Coexistence of Flexo- and Ferro-Electric Effects in an Ordered Assembly of BaTiO3 Nanocubes

It has been reported that the flexoelectric effect could be dominant in the nanoscale. The discrepancy between theory and experiments on the frequency dependence of the dielectric constant of an ordered assembly of BaTiO3 nanocubes is nearly resolved by assuming the coexistence of flexo- and ferro-electric effects. Although flexoelectric polarizations perpendicular to the applied alternating electric field contribute to the dielectric constant, those parallel to the electric field do not contribute because the magnitude of the flexoelectric polarization does not change due to the mismatch of strain at the interface of the nanocubes. On the other hand, some dielectric response is possible for the ferroelectric component of the polarization parallel to the electric field.

Исследование процесса коалесценции капель эмульсии в неоднородном переменном электрическом поле при наличии межфазной асфальтеновой пленки на границе раздела масло-вода

The behavior of a water-in-oil emulsion stabilized with asphaltenes under the action of an inhomogeneous alternating electric field has been studied. The experimental technique is based on the use of microfluidics, optical microscopy, and high-speed video filming. Quantitative estimates of the parameters characterizing the dynamics of the destruction of the emulsion, depending on the frequency and amplitude of the applied field, are obtained. The method will be useful in the development of effective methods for breaking emulsions and modifying existing technologies for separating oil emulsions into phases.

Time-Resolved Nanobeam X-ray Diffraction of a Relaxor Ferroelectric Single Crystal under an Alternating Electric Field

Lead-containing relaxor ferroelectrics show enormous piezoelectric capabilities relating to their heterogeneous structures. Time-resolved nanobeam X-ray diffraction reveals the time and position dependences of the local lattice strain on a relaxor ferroelectric single crystal mechanically vibrating and alternately switching, as well as its polarization under an alternating electric field. The complicated time and position dependences of the Bragg intensity distributions under an alternating electric field demonstrate that nanodomains with the various lattice constants and orientations exhibiting different electric field responses exist in the measured local area, as the translation symmetry breaks to the microscale. The dynamic motion of nanodomains in the heterogeneous structure, with widely distributed local lattice strain, enables enormous piezoelectric lattice strain and fatigue-free ferroelectric polarization switching.

Direct Evidence of Ice Crystallization Inhibition by Dielectric Relaxation of Hydrated Ions

In this paper, the inhibition effect of an alternative current (AC) electric field on ice crystallization in 0.9 wt % NaCl aqueous solution was confirmed thermodynamically with characterization. An innovative experimental and analytical method, combining differential scanning calorimeter (DSC) measurement with an externally applied electric field was created by implanting microelectrodes in a sample crucible. It was found that the ice crystallization, including pure ice and salty ice, was obviously inhibited after field cooling with an external AC electric field in a frequency range of 100 k–10 MHz, and the crystallization ratio was related to frequency. Compared with non-field cooling, the crystallization ratio of ice crystals was reduced to less than 20% when E = 57.8 kV/m and f = 1 MHz. The dielectric spectrum results show that this inhibition effect of an alternating electric field on ice crystal growth is closely related to the dielectric relaxation process of hydrated ions.

Hopping Conductivity and Dielectric Relaxations in Ag/PAN Nanocomposites

The dependence of the conductivity and electric modulus of silver/polyacrylonitrile nanocomposites on the frequency of an alternating electric field has been studied at different temperatures and starting mixture AgNO3 contents. The frequency dependences on the conductivity of the nanocomposites in the range of 103–106 Hz are in good agreement with the power law f0.8. The observed relaxation maxima in the relation of the imaginary part of the electric modulus on the frequency can be explained by interfacial polarization. It was shown that the frequency dispersions of conductivity and electric modulus were well described by the Dyre and Cole-Davidson models, respectively. Using these models, we have estimated the relaxation times and the activation energies of these structures. A mechanism of charge transport responsible for the conductivity of nanocomposites is proposed. An assumption is made regarding the presence of Ag42+ and Ag82+ silver clusters in the polymer.