Strain-induced ferroelectricity and piezoelectricity in centrosymmetric binary oxides

First-principles calculations are performed to predict ferroelectricity in the binary rocksalt oxide family (AO with A=Cd, Ba, Sr, Ca, Mg, etc.) via the application of biaxial strain. The origins of such ferroelectricity are discussed from the lattice dynamics perspective and electronic structure properties. Under compressive strain, the strikingly large longitudinal piezoelectric effect is induced due to the deformation along the c direction as a response to the stress. These findings have the potential to motivate the search of new simple binary oxides possessing ferroelectricity that may lead to novel devices.