Investigation of the relaxor-photoferroelectric Ba(Sn,Ti)O3 compounds using neutron pair distribution function

The local structural distortions in BaTiO3-based solid solutions, where the Ti4+ site is substituted by isovalent Sn4+ cation Ba(Sn,Ti)O3, are characterized by no oxygen tilts and predicted to promote different Ti(Sn)-O bonds leading to different polar orders through the phase diagram, from ferroelectrics to relaxors. The last ones are characterized by the presence of polar nanoclusters with different dynamic regimes depending on the Ti/Sn ratio. We carried out atomistic calculations indicating a distribution of Ti(Sn)-O bond distances for relaxor compositions, which is compatible with a local induced polarization on the Sn sites from the Ti ones. Neutron scattering pair distribution function on different compositions and at room and low temperature will allow us quantifying the local disorder on these compounds above and below the activation temperature of the polar nanoclusters.