The search for thermoelectric materials for power generation and for solid-state cooling have led to the increased interest of layered cobalt-containing oxides because of their thermal stability at high temperature and their desirable thermoelectric properties. This paper examines the effect of substitution of Co in the layered perovskite, Ba2Ho(Cu3-xCox)O6+y (x=0.0, 0.3, 0.4, 0.5, 0.6, 1.0). Structural analysis using the neutron Rietveld refinement technique reveals that when x = 0.4 or x < 0.4, Co mainly substitutes for Cu in the Cu-O chain site (basal plane) of the Ba2Ho(Cu3-xCox)O6+y structure. As x>0.4, a small amount of Co progressively enters in the Cu-O plane site as well. The thermoelectric properties of polycrystalline Ba2Ho(Cu3-xCox)O6+y samples were studied in the temperature range of 10K to 390 K. In general, as the cobalt content, x, increases the resistivity of these samples increases while the thermal-conductivity decreases. Among the six Ba2Ho(Cu3-xCox)O6+y compositions, the x=0.4 member gives the highest ZT of 0.018 at approximately 270 K.
Citation: Journal of Applied Physics
Pub Type: Journals
Ba2Ho(Cu3-xCox)O6+y, neutron structural study, resistivity, Seebeck coefficient, thermal conductivity, ZT