Giant dielectric properties of Mg doped CaCu3Ti4O12 fabricated using a chemical combustion method: Theoretical and experimental approaches

Abstract

In this work, CaCu3-xMgxTi4O12 (x = 0, 0.05, and 0.10) ceramics were successfully prepared via a chemical combustion method. No impurity phase was detected in these two ceramics. Fine−grained microstructures were formed in all CaCu3-xMgxTi4O12 ceramics. Interestingly, high dielectric permittivities of ∼6.58 × 103 − 2.87 × 104 with low loss tangents of ∼0.011 − 0.025 were obtained in the Mg-doped CaCu3Ti4O12 ceramics. According to the electrical measurements, improved dielectric properties in the doped ceramic samples were a result of an enhanced grain boundary response. To elucidate the electronic structure of CaCu2.90Mg0.10Ti4O12, first-principles calculations were carried out. It was found that two Mg atoms preferentially interact. Moreover, by adding an oxygen vacancy into the CaCu2.90Mg0.10Ti4O12 structure, our results revealed that it was likely to be isolated from the Mg atoms, indicating an oxygen loss suppression during the sintering process. This resulted in an enhanced grain boundary resistance in the CaCu2.90Mg0.10Ti4O12 ceramic. Based on both the experimental and computational studies, the internal barrier layer capacitor (IBLC) model was found to be the primary origin of the colossal dielectric response in all CaCu3-xMgxTi4O12 ceramics examined in the current study.