Spark Plasma Sintering of some Ferroelectric and Multiferroic Materials

Reference	Presenter	Authors (Institution)	Abstract
12-052	José Antônio Eiras	Eiras, J.A.(Universidade Federal de São Carlos);	Displacive ferroelectrics are the most used materials as dielectrics, ferroelectrics, piezoelectrics, pyroelectric, among others. Materials exhibiting simultaneously ferroelectric and magnetic ordering, termed multiferroics, offers the singular ability to control or sense the material polarization state with either electric or magnetic field (magnetoelectric effect). This opens the possibility to improve multifunctionalities, to develop devices for new technological applications. In the last years semiconductors ferroelectrics and multiferroics are being investigated due to their interesting photovoltaic properties, which promise to improve the efficiency of photovoltaic conversion. It is well known that in these materials most of the physical properties, such as electrical conductivity, dielectric permittivity, spontaneous polarization, domains structure, microstructure, type and concentration of defects and grain size, are strongly dependent and can be controlled through the processing procedure (sintering conditions, thermal annealing, among others). In this presentation ferroelectric (Pb(Zr0.52Ti0.48)O3 PZT) and multiferroics (Pb(Fe1/2Nb1/2)O3 PFN and Pb(Fe2/3W1/3)O3-PFW) ceramics have been prepared through different sintering procedures, Spark Plasma Sintering (SPS), Uniaxial Hot Pressing (UHP) and Conventional Sintering (CS), in order to obtain high densities samples with different kind of defects and different electric conductivity levels. Experimental results of electric, dielectric, ferroelectric and photovoltaic properties of will be presented and correlated, viewing to highlight the advantages of each sintering process. PFN and PFW samples, in contrast with PZT, obtained through the SPS present high conductivity at room temperature, as compared to those prepared by conventional and UHP sintering. Defects induced by SPS show strong influence on dielectric and photovoltaic properties, which can be modified by thermal annealing.
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