Enhanced electrical transport by texture modulation and co-doping for Ca3Co4O9+δ materials

Abstract

The powders as well as the texture modulated Ca2.8BaxPryCo4O9+δ (x, y=0, 0.05, 0.1, 0.15 and 0.2) bulk materials are prepared via solid state reaction, sol–gel and spark plasma sintering method. The powder and bulk materials are analyzed with regard to their phase composition and microscopic character by X-ray diffraction (XRD) and scanning electron microscope (SEM). The thermoelectric transport properties of the bulk materials are measured and investigated. The results show that the plate-like powders with uniform particle size tend to align regularly rather than the powders with anomaly shape and particle size distribution by spark plasma sintering method. The bulk materials co-doped by elements with lower electronegativity tend to form better texture rather than that of the bulk materials co-doped by elements with higher electronegativity via spark plasma sintering method. The resistivities and Seebeck coefficients are in negative accordance to the bulk material texture as a whole, and the carrier transport mechanism is not influenced. The electrical performance is tuned with optimized power factor 462μWm−1K−2 at 973K for Ca2.8BaxPryCo4O9+δ (x=y=0.1) bulk materials.