Modulating trap levels via co-doping Ca2 + /Si4+ in LiTaO3:Pr3+ to improve both the intensity and threshold of mechanoluminescence

Abstract

We report a novel mechanoluminescent phosphor Li1−xCaxSixTa1−xO3:0.01Pr3+ (x = 0–0.04). The crystal structure, photoluminescence (PL), optical diffuse reflectance spectra, afterglow (AG), fluorescence decay curves, and mechanoluminescence (ML) properties were investigated. To clarify the defect types and the mechanoluminescence mechanisms, an X-ray photoelectron spectroscopy (XPS) and thermoluminescence curve (TL) were measured. The dopants Ca2+ and Si4+ ions occupied the Li+ and Ta5+ sites, respectively. An optimal sample Li0.98Ca0.02Si0.02Ta0.98O3:Pr3+ was obtained with great enhancement in mechanoluminescence intensity, higher than that of non-doped sample LiTaO3:Pr3+ by 262%. And the compression threshold, over which the ML intensity could not maintain the linear increase, has also been greatly improved. Furthermore, the stable output of Tribo-L was achieved, which was visible to the naked eye. A probable mechanism was proposed to illustrate the mechanoluminescent process in Li1-xCaxSixTa1-xO3:0.01Pr3 + (x = 0–0.04). The study indicates that adjusting trap distribution by substituting host ions may be a novel way to develop high-quality mechanoluminescence.