In Situ Surface Exsolution of Chang'e-5 Lunar Soil Architected by the Trinity Effect of Electron Beam

It is known that the interaction between electron beam and material surface enables a variety of physical phenomena, which hold significant inspiration for functional application. Herein, the process of in situ surface exsolution was observed and documented for the basalt phase in the Chang'e-5 lunar samples via scanning electron microscopy. Energy dispersive x-ray spectroscopy analysis confirmed the main existence of metal oxides such as plagioclase and pyroxene. Under electron beam irradiation, these components have undergone in situ dynamic mass loss and radiation decomposition, leading to an interesting in situ surface exsolution, as the energy of the electron beam exceeds the dissociation energy of metal-oxide bonds. It is clarified that the thermal effect of the electron beam is negligible under the experimental conditions. Alternatively, the “trinity” of electron beam-induced electric field-radiolysis-electron beam deposition is the key factor driving the surface exsolution. Our result not only deepens our understanding of the physical and chemical properties of lunar soil but also lays the groundwork for future applications of lunar soil for functional application.