Nenian Charles and Prof. Rondinelli report in their new paper titled Ferroelectricity in d0 double perovskite fluoroscandates that polar double perovskite fluorides may be realized by suppression of octahedral rotations about more than one Cartesian axis [Phys. Rev. B, 92, 054111 (2015)]. Unlike oxides, polar fluorides are compatible with single BF6 octahedral tilt patterns and these can be stabilized by epitaxial strain.
