Fabrication and transport properties of ternary thermoelectric composites 0.7 Ca 3 Co 3.9 Cu 0.1 O 9 /0.3 Bi 2 Ca 2 Co 1.9 Cu 0.1 O y / x Ag

Ag inclusions were introduced into 0.7 Ca3Co3.9Cu0.1O9/0.3 Bi2Ca2Co1.9Cu0.1Oy composites. Characteristic diffraction peak (111) of Ag is detected. Ag inclusions are with irregular particle shape, and the largest particle is about 10 μm. As Ag content (≤ 9 wt%) increases, the electrical resistivity reduces; meanwhile, transformation from semiconductor transport to metallic transport happens. With the rise of Ag content, the Seebeck coefficient reduces in the temperature range 373 K to 773 K apparently. However, its divergence among samples gradually becomes narrow above 773 K. The highest ZT of composites reaches 0.29 at 973 K.