BiFeO3(BFO)and Bi0.9Nd0.1Fe0.9Ni0.1O3 (BNFNO) nanocrystalline samples have been synthesized through the sol-gel auto combustion process. Frequency and temperature dependent dielectric measurements have been performed in order to apprehend the influence of (Nd,Ni) co-doping on the conduction mechanism of pristine BFO.Thereal part of the dielectric constant is found to increase with the Nd and Ni doping, which is accredited to higher space charge polarization induced by the dopant ions.The dielectric constant measured as a function of frequency exhibits a dispersivebehaviour within low frequency region and attains a constant value at higher frequencies. A thermally activated relaxation peak is found at around 500K in the BNFNO samplewhich shifts towards lower temperatures at higher frequencies. The AC conductivity follows the Jonscher's universal dynamic law, which has been utilized to evaluate the value of frequency exponent „s‟. The decrease in the value of the „s‟ parameter with the increase in temperature establishes that the conduction mechanism is governed by the correlated barrier hopping (CBH) model. The ac conductivity data has been utilized to evaluate the minimum hopping distance (Rmin) and the binding energies (Wm) of the electrons in BNFNO. Arrhenius equation has been used to fit the experimental data and activation energy has been evaluated at different temperatures. The Activation energy is found to increase with the increase in the temperatures, owing to the creation of more oxygen vacancies instigated by (Nd, Ni) co-doping.
Keywords: Dielectric constant, AC Conductivity, Activation Energy, Minimum Hopping Distance

Organic devices have achieved substantial progress due to its flexibility, cost effectiveness, simple processing and wide customizability. But there are certain limitations of these devices. One of the main limitations is the lower charge injection from metal electrodes to the organic layer which affects the performance of these devices. The charge injection process is strongly dependent on the injection barrier height at metal- organic layer interface. Due to high barrier height at metal – organic layer interface, the charge injection is reduced at the interface. Attempts need to be made to reduce the injection barrier height at metal – organic layer interface to improve the charge injection process. In the present work, we have studied the injection barrier height of Indium tin oxide coated glass/Crystal violet dye/Aluminium based organic device and subsequently we have also observed the effect of zinc oxide nanoparticles on injection barrier height of this device. Indium tin oxide coated glass and aluminium are used as front electrode and back electrode respectively to form this device. The device has been prepared with and without zinc oxide nanoparticles by using spin coating technique. We have analyzed the steady state current-voltage characteristics of the device to determine the barrier height of the device. Barrier height is reduced from 0.87 eV to 0.78 eV in the presence of zinc oxide nanoparticles. The barrier height is also estimated by using another alternative method which is known as Norde method. By using Norde method, barrier height is measured which reduces from 0.83 eV to 0.77 eV in presence of zinc oxide nanoparticles. Both the methods show good consistency with each other. Reduction of the injection barrier height in presence of zinc oxide nanoparticles indicates better charge injection through the metal - organic dye interface. The higher electron mobility of zinc oxide nanoparticles facilitates efficient charge injection at the interface. Thus, this work will be informative to study the effect of zinc oxide nanoparticles on injection barrier height as it reduces the barrier height to improve the charge flow at metal – organic dye interface.
Keywords: Crystal Violet Dye, Injection Barrier Height, Metal – Organic Dye Interface, Zinc Oxide Nanoparticles.

The spin-Hall conductance in a two-dimensional tight-binding model is studied in the presence of Rashba spin-orbit interaction and random impurities. The conventional definition of spin current falls through for a system with Rashba spin-orbit interaction because of the non-conservation of the spin magnetic moment in the presence of Rashba coupling. Using a modified definition of spin-current operator, the relaxation time for electron-impurity scattering is calculated with the help of Matsubara Green function and the spinHall conductivity is determined by employing the Kubo-Greenwood formalism. Our results show the explicit behavior of the spin-Hall conductance as a function of chemical potential, Rashba spin-orbit coupling constant and the impurity strength
Keywords: Rashba Spin-Orbit Interaction, Random Impurities, Kubo Greenwood formalism, Spin Hall Conductivity, Relaxation Time

Graphene has attracted the scientific research community due to its unique two-dimensional structure, high conductivity, large surface area, superior charge carrier mobility, superior thermal and mechanical properties etc. To obtain graphene by chemical route, graphite oxide (GO) is used as a medium which is obtained from graphite. There is large amount of hydroxyl, carboxyl, carbonyl, epoxide etc. functional groups attached onto the basal or edge plane of GO making it strongly hydrophilic and easily exfoliated in water. Further reduction of GO get rids of unwanted accessory functional groups results in formation of reduced graphene oxide (r-GO) having desired properties. Further its properties can be manipulated by synthesis of graphene/r-GO-metal/metal oxide composites according to the applications to be drawn. These composites can be used in various applications, such as, in energy storage devices like anode materials in lithium ion batteries (LIBs), supercapacitors, photocatalysts, sensors, removal of organic pollutants etc. In the present study, Graphene Oxide-ZnO composites are synthesised by a simple chemical precipitation method. Further the structural characterizations of the samples prepared are done by X-Ray Diffraction (XRD), UV-Visible Spectrophotometry, Fourier Transform Infrared Spectroscopy and Raman spectroscopy.
Keywords: Reduced- grapheme oxide, ZnO-graphenenano composites, chemical co-precipitation, structural characterization

Quantum transport in a single molecular transistor device is studied at finite temperature in the presence of electron-electron and electron-phonon interactions and dissipation using the Anderson-HolsteinCaldeira-Leggett model. The dissipation due to substrate is treated exactly by a canonical transformation and the electron-phonon interaction is eliminated by the Lang-Firsov transformation. Finally the effective Hamiltonian is studied using the Keldysh non-equilibrium Green function technique and the tunnelling current through the single molecular transistor is obtained at finite temperature.
Keywords: : Quantum Dot, Keldysh Green function, Tunnelling current, Anderson-Holstein model and CaldeiraLeggett model.

In the present work we have investigated the use of fluroscence spectroscopy in the field of cancer treatment. The disease cancer is a curse to our human world . In most of the cases , the disease is diagonised at the last stage where it is almost impossible to cure the patient .And sometimes the technique of chaemotherapy and radiation does not suits down the patient. The technique of fluroscence spectroscopy has been applied for the diagnosis of multisysterm cancer and it minimizes the need for repetitive biopsy. There are various techniques, in the field of fluroscence spectroscopy but here the process of optical imaging will be discussed.Optical imaging is a technology that measures light produced by biological or chemical moieties.This technique has been applied over animals in research and laboratories. The technique of optical imaging is safe as it is nonradiating and cheap . Our research would mainly focus on the techniques and fluroscent probes.
Keywords: Fluroscence, cancer, moieties, optical imaging