Structural coherence and ferroelectricity decay in submicron- and nano-sized perovskites

Understanding the loss of ferroelectricity in submicron- and nano-sized perovskites is an issue that has been debated for decades. Here we report results from a high-energy x-ray diffraction (XRD) study on a prime example of the perovskite's family, BaTiO3 ceramics with a grain size ranging from 1200 to 5 nm. We find that the loss of ferroelectricity in submicron- and nano-sized BaTiO3 has an intrinsic origin related to the increased atomic positional disorder in spatially confined physical systems. Our results imply that no particular critical size at which ferroelectricity in BaTO3, in particular, and perovskites, in general, is completely lost exists. Rather it weakens exponentially with the decreasing of their physical size. Smart technological solutions are needed to bring it back.