On the structure of the ferroelectric-paraelectric transformation interface in barium titanate. I. Basic structure and characteristics

Heating tests in the transmission electron microscope (TEM) have been conducted into the nature of the ferroelectric-paraelectric transformation interface in BaTiO₃. Observations on the manner in which 90° domain boundaries disappeared during passage of this interface, together with variations in the electron diffraction pattern across it, indicate that it is of the order of microns wide. This suggests a coherent interface structure by which tetragonal lattice cells of the ferroelectric phase continuously transform to cubic cells of the paraelectric phase. The relatively high mobility implied by such an interface agrees with the primarily martensitic nature of the transformation.