The impact of SrTiO3, CaTiO3 and BaTiO3 on the formation of core-shell structures in solid solutions with Na0.5Bi0.5TiO3

The solid solution 75Na 0.5 Bi 0.5 TiO 3 -25SrTiO 3 (NBT-ST) can achieve outstanding high-strain properties for actuator applications. Whether these properties arise from microscopic core-shell structures or coexisting polar nanoregions remains uncertain, thus opening up a promising research field for tuning functional properties. One possible way to reveal the underlying core-shell formation mechanism and the structure’s impact on functional properties is to test related solid solutions with NBT. This study examines the applicability of core-shell formation conditions and associated property changes in NBT-ST to 87Na 0.5 Bi 0.5 TiO 3 -13CaTiO 3 (NBT-CT) and 94Na 0.5 Bi 0.5 TiO3-6BaTiO 3 (NBT-BT). Thermal analysis and scanning electron microscopy revealed that two-step reactions, as in NBT-ST and NBT-CT, are the key factor enabling core-shell structures. A single-step reaction, like in NBT-BT resulted in no core-shell structures. As already demonstrated for NBT-ST, core-shell structures in NBT-CT led to comparably high strains of 0.29% and slim polarisation loops, confirming the transferability of property changes associated with chemical inhomogeneities.