Synthesis And Thermoelectric Properties Of Skutterudite Compounds With Double-atom Filled

Double atoms filled single-phase M_mN_nFe_xCo_4-xSb₁₂ (M=Ba 或 Ca, N=Sm, m+n=0.3⁰.8, x=1.5) compounds were synthesized using melting reaction method, M and N were used as filling atoms. The lattice constant of M_mN_nFe_xCo_4-xSb₁₂ increased with increasing total filling fraction(m+n), and reached maximum 0.9083nm and 0.9095nm when m+n was about 0.45. The effects of double atoms filled and replacement of Fe on the structure and thermoelectric properties of compounds were investigated.For Sm_yFe_xCo_4-xSb₁₂ compounds, the electrical conductivity and carrier concentration decreased with increasing Sm filling fraction. The Seebeck coefficient increased with increasing temperature and Sm filling fraction. The lattice thermal conductivity decreased evidently, which is decreased with the Sm filling fraction. The maximum figure of merit ZT_max of Sm_0.19Fe_1.47Co_2.53Sb₁₂ is 0.55 at 750K.For Ba_mSm_xFe_xCo_4-xSb₁₂ compounds, with the same filling fraction, the electrical conductivity are intervenient between that of single atom filled compounds Ba_mFe_xCo_4-xSb₁₂ and Sm_nFe_xCo_4-xSb₁₂, and decreased with increasing Ba and Sm;The Seebeck coefficients are increased with increasing total filling fraction;And with the same filling fraction, the lattice thermal conductivity of Ba_mSm_nFe_xCo_4-xSb₁₂ is smaller than that of Ba_mFe_xCo_4-xSb₁₂ and Sm_nFe_xCo_4-xSb₁₂. The greatest ZT value of 0.72 was obtained at 800 K for Ba_0.22Sm_0.12Fe_1.43Co_2.57Sb₁₂ compound.For Ca_mSm_nFe_xCo_4-xSb₁₂ compounds, the electrical conductivity decreased with increasing Ca and Sm filling fraction;With the same filling fraction, the electrical conductivity of Ca_mSm_nFe_xCo_4-xSb₁₂ is smaller than that of Ba_mSm_nFe_xCo_4-xSb₁₂ compounds;The Seebeck coefficients are increased with increasing total filling fraction, and the influence of Sm filling fraction to the Seebeck coefficients is more notable than that of Ca. With the same filling fraction, the lattice thermal conductivity of Ca_mSm_nFe_xCo_4-xSb₁₂ is smaller than that of Ba_mSm_nFe_xCo_4-xSb₁₂. The greatest ZT value of 0.54 was obtained at 650 K for Ca_0.20Sm_0.16Fe_1.43Co_2.57Sb₁₂ compound.