Piezoelectricity enhancement in Dion-Jacobson RbBiNb₂O₇ via negative pressure

We use first-principles calculations to study the structural, ferroelectric and piezoelectric properties of the recently synthesized Dion-Jacobson RbBiNb₂O₇, a novel layered-perovskite piezoelectrics with extremely high Curie temperature T_C. We show that ferroelectric RbBiNb₂O₇ crystalizes in orthorhombic Pmc2₁ phase, exhibiting in-plane spontaneous polarization. We well reproduce the major experimental results for RbBiNb₂O₇. We further propose that under 5% volume-expansion-induced negative pressure, ∼3× increase of dielectric permittivity and ∼2× increase of piezoelectricity can be achieved in RbBiNb₂O₇. The decomposed piezoelectricity analysis reveals that the activation of piezoelectric response of cation Rb by negative pressure can lead to large piezoelectricity enhancement. Based on our calculations, we demonstrate that negative pressure is a promising way to optimize the performance of RbBiNb₂O₇ as high-T_C piezoelectrics.