Barium titanate is one of the most prominent ferroelectric material systems. Due to the high permittivity it is interesting for capacitor applications. However, also the piezoelectric coefficient reaches high values in barium titanate. The strain mechanisms in this material system are still unclear, although it is well known that the properties are dependent on grain size. In a recent study we were able to uncover an electric field induced phase transformation in barium titanate [1]. With sophisticated diffraction experiments we were able to reveal the structural details of this phase transformation and correlate it with the macroscopic properties. Highest angular resolution and synchrotron radiation was necessary to distinguish between coexisting phases. However, large grain sizes above 5 µm were not feasible at synchrotron instruments. With in situ neutron diffraction we were able to resolve the structural details of the field induced phase transformation and to investigate a broad range of grain sizes. The results demonstrate that even in single component ferroelectric materials such as barium titanate, the structural processes under the influence of external stimuli are highly complex. This contribution will elucidate the details of sophisticated characterisation methods such as the STRAP method (Structure Texture and Strain Analysis for Piezoceramics) with synchrotron and neutron data [2]. With such methods detailed insight into the strain mechanisms and material processes is possible. This helps to develop new materials with superior properties and tailored responses to external stimuli.

[1] Lemos da Silva, L., Lee, K.-Y., Petrick, S., Etter, M., Schökel, A., Chaves, C. G., Oliveira da Silva, N., Lalitha, K. V., Picht, G., Hoffmann, M. J. & Hinterstein, M. (2021). J. Appl. Phys. 130, 234101.
[2] Hinterstein, M., Lee, K.-Y., Esslinger, S., Glaum, J., Studer, A. J., Hoffman, M. & Hoffmann, M. J. (2019). Phys. Rev. B. 99, 174107.