Creating Recoverable Mechanoluminescence in Piezoelectric Calcium Niobates through Pr3+ Doping

Recoverable mechanoluminescence (ML), characterized by nondestructive and repetitive luminescence in response to a mechanical stress, has shown considerable promise in a variety of practical applications including lighting and display, as well as stress sensing and imaging. However, the progress in utilizing ML processes has been constrained by the difficulties in developing new ML materials and in ascertaining ML mechanism. In this paper, we report a new strategy to constructing recoverable ML materials by doping piezoelectric hosts with luminescent lanthanide ions, which simultaneously create luminescent centers and carrier traps in the host lattice. The viability of the strategy has been confirmed by assessing a series of Pr3+ activated calcium niobates composed of mCaO·Nb2O5 (m = 1, 2, and 3). Furthermore, systematical characterizations of the series of calcium niobates also reveal an unusual host dependent ML phenomenon. Our results are expected to expand the scope of designing ML materials and to deepen our understanding of ML mechanism, thereby promoting further utilization of recoverable ML.