Synergistic defect engineering and microstructure tuning in lithium tantalate for high-contrast mechanoluminescence of Bi3+: toward application for optical information display

Abstract

Mechanoluminescence (ML) materials possess the mechano-optical conversion property that can produce luminescence emission upon a mechanical stimulus. This stress-luminescence responsiveness endows ML materials with application potential for optical information display. For the existing ML materials, the consecutive and overlapped trap-depth distribution in ML materials can sustain persistent afterglow noise and hinder the recognition of ML signals continually. In this study, we designed a synergistic strategy that combines defect engineering with microstructure tuning to achieve the high-contrast ML emission of Bi³⁺ in lithium tantalite. Non-luminous Ga³⁺ ions are employed as co-dopants to tune the defect trap distribution and microstructure in Bi³⁺-doped LiTaO₃ crystals. The as-prepared Bi³⁺/Ga³⁺ codoped LiTaO₃ material showed intense high-contrast ML emission with no afterglow interference under an external mechanical stimulus. Its high-contrast ML intensity increased linearly with increasing applied force (>1200 N), showing no threshold force. The composite film combined with LiTaO₃:Bi/Ga particles can respond sensitively and notably to multifarious mechanical stimuli by radiating indigo blue ML light, including stretching, bending and friction. These discoveries provide a new research perspective to investigate stimuli-responsive luminophors toward various application requirements especially with optical information storage and display.