Extended Data Fig. 1: The role of the interaction between octahedral tilt and B-site ionic displacements in the phase diagram of sodium niobate.
From: Ultrahigh electromechanical response from competing ferroic orders
(a) The schematic of perovskite structure and the preferable behaviour of ionic displacements (t > 1) or oxygen octahedral rotation (t < 1) in terms of the tolerance factor t. The tilt will be considered equal when the tilting angle is equal, while the tilt is independent when the tilt angle is different. (b) Phase diagram of sodium niobate as a function of temperature, where D represents the displacement and T represents the tilts. The notation eq and in represent the equal and independent respectively. The independent tilting promotes the stabilization of the antiferroelectric phase. The ionic displacements and octahedral rotations induce the competition of ferroelectric and antiferroelectric orders in sodium niobate.
