J. A. Eiras

Publications (2)4.71 Total impact

• Article: Grain growth kinetics and electrical properties of lanthanum modified lead zirconate titanate (9/65/35) based ferroelectric ceramics

  R. Alvarez Roca, E. R. Botero, F. Guerrero, J. D. S. Guerra, D. Garcia, J. A. Eiras
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  ABSTRACT: The influence of the microstructural characteristics on the dielectric and electrical properties has been investigated for Nd ³⁺ doped lanthanum modified lead zirconate titanate ferroelectric ceramics, obtained by the conventional solid-state reaction method, by taking into account different sintering conditions. The grain growth mechanism has been investigated and a cubic-type grain growth law was observed for samples with grain size varying from 1.00 up to 2.35 μ m . The porosity and grain size dependences of the phase transition parameters, such as the maximum dielectric permittivity and its corresponding temperature ( ε_m and T_m , respectively) were also investigated. The ac conductivity analyses followed the universal Jonscher law. The behavior of the frequency exponent (s) was analyzed through the correlated barrier hopping model. Both ac and dc conductivity results have been correlated with the observed microstructural features.
  Journal of Applied Physics 02/2009; · 2.17 Impact Factor
• Article: Effect of the sintering conditions on the electrical properties of Nd3+ modified PLZT ceramics

  R Alvarez Roca, E R Botero, F Guerrero, J D S Guerra, D Garcia, J A Eiras
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  ABSTRACT: The effect of the sintering method on the microstructural and electrical properties of (Pb0.89Nd0.02La0.09)(Zr0.65Ti0.35)O3 (PNLZT) ceramics was studied by impedance spectroscopy. Structural and microstructural analyses were performed using x-ray and scanning electron microscopy techniques. Two different sintering routes were employed: the conventional and the hot-pressing sintering methods. The impedance analysis provided a convincing evidence for the existence of both grain (g) and grain boundary (gb) contributions to the conduction process. An equivalent circuit for the impedance behaviour has been proposed and discussed. The variation in the sintering method produces significant changes in the grain and grain boundary conductivities. For the grain effect, the main conduction mechanism has been associated with oxygen vacancy migration. Otherwise, for grain boundary conductivity the impedance behaviour has been discussed in terms of the brick-layer and the constriction resistance models (BLM and CRM, respectively).
  Journal of Physics D Applied Physics 01/2008; 41(4):045410. · 2.54 Impact Factor