Pressure-induced material color change and persistent luminescence suppression in SrS:Eu2+,Sm3+ revealing coupled defect mechanisms

Pressure-induced color changing materials are rare and limited to organic molecules, coordination polymers or liquid crystals[1,2]. Here we present a unique ceramic material (SrS:Eu²⁺,Sm³⁺) with simultaneous tribochromism and pressure-sensitive persistent luminescence.  The material was prepared via microwave assisted solid state (MASS) method [2], and its color in day light changes from orange to light-purple after mechanical pressure is applied. Besides, the luminescence intensity and persistent luminescence duration decreases abruptly with increasing pressure, indicating that the defect responsible for the color change is related to defects responsible for energy storage. These effects were only observed under grinding or controlled mechanical pressure (up to 10 bar) but not under gas pressure (up to 200 bar). These remarkable dual-mode pressure-sensing capabilities—combining optical readout through both body-color change and luminescence quenching—open new pathways for developing sensitive and reusable pressure sensors.