High-temperature biferroicity in a chiral 3D hybrid rare-earth-based double perovskite

A 3D hybrid rare-earth double perovskite ( R M3HQ) 4 K 2 [Nd(NO 3 ) 6 ] 2 is reported, with a record-high ferroelectric phase transition temperature (∼410 K) for such a system, and simultaneous switchable ferroelectricity and reversible ferroelasticity.