Ferroelectric materials find many applications, however ferroelectric behaviour is rare as it requires a material to have a non-centrosymmetric (NCS) structure.We have been studying the role of the cooperative twisting and tilting distortions of the octahedral units in layered Dion-Jacobson and Ruddlesden-Popper phases on NCS structure formation. DFT calculations predict that the ground state structures of A’NdB2O7 (A’ = Cs, Rb; B = Nb, Ta) phases should be polar. SHG measurements have confirmed these phases have acentric crystal structures.Furthermore, the large A’ cations in Dion-Jacobson phase can be exchanged for lithium, to yield phases with Ruddlesden-Popper type structures. SHG measurements indicate these phases are also acentric. We propose to collect powder neutron diffraction data from these phases to determine their structures accurately.