Thermoelectric Properties of Bi2-xSmxCa2Co2Oy (x=0.00, 0.01, 0.02, 0.03)

In this paper, the polycrystalline samples of Bi2-xSmxCa2Co2Oy (x = 0.00, 0.01, 0.02, 0.03) were prepared using conventional solid state reaction method. The X-ray Diffraction (XRD) results showed that all samples were found to be single phase. The lattice parameters of Bi2-xSmxCa2Co2Oy samples and relative densities decreased slightly with increase in Sm content, whereas the angle decreased with the increasing x content. The decrease of the b(RS)/b(CoO2) corresponds to the increasing Sm content. The Seebeck coefficient and resistivity increased with increasing Sm content. The substitution of trivalent Sm3+ for trivalent Bi3+ may decrease the hole concentration and mobility of the system, which also can lead to an increase in the Seebeck coefficient and resistivity. The Sm substitution for Bi leads to a decrease in the size of particle, which increased the scattering of charge carriers across grain boundaries. Among all the samples, Bi1.97Sm0.03 Ca2Co2Oy exhibited the highest power factor of 5.4 x 10(-5) Wm(-1)K(-2) at 752K. These results suggest that the Sm is an effective substitution element for improving the thermoelectric properties of Bi2Ca2Co2Oy.