Production of multifuctional ceramic composites: bulk materials and thick films

MULTIFERROIC COMPOSITE BILAYER FILMS BY ELECTROPHORETIC DEPOSITION. In the recent years the interest of the research community towards multiferroic composite materials was growing fast [1,2]. The cross coupling effects that can occur between the order states facilitates the conversion between energies stored in magnetic and electric fields and it makes multiferroic materials fascinating for the modern technology requirements of multifunction, integration and high performance devices. In this work we have been focused on thick films. Electrophoretic deposition (EPD) was applied to prepare multiferroic composite bilayer thick films based on piezoelectric phases and cobalt ferrite. The deposition were made from colloidal suspensions in ethanol keeping constant voltage and recording the current. Good adhesion and compaction of the green film were achieved by optimization of deposition voltage and time while high density of the film and minimized interphase reactions occurred after sintering. The chemical activity between the two layers was controlled through the batches composition and it could lead to the synthesis of complex engineered structures. The deposited volume, the mixing of dielectric and magnetic phases and the density and ordering of the films have been verified by electron scanning microscopy after heat treatment. The piezoelectric properties and the magnetic one were measured on the sintered films. MAGNETO DUAL-COMPOSITE CERAMIC MATERIALS BASED ON PZTN-CFO COMPOUNDS In the recent years the interest of the research community towards multiferroic composite materials was growing fast [1,2]. The cross coupling effects that can occur between the order states facilitates the conversion between energies stored in magnetic and electric fields and it makes multiferroic materials fascinating for the modern technology requirements of multifunction, integration and high performance devices. In this work we have been focused on the solid state process to prepare particulate composite based on PZTN-CFO compounds. The synthesis, milling and sintering of the powders mixture, were optimized to achieve a proper dispersion of the ferromagnetic phase in the ferroelectric matrix. The magnetic-electric coupling of the fully densified samples were characterized through the keer effect. [1] N.A. Spaldin, M. Fiebig, Science 309 (2005) 391. [2] R. Ramesh, N.A. Spaldin, Nat. Mater. 6 (2007) 21.