pellet configuration under illumination. All the obtained results are discussed in detail.

Catalytic action of CuAlS2 microparticles and nanoparticles in cellulose pyrolysis

This paper explores the catalytic action of as-synthesized CuAlS2 microparticles and nanoparticles on cellulose pyrolysis. The CuAlS2 microparticles were synthesized by heating precursor elements at high temperatures in an evacuated quartz ampoule. CuAlS2 nanoparticles were synthesized at ambient temperature by using a simple wet chemical technique. Before using the microparticles and nanoparticles for catalytic study, they were comprehensively characterized. The thermal analysis, including catalytic study of both the CuAlS2 microparticles and nanoparticles on cellulose pyrolysis, was carried out by thermogravimetric (TG), differential thermogravimetric (DTG) and differential thermal analysis (DTA) techniques. Prior to studying their role as catalysts in cellulose pyrolysis, the CuAlS2 microparticles and nanoparticles were characterized by thermal analysis in an inert N2 atmosphere. The TG analysis of as-synthesized CuAlS2 microparticles and nanoparticles showed three and five steps of decomposition, with total weight losses of 6.89% and 53.37%, respectively. The TG analysis of pure cellulose and cellulose mixed with 10%, 5% and 2.5% CuAlS2 microparticles and nanoparticles demonstrated that the nanoparticles are better catalysts in cellulose pyrolysis than the microparticles. The TG analysis results of cellulose pyrolysis have been supported by the DTA and DTG curves recorded simultaneously. The obtained results are explored in detail.

Effect of Indium and Antimony Doping on SnS Photoelectrochemical Solar Cells

Single crystals of pure SnS, indium (In) and antimony (Sb) doped SnS are grown by the direct vapor transport technique. Two doping concentrations of 5at.% and 15 at.% are employed for both In and Sb dopants. In total, five samples are studied, i.e., pure SnS, 5at.% In-doped SnS, 15 at.% In-doped SnS, 5at.% Sb-doped SnS and 15 at.% Sb-doped SnS single crystals. The energy dispersive analysis of x-ray (EDAX) and x-ray diffraction (XRD) analysis show that all the five as-grown single crystal samples possess near perfect stoichiometry and orthorhombic structure, respectively. The doping of In and Sb in SnS is established from the EDAX data and from the shift in the peak positions in XRD. Photoelectrochemical (PEC) solar cells are fabricated by using the as-grown single crystal samples along with iodine/iodide electrolytes. Mott—Schottky plots for different compositions of iodine/iodide electrolytes show that 0.025M I2+1M NaI+2M Na2SO4+0.5M H2SO4 will be the most suitable electrolyte. Study of efficiency (η) and fill factor for different intensities of illuminations at room temperature is carried out for the five samples. The In-doped SnS single crystals show better PEC efficiency than the undoped and Sb-doped SnS single crystals.

Growth and microtopographic study of CuInSe2 single crystals

The CuInSe2 single crystals were grown by chemical vapour transport (CVT) technique using iodine as transporting agent. The elemental composition of the as-grown CuInSe2 single crystals was determined by energy dispersive analysis of X-ray (EDAX). The unit cell crystal structure and lattice parameters were determined by X-ray diffraction (XRD) technique. The surface microtopographic study of the as-grown CuInSe2 single crystals surfaces were done to study the defects, growth mechanism, etc. of the CVT grown crystals.

Thermal decomposition study of Mn doped Fe3O4 nanoparticles

Fe3O4 is an excellent magnetic material among iron oxides. It has a cubic inverse spinel structure exhibiting distinguished electric and magnetic properties. In this paper the authors report the synthesis of Mn doped Fe3O4 nanoparticles by wet chemical reduction technique at ambient temperature and its thermal characterization. Ferric chloride hexa-hydrate (FeCl3•6H2O), manganese chloride tetra-hydrate (MnCl2•4H2O) and sodium boro-hydrate (NaBH4) were used for synthesis of Fe3O4 nanoparticles at ambient temperature. The elemental composition of the as-synthesized Mn doped Fe3O4 nanoparticles were determined by energy dispersive analysis of X-rays (EDAX) technique. Thermogravimetric (TG) and differential thermal analysis (DTA) were carried out on the Mn doped Fe3O4 nanoparticles in the temperature range of ambient to 1124 K. The thermo-curves revealed that the particles decompose by four steps. The kinetic parameters were evaluated using non-mechanistic equations for the thermal decomposition.

Preparation and characterization of Bi2S3 compound semiconductor

Bi2S3 single crystals were grown by the chemical vapour transport technique using ammonium chloride (NH4Cl) as a transporting agent. The stoichiometry of Bi2S3 single crystal was confirmed by energy-dispersive analysis of X-rays (EDAX). The powder X-ray diffraction (XRD) pattern showed that Bi2S3 crystals belong to the orthorhombic phase with calculated lattice constant a = 11.14 Å, b = 11.30 Å and c = 3.96 Å. Scanning electron microscopy (SEM) pictures indicate the presence of layer lines on the surface of crystals thereby proving that these crystals are grown by layer by layer mechanism. We studied the transport properties viz. Hall effect, resistivity, thermoelectric power and thermal conductivity on Bi2S3 pellets. Raman spectroscopy and thermal gravimetric analysis (TGA) were carried out on Bi2S3 single crystal for studying their optical and thermal behaviours.

Chemical Bath Deposition of Lead Sulphide (PbS) Thin Film and their Characterization

Thin film deposition of PbS is conveniently carried out by chemical reactions of lead acetate with thiourea at room temperature. Energy dispersive analysis of X-ray (EDAX), X-ray diffraction (XRD), selected area electron diffraction patterns (SAED), UV-Vis-NIR spectrophotometer, Scanning Electron Microscopy (SEM), Atomic force microscopy (AFM), Photoluminescence (PL) and Raman spectroscopy techniques are used for characterizing thin films. EDAX spectra shows that no impurity is present and XRD pattern indicates face centered cubic structure of PbS thin films. The average crystallite size obtained using XRD is about 15nm calculated using Scherrer’s formula and that determined from Hall-Williamson plot was found to be 18nm. SAED patterns indicate that the deposited PbS thin films are polycrystalline in nature. Blue shift due to quantum confinement was seen from the UV-Vis-NIR absorption spectra of thin film in comparison with bulk PbS. The Photoluminescence spectra obtained for thin film with different excitation sources shows sharp emission peaks at 395nm and its intensity of photoluminescence increases with increasing the excitation wavelength. Raman spectroscopy of deposited thin film was used to study the optical phonon modes at an excitation wavelength of 488nm using (Ar+) laser beam.

Raman scattering in 2H-MoS2 single crystal

A study of a molybdenum disulfide (MoS2) grown by the direct vapor transport method was conducted by using Raman scattering measurements. The first and second order Raman spectra of 2H-MoS2 has been observed in the range 100 cm−1 to 900 cm−1 at room temperature. The central force model is applied to the high-frequency phonons to calculate the force constant.