An approach for correlating electrically heterogeneous structure to enhanced dielectric properties of Sr and Zn co-substituted CaCu3Ti4O12 ceramics.

Abstract In the present work, the most pristine as well as strontium (Sr) and zinc (Zn) modified Calcium copper titanate ceramics having formula Ca 0.95 Sr 0.05 Cu 3 Ti 4-x Zn x O 12 (x = 0.01, 0.025, 0.05 & 0.10) were synthesized by the solid state reaction method. X-ray diffraction pattern and Raman analysis confirmed the single phase formation of the samples. Detailed structural information was carried out by Rietveld refinement, analysis of X-ray data. Microstructure investigation revealed that the grain development of the doped ceramics was controlled by dopant (Zn) ions due to solute drag effect. Impedance spectroscopy was used to investigate the contribution of grains, grain boundaries and electrode interface effect to the dielectric response. Dielectric parameters observed to be improved for higher Zn/Sr ratio in studied compositions. The Ca 0.95 Sr 0.05 Cu 3 Ti 3.90 Zn 0.10 O 12 ceramic composition shows a colossal dielectric permittivity of ∼37,788 and loss ∼0.049, which are stable within a broad frequency region. Reduced tanδ over a broad range of frequency was well ascribed to the highly insulating grain boundaries. The giant dielectric properties of the system were found to be in accordance with Internal Barrier Layer Capacitance (IBLC) model and correlated to their electrically heterogeneous structure. Graphical abstract Image 1 Highlights • Single phased Ca 0. 95 Sr 0. 05 Cu 3 Ti 4-x Zn x O 12 (x = 0.01, 0.025, 0.05 & 0.10) ceramics synthesized using solid state reaction. • Crystal structure and microstructure of all ceramic samples have been characterized by using XRD, Raman spectroscopy and SEM. • Grain resistance decreases and grain boundary resistance increases with increase in Zn content in CCTO matrix. • Correlation between the heterogenous structure and IBLC effect is established to understand the giant dielectric response. [ABSTRACT FROM AUTHOR]