Structural, dielectric and impedance spectroscopic studies of CaCu2.9Ni0.1Ti4−xCoxO12 electro-ceramic

In the present work, C and B-sites modified structured CCTO composition with the nominal formula CaCu 2.9 Ni 0.1 Ti 4− x Co x O 12 ( x = 0.1, 0.2 and 0.3) were prepared by solid-state reaction. XRD analysis confirmed the formation of single-phase material in samples sintered at 1100 °C for 12 h and 24 h. The effects of Nickel (Ni) and Cobalt (Co) were investigated thoroughly by scanning electron microscopy (SEM), Raman spectroscopy and Impedance spectroscopy. SEM micrographs of co-doped samples noted (CCTO–Ni–Co) revealed amazing morphological change. Pure CCTO exhibits regular polyhedric grains while leaf grains occur in CCTO–Ni–Co particularly when the content of Co increases to 0.3. EDX studies confirm the rich phase of copper oxide at grain boundaries. The complex dielectric and impedance properties of dielectric compound CaCu 3 Ti 4 O 12 co-doped by Ni and Co as a function of frequency were interpreted to understand the grain and grain boundary contributions to its dielectric response. The frequency-dependent dielectric permittivity data shows a sharp increase in permittivity by 0.2 and 0.3 Co doping content sintered at 1100 °C for 12 h accompanied with a frequency-dependent peak in tanδ. However, the dielectric response associated with these compositions drops considerably as the sintered time reaches 24 h. Contrary, the sample doped with 0.1 content Co show clear ameliorate on the dielectric permittivity. So, it was necessary to consider not only the electrical characterization, but also the microstructure in a discussion of the dielectric properties of the estimate CaCu 2.9 Ni 0.1 Ti 4– x Co x O 12 composition.