B. M. Harish

Bio: B. M. Harish is an academic researcher from Kuvempu University. The author has contributed to research in topics: Dielectric & Scanning electron microscope. The author has an hindex of 3, co-authored 14 publications receiving 48 citations.

Effect of particle size on band gap and DC electrical conductivity of TiO2 nanomaterial

Abstract: Materials reduced to the Nano scale can exhibit different properties compared to what they exhibit on a micro scale, enabling unique applications. When TiO2 is reduced to Nano scale it shows unique properties, of which the electrical aspect is highly important. This paper presents increase in the energy gap and decrease in conductivity with decrease in particle size of pure Nano TiO2 synthesized by hydrolysis and peptization of titanium isopropoxide. Aqueous solution with various pH and peptizing the resultant suspension will form Nano TiO2 at different particle sizes. As the pH of the solution is made acidic reduction in the particle size is observed. And it is confirmed from XRD using Scherer formula and SEM, as prepared samples are studied for UV absorbance, and DC conductivity from room temperature to 400°C. From the tauc plot it was observed, and calculated the energy band gap increases as the particle size decreases and shown TiO2 is direct band gap. From Arrhenius plot clearly we encountered, decrease in the conductivity for the decrease in particle size due to hopping of charge carriers and it is evident that, we can tailor the band gap by varying particle size.

Synthesis and dielectric properties of Cr-substituted CeO 2 nanoparticles

Abstract: Chromium doped ceria nanoparticles have been synthesized by using a novel solution combustion method with chromium nitrate hexahydrate as oxidizers and glycine as a fuel The main objective of the present study is to find the effect of chromium on structural, optical, dielectric properties and ac- conductivity of cerium oxide nanoparticles (CeO2 NPs) The prepared samples were characterized by various physicochemical techniques such as UV–Vis absorption spectra, X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and energy dispersive X-ray (EDS) analysis The powder XRD patterns confirm the cubic fluorite structure of CeO2 NPs The UV–Vis absorption spectra showed that the doping causes the red shift of absorption peaks The optical band gap of all samples has been measured by Tauc plot, which is found to be decreases with chromium concentration The uniform shaped NPs with the range of ~ 20 nm is observed by FESEM images EDS analysis confirms the expected elemental composition of Ce1−xCrxO2 NPs The dielectric constant ɛ′, dielectric loss factor (tanδ) and AC conductivity of the samples were studied as function of frequency range from 20 Hz to 3 MHz and found to be decreases with increasing the chromium content

Dielectric and magnetic properties of high porous Gd+3 substituted nickel zinc ferrite nanoparticles

Abstract: We report on the synthesis and characterization of Gd+3 substituted Ni-Zn nano ferrites (Ni0.6Zn0.4GdyFe2−yO4; y = 0, 0.1, 0.15, and 0.2) via low-temperature citrate gel auto-combustion method. The structural studies carried out by PXRD revealed a decrease in the lattice constant and crystallite sizes upon Gd+3 substitution with low concentration but increases with further increase in the concentration. We found the porosity of the samples decreases linearly as a function of Gd+3 concentrations. Well defined spherical grains with a higher porosity of the samples are confirmed by FESEM analysis. With an increase in the Gd+3 concentrations, the dielectric constant increased up to five folds in the magnitude. The contribution of grain boundary and other factors on the electrical properties was revealed by impedance spectroscopy. The reduced remanence ratios showed in the magnetic hysteresis imply the charge in change in the magnetic properties upon the substitution of Gd+3 in the prepared ferrite.

Solution Combustion Synthesis: Towards a Sustainable Approach for Metal Oxides.

Abstract: Solution combustion synthesis (SCS) has been widely used to produce simple and complex oxides with a desired morphology (size and shape). SCS is valuable due to low cost, simplicity and energy efficient synthesis. To guarantee the best molecular-level mixing of reactants in an aqueous or solvent-based solution some parameters need to be controlled, such as fuel type, metal cations precursors, stoichiometry ratio (φ), pH effect, atmosphere and initiation type. These determine the final properties of the oxide materials, providing the potential to reach different morphologies, which are essential for their final applications. This Review article focuses on the crucial parameters in SCS and how these affect the overall materials properties from nanostructures to thin films. To finalize, special attention is given to the application of SCS to form metal oxide thin films at low temperature and their application in thin film transistors (TFTs).