Switching between Proper and Hybrid-Improper Polar Structures via Cation Substitution in A2La(TaTi)O7 (A = Li, Na)

Neutron powder diffraction data indicate that Li2La(TaTi)O7 adopts a polar, a–a–c+/a–a–c+ distorted, n = 2 Ruddlesden–Popper structure described in space group A21am (#36), consistent with a hybrid...