Chromism

By adding mechanical stresses to the crystalline sample, regular structures disappeared, followed by luminescent chromism from orange to yellow.

There are different types of chromism such as photochromism (induced by sunlight or UV rays), thermochromism (induced by changes in temperature), solvato chromism (induced by polarity of the solvent), hygrochromism (induced by moisture), ionochromism (induced by ions), halochromism (induced by pH value), acido chromism (induced by acids), chemochromism (induced by specifice chemical agents like dangerous gases, warfare agents, etc.) electrochromism (induced by electricity), piezochromism (induced by pressure), mechanochromism (induced by deformation of substances).