Fig. 5: Mechanically excited multiexcitonic emissions

a ML and CL spectra of Cs₂NaScCl₆:Sb³⁺ (0.75%) crystal. Insets show the ML photographs of the crystal in the ambient light or dark under continuous grinding with a glass rod. b The cyclic stability of ML intensity in Cs₂NaScCl₆:Sb³⁺ crystal in the dark under continuous grinding and recrystallization treatment. Inset shows the schematic of reproducible ML. c ML spectra of as-prepared crystal, ground powder, and recrystallized Cs₂NaScCl₆:Sb³⁺. d TL spectra of as-prepared crystal and ground powder sample, and inset shows the TL image of the ground sample at around 395 K. e Initial ML intensity versus applied force for Cs₂NaScCl₆:Sb³⁺ crystal (top panel) and corresponding intensity decay profile (bottom panel). f ML intensity of composite films versus the grain size of single crystals under continuous mechanical excitation at 20 N. Insets show the photographs of millimeter-sized single crystals under daylight conditions. Scale bar = 1 mm. g Proposed mechanism of possible luminescence process in Cs₂NaScCl₆:Sb³⁺ crystal under mechanical excitation