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La doping effects on intergrowth Bi 2 WO 6 -Bi 3 TiNbO 9 ferroelectric ceramics were studied by X-ray diffraction, electron probe microanalysis and dielectric spectroscopy. It was found that the La 3+ distribution, ferroelectric phase transition and dielectric relaxation behavior are apparently affected by La doping. With increasing La 3+ content, the site of dopant ion varies, the grain growth of Bi 5 TiNbWO 15 is restrained, the Curie temperature is reduced and broadened. Furthermore, two dielectric relaxation loss peaks were observed both in temperature and frequency spectra. The calculated relaxation parameters revealed the oxygen vacancy related to the relaxation process.

The electron acoustic images of domain structure BaTiO3 single crystal under the applied electric field have been observed with Scanning Electron Acoustic Microscope (SEAM). By increasing applied electric field, the growth and merging of domains were revealed. The successive images of domain movement in real time demonstrated the promising potential application of SEAM in the dynamic study of ferroelectric domains. The influence of the applied electric field on the incident electron beam was also discussed in this paper.

The domain structure of ferroelectric BaTiO3 ceramics were directly observed with Scanning electron acoustic microscope (SEAM) made in our lab. The relationships of domain structures with surface grains in BaTiO3 ceramics were revealed with electron acoustic imaging. The generation of the electron acoustic signal and imaging mechanism of ferroelectric domain was analyzed. The electron acoustic imaging of BaTiO3 Crystal and semiconducting BaTiO3 ceramics were also shown for deducing electron acoustic imaging mechanism of ferroelectric domain.

A scanning acoustic microscope (SAM) and a scanning electron acoustic microscope (SEAM) have been used to study domain structures in ferroelectric BaTiO3, Bi4Ti3O12 and ferroelastic NdP5O14 single crystals. In SAM, domain walls act as scattering boundaries for leaky surface acoustic waves and thus sources of image contrast; While in SEAM, different signal generation and image contrast mechanisms may arise, mainly thermal elastic and piezoelectric effects. Further insight into the properties of domains was approached by discussing and comparing the image contrasts involved in both techniques.

Scanning electron acoustic microscopy (SEAM) has been used in the observation of ferroelectric domain configurations in barium titanate single crystals. The contribution to the image contrasts is related to signal generation through a piezoelectric coupling mechanism. The results prove that SEAM really has the ability to show not only the surface shape and domain structures but also the subsurface domain structures. Furthermore, SEAM is a convenient, fast and nondestructive way of observing the ferroelectric domains compared with other methods.

This work was supported by the Ministry of Science and Technology of China through 973-Project No. 2002CB613307, the National Natural Science Foundation of China No. 50572113, and the Innovation Project of Shanghai Institute of Ceramics No. SCX200409.

This work was supported by the Ministry of Science and Technology of China through 973-Project No. 2002CB613307, the National Natural Science Foundation of China No. 50572113, and Shanghai Commission of Science and Technology No. 05JC14079.

Dielectric, impedance, and electric modulus spectroscopies were employed to study the dielectric anomalies in Bi 5 Ti 1.5 W 1.5 O 15 ceramics. It was found that the ferroelectric transition temperature is at 986 K. Besides, two relaxation processes attributed to bulk and grain boundary effects were observed both in the dielectric and impedance spectra. However, only one relaxation process corresponding to the bulk response was observed in the electric modulus spectra. The relaxation parameters were deduced. It was found that the bulk response of the material was of localized relaxation process at low temperatures, and long-range conductivity only emerged at high temperatures. Finally, the relaxation species and dynamics of the bulk response were discussed.