Preparação de cerâmicas nanoestruturadas de Ca3Co4O9 para aplicação em dispositivos termoelétricos

Abstract

In this work we propose the preparation and the characterization of the Ca3Co4O9 (CCO). The CCO is a potential material to be used in the development of thermoelectric devices for energy harvesting. The CCO was prepared via the polymeric precursor method, modified Pechini. With the control of the pH of the metallic citrates we obtained nanostructured powders with different granulometries and different morphologies of grains. The powders with different characteristics were used to prepare sintered pellets via diferent pressing techniques: conventional mode and with free borders. By the diferent techniques of pressing with diferent powders we obtained pellets with different densities and texturing. These characteristics are well known to exert directly influence on the thermoelectric properties of the CCO. The analysis and the characterization of the samples were conducted via the techniques: thermogravimetry (TG) and differential thermal analysis (DTA), X-ray diffraction (DRX), Fourier-transform infrared spectroscopy (FTIR), Raman scattering spectroscopy and scanning and transmission electron microscopy (SEM and TEM).