To determine the phase relationships in the (1 – 2 x )BiScO 3 ⋅ x PbTiO 3 ⋅ x PbMg 1/3 Nb 2/3 O 3 system near the morphotropic phase boundary, the ceramic samples for x = 0.34 and x = 0.46 were studied by the XRD method. The profiles of nine regions of the XRD patterns were analyzed using the WinFit software program. In both cases, the best agreement with the experimental data was observed when additional phases with the cubic symmetry were introduced. Simulation of the full X-ray diffraction patterns of the samples using the Le Bail method showed that the samples under study contained two phases: the main phase with a cubic ( a = 4.0432 Å) ( x = 0.34) and a tetragonal ( a = 3.9963 Å, c = 4.0580 Å) ( x = 0.46) unit cell and an additional one. The additional phases with broad diffraction peaks can be considered to be cubic ones with the unit cell parameters a = 4.045 Å and a = 4.017 Å, respectively.

— (1 – x )Ba(Ti 0.75 Sn 0.25 )O 3 ∙ x PbTiO 3 (0 ≤ x ≤ 1) samples prepared by a standard ceramic processing route have been characterized by X-ray diffraction, thermogravimetry, and dielectric, piezoelectric, and pyroelectric measurements. The results demonstrate that the system in question contains solid solutions with the perovskite structure, which have cubic symmetry for x < 0.2 and tetragonal symmetry for x ≥ 0.2. Increasing the percentage of PbTiO 3 in the samples has been shown to cause sequential changes in their dielectric properties in the following sequence: ferroelectric relaxor, reentrant ferroelectric relaxor, ferroelectric with a diffuse phase transition, and conventional ferroelectric.

Bi-based layer structure ferroelectrics are the most promising compounds for the fabrication of high-temperature piezoelectric materials. Studies aiming to develop and optimize the techniques to produce efficient high-density piezoelectric ceramics, and to investigate the effects of ceramics production conditions on their structure and functional properties, have become high-priority objectives of modern piezo-engineering. We applied ultra high dilution (UHD) technology to pre-treat Bi3TiNbO9 powders and used hot pressing to prepare perovskite-layer structured ceramic specimens. Main characteristics of the synthesized piezoelectric ceramic specimens (the dimensions of the Bi3TiNbO9 orthorhombic unit cell, dielectric permittivity, dielectric loss, piezoelectric coefficient d33 and pyroelectric coefficient pσ) and their temperature-dependent variations were studied using piezoelectric, dielectric, and pyroelectric measurements. X-ray diffraction studies demonstrated that the prepared ceramics were single phased, and highly textured, as their plate-like crystallites were preferentially aligned perpendicularly to the pressure axis on hot pressing. For d33, an increase in values of more than 20% was found for samples obtained using a combined modification of the UHD technology and hot pressing (12 pC/N) relative to intact samples, and more than two times relative to unmodified Bi3TiNbO9 ceramics (6 pC/N). Due to their characteristics, the obtained ceramics are promising materials for high-temperature applications; of particular interest is potential use, as electroacoustic transducers and sensors for operation at high temperatures. Thus, the UHD technology can modify the properties of ceramics and is relatively easy to implement. This makes it attractive for use in various fields of science and technology.

(1 – x)Ba(Ti0.75Sn0.25)O3 ∙ xPbTiO3 (0 ≤ x ≤ 1) samples prepared by a standard ceramic processing route have been characterized by X-ray diffraction, thermogravimetry, and dielectric, piezoelectric, and pyroelectric measurements. The results demonstrate that the system in question contains solid solutions with the perovskite structure, which have cubic symmetry for x < 0.2 and tetragonal symmetry for x ≥ 0.2. Increasing the percentage of PbTiO3 in the samples has been shown to cause sequential changes in their dielectric properties in the following sequence: ferroelectric relaxor, reentrant ferroelectric relaxor, ferroelectric with a diffuse phase transition, and conventional ferroelectric.

