Investigation of Dielectric Properties of ZnAl2O4/MWCNTs Nano-composite

Abstract

In the promising field of nanoscience and engineering, the synthesis of nano structured aluminates has great interest in recent years, with the investigation of their dielectric and electrical properties will be different and better as compared to those of bulk materials. This is due to the high aspect ratio which leads to dominance of the atomic behavior on the surface over those in the core of the particles. The nanoparticles are made of nanometer sized building blocks called which are also known as crystallite or grain. The crystallites are different in their atomic structure and crystallographic orientation which results in incoherent or coherent interfaces which are called grain boundaries are formed between them. The dielectric and electrical behavior of these nano sized materials are mostly contributed by these grains and grain boundaries. The heterogeneity of the microstructure is also resulted by these grains and grain boundaries. The enhanced contribution of band structure modification, grain and grain boundaries and possibility of holes and defects in the grains results in different dielectric and electrical properties as compared to those of their single crystalline. The ZnAl2O4 / MWCNTs nano-composites were synthesized through a unique one step ultra-sonication assisted process in which the O-xylene used as a dispersive medium. Sol-gel method was adopted for the synthesis of zinc aluminate (ZnAl2O4) nanoparticles. MWCNTs concentrations (0.0%, 2.0%, 4.0%, 6.0% 8.0% and 10.0%) were continuously changed in zinc aluminate. The different techniques were used to characterize the nano-composite, (i) XRD (ii) SEM (iii) FTIR and (iv) Impedence Analyzer. The obtained XRD patterns verified the formation of Face Centered Cubic (FCC) single phase of ZnAl2O4/MWCNTs nano-composite. Crystallite size of each sample was determined using scherrer formula which is in the range of 13 to 20 nm. The zinc aluminate nanoparticles decorated on MWCNTs and it showed in SEM images. The particle size is in the range of 16 to 28nm. The FTIR confirms the formation spinel structure and zero effect of MWCNTs on its spinel structure. The increasing concentration of MWCNTs was found to increase the dielectric properties. For 10.0% MWCNTs concentration, the results showed enhanced values of dielectric constant from (1.21×1002 to 5.2×1013), dielectric loss from (1.38×1002 to 1.22×1019) and dielectric loss tangent from (1.139 to 1.31×105) respectively at 100 Hz. Such enhanced properties of ZnAl2O4 / MWCNTs nano-composite render its applications for the super capacitors, microwave absorbers and high frequency applications.