Synthesis And Thermoelectric Properties Of Skutterudite Compounds With Ca And Ce Filled

Double atoms filled single-phase p-type Ca_mCe_nFe_xCo_4-xSb₁2 compounds were synthesized using melting reaction method, Ca and Ce were used as filling atoms. The effects of double atoms filled and replacement of Fe on the structure and thermoelectric properties of compounds were investigated.The lattice constant of Ca_mCe_nFe_xCo_4-xSb₁2 increased with increasing total filling fraction(m+n), and reached maximum 0.9089nm when m+n was about 0.5. The result of Rietveld refinement indicated high reliabilities with filling fraction consistent with the ICPES analysis and Ca_mCe_nFe_xCo_4-xSb₁2 compounds possess of skutterudite structure. The thermal parameter (B) of Ca/Ce was much larger than those of Sb and Fe/Co; The specific chemical states of atoms were obtained from XPS quantitative analysis, it showed that the filling atoms tend to fill the middle of the voids of icosahedrons of Sb, preferentially.With the same filling fraction, carrier concentration and electrical conductivity of p-type Ca_mCe_nFe_xCo_4-xSb₁2 are intervenient between that of single atom filled compounds Ca_mFe_xCo_4-xSb₁2 and Ce_nFe_xCo_4-xSb₁2, and decreased with increasing Ca and Ce, especially Ce, filling fraction; The Seebeck coefficients are increased with increasing total filling fraction, and the influence of Ce filling fraction to the Seebeck coefficients is more notable than that of Ca.And with the same filling fraction, the lattice thermal conductivity of Ca_mCe_nFe_xCo_4-xSb₁2 is smaller than that of Ca_mFe_xCo_4-xSb₁2 and Ce_nFe_xCo_4-xSb₁2, furthermore, when the total filling fraction (m+n) is about 0.3 and respective filling fraction of Ca and Ce is approximately identical, the lattice thermal conductivity reached the minimum value. The greatest ZT value of 1.17 was obtained at 750 K for p-type Cao.1gCeo.12Fe_1.45Co_2.55Sb_12.21 compound.