Hussain S, Lalla N P, Kuo Y-K, Lakhani A, Sathe V G, Deshpande U, Okram G S
UGC-DAE Consortium for Scientific Research, University Campus, Khandwa Road, Indore-452001, India.
UGC-DAE Consortium for Scientific Research, Kalpakkam Node, Kokilamedu-603104, India.
Phys Chem Chem Phys. 2018 Feb 21;20(8):5926-5935. doi: 10.1039/c7cp07986a.
We report the first thermoelectric properties of CuAgS, x = 0-0.75 nanocomposites, synthesized by using a facile polyol method. Systematic characterizations using powder XRD, Rietveld refinement of XRD, EDAX, XPS and Raman spectroscopy confirmed their single phase, hexagonal crystal structure with the space group P6/mmc, nominal elemental composition, valence states of the constituent elements and stoichiometric nature. The TEM images showing the CuS formation of nearly perfect hexagonal disk-like particles of average thickness 26.7 nm and breadth ranging in a few hundreds of nanometers with nanorods stacked from these hexagonal nanodisks (NDs) elongated along the c axis corroborate the FESEM images. Attributed to structural phase transition, an anomaly at 55 K is clearly observed in both the thermopower and Hall resistivity data. By increasing x, a systematic reduction in thermal conductivity was observed near 300 K. Consequently, a 50% enhancement in figure of merit was observed for CuAgS as compared to pure CuS at 300 K. These results therefore are expected to provide a new direction in improving ZT near 300 K.
我们报道了采用简便的多元醇法合成的CuAgS（x = 0 - 0.75）纳米复合材料的首次热电性能。使用粉末XRD、XRD的Rietveld精修、EDAX、XPS和拉曼光谱进行的系统表征证实了它们具有单相六方晶体结构，空间群为P6/mmc，确定了其元素组成、组成元素的价态以及化学计量性质。透射电子显微镜图像显示，硫化铜形成了近乎完美的六方盘状颗粒，平均厚度为26.7 nm，宽度在几百纳米范围内，纳米棒由这些沿c轴拉长的六方纳米盘堆叠而成，这与场发射扫描电子显微镜图像相符。由于结构相变，在热电势和霍尔电阻率数据中均清楚地观察到55 K处出现异常。通过增加x，在300 K附近观察到热导率系统性降低。因此，在300 K时，与纯硫化铜相比，CuAgS的优值提高了50%。因此，这些结果有望为在300 K附近提高ZT提供新的方向。
