Effect of sintering conditions on the micro structural, dielectric, ferroelectric and varistor properties of CaCu3Ti4O12 and La2/3Cu3Ti4O12 ceramics belonging to the high and low dielectric constant members of ACu(3)M(4)O(12) (A = alkali, alkaline-earth metal, rare-earth metal or vacancy, M = transition metal) family of oxides

摘要

Effect of sintering conditions on the microstructural, dielectric, ferroelectric (FE) and varistor properties of CaCu3Ti4O12 and La2/3Cu3Ti4O12 ceramics belonging to the high and low dielectric constant members of ACu(3)M(4)O(12) (A = alkali, alkaline-earth metal, rare-earth metal or vacancy, M = transition metal) family of oxides was investigated in detail and a comparison was made. While sintering conditions had an imprinting effect on the physical properties of CaCu3Ti4O12 ceramic, these have minimal influence on the La2/3Cu3Ti4O12 ceramic. Contrary to the previous observations that the CaCu3Ti4O12 and the other oxides of the family belong to the centrosymmetric space group Im3, both CaCu3Ti4O12 and La2/3Cu3Ti4O12 ceramics exhibited FE hysteresis loops with remnant polarization and coercive field values depending strongly on sintering conditions. The dc bias studies suggested that the electric field had significant effect on resistance and capacitance of grain and the grain boundary in CaCu3Ti4O12, whereas it had only subtle effect in the case of La2/3Cu3Ti4O12. CaCu3Ti4O12 exhibited strong nonlinear current-voltage characteristics and the electric field at which nonlinearity sets in decreased with increase in the sintering duration. On the contrary, all La2/3Cu3Ti4O12 samples under study exhibited linear current-voltage behavior in the entire voltage range of measurement, irrespective of the sintering durations.