Effect of GaSb Addition and Sb Doping on the Thermoelectric Properties of Mg2Si0.5Sn0.5 Solid Solutions

摘要:

利用B2O3助熔剂法结合热压法制备了Mg2Si0.487-2xSn0.5(GaSb)xSb0.013 (0.04 ≤ x ≤ 0.10)固溶体。X射线衍射结果表明样品呈单相。Sb掺杂有效提高了样品的电导率。随温度升高，Mg2Si0.487-2xSn0.5(GaSb)xSb0.013 (0.04 ≤ x ≤ 0.10)样品的电导率降低而塞贝克系数升高。随GaSb含量的增多，样品的电导率呈现出先增大后减小的变化趋势。所有样品中Mg2Si0.287Sn0.5(GaSb)0.1Sb0.013具有最低晶格热导率，其室温晶格热导率比Mg2Si0.5Sn0.5[11]低15%。由于电导率较高使Mg2Si0.327Sn0.5(GaSb)0.08Sb0.013具有最高热电优值，在720 K达到0.61，显著高于基体Mg2Si0.5Sn0.5[11]的最高热电优值0.019

Abstract:

Mg2Si0.487-2xSn0.5(GaSb)xSb0.013 (0.04 ≤ x ≤ 0.10) solid solutions were synthesized by a B2O3 flux method followed by hot pressing. X-ray power diffraction analysis confirms that single-phased samples are obtained. It is found that the Sb-doping effectively enhances the electrical conductivity. The Seebeck coefficients increase while the electrical conductivity decreases for Mg2Si0.487-2xSn0.5(GaSb)xSb0.013 with the increase of temperature. With increasing of GaSb content the electrical conductivity first increases and then decreases. Among all the samples, Mg2Si0.287Sn0.5(GaSb)0.1Sb0.013 sample has the lowest lattice thermal conductivity which is about 15% lower than that of Mg2Si0.5Sn0.5 [11] at room temperature. A maximum dimensionless figure of merit of 0.61 at 720 K has been obtained for Mg2Si0.327Sn0.5(GaSb)0.08Sb0.013 mainly due to its high electrical conductivity, which is obviously higher than that (0.019 at 540 K) of Mg2Si0.5Sn0.5 [11]