Hybrid-improper ferroelectric behavior in Ba3SiO/Ba3GeO oxide antiperovskite superlattices Andrés Camilo Garcia-Castro, Jorge Hernan Quintero Quintero Orozco and Carlos José Paez Gonzalez Eur. Phys. J. B, 92 9 (2019) 203 Published online: 11 September 2019 DOI: 10.1140/epjb/e2019-100175-1