Thermal conductivity of thermoelectric clathrates
Thermal conductivity of thermoelectric clathrates
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DOI：
10.1103/physrevb.69.045107
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发表时间：
2004-01-01
影响因子：
3.7
通讯作者：
Iversen, BB
中科院分区：
文献类型：
--
作者：
Bentien, A;Christensen, M;Iversen, BB
研究了用过量Ga制备的Ba8Ga16Ge30单晶样品的输运性质。过量的Ga不仅产生p型输运性质，而且还产生热导率(Kappa)，与文献中报道的任何其他Ba8Ga16Ge30样品不同，它类似于同结构的Eu8Ga16Ge30和Sr8Ga16Ge30的热导率。这些观测结果不同于通常的假设，即Eu8Ga16Ge30和Sr8Ga16Ge30在很低的温度下的kappa是由客体原子隧穿态散射的声子决定的，因为Ba8Ga16Ge30中不存在这样的态。相反，我们提出必须考虑声子载流子散射才能解释低温下的卡帕现象。输运数据还表明，在中温下占主导地位的共振散射强烈地依赖于载流子浓度。
Transport properties of Ba8Ga16Ge30 single-crystalline samples prepared with an excess of Ga are presented. The excess Ga does not only produces p-type transport properties but also a thermal conductivity (kappa) that, unlike in any other Ba8Ga16Ge30 samples reported in the literature, is similar to that of the iso-structural Eu8Ga16Ge30 and Sr8Ga16Ge30. These observations disagree with the commonly made assumption that kappa of Eu8Ga16Ge30 and Sr8Ga16Ge30 at very low temperatures is determined by phonons scattered from guest atom tunneling states, since such states are believed to be absent in Ba8Ga16Ge30. Instead we propose that phonon charge carrier scattering must be considered in order to explain kappa at the low temperatures. The transport data also suggest that the resonant scattering, which dominates at intermediate temperatures, strongly depends on the charge carrier concentration.