A. Sarkar

Variation of effective dielectric constant of dilute magnetic dielectrics with magnetic field

The objective of this paper is to study the variation of effective dielectric behavior of dilute magnetic dielectrics (DMD) under variation of external magnetic field. The said variation is studied over developed Nickel Oxide as a DMD system. The observed experimental field variation of the effective dielectric constant is compared to the proposed simple theoretical formulation for effective dielectric constant of composite material or DMD. The effect of magnetic susceptibility and electromagnetic coupling term is taken into account to describe the dielectric behavior of DMD system. The overall results obtained and agreement between theory and experiment are good.

Experimental Investigation on Core Shell Nanocomposite of Cr1-xVxS2

Electrical and optical character of nanostructured Cr1-xVxS2 is studied here. This sulphide based nanoClusters (NC) was developed through chemical sol-gel route using (NH4)2Cr2O7 and NH4VO3 as active reagent and biopolymer gum acacia is used as capping agent. Core-shell NC has developed with sequential addition of active reagents in sulphation process. It is also possible to develop another type of core shell NC by reversal of the sequence of added reagents, i.e. interchanging the core and shell part. Experimental investigation including UV-VIS spectroscopy, dc current-voltage characteristics (CVC) have carried on. The results of CVC at room temperature (RT) show the distinctive features of localized energy levels. UV-VIS spectroscopic analysis shows absorption peak is blue shifted due to quantum confinement of nanoparticles. Overall appearance of optical absorption curve is completely different for two NCs. Peak positions are different for two types of core shell NC which confirms that the constituent materials of core and shell of two NC s has interchanged.

Estimation of particle size distribution of nanoparticles from electrical characteristics

An indirect method of estimation of size distribution of nanoparticles in a nanocomposite is proposed in this paper. The present approach exploits DC electrical current–voltage characteristics (CVC) of ZnO nanocomposite specimen in bio-polymer background. The nature of DC CVC is found to be oscillatory with respect to applied voltage. The nature of CVC is a consequence of Coulomb blockade (CB) phenomena of electrical conduction through a tiny nanoparticle. Considering the ZnO nanocomposites to be spherical, Coulomb-blockade model of quantum dot is applied here. The size distribution of particle is estimated from that model and compared with the results obtained from AFM and XRD analyses. The results from CVC are found to be consistent with these conventional microscopic results.

FTIR Investigation of Rotational Spectra and Structural Change due to Deuterium Exchange in Bio-Molecule

This paper summarizes research on infrared absorption spectrum of gum Arabica, a Bio-material. The frequency shift due to deuterium exchange in gum Arabica molecule and rotational spectrum of bio-molecules are estimated from the measured data of FTIR spectra. The obtained shift of the characteristics frequency caused due to deuterium exchange in the –OH bond of gum Arabica. Normally two major region in the IR spectrum of a molecule are the functional group region ( 7000 cm-1 to 1500 cm-1) it includes the X-H stretching region and finger print region ( 1500 cm-1 to 350 cm-1). The mentioned region is very important in bio-molecular dynamics and it may provide much relevant information about the internal motion of the molecule and is related bio-molecular function in living systems. The change in molecular structure, of the constituent bio-molecules of Gum Arabica, due deuterium exchange is directly determined from analysis of FTIR spectrum in functional group region. The rotational constants as well as the ground state rotational energy levels are estimated from analysis of FTIR spectrum of the experimental specimens. A map of quantum energy levels of the bio-molecule has been extracted from this present FTIR analysis.

Optical investigation of effective permeability of dilute magnetic dielectrics with magnetic field

The prime objective of this paper is to investigate the magnetic nature of dilute magnetic dielectrics (DMD) under variation of external magnetic field. The said variation is studied over developed nano-sized Gadolinium Oxide as a DMD system. The observed experimental field variation of the effective magnetic permeability is analyzed results of optical experiment. The experiment records the variation of Brewster angle of incident polarized LASER beam from the surface of developed DMD specimen with applied out of plane external magnetic field. The effective refractive index and hence relative magnetic permeability were estimated following electro-magnetic theory. The overall results obtained and agreement between theory and experiment are good.

Formulation of Dielectric Behaviour of Composite Material

A simple formula for effective dielectric constant of composite material or DMD is proposed. In case of magnetic element in the composite the effect of magnetic susceptibility is taken into account to describe the dielectric behavior. A theoretical formulation of the proposed dielectric function along with an experimental result is presented here. The overall results are found to be good and consistent .

Left-handed Maxwellian aspects of natural pearl

Meta- material like behavior of natural Pearl are studied in this work. This work makes an attempt to analyze the Left Handed Maxwellian (LHM) properties of Pearl surface. The investigations carried out on natural Pearl specimen are optical reflectance and optical absorbance. Optical reflectance of Pearl surface with plane polarized monochromatic light in the form of verification of Fresnel equation shows distinct difference with that of conventional ordinary material. The UV-VIS analysis is also carried out for further analysis. The results obtained from the optical reflectance characteristics using polarized light indicate LHM behavior as expected for a LHM (type II or type II) meta-material. The overall analysis of the results shows the LHM character of Pearl surface.