Promising perovskite materials with robust piezoelectricity and dielectric constants: CaSnO3/BaTiO3 multilayered superlattices

To enhance the piezoelectric and dielectric responses of perovskite for prospective applications in emerging microelectromechanical systems, integrating compounds to form ordered multilayer superlattices is a promising approach. The ferroelectric, dielectric, and piezoelectric properties of the (CaSnO3)n/(BaTiO3)n (n = 1–6) superlattices are investigated by first-principles calculations. The calculations reveal that the (CaSnO3)n/(BaTiO3)n (n = 2.6) superlattices have more robust ferroelectricity than their individual structures. Ps tend to saturate for n > 3, which is attributed to lattice constant stabilization. Due to the large e33 and extremely low C33 for (CaSnO3)3/(BaTiO3)3 superlattices, it exhibits a giant piezoelectric charge coefficient d33 (360 pC/N), which is the second-highest and only surpassed by that of SrTiO3/BaTiO3 among perovskite superlattices reported to date. The large e33 primarily originates from the displacement of Ti and Ba atoms, while the electronic contribution is negligible. Moreover, the (CaSnO3)3/(BaTiO3)3 superlattice has a high dielectric permittivity of 40.91, which is primarily attributed to the synergistic effects of ionic displacement and charge transfer. The (CaSnO3)3/(BaTiO3)3 superlattice also possesses a high electromechanical coupling coefficient, making it a promising candidate for future miniaturized and integrated multi-functional electronic devices.