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The T–x phase diagram of (1 − x) [0.7PbZrO3–0.3(K0.5Bi0.5)TiO3]– xSrTiO3 (x = 0–0.7) solid solutions has been plotted using data from x-ray and dielectric studies. It was found that compounds with x < 0.25 and 0.25 < x ⩽ 0.70 undergo diffuse phase transitions to ferroelectric rhombohedral and tetragonal phases, respectively. The diffuseness of phase transitions is due to the ionic radii difference of cations which occupy positions in the A sublattice of perovskite ABO3 type structure. The study of the dielectric constant dispersion (10−1–3 × 106 Hz) revealed a wide spectrum of relaxation times. The average relaxation time follows the Arrhenius law with temperature dependent activation energy U*(T). It was found that the U*(T) dependence weakened as the diffuseness of the phase transition was increased.

This paper reports a detailed study of the electrostrictive effect and related properties of unpoled ferroelectric ceramics (l-x).F'bZrOs . K~,~B~ Ti0 where GO-1, using a sensitive cascitance dl?a?ome&k at room temperature. ?he mat-erial was found to eshibjt p large electrostrictive coefficient Q,, of ~0 . 3 m /C whlch is more than three times as large as that of single crystal BaTiO .3Comparison with E T ceramics indicates that new material is a pt-entially useful one for transducer application.The elmtrostrictive actuators are widely used in various devices of adaptive optics and laser techniques, scanning microscopy and litography, linear motors etc. The main advantages of the electrostrictive devices in comparison h-ith the piezoelectric ones are smaller electromechanical hysteresis, higher temperature and time stabilities and absence of aging [ l -3 1 . The most es-periments on the electrostriction in ferroelectrics with diffuse phase transition were prformed for lead magnesium niobate [ 1, 4 1 and its solid solut.ions [ 2 , 51 or for the lead zirconate titanate [6, 7 1 . They are t o day increasingly used as actuator materials. However, recent requirements for new displacive transducers with lower hysteresis and aging effects have promotd the developnent and study of a new family of electrostrictive ceramics.The purpse of this paper is to show the esprimental features of the electrostrictive properties of (l-x)PbZrO -SI( 5 B b . S Ti? solid solutions near the morphotrop?c pfiase ransi ions and t-o try to understand an origin of a large electrostrictive effect of these materials.The complex perovskite PbZr03 -5 B& Ti0 ceramics were prepared by the conventional mnd ox?de route, described in detail in the literature [81. A 1 1 the starting oxide powders, in stoichiometric proportions, were mixed in a jar with agate balls in distilled water for 20 hours. The mixed reagents were dried and then calcined at 850°C for 3 hours in air. After remilling the screened pohder was dry-pressed into discs of 10 my diameter and 1 nun thick under a pressure of 1000 @/cm. The samples were held for 1.5 hours at the sintering temperature of 1050°C and were cooled at the natural rate of the furnace. The high vapour pressure of PtQ made it necessary to use 5 ut% excess PW to keep a PtQ atmospheres during the sintering process. Ceramic samples obt,ained were electroded with silver paint for the measurements of the dielectric and electrostrictive properties. The characterization of the ceramic structure was carried out by X-ray powder diffraction method withCu Ka-radiation and Ni-filter.Temperature dependences of dielectric constant ( c ) and loss tangent (t&) of unpoled samples were measured at 10 KHz by a bridge LCR meter. The electrostrictive coefficient Q,, was measured at room temperature using a sensitivg capacitive dilatometer. DC electric field up to 10 I7/m were applied perpendicular to the large plane of the samples. The length change AL, or strain S=AL/L, of the samples along the electric field direction, was measured by d...

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