Institut für Anorganische Chemie und Analytische Chemie der Johannes Gutenberg-Universität, Duesbergweg 10-14, D-55099 Mainz, Germany.
J Am Chem Soc. 2012 Apr 25;134(16):7147-54. doi: 10.1021/ja301452j. Epub 2012 Apr 12.
Engineering nanostructure in bulk thermoelectric materials has recently been established as an effective approach to scatter phonons, reducing the phonon mean free path, without simultaneously decreasing the electron mean free path for an improvement of the performance of thermoelectric materials. Herein the synthesis, phase stability, and thermoelectric properties of the solid solutions Cu(2+x)Zn(1-x)GeSe(4) (x = 0-0.1) are reported. The substitution of Zn(2+) with Cu(+) introduces holes as charge carriers in the system and results in an enhancement of the thermoelectric efficiency. Nano-sized impurities formed via phase segregation at higher dopant contents have been identified and are located at the grain boundaries of the material. The impurities lead to enhanced phonon scattering, a significant reduction in lattice thermal conductivity, and therefore an increase in the thermoelectric figure of merit in these materials. This study also reveals the existence of an insulator-to-metal transition at 450 K.
在大块热电材料中进行纳米结构工程最近已被确立为一种有效的方法，可以散射声子，减小声子平均自由程，同时不降低电子平均自由程，从而提高热电材料的性能。本文报道了固溶体 Cu(2+x)Zn(1-x)GeSe(4)（x = 0-0.1）的合成、相稳定性和热电性能。Zn(2+) 被 Cu(+) 取代会在系统中引入空穴作为载流子，从而提高热电效率。通过在较高掺杂含量下的相分离形成的纳米级杂质已被确定，并位于材料的晶界处。这些杂质导致声子散射增强，晶格热导率显著降低，从而提高了这些材料的热电优值。本研究还揭示了在 450 K 处存在绝缘-金属转变。
