Ⅰ型锗基笼合物Ba_8Ga_(16-x)Sb_xGe_(30)的合成及热电性能

Synthesis and thermoelectric properties of Sb-doped type-Ⅰ Ge clathrates Ba_8Ga_(16-x)Sb_xGe_(30)

用高温熔融结合放电等离子烧结(SPS)方法合成了Sb掺杂的单相n型Ba8Ga16-xSbxGe30化合物,探索了Sb对Ga的取代对其热电性能的影响规律.研究结果表明:随着Sb取代分数x的增加,Seebeck系数逐渐降低,Seebeck系数峰值对应的温度向低温方向偏移.电导率随着x的增加先增大后减小,当x=2时达到最大值.Sb取代Ga后对化合物的热性能有较大影响,其热导率和晶格热导率都有不同程度的降低.在所有n型Ba8Ga16-xSbxGe30化合物中,Ba8Ga14Sb2Ge30化合物的ZT值最大,在950K左右其最大ZT值达1·1.

The single-phase Sb-doped n-type Ba8 Ga16-x Sbx Ge30 compounds were synthesized by melting reaction combined with spark plasma sintering. Influences of substituting Sb for Ga on the thermoelectric properties of the compounds were investigated. The results indicate that with the increase of Sb substitution fraction the Seebeck coefficient is decreased gradually, and the temperature which corresponds to the peak value of Seebeck coefficient moves to low-temperature. The electrical conductivity of the compounds increases at first and then decreases with the increase of x ; when x = 2, it reaches maximum. Substituting Sb for Ga has a great influence on the thermal properties of the compounds. Both the thermal conductivity and lattice thermal conductivity decrease in various degrees. Of all n-type Ba8Ga16-x Sbx Ge30 compounds, the compound Ba8Ga14Sb2Ge30 has the greatest ZT value, the maximal value of which reaches 1.1 at about 950 K.