The cationic distribution in the co

The cationic distribution in the cold sintered samples was investigated using high-angle annular darkfield scanning transmission electron microscopy (HAADF-STEM) combined with EDS elemental mapping (Figure 2). To investigate sintering mechanisms in this system, we assumed that lattice and grain boundary diffusion do not occur at our highest sintering temperature T (T = 275°C, T/Tm of ~ 0.17 where Tm is the melting temperature of BaTiO3). Indeed, the T/Tm ratio required to enable creep mechanisms involving lattice and grain boundary diffusion, known as the Nabarro-Herring creep and Coble creep, is between 0.5 to 0.95.33 Therefore, we considered that Sr in the sample could be used as a chemical tracer to identify mechanistic paths towards densification. The HAADF image (Figure 2A), showing a highly dense microstructure, is in good agreement with previous SEM analysis (Figure 1D). EDS mapping images show that Ba and Ti are homogeneously distributed through the microstructure (Figure 2C,D), while Sr is more segregated (Figure 2B). This entails the inhomogeneous distribution of Ba1-xSrxTiO3 crystals in the ceramic. The presence of Ba1-xSrxTiO3 is also confirmed by the peak shift in XRD and Curie temperature, as described above.