Synthesis and characterization of BaTiO3 nanoparticles for nanocapacitors

NADIA MAMANA; NORA PELLEGRI

Porto

Congreso; 13th European Meeting on Ferroelectricity EMF 2015; 2015

IFIMUP-IN, FCUP - University of Porto

Regarding the issue of electronic devices there are two current tendencies, one towards miniaturization of electronic devices and other towards to the use of an environmentally friendly composition. The first one has driven the interest in developing ferroelectric materials in low dimensions. The second one has promoted the search for ferroelectric materials with lead-free compositions. In this work, we develop the preparation of lead-free BaTiO3 nanoparticles fixed and immobilized on substrates (Pt/TiO2/SiO2/Si) which then could be used in the fabrication of nanocapacitors. With this purpose we used a combination of the sol-gel method with the reverse micelles techniques. This combination was used because the sol-gel method allows obtaining compounds with high purity and low temperature synthesis and reverse micelle technique allows controlling the final size of the particles in nanoscale. The precursor solution of BaTiO3 was prepared from barium acetate aqueous solution and an alcoholic solution of titanium butoxide (IV) with acetoin as a chelating agent. Then, in order to obtain a micellar system containing precursor solution (BT), sodium dioctylsulfosuccinate (AOT) was employed as surfactant and heptane as the organic phase. Subsequently, the removal of AOT was necessary to obtain the material free of the surfactant. It was found that the addition of oleic acid prior to the surfactant extraction step is relevant to avoid the agglomeration of the nanoparticles.Thereby, this combination of methods allows obtain the precursor material of the nanoparticles suspended in a solution of heptane. Then this material was deposited on different substrates by spin coating, after the heat treatment, the nanoparticles were fixed and immobilized on the substrate. The complete characterization of the synthesis evolution and nanoparticles is presented. Several techniques were used such as UV-visible spectroscopy (UV-Vis), Dynamic light scattering (DLS), Atomic force microscopy (AFM), Scanning Electronic Microscopy (SEM), X Ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), etc. This work shows that the micellar systems have, in all synthesis stages, a lower size than 20 nm and the nanoparticles remain attached to the substrate. XRD show that the samples have a perovskite structure with a tetragonality of 1.005. Also, the nanoparticles present good electrical properties, determined by several techniques.