Yunqi Fang,Yang Sun,Bing Guo,Hangyan Shen,Ruirui Yang
Materials with oriented structures exhibit excellent mechanical, electrical, and tribological properties. In this study, WS 2 films with a preferred orientation along the (002) plane were prepared using shear flow technology, and the influence of polyvinyl alcohol (PVA) concentration and wedge angle on the oriented structure of the WS 2 films was systematically studied. The results indicated that the diffraction peak intensity ratio of the (002) and (103) planes of the WS 2 films (I (002) /I (103) ), increased from 46.68 to 116.11 when the PVA concentration increased from 5 to 25 g/L. When the wedge angle increased from 5° to 40°, I (002) /I (103) showed a similar trend, increasing from 80.99 to 347.22. Thus, the higher I (002) /I (103) value confirmed a preferred (002) plane orientation of WS 2 in the films, indicating that an increase in PVA concentration and wedge angle significantly enhanced the shear stress of the slurry. Under shear stress, the WS 2 particles had a tendency to orient along the shear stress direction, forming a preferred (002) plane-oriented structure. Therefore, this research may provide theoretical and technical support for preparing preferred orientation 2D materials .
Nan Xin,Yifei Li,Guihua Tang,Tian Lan,Jimin Xu,Xin Zhao,Min Zhang,Yinan Nie,Hao Shen
Thermoelectric materials have great potential in the energy recovery and environmental protection, and thermoelectric films can also effectively achieve heat dissipation of the chip through thermoelectric refrigeration. WS 2 films show good thermoelectric performance in prediction, but the figure of merit ( ZT ) of the synthesized WS 2 films still needs improvement. In this work, Cu was doped into WS 2 films by magnetron sputtering combined with chemical vapor deposition and sulfurization annealing. Cu doping narrowed the band gap and increased the hole concentration from 5.6 × 10 19 cm −3 to 2.2 × 10 21 cm −3 , greatly improved the electrical properties of WS 2 film. At 300 K, the electrical conductivity and power factor of Cu-doped films increased by 1086 % and 575 % compared to pristine WS 2 , respectively. In addition, Cu doping reduced the grain size and introduced more grain boundaries, which decreased the in-plane thermal conductivity to as low as 0.22 W m −1 K −1 at 300 K. The coupling of the electrical and thermal properties optimization greatly improved ZT . The ZT value of Cu 5.5 -WS 2 films is as high as 0.181 at 425 K. This work provides a new idea for improving the thermoelectric performance of transition metal dichalcogenides (TMDCs) films.
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