Application of electron holography to ferroelectric study

With the development of FE TEM, electron holography becomes a reality to materials scientists, which opens a new window for materials study. Weak phase objects, such as a thin transparent specimen or an electric or a magnetic field, which have little or no effect on the intensity of the transmitted wave, can readily be observed via holography because of the phase shift that they produce. Application of the electron holographic method has been extended to the study of ferroelectric domain wall structures. This work presents the most recent results in this area.Polarization gradients within domain walls are extremely important for the understanding of the extrinsic elastio-dielectric properties of ferroelectrics. Electron holographic studies of the local domain wall profiles provide essential input parameters for phenomenological theories of domain structure and of the macroscopic properties derived from the theories. Figure 1(a) is an electron hologram of the ferroelectric (BaTiO3) 90° domain wall area.