부산대학교 도서관

We have studied the thermal, electrical, and thermoelectric properties of CaBiCoO (0.0 ≤ x ≤ 1.5) ceramics prepared by solid-state reactions. Phase-pure CaBiCoO solid solutions were obtained at x ≤ 0.3. The samples with 0.3 < x < 1.5 consisted of three phases: CaBiCoO, BiCaCoO, and СоО. The sample with the composition CaBiCoO consisted of two phases: BiCaCoO and CoO. The materials are p-type semiconductors with linear thermal expansion coefficients in the range (10.6-12.8) × 10 К. Their electrical and thermal conductivities are nonmonotonic functions of x, and their thermoelectric power increases with increasing x. The mixed-phase ceramics have been shown to have better thermoelectric properties: the highest thermoelectric power factor, ≈0.24 mW/(m K) at T = 1100 K, is offered by the ceramics with x = 0.9-1.0, which contain nearly equimolar amounts of CaBiCoO and BiCaCoO. This power factor is 2.5 times that of the layered calcium cobaltite CaCoO and solid solutions based on it: 0.094-0.098 mW/(m K) at the same temperature. [ABSTRACT FROM AUTHOR]