The structural off-centering of the heavier p-block elements in oxides, associated with their stereochemically active s2 lone pair, allows them to play a dominant role in polar, and more specifically, ferroelectric materials. We have investigated the ferroelectric compounds Sr0.9Sn0.1TiO3 and Ba0.79Ca0.16Sn0.05TiO3 using neutron total scattering techniques with data acquired at different temperatures and we compare the local and long-range structures of the Sn2+-substituted compositions to the unsubstituted compounds SrTiO3 and BaTiO3. We find in both samples that even at these small substitution levels, the Sn2+ lone pair influences the local ordering behavior, with both compounds more closely following the structural behavior of PbTiO3 rather than the unsubstituted compounds. The analysis of the local structure of Sn2+-substituted samples at various temperatures revealed the surprising result of a distorted Ti coordination environment at elevated temperatures, and displayed an increase in the uniformity of the TiO6 octahedra with decreasing temperature, behaving contrary to the average structure at the respective temperatures.

Influence of Sn2+-substitution on the local structure of the Pb-free ferroelectric perovskites (Sr,Sn)TiO3 and (Ba,Ca,Sn)TiO3

251st National Meeting (2016)

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