The dielectric property complemented by the mechanical measurement (internal friction) in the doped Bi4Ti3O12 [Bi4−xLaxTi3O12 (x=0.5,0.75,1) and Bi4−y/3Ti3−yNbyO12 (y=0.015,0.03,0.06)] was systematically investigated from room temperature to 350 °C. In the plot of dielectric loss versus temperature for Bi4Ti3O12 (BiT), a relaxation peak was confirmed to be associated with the motion of the oxygen vacancy. It is found that the La doping at site A is in favor of improvement of the fatigue property, in contrast, the Nb doping at site B can mainly enhance the remanent polarization. Appropriate La doping at site A of perovskite-type unit in BiT enhances the chemical stability of oxygen vacancy by improving the height of the potential barrier for hopping and enhances the mobility of domain by the changing of domain structures. While the Nb doping at site B could induce the distortion of oxygen octahedral and reduce the oxygen vacancy concentration by a compensating effect so that it results in an enhancement of remanent polarization.

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The temperature dependence of the dielectric constant and dissipation in potassium dihydrogen phosphate ͑KDP͒, its deuterated compound ͑DKDP͒, triglycine sulfate ͑TGS͒, and TGS doped with ␣-alanine ͑LATGS͒ has been studied at various frequencies. It is found that the relaxation time of domain freezing in KDP and DKDP in the kHz range can be described by the Vogel-Fulcher relation. Evidence of domain freezing in TGS is presented through an analysis of relaxation time related to domain walls and a comparison between TGS and LATGS. Studies of internal friction and compliance show preliminary evidence of domain freezing in CuAlZnNi alloy. A domain-freezing model is proposed based upon the collective pinning of randomly distributed pinning centers to domain walls. Some key experiments related to domain freezing, such as ͑1͒ the Vogel-Fulcher relation for relaxation time; ͑2͒ the size effect of domain freezing; ͑3͒ two kinds of relaxation in low-and high-frequency ranges, respectively; and ͑4͒ the dependence of T F on defect density and applied field, etc., are explained. ͓S0163-1829͑97͒01323-4͔

Bi 4 Ti 3 O 12 , (BTO) a Bi-layered perovskite oxide, shows fatigue after repeated ferroelectric polarization reversals. On the other hand, Bi3.25La0.75Ti3O12 (BLT) is fatigue free. From an extensive transmission electron microscopy study, it was found that there is a high density of antiphase boundaries (APBs) in BLT like in the fatigue-free SrBi2Ta2O9 but not in BTO. It is proposed that the existence of APBs possibly plays a key role in the fatigue-free behavior of Bi-layered perovskite oxides.

A transmission electron microscopy investigation has been conducted on the domain structure in SrBi2Ta2O9 ceramics. From the 90° rotation relationship of the electron diffraction pattern of the [001] zone axis, a 90° domain wall can be confirmed. It is due to the failure of Friedel’s law that the contrast of a 180° domain wall can be identified. The antiphase boundary can be seen clearly in the dark-field image, which is taken by the (300) superlattice reflection. The 90° domain wall, as well as antiphase the boundary (APB), has an irregular configuration. The APB combined with the 90° domain wall is also identified.

Heat capacity in the glass transition range modeled on the basis of heterogeneous dynamics Short range order, glass transition, and enthalpy relaxation of a binary mixture ( glycerol+propanediol ) AIP Conf.A dynamically heterogeneous coupled dissipation scenario of the glass transition is presented. The model predicts a splitting from a high-temperature single ͑␣␤͒-relaxation to low-temperature ␣and ␤-processes at a certain temperature, T S . The model also predicts a glass transition and some anomalies dependent on the thermal history during the glass transition. Some general features of glass formers emerge from the predictions of the model proposed.

Polycrystalline SrBi2Ta2O9 (SBT) ferroelectric thin films were synthesized on Pt/Ti/SiO2/Si substrates by metalorganic decomposition. Electric measurements demonstrate that the polarization decay increases with increasing the write/read voltage within the first second. This could be attributed to the depolarization fields, which increases with increasing the retained polarization. However, we found that the polarization loss is insignificant with different write/read voltages over a range of 1–30 000 S. Furthermore, experiment indicates that there is weak pinning of domain walls existing in SBT, which plays an important role for SBT thin film over a range of 1–30 000 S with a low write/read voltage.

A model describing dynamically heterogeneous relaxation in complex coupled systems is presented. The model predicts the splitting of a high-temperature single Debye relaxation to a low-temperature bimodal relaxation. The bimodal process shows a crossover from a Debye-type relaxation to an approximately stretched-exponential relaxation. Some general features of relaxation in complex systems emerge from the predictions of the model, and a comparison of the model with experiments is reported.