Revealing the essence of luminescence energy transformation from silica surfaces

Up to now, the underlying mechanism of the energy dissipation process of mechanoluminescence (ML) is still dubious. It is challengeable and significant to take the initiative to control in terms of light intensity and colour. Here, by rubbing silica surface against other materials, we are able to detect a controllable luminous energy emission, the colour as well as the intensity of which can be dominated by the crystal structural state of silica. The results show that Purplish blue light is observed between quartz and alumina, while the light emitted from the interfaces of amorphous silica and alumina is orange red which is also affected by external force. The basics of such phenomenon are well explained by both experimental and theoretical simulation analysis. Our results show that the emitted light colour transition from purplish blue to orange red, is suggested to be strongly related to the increase of defect centers in amorphous silica resulting from the structural changes in the rubbing surface. Our work provides a promising way for controlling mechanoluminescence, as well as a deep view into the basic mechanism of ML light emission.