Evidence of tetragonal nanodomains in the high-pressure polymorph of BaTiO3

The pressure induced P4mm -> Pm (3) over barm phase transition in BaTiO3 perovskite was investigated by x-ray total scattering. The evolution of the structure was analyzed by fitting pair distribution functions over a pressure range from ambient pressure up to 6.85(7) GPa. Evidence for the existence of tetragonal ferroelectric nanodomains at high pressure was found. The average size of the nanodomains in the high-pressure phase decreases with increasing pressure. Extrapolation of the domain size to pressures higher than studied experimentally suggests a disappearance of the ferroelectric domains at about 9.3(5) GPa and a cubic symmetry of BaTiO3 high-pressure phase. (C) 2011 American Institute of Physics. [doi:10.1063/1.3535611]