The observed dense shell region in

The observed dense shell region in Figure 1(c) may grow during CSP. Someminor pores at core region may affect some properties under high voltage.[25] The CSP for BaTiO3 using a powder derived in the solid-state route is under investigation. Besides these minor defects and closed pores, specimens show equiaxed grains with equilibrated triple points which are a feature of the final stage of the sintering. Ferroelectric-ferroelastic non-180º domain structures are not observed in the grains. Figure 1(d) and (h) revealed the well-crystallized grain boundaries after the cold sintering. The clean grain boundary formation without glassy phase was previously not observed until a second heat treatment was applied after cold sintering to temperatures 800-900 oC.[5] An elemental analysis with energy dispersion spectroscopy in the TEM indicates there are no detectable alkaline ions in the grains or grain boundaries (Figure S3).