From first- to second-order phase transitions in hybrid improper ferroelectrics through entropy stabilisation

Abstract

Hybrid improper ferroelectrics (HIFs) have been intensely studied over the last few years to gain understanding of their temperature induced phase transitions and ferroelectric switching pathways. Here we report a switching from first- to second-order phase transition pathway for topical HIFs $C{a}_{3-x}S{r}_{x}T{i}_2{O}_7$, which is driven by the differing entropies of the phases that we identify as being associated with the dynamic motion of octahedral tilts and rotations. A greater understanding of the transition pathways in this class of layered perovskites, which host many physical properties that are coupled to specific symmetries and octahedral rotation and tilt distortions -- such as superconductivity, negative thermal expansion, fast ion conductivity, ferroelectricity, among others -- is a crucial step in creating novel functional materials by design.

References in corpus (8)

• Restoring the density-gradient expansion for exchange in solids and surfaces
• Generalized gradient approximation for solids and their surfaces
• Experimental demonstration of hybrid improper ferroelectricity and presence of abundant charged walls in (Ca,Sr)${}_3$Ti${}_2$O${}_7$ crystals
• Octahedral rotation-induced ferroelectricity in cation ordered perovskites
• Domain Topology and Domain Switching Kinetics in a Hybrid Improper Ferroelectric
• Topological defects at octahedral tilting plethora in bi-layered perovskites
• Infrared nano-spectroscopy of ferroelastic domain walls in hybrid improper ferroelectric Ca${}_3$Ti${}_2$O${}_7$
• Mapping the structural transitions controlled by the trilinear coupling in Ca3-xSrxTi2O7

Cited by in corpus (2)

• Soft mode anisotropy in negative thermal expansion material ReO${}_3$
• Probing $C{a}_{3}T{i}_2{O}_7$ crystal structure at the atomic level: Insights from ${}^{111m}Cd{/}^{111}Cd$ PAC spectroscopy and ab-initio studies