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Methods for increasing thermal stability of the resonance frequency f r of the PZT-based piezoceramic resonators are shown. An influence of ( x )PbTiO 3 content and an effect of doping ions on j f r / f r in the PZT solid solution has been considered. Correlation between qualities of the domain structure, spontaneous deformation parameters i T , i Re , degree of domain reorientation m , internal friction Q m m 1 and mechanical quality factor Q m , has been revealed. An impact of electronegativity of the doping ions on f r thermal stability have been cleared up. Ferroelectric hardness has also been considered. The piezoceramic band filters exhibiting j f r / f r <0.2% and Q m =3225 have been thus obtained.

Results of studies are presented on the switching process of ferroelectric Ba/Ti0.98, Sn0.02/O3 films obtained by the sintering method. Two switching mechanisms were observed, i.e. nucleation with an activation field α1 = 22.7 kV/cm and lateral motion of the domain walls with an activation field of α2 = 6 kV/cm. The observed asymmetry of switching currents is due to defects on the boundary between substratum and ferroelectric film.

Heteroepitaxial PbTiO3 and (Ba1-xSrx)TiO3 thin films were obtained by the r.f. sputtering method. The (100) surface cuts of MgO single crystals served as substrates. The films obtained exhibited ferroelectric properties closely similar to those of the ceramic targets. Depending on substrate temperature (Ts) with other deposition parameters constant, heteroepitaxial films of various degrees of perfection of the crystal structure were obtained. Films deposited at a temperature slightly higher than critical temperature (Tcr) for the heteroepitaxy process exhibited an insular growth mechanism while for Ts ≥ Tcr layer-by-layer growth was found. At room temperature the crystal structure of the PbTiO3//(100)MgO films and of the (Ba1-xSrx)TiO3//(100)MgO films for × ≤ 0,3 exhibit symmetry of the tetragonal system P4mm. Phase transitions in the (Ba1-xSrx)TiO3//(100)MgO films unlike those in the PbTiO3//(100)MgO films exhibited marked diffusion.The domain structure of the heteroepitaxial films, in comparison with that of free ferroelectric single crystals shows certain singular features. The PbTiO3//(100)MgO films exhibit characteristically a-c-domain structure while the (Ba1-xSrx)TiO3//(100)MgO films have c-c-domain structure. A simple phenomenological model is presented here in order to explain the causes of the appearance of various domain configurations in the studied films.

Polycrystalline BaTiO, thin films of thickness dw = 0.5-5 μm were obtained by the cathode sputtering method in a radio frequency field. Depending on the technological conditions the films obtained exhibited varying degrees of perfection of the crystal structure. As the measure of degree of structural perfection of the thin films was taken the value of mean dimensions of areas of coherent X-rays scattering (D) and of mean microdeformations (Δd/d), in the direction normal to the substrate surface. With increase in (Δd/d) and decrease in D, there is a decrease in value of permittivity (ε) of orientation polarization (Pr) and residual polarization (PR), while an increase is found in the coercive field (Ec). in the switching time (ts) and in degree of diffuseness of the ferroelectric phase transition. Results obtained on the relations between structure and ferroelectric properties are interpreted basing on the phenomenological model of ferroelectrics with a diffused phase transition and the dynamic model of dimension effects in ferroelectrics.

Thick Ba (Ti1-xsnx)03 films of a broad range of the Sn4+ion density were obtained. The films of a thickness greather than 10 μm have got very good ferroelectric properties approximate the properties of ceramic materials with the same chemical constitution.

AbstractThe heteroepitaxial ferroelectric thin films of (Ba0.85Sr0.15)TiO3 were deposited on (001) fractures of MgO single crystals by r.f. sputtering. The films are characterized by the perovskite-type structure with clear tetragonal deformation and complete parallel orientation in relation to the substrate. The parameters of the elementary cell as well as character of the domain structure and dielectric parameters show strong dependence on the thickness of the thin films (thicknesses within the range df < (10–5000) × 10−9m). The thin films of a very small thickness (df < 20 × 10−9m) have the 90° a-a-domain structure which transits into the c-domain structure when the thickness increases. The permittivity ε; of the thin film and the remanent polarization Pr decrease when the thickness of the film increases. The temperature T which corresponds with the transition P4mm ↔ Pm3m shifts towards higher temperatures, whereas the temperature T which corresponds with the transition Amm2 ↔ P4mm reduces when the thickness of the thin film increases. The theoretical model describing anomalous properties of the heteroepitaxial (Ba, Sr)TiO3 thin films has been developed.

On barium titanate basis ferroelectric ceramics with semiconductor properties was obtained and it was established that at the different deposited electrodes the dependence of the current intensity through it depending on the applied voltage has a nonlinear character and also presents characteristically marked PTC effect in the vicinity of the ferroelectric phase transition. The electrical properties of the samples of the system as metal-semiconductive ferroelectric ceramics-metal (M-S-M) are dependent on the type of electrode metal (M) and on the method of its deposition on the ferroelectric semiconductor ceramics (S). It was established that all the used electrodes may be divided into two groups: first, those causing the formation of a Schottky type contact layer and second, those forming transition layers on the boundaries of the system M-S. By suitable choice of the electrode material and the deposition method, it is necessary to control the electrical properties of the system M-S-M and in particular to influence on the value of electrical resistance R; to influence on the form of the dependences R(T), R(U) and R(v); to decide on the scale of the PTC effect.

Results are presented of investigations conducted on the dielectric properties of BaTiO3, Ba(TixSn1-x)O3 and (BaxSb1-x)TiO3 films and also films of BaTiO3 with an admixture of selenium or cadmium oxide. These films, obtained by the method of electrophoresis or by screen printing, and next subjected to annealing on a thermo-resistant base, exhibit typical ferroelectric properties. Film thickness was from 1 - 100 μm. By suitable choice of technological conditions, distinctly textured polycrystalline films were obtained. Due to the high values of permittivity, relatively low dielectric losses, switching ability, strong pyroelectric properties and photosensitivity, these films are of interest not only as the subject of basic research investigations but also from the aspect of practical application.It was shown that apart from the influence of the technological conditions, the dielectric properties of the films obtained are strongly influenced by the measurement field, the type of electrodes deposited, the illumination ultraviolet radiation and the thickness of the films themselves.

The connection between the phase transition conditions and the domain structure of BaTiO3 and PbTiO3 crystals is determined.