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SYNTHESIS OF 0.7BiFeO 3 -0.3BaTiO 3 CERAMICS: THERMAL, STRUCTURAL AND AC IMPEDANCE STUDIES OTRZYMYWANIE I WŁAŚCIWOŚCI DIELEKTRYCZNE CERAMIKI 0,7BiFeO 3 -0,3BaTiO 3 In a present paper results of the process of synthesis and study of a perovskite-type solid solution of the chemical composition (1-x)BiFeO 3 -xBaTiO 3 for x=0.3 are reported. Synthesis of 0.7BiFeO 3 -0.3BaTiO 3 (BF-BT) ceramics was carried out according to the solid-phase reaction from the mixture of powders. Simultaneous thermal analysis (STA) and X-ray diffraction method were utilized to study the synthesis of BF-BT ceramics. On the basis of STA analysis the optimum conditions of the thermal treatment were found. BF-BT ceramics was studied in terms of its microstructure (SEM), chemical composition (EDS), crystalline structure (XRD), and dielectric properties (impedance spectroscopy) at room temperature. It was found that dense BF-BT ceramics with a cubic structure of Pm3m space group and desired stoichiometry (±3%) was fabricated under technological conditions differing in both sintering temperature (T =750• C-850• C) and soaking time (t=2h-40h). It was found that an increase in sintering temperature for ∆T =100• C made it possible to decrease the soaking time 10 times. Impedance spectroscopy was utilized for characterizing dynamical dielectric properties of 0.7BF-0.3BT ceramics. The alternative representation of impedance data in a form of complex plot (Z vs. Z ) as well as simultaneous Bode plots (imaginary parts of impedance Z , admittance Y , electric modulus M and tanδ versus frequency in a log-log scale) were used for preliminary visual analysis. Kramers-Kronig transform test was utilized for experimental data validation. To analyze the room temperature impedance spectroscopy data complex nonlinear least squares fitting method was used and the data were fitted to the corresponding equivalent circuit consisting of resistors and constant phase elements. Agreement between experimental and simulated data was established.Keywords: dielectric properties, impedance spectroscopy, BiFeO 3 -BaTiO 3 , ceramics W niniejszej pracy przedstawiono rezultaty badań poświęconych wytwarzaniu i charakterystyce właściwości roztworu stałego o strukturze typu perowskitu i składzie chemicznym (1-x)BiFeO 3 -xBaTiO 3 dla x=0,3. Proces syntezy ceramiki 0,7BiFeO 3 -0,3BaTiO 3 (BF-BT) przeprowadzono w wyniku reakcji w fazie stałej z mieszaniny prostych tlenków. Przy pomocy analizy termicznej (STA) oraz rentgenowskiej analizy strukturalnej dokonano charakterystyki procesu syntezy ceramiki BF-BT. Przeprowadzono badania mikrostruktury ceramiki BF-BT za pomocą skaningowego mikroskopu elektronowego (SEM), określono stechiometrię składu chemicznego przy użyciu metody EDS, a strukturę krystaliczną badano metodą dyfrakcji rentgenowskiej (RTG). Przeprowadzono badania właściwości dielektyrcznych wytworzonej ceramiki metodą spektroskopii impedancyjnej. Wykorzystując metodę swobodnego spiekania dla trzech różnych warunków technologicznych (T =750-880• C, t=2-40h) otrzymano ceramikę 0...

The solid solution of the perovskite type structure Ba0.996La0.004Ti1−yFeyO3 (BLTF) for varying iron content (y = 0.1−0.4 mol.%) was obtained as a result of a solid state reaction using the conventional method. At room temperature (Tr < TC), the as-received ceramics reveals a single-phase, tetragonal structure and a P4mm space group. An increase in the iron content causes a slight decrease in the volume of the elementary cell. In addition, this admixture significantly reduces the maximum permittivity value (εm) and the shift of the phase transition temperature (TC) towards lower temperatures. The BLTF solid solution shows a classical phase transition and low values of dielectric loss tangent (tgδ), both at room temperature and in the phase transition area. The Curie–Weiss temperature (T0) and Curie constant (C) were also determined on the basis of the dielectric measurements results. The analysis of temperature changes in DC conductivity revealed presence of the positive temperature coefficient of resistivity (PTCR) effect in the phase transition area.

ders were first synthesized by the conventional mixed oxide method (MOM). Then BF powder was dispersed in a BiT ceramic powder, and next such composite was pressed and sintered. A free sintering method was utilized. Properties of the BF//BiT composites were studied in terms of their density, crystalline structure (X-ray diffraction) and surface morphology (SEM). It was found, that bismuth ferrite powder crystallized in rhombohedral symmetry and bismuth titanate crystallized in monoclinic phase for c V = 2% of BiFeO 3 and orthorhombic phase for c V = 4% and c V = 6% of BiFeO 3 component of the composite. Apparent density of the composites varied within the range ρ = (6.2-6.6) × 10 −3 kg/m 3 . Clear change in surface morphology was found for the composites under study.

In the paper two compositions of the multi-component PZT-type ceramics admixtures by Mn , Ni 2+ were presented. The ceramic powders were synthesized by the calcination of powders while their densification was carried out by free sintering method. The dielectric, ferroelectric, piezoelectric studies and DC electrical conductivity of the multicomponent PZT-type samples were presented. The results of the multi-component ceramics predispose these type materials in micromechatronic and microelectronic applications for example as element of the actuators.