无机clathrate结构化合物是非常有前景的热电材料.在镓取代的锗基clathrate结构热电材料的合成中,普遍存在锗的第二相.本研究合成了多晶Sr_8Ga_(16)Ge_(30) clathrates 结构热电材料.用X射线衍射结合样品抛光表面的背散射电子像对样品中锗相的含量进行表征.测试可知,材料表现为n型半导体,随着Ge相含量的增大,Seebeck系数绝对值增大,电导和热导率减小.功率因子最大为12.8 μW·K~(-2)cm~(-1).Sr_8Ga_(16)Ge_(30)样品在650 K的最大ZT值达到0.65.
Ga-substituted Ge based type-I clathrates with the general formula X_8Y_(16-x)Ge_(30+x) display promising thermoelectric performance. Using high purity elemental Sr, Ba, Ga, and Ge as starting materials, polycrystalline type-I clathrate compound Sr_8Ga_(16)Ge_(30) were synthesized. Ge phase was detected by XRD and EPMA. Because of the bulk effect and scattering effect, the sample with more Ge phase got lower electrical conductivity, larger absolute Seebeck coefficient and lower thermal conductivity. The power factor is up to 12.8 μW·K~(-2)cm~(-1). The calculated ZT_(max) is 0.65 at 650 K for sample 3#.
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