MgBr2 and SnCl2 inorganic crystal scintillator

We did an experiment in lab about creating a scintillator by grinding MgBr2 and SnCl2 with mortar and pestle. The solid-solid mixture gave us a yellow luminescence under UV in an UV cabinet. I'm curious about how i can find a theoretical base for luminescence. We didn't heated the mixture. How does grinding cause combining in crystal structure, or a placement of activator ion into crystal structure? Is mechanical grinding alone able to do that? or is there another mechanism? In which title should i search this in?