Multilayer piezo stack based on Na0,5Bi4,5Ti4O15 was produced by tape casting slurry technology. X-ray diffraction, dielectric permittivity, piezoelectric and pyroelectric studies have been performed on the specimens. It was established that specimens have a textured structure due to the orientation of basal planes (001) plate-like grains parallel to the direction of film casting. The Curie point (T-c = 645 degrees C) of the obtained stacks have been determined from the temperature-frequency dependences of the dielectric permittivity and loss tangent, it is established that they have a relatively high effective piezoelectric constant (d(33)*= 180 pC/N) for NBT based ceramic system. In concluding it has been analyzed the prospect of the specimens in high temperature applications.

Ceramic samples of the (1-2x)BiScO3-xPbTiO3-xPbMg1/3Nb2/3O3 system in the whole compositions region x = 0-0.50 were synthesized. According to the X-ray diffraction studies (XRD), the region of solid solutions with perovskite structure formation in the system was determined (x = 0.23-0.50). The presence of a morphotropic phase boundary between tetragonal and rhombohedral forms of solid solutions was established at x = 0.40-0.42. Refined XRD with profile peak analysis established the presence of the additional cubic phase with broadened X-ray reflexes in the solid solutions along with the main phase. It was concluded that the main and additional phases are located in the volume and in the surface layer of ceramic crystallites, respectively. The crystal structures of phases in the polarized and depolarized sample with x = 0.42 were determined by the Rietveld method. It was found that the monoclinic perovskite phase is present in the polarized sample. Temperature-frequency dependences of dielectric permittivity and losses of solid solutions were studied. It was found that the increasing content of BiScO3 in samples causes a change in their dielectric properties from the usual ferroelectric (FE) in the region (1-2x) = 0-0.08 to ferroelectric-relaxor (FE-R) in the region (1-2x) = 0.08-0.40, and then to the properties of dipole glass with weak correlations in the region (1-2x) > 0.40. It was found that the samples with x = 0.434 and 0.446 below Tc = 414 and 445 K spontaneously pass to the FE state. In the samples with x = 0.42 the application of an electric field of 2.0 kV/ cm induces a transition from FE-R to FE state with Tc = 350 K, which remains after the field is removed.

Some results of studying the dielectric and electromechanical properties of ceramic 16BiScO3–42PbMg1/3Nb2/3O3–42PbTiO3 relaxor ferroelectric samples in electrical fields (0 < E < 20 kV/cm) are presented. An appreciable decrease in the dielectric permittivity with time, and the disappearance of hysteresis in the dependence of the longitudinal strain on the electrical field intensity were revealed in the fields exceeding the coercive field (E > 10 kV/cm) and explained by the induced ferroelectric phase transition. The field-induced phase (presumably, tetragonal) was shown to be unstable and partially ordered. A nonmonotonical character demonstrated by the dielectric permittivity–time dependences of the studied ceramics unlike the other relaxor ferroelectrics was explained by the coexistence of glassy and ferroelectric phases.

AbstractSome results of studying the dielectric and electromechanical properties of ceramic 16BiScO_3–42PbMg_1/3Nb_2/3O_3–42PbTiO_3 relaxor ferroelectric samples in electrical fields (0 < E < 20 kV/cm) are presented. An appreciable decrease in the dielectric permittivity with time, and the disappearance of hysteresis in the dependence of the longitudinal strain on the electrical field intensity were revealed in the fields exceeding the coercive field ( E > 10 kV/cm) and explained by the induced ferroelectric phase transition. The field-induced phase (presumably, tetragonal) was shown to be unstable and partially ordered. A nonmonotonical character demonstrated by the dielectric permittivity–time dependences of the studied ceramics unlike the other relaxor ferroelectrics was explained by the coexistence of glassy and ferroelectric phases.

