Investigation of coherent interface on relaxation behavior and reliability of Mg-doped BaTiO3 dielectric ceramics: Experiments and first-principle calculations

The addition of Mg generally enhances the high-temperature stability and reliability of BaTiO3-based multilayer ceramic capacitors (MLCCs). Herein, a series of Mg-doped BaTiO3-based ceramics and ultra-thin MLCCs were successfully fabricated, and the coherent and semi-coherent interface has been observed in samples. Based on the density functional theory (DFT) calculations, the improvement in temperature stability is due to changes in the coherent interface and electronic structure that promote the formation of polar nano-regions (PNRs) and induce relaxation behavior. Based on the atomic displacement, it is found that the excess substitution released the coherent stresses in the form of defects and formed semi-coherent interfaces. The reliability degradation of MLCCs is mainly due to the evolution of the semi-coherent interfaces. This work points out an avenue to obtain high-temperature stability and high reliability in BaTiO3-based MLCCs.