Browsing by Author "Sunita Sharma"

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Dielectric and ac impedance studies of nanostructured CaCu 3Ti3.90Ce0.10O12 electro-ceramic synthesized by citrate-gel route
(2013) K.D. Mandal; Laxman Singh; Sunita Sharma; U.S. Rai; M.M. Singh
Effect of doping at Ti4+ site by Ce3+ has been examined in CaCu3Ti3.90Ce0.10O12 synthesized by citrate-gel route. DTA/TG analysis of dry powder gives pre-information about formation of final product around 850 C. X ray diffraction analysis confirmed the formation of CaCu3Ti3.90Ce 0.10O12 phase of the ceramic sintered at 950 C for 12 h. Microstructure has been studied using scanning electron microscopy and confirmed the average grain size found in nano range 200-400 nm in system CaCu 3Ti3.90Ce0.10O12.The nature of relaxation behavior of ceramic was also rationalized by using the impedance and modulus spectroscopy. The bulk conductivity indicates an Arrhenius-type thermally activated process. The ac conductivity spectrum obeyed the Jonscher power law. The complex impedance diagrams of the ceramic exhibited a significant contribution from the grains, grain boundaries and electrode. The activation energies calculated from the grain-boundary relaxation time constant was found to be 0.49 eV which confirmed the Maxwell-Wagner type of relaxation present in the ceramic. © 2013 Springer Science+Business Media New York.