AbstractA series of LaCo1-xRhxO3 (x=0-1) samples and La1-ySryCo1-xRhxO3 (y = 0.05, 0.15 and x = 0.1-0.3) samples were prepared to study the effect of Rh substituion for Co in the four component system and Sr substitution for La in the five component system on the crystal structure and thermoelectric performance of the LaCoO3. At Rh substitution for Co of x=0.2 greater, the crystal structure shifts from rhombohederal (LaCoO3) to orthorhombic (LaRhO3). Thermoelectric evaluation revealed that Rh doped samples (0.3 <x <1) show large positive seebeck coefficients indicating a P-type conduction in the temperature range of the tests (273 to 775K). Rh substitution for Co decreases thermal conductivity, increases Seebeck coefficient and consequently increases the theroelectric figure of merit ZT. Sr substitution for La increases thermal and electrical conductivity and consquenently negligiblely decreases the seebeck coefficient. A thermoelectric figure-of-merit (ZT) around 0.075 has been achieved for LaCo0.5Rh0.5O3 at 775 K, and is expected to be above 0.1 at 1000 K. Sr substitution improved the TE properties throughout the lower temperature range with a ZT =0.045 observed for La0.95Sr0.05Co0.9Rh0.1O3 at 425 K and ZT = 0.05 for La0.85Sr0.15Co0.5Rh0.5O3 at 775 K. These findings provide new insight into thermoelectric perovskite oxides containing rhodium and strontium.
Crystal structure and thermoelectric performance of p−type Bi0.86Ba0.14CuSeO/Cu2−Se composites
