In this study, well-crystallized black phosphorus nanosheets are obtained via shock-induced phase transformation. Red phosphorus powder is filled in a sample container and subjected to high shock pressure and temperature using a shock-driven flyer. Moreover, flyer impact velocity is adjusted to investigate the influence of shock pressure and temperature on the phase transformation of red phosphorus. The recovered black samples are characterized via multiple techniques, such as X-ray diffraction, Raman spectroscopy, scanning electron microscopy, transmission electron microscopy and atomic force microscopy. The characteristic results demonstrate the presence of black phosphorus nanosheets with a lateral size of 0.5–20 μm and a thickness of 1.5–50 nm. Moreover, the results also confirm the critical influence of the shock pressure on the micromorphology of the recovered samples. The increase of shock pressure thickens the formed black phosphorus nanosheets and decreases their lateral size. In addition, the formation mechanism of black phosphorus nanosheets by shock-induced phase transformation of red phosphorus is carefully analyzed. This research provides a new method to prepare gram-scale black phosphorous nanosheets through shock treatment for the first time.
Yimou Fu,Xiaocheng Hu,Yide Liu,Peng Wang,Shuo Chen,Haofei Zhou,Honghui Yu,Shaoxing Qu,Wei Yang
Cavitation in soft materials attracts many attentions due to its importance for a range of biomedical problems and applications, such as cavitation-induced traumatic brain injury, high-intensity focused ultrasound lithotripsy, and the treatment of tumors. However, existing studies are mainly focused on the deformation behavior of a single bubble. The dynamic configuration and the failure process of multiple bubble interactions, which are significantly different from those of a single bubble, remain largely unknown. Here, we performed experimental and analytical studies to investigate the impact-induced interactions of bubbles in soft materials, where bubbles of controllable size and spacing were introduced with the aid of a highly efficient rheology modifier, namely carbomer. A drop tower system paired with a high-speed camera was utilized to conduct impact tests and concurrently visualize the evolution of the bubble configuration. A theoretical model containing pressure radiated by bubbles is proposed to predict the spherically symmetric deformation of multi-bubble interactions, as well as the inhibition between bubbles during deformation. A combination of energy-based strength theory and finite element analysis is used to reveal the squeeze and coalescence mechanisms of the bubbles. The failure of soft material is shown to depend on stress triaxiality ; in particular, the material can rupture at unloading and under a stress lower than the historic maximum. A phase diagram was drawn to predict the critical impact loads for bubble coalescence at different conditions. Our work provides a promising clue to the understandings for the interactions and coalescence behavior of bubbles those ubiquitously exist in natural and artificial soft materials.
危险品化学品经营许可证（带存储）