In present work, erbium-doped PZT 52/48 ceramics at sites A and B were prepared by the Pechini method in order to study their dielectric properties. The aim was investigated the dielectric anomalies of interfacial origin in these ferroelectrics. The ceramics were also submitted to electrical measurement analysis. The dielectric response of the grains showed characteristics of materials that follow Curie-Weiss law which is typical of ferroelectrics. In high temperatures and low frequencies, it was detected the dielectric anomaly phenomenon for the ceramic samples. Impedance spectroscopy analyzes through equivalent circuit (brick-layer model), grain and grain boundary in series, exposed a predominance of dielectric properties of intergranular interfaces as the cause of this anomaly. The electrical characterization showed a peculiar ferroelectric-paraelectric phase transition around 390 °C for both samples.

The effect of Er on the structural and electrical properties of doped PZT 52/48 ceramics has been studied in this work. The ferroelectric properties (permittivity, ferro-paraelectric phase transition and hysteresis) of such materials are thus found to be strongly dependent on the degree of densification and structural phase development during sintering at high temperatures. In particular, the nature of the ferroelectric to paraelectric phase transition is in these materials that can be represented through the Curie-Weiss Law equation modified, appropriate for the characterization diffuse transitions. The substitution of Er3+ for (Zr,Ti)4+ is found to induce strong diffuse phase transition in these materials. The electrical properties reported in this work are in magnitude comparable to those exhibited by PZT52/48 materials.

The scientific community has shown a growing interest in relating to the ferroelectric materials and it has made an effort to develop them. Among these several ferroelectric materials, we proposed to investigated Pb(ZrTi)O3 doped with distinct Er+3 concentrations. Our aim was to investigate how the erbium affects the PZT electrical properties. To determine the ideal sintering temperature of our ceramic samples, the dilatometry tests were performed. These results have showed that the erbium caused a change in sample densities (91.9% < ρ < 99.0%) as compared to undoped PZT sample. Furthermore, the X-ray diffraction results indicated that all samples are monophasic and peaks are indexed to tetragonal crystalline structure. According to these also results, there was an increment of the parameter a and a reduction of parameter c as compared to undoped PZT sample. On the other hand, the average grain size have decreased with the increment of erbium content. The electrical characterization of ours ceramics showed a peculiar ferrelectric-paraeletric phase transition around 390 ºC. Finally, the ferroelectric hysteresis measurements for doped samples in site A have revealed that remnant polarization and coercive field values depend on content. Whereas, doped samples in site B, the corresponding values are similar.

Several reports describing Superconducting Fault Current Limiter (SFCL) containing members of the bismuth or yttrium ceramics were already described. However, none of these included the mercury and samarium cuprates. Consequently, we have conducted a study of a resistive-type superconductor fault current limiter based on Hg0.82Re0.18Ba2Ca2Cu3O8+d samples and SmBa2Cu3O7-d ceramics. All polycrystalline samples were prepared by solid-state reaction method using commercial oxide and carbonate powders. The superconducting ceramic with 2.4 × 2.6 × 6.0 mm³ dimensions was set up such that the electrical current flew through the area of 2.6 × 6.0 mm². All measurements were done at 77K and without applied magnetic field (Happ = 0). In the case mercury sample, the fault current of 16.1 Apeak was reduced to 8.1 Apeak by the superconducting element and sustained for 100 ms. The prospective/limited of current ratio observed in this experiment was ~ 2.0, as considered a 2.4 mm pellet thickness. When the test was realized with the samarium sample, the prospective/limited current ratio observed was approximately 1.2, for same ceramic thickness. The tests confirmed the capability of the resistive type SFCL to limit the fault current. These results open the possibility of future investigations into SFCL devices based on those superconducting ceramics in low power electronics and electrical motor.

Hg based superconducting ceramics present the highest critical temperatures ever reported, particularly the phase 1223 with the highest Tc so far obtained -135 K. However, these compounds are obtained by a complex synthesis route and suffer degradation at ambient atmosphere. This disadvantage may be overcome by doping with an appropriate amount of Re. Samples of nominal composition Hg0.82Re0.18Ba2Ca2Cu3O8+δ having different oxygen contents were studied by X ray absorption and diffraction techniques. Using XANES we determined the Re valence = +7 in an octahedral distorted coordination. We determined the distances of Re-O bonds (1.85 Å and 2.10 Å) by EXAFS. XRD Rietveld fits showed segregation of two superconducting phases with distinct lattice parameters. The main phase is associated with Hg, Re-1223 with higher oxygen content, and the secondary superconducting phase is related to undoped Hg-1223.