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.

RESUMO As soluções sólidas de titanato de zirconato de chumbo, Pb(Zr1-xTix)O3 – PZT, são amplamente reconhecidas por representar um grupo especial de materiais ferroelétricos com várias aplicações potenciais em eletro-cerâmica e (micro) dispositivos eletrônicos. A cerâmica PZT é produzida por reação em estado sólido (via convencional) e temperaturas frequentemente acima de 1200 °C. Como conseqüência, o custo do produto cerâmico é caro. Apresentamos aqui as condições de síntese e processamento da cerâmica PZT 52/48 (x = 0,48), na qual foi possível reduzir a temperatura de sinterização para cerca de 900 ° C. Aplicamos uma rota para a obtenção de cerâmica ferroelétrica PZT52/48 através da sinterização de pós nanométricos preparados pelo método de síntese de precursores poliméricos (método de Pechini modificado). A sinterização foi realizada a uma temperatura de 900ºC por 2 horas e as amostras obtiveram 96% de sua densidade teórica e tamanho médio de grão de 1,3 µm. A permissividade elétrica das cerâmicas, estudada por espectroscopia de impedância, apresentou temperatura de Curie em torno de 390 ºC. As curvas da histerese ferroelétrica revelaram que a polarização remanescente é de 3,2 μC/cm2 e o campo coercitivo é de 10 kV/cm a 60 Hz. Todos os resultados e caracterizações mostraram que as amostras de PZT obtidas com a via polimérica são eficientes como as preparadas no protocolo SSR convencional.

ABSTRACT Lead zirconatetitanate solid solutions, Pb(Zr1-xTix)O3 – PZT, are widely recognized for representing a special group of ferroelectric materials with various potential applications in electroceramics and (micro)electronic devices. The PZT ceramics is produced by solid state reaction (conventional route) and temperatures frequently above 1200 °C. As a consequence, the cost of ceramic product is expensive. Herein, we present the synthesis and processing conditions of PZT52/48 (x = 0.48) ceramics in which it was possible to lower the sintering temperature down to around 900°C. We have applied a route for PZT52/48 obtaining ferroelectric ceramics through sintering of nanometric powders prepared by the polymeric precursor synthesis method (modified Pechini’s method). The sintering was achieved with a temperature of 900ºC for 2 hours and the samples got 96% of their theoretical density and 1.3 mm mean grain size. The electrical permittivity of the ceramic plates, studied by impedance spectroscopy, presented Curie temperature around 390 ºC. Ferroelectric hysteresis measurements revealed that the remnant polarization is 3.2 μC/cm2 and coercive field is 10 kV/cm at 60 Hz. All results and characterizations have shown that the PZT samples obtained with the polymeric route are efficient as the ones prepared in the conventional SSR protocol.

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.