Magnesium Oxide (MgO) nanoparticles have been synthesized by solution combustion technique using stoichiometric composition of magnesium nitrate as oxidizer and urea as fuel. Structure of the MgO was studied with the X-ray diffraction (XRD) using Cu-Ka radiation. MgO/polyvinylpyrrolidone (PVP) nanocomposites have been prepared by blending MgO nanoparticles with the polyvinylpyrrolidone. MgO/PVP nanocomposites were characterized by Fourier transform infrared (FTIR) spectroscopy. Frequency dependence of dielectric constant (e'), dielectric loss tangent (tand) and AC conductivity studies have been undertaken on the MgO/PVP nanocomposites in the frequency range 50Hz-5MHz at room temperature. Dielectric properties such as dielectric constant (e') and dielectric loss tangent (tand) are found to decrease with the increase in the frequency. Further, AC conductivity of MgO/PVP nanocomposites was found to increase with an increase in the frequency. Observed variation in the a. c. conductivity with the frequency has been understood on the basis of electron hopping model.
TopIntroduction
Nanotechnology deals with various structures of matter having dimensions of the order of a nanometer. Nanotechnology is very diverse, ranging from extensions of conventional device physics to completely new approaches based upon molecular self-assembly, from developing new materials with dimensions on the nanoscale to investigating whether we can directly control matter on the atomic-scale. Further, nanotechnology has the potential to create many new materials and devices with a vast range of applications, such as in medicine, electronics and energy production (Franke et al., 2006; Boucle et al., 2007; De et al., 2008; Sarkar, Guibalet al., 2012; Patil et al., 2008; Kulkarni, 2009).
In recent decades, nanoparticles have attracted great interest in fundamental science and also in technological applications. Nanoparticles exhibit physical and chemical properties which are quite different from those of their bulk counterparts. Nanocrystalline oxide materials have attracted special attention in the field of electronics and telecommunication industry because of their novel dielectric and electrical properties. Metal oxide nanoparticles, represent great scientific and technological values as a result of the extraordinary physical and chemical features originating from their nanoscale size and increased amount of surface atoms. Due to the fact that their features are dependent on the increased surface area to volume ratio and the quantum confinement effect, their prospective uses span across nearly all discipline (Franke et al., 2006; Bouclé et al., 2007; De, Ghosh & Rotello, 2008; Sarkar et al., 2012; Patil et al., 2008; Kulkarni, 2009). Further, their highly specific surface area combined with their smallness lead to the observation of several other unique behaviors.
A number of physical phenomena become pronounced as the size of the system decreases. These include statistical mechanical effects, as well as quantum mechanical effects, for example the “quantum size effect” where the electronic properties of solids are altered with great reductions in particle size. However, quantum effects become dominant when the nanometer size range is reached, typically at distances of 100 nanometers or less, the so called quantum realm. Additionally, a number of physical properties such as mechanical, thermal, electrical, optical, etc., change when compared to macroscopic systems. One example is the rise in surface area to volume ratio altering mechanical, thermal and catalytic properties of materials (Kulkarni, 2009).
There are large numbers of techniques available to synthesize different types of nanomaterials in the form the colloids, clusters, powders, tubes, rods, wires and thin films etc. Some of the already existing conventional techniques to synthesize different types of materials are optimized to get novel nanomaterials and some new techniques are developed. There are various physical, chemical, biological and hybrid techniques available to synthesize the nanomaterials. The technique to be used depends upon the material of interest and the type of nanostructure. Some of the important techniques are discussed below (Patil et al 2008; Kulkarni, 2009).