Enhancement of electrical conductivity of Ca2.93Sr0.07Co4O9 thick films via hot uniaxial pressing
Résumé
Sr-doped Ca3Co4O9 thermoelectric thick films have been prepared by dip-coating technique, followed by sintering and hot uniaxial pressing. XRD patterns are very similar in both types of samples, with only differences in the relative intensity of peaks, pointing out to a better grain orientation in hot-pressed films. Moreover, SEM observation showed a drastic decrease in the hot-pressed films thickness. Electrical resistivity is decreased in textured materials due to the higher grain orientation and density, confirmed through Hall measurements. On the other hand, Seebeck coefficient is maintained practically unchanged. Power factor at 800°C is much higher in textured materials (0.44 mW/K2m) than determined in sintered films (0.30 mW/K2m), and in the order of the best typically reported in the literature (0.43 mW/K2m). © 2019 The American Ceramic Society