L.P. Deshmukh

Synthesis and Study of Electrical Properties of SbTeI

Needle shaped SbTeI crystals were obtained by solid state reaction. Electrical resistance was measured in the temperature range of 4 K to 550 K. SbTeI shows a metallic behavior from 4 K to 300 K, and at higher temperature (>300 K), it shows semiconducting behavior. Unlike SbSI, this material shows almost zero resistance around 550 K. It shows a piezoelectric behavior with a capacitance of 717 pF and its carrier density and nobilities are found to be 2.12 × 1016 cm−3 and 1.01 cm2/(V·s), respectively. Crystals of SbTeI are characterized by XRD, SEM, and Raman analysis. Electrical activation energy is found to be 0.52 eV. It is suggested that this material may be studied for its application as a superconductor with Tc higher than room temperature.

Cost-effective synthesis of ultrafine BaTiO 3 nanoparticles: Some structural and morphological observations

Synthesis of ultrafine barium titanate (BT) nanoparticles using a simple cost effective precipitation method and their structural and morphological changes are outline in this paper. In actual, BTO precipitate was subjected to centrifuge, washing and heating processes to obtain BT nanoparticles. Special emphasis was given to the concentration of precursor (barium nitrate) and capping ligand (PVP) while synthesizing the material because they are least studied and found a deep influence on the size of BT particles. To study their effect on the properties of BT samples the concentration of barium nitrate and PVP were varied from 0.005 to 0.05 M and 0.001 to 0.008 M respectively. The structure of these nanoparticles was determined using the X-ray diffraction and FTIR techniques. The X-ray diffraction demonstrated the formation of pure tetragonal phase of BT with average crystallite size, strain and dislocation density of ~13 nm, 2.8×10-3 and 6×1015 m-2 respectively. The surface morphologies of the different BT samples were viewed through the FESEM. Nearly spherical grains with some sort of fusing (agglomeration) have been observed at higher concentrations of both the barium precursor and PVP. FTIR spectra signified the presence of Ti-O bond at 490 cm-1 and 1420 cm-1 confirming the formation of BT. Thin films of the as-synthesized BT nanoparticles can be employed for the sensing application.

Morphological and Optical Properties of Cd1-xCoxS Thin Films by Liquid Phase Chemical Bath Deposition

Cd1-xCoxS (0 x 0.5) thin films have been deposited by liquid phase chemical bath deposition method on glass substrate from a complex liquid phase formed by equimolar volumes of cadmium sulphate, thiourea and cobalt sulphate. For deposition various preparative parameters, such as speed, temperature, pH, and time were optimized and found to be 70 ± 2 rpm, 56 °C, 11±0.2 and 80 min. respectively. The samples were thin, uniform and tightly adherent with colour changing from orange red to dark chocolate as x was varied from 0 to 0.5. The films were characterized to evaluate the surface morphology, composition and optical measurements. The surface morphologies of these films revealed random orientation of the crystallites of elongated rhomboids with sharp and clear edges having leaf like appearance. The grain size is found to be enhanced continuously from x = 0 to x = 0.1 with fine and more clear grain boundaries and decreased for higher x values. Energy Dispersive X-ray analysis suggests that the deposits are Cd rich. The optical studies were performed on these samples in the range of wavelengths between 500 nm to 1300 nm and yield a high absorption coefficient (α 104-105 cm-1) with a direct type of transitions. The estimated band gap decreased from 2.42 eV to 1.94 eV as x was varied from 0 to 0.5.