[en] Published in summary form only

[en] Published in summary form only

[en] Synthesis and sintering studies of ferroelectric ceramics of (Pb, Ba) Nb₂ O₆, or PBN, were performed by conventional method. The raw materials Ba (NO₃)₂ and Ba O were tested for the comparison of the homogeneity and the reactivity of the powders. The X-ray diffraction analysis showed that the material studied presents only the PBN phase and the raw material influences strongly the structure symmetry of the final product. The dielectric properties, obtained by impedance spectroscopy in function of temperature, were compared to those reported by literature in single crystals of same composition. (author)

[en] Published in summary form only

[en] Ceramics of SBN, undoped and doped with rare earth oxides, were prepared to the study of the influence of the doping on the dielectric properties. The samples were characterised through dielectric measurements as a function of temperature (30 K to 500 K) and frequency (1 kHz to 1 MHz). In all samples two distinct dielectric relaxation processes were observed. The first one at temperatures below 100 K; the second one is near room temperature, where the dielectric constant is maximum. The doping causes distinct effects in the maximum temperatures of the dielectric constants in the two dielectric regions. (author)

[en] This work presents a study of lanthanum on the microstructural properties of ferroelectrics ceramics of the system (Pb_1-x La_x) Ti O₃. Ceramics were prepared by the traditional method of oxide mixture, for x equal to 0,08, 0,15 and 0,23. For the characterization of the samples was employed the scanning electron microscope, density measurements and particles size distribution analyze. Actual results show that after the addition La₂ O₃ to lead titanate increases densification. (author)