Many substances exhibit triboluminescence including sugar and tape. But Europium Tetrakis (Dibenzoylmethide)Triethylammonium is one of the strongest available and its glow can easily be captured by a camera.Video and text from Nurd Rage. I thought the use of a vacuum bottle to allow slow cooling and larger crystal formation was clever.
It's made by mixing 100mL of Ethanol, 2.93g of dibenzoylmethane, 1.4g of europium nitrate pentahydrate and 1.9mL of triethylamine. The mixture is heated until everything dissolves and then allowed to cool slowly to obtain crystals that are filtered off and washed with ethanol. After thorough drying they are ready for use.
A frequently asked question is if this stuff is hot when it is used. The answer is no, the crystals do not undergo a chemical transformation and thus they do not release or consume heat, but remain at constant temperature. There may be some small heating due to friction when they are broken, but that is not from the crystals or a special property of triboluminescence.
More on the discovery and use of triboluminescence of quartz crystals by ancient peoples later.