To determine the phase relationships in the system (1 - 2x)BiSc0 3 • xPbTi0 3 • xPbMg 1/3 Nb 2/3 0 3 near the morphotropic boundary, the ceramic samples for x = 0.34 and x = 0.46 were studied by the XRD method. The profiles of nine regions of the XRD patterns were analyzed using WinFit software. In both cases, a much better agreement with the experimental data was observed with the introduction of additional phases with cubic symmetry. The simulation of the full x-ray diffraction patterns of the samples using the Le Bail method was also carried out. The studied samples contain two phases: the main with a cubic (o = 4.0432 A) (x = 0.34) and tetragonal (o = 3,9963 А, с = 4.0580 A) (x = 0.46) unit cells and additional one. The additional phases with broad diffraction peaks can be considered cubic (with the unit cell parameters a - 4.045 A and a - 4.017 A, respectively).

Some results of studying the dielectric and electromechanical properties of ceramic 16BiScO 3 –42PbMg 1/3 Nb 2/3 O 3 –42PbTiO 3 relaxor ferroelectric samples in electrical fields (0 < E < 20 kV/cm) are presented. An appreciable decrease in the dielectric permittivity with time, and the disappearance of hysteresis in the dependence of the longitudinal strain on the electrical field intensity were revealed in the fields exceeding the coercive field ( E > 10 kV/cm) and explained by the induced ferroelectric phase transition. The field-induced phase (presumably, tetragonal) was shown to be unstable and partially ordered. A nonmonotonical character demonstrated by the dielectric permittivity–time dependences of the studied ceramics unlike the other relaxor ferroelectrics was explained by the coexistence of glassy and ferroelectric phases.

High-density ceramic samples of the Bi3TiNbO9 ferroelectric phase with a layered perovskite-like structure have been produced by tape casting slurry technology and hot pressing processes. The samples have been characterized by X-ray diffraction and dielectric, piezoelectric, and pyroelectric measurements. The results demonstrate that the samples have a well-defined texture due to the preferential orientation of the basal planes of their platelike grains across the pressing axis or along the film casting direction. The Curie temperature of the samples has been determined to be T (C) = 1180 K. The samples have anisotropic electrical transport characteristics. Their piezoelectric constants d (33) in directions perpendicular and parallel to the texture plane is 22 and 5 pC/N, respectively. The conclusion has been drawn that the synthesized materials are potentially attractive for producing high-temperature piezoelectric elements.

An X-ray diffraction study of ceramic samples of relaxor ferroelectric (1 – 2х)BiScO3 · хPbTiO3 · хPbMg0.33Nb0.67O3 with х = 0.42 in the polarized and depolarized states has been performed. It is established by Rietveld method that in both cases samples contain two perovskite-like phases, which are solid solutions. One of them has cubic symmetry. The second phase is characterized by the polar tetragonal sp. gr. P4mm in the polarized state and the monoclinic noncentrosymmetric sp. gr. Cm in the depolarized state.

Осуществлен синтез высокоплотных керамических образцов сегнетоэлектрической фазы Bi3TiNbO9 со слоистой перовскитоподобной структурой методом горячего прессования и технологией шликерного литья. На полученных образцах проведены рентгенографические, диэлектрические, пьезоэлектрические и пироэлектрические исследования. Установлено, что полученные образцы из-за преимущественной ориентации базисных плоскостей пластинчатых зерен перпендикулярно оси прессования или параллельно направлению литья пленки представляют собой выраженные текстуры. Определена точка Кюри образцов ТС = 1180 К, образцы проявляют анизотропию электрофизических характеристик, при этом значения пьезомодуля d33 в направлениях, перпендикулярном и параллельном плоскости текстурирования, достигают соответственно 22 п и 5 пКл/Н. Сделано заключение о перспективности полученных образцов для создания высокотемпературных пьезоэлементов.

This paper discusses technological and construction ways to achieve a high working temperature with a high displacement in linear piezo motors. The first part reviews the results of the piezoelectric material development, its temperature stability testing and basic parameters for piezo motors. The second part focuses on the multilayer structure of piezoelectric elements, which are based on high-temperature piezoelectric materials (HTPM). Also analyzed are working temperatures of multilayer piezoelectric elements (MPE) and their hysteresis. Finally, the third part shows a comparison of three recent prototypes of high-temperature MPEs that were in our lab using different materials.