Mechanoluminescence Properties Of SrAl₂O₄:(Eu²⁺,Dy³⁺) Under Background Light Irradiation

Mechanoluminescence（ML）refers to the luminescence phenomenon of the solid material which induced by mechanical force.It has potential application prospect in pressure sensor,breakage sensor,impact force sensor,structure monitoring sensor and so on.In recent years,it has attracted more and more researchers’ attention.However,as the persistent luminescence（PL）intensity is related to the afterglow intensity of the long afterglow material,under the impact of the same intensity,the intensity of the luminescence intensity decays exponentially with time,it is difficult to take quantitative analysis of ML intensity,which is not conducive to the practical use.Our group has done some research on the ML,and some experimental results have been achieved.Inspired by the previous research on the SrAl₂O₄:(Eu²⁺,Dy³⁺)in the background of the study of light assisted infrared up-conversion,We solved this problem by adding the background light-assisted irradiation during the experiment.In order to improve the measurement accuracy,we have made a set of force measurement device,which greatly improves the sampling frequency.Taking the above problems as the breakpoint,we use commercially mature SrAl₂O₄:(Eu²⁺,Dy³⁺)phosphors as experimental materials.The luminescent powder was mixed with the optical epoxy resin in a ratio of 1:1 and then coated on a polycarbonate（PC）plate to prepare a fluorescent film which having a thickness of about 0.5mm.Using UV-LED light source and test device.The relationship between the drop height and the ML intensity and the effect of the falling time on the ML intensity were studied.The following conclusions are obtained:1.The PL intensity of SrAl₂O₄:(Eu²⁺,Dy³⁺)is exponentially decaying in the absence of background light-assisted irradiation.That is,the longer the decay time,the ball that drop from the same height can produce less ML intensity.2.With UV-LED irradiation,a ball falling from the same height will produce ML of the same intensity.That is,with the use of the background light we solved the problem that the ML intensity gradually decays with time.Making it possible to quantitatively analyze the magnitude of the impact force using long afterglow materials.3.Using a high sampling frequency of the data interface we obtain a more reliable experimental data.It was found that the PL intensity was linearly related to theheight of the ball,that is,the ML intensity was proportional to the energy before the ball impact occurred.