A hybrid double perovskite ferroelastic exhibiting the highest number of orientation states.

Integrating NH 4 + as a B'-site ion within a three-dimensional double hybrid perovskite resulted in a novel high-temperature ferroelastic, (Me 3 NOH) 2 (NH 4 )[Co(CN) 6 ], which uniquely demonstrates a reversible triclinic-to-cubic phase transition at 369 K and offers a record-setting 24 orientation states, the highest ever reported among all ferroelastics.