Title: Effect of Sr Substitution on Electric and Magnetic Properties of Cobalt Ferrites Nanoparticles.

Supervisor: Prof. Dhrubananda Behera

Abstract: Dielectric properties of Strontium (Sr) substituted cobalt ferrite have been studied. Sr substituted cobalt ferrite (CoFe2-xSrxO4, x=0.0, 0.1, 0.2, 0.3) samples were prepared by sol-gel auto-combustion technique. The ashes thus formed were grinded properly and then were kept on the muffle furnace for 3 hours at temperature 600° C. The powder was then made into pallets and they were sintered again with the same condition as used above. They were coated with silver paste on both sides before dielectric study was done. The XRD pattern confirms the phase formation and successful doping of Sr in cobalt ferrite which effectively changes the electrical behaviour of cobalt ferrite. FESEM shows the morphological and structural behaviour of the samples and amount of doping matched with the EDX results. Studies on dielectric properties reveal that the dielectric constants for both the cases (real imaginary part of dielectric constant) decreases with increasing frequency and it becomes independent of frequency beyond 104 Hz. Dielectric loss also follows the same trend as dielectric constant. Cole-Cole plots have been investigated and the plots represent the formation of single semi-circles. It is evident from Cole-Cole plots that at higher concentration radius of the semicircles are large, indicating the increase in resistance of the material as Sr content increases.

Master’s thesis and Dissertation VSSUT, Burla

Title: Mesophase behavior of a cyanobiphenyl molecule in Polar aprotic solvent: Role of molecular

rigidity.

Supervisor: Dr. P. Lakshmi Praveen

Abstract: In this dissertation a theoretical study has been done on a liquid crystal compound named p-npropyl cyanobiphenyl (3CB). The different modes of interaction energy values for small amount of translation at both room temperature and transition temperature have been obtained and the corresponding probabilities have been calculated. The rigidity parameter for stacking and in-plane interaction was found out and then the stability of molecule according to probability and rigidity at definite translation and rotation has been studied. The change in the characteristics and stability of the compound at transition temperature has been observed. The dependence of phase transition property with change in the certain configurations and orientation of the molecules have been discussed. These observed results provide an insight about the process of mesophase structure and its formation. Group charge analysis has been carried out for 3CB molecule and with respect to fluorine substitution. Based on this study a comparison and prediction of the transition temperature may be done.