Preparation And Properties Of ABAl₃O₇?A=Ca,Sr;B=Y,La? Based Mechanoluminescence Materials

Mechanoluminescence?ML?refers to the phenomenon of light emission caused by mechanical stimulation of materials such as grinding,extrusion,impact,and friction.MLmaterials have great application value in mechanical sensing,engineering and biological structure damage detection,stress recording,internal stress detection,and wind energy utilization.Its research has received extensive attention in recent years.In order to enrich the structural system of ML materials and improve the MLmechanism,this article has carried out research from the following aspects:?1?CaYAl₃O₇,CaLaAl₃O₇ and SrLaAl₃O₇ three kinds of ABAl₃O₇?A=Ca,Sr,B=Y,La?based ML materials were synthesized by solid-state reaction.The photoluminescence spectrum shows that under excitation of wavelengths around 350 nm,all three host materials exhibited blue luminescence at about 425 nm.The three host powders were composited with polydimethylsiloxane?PDMS?to fabricate further ML composite elastomers.When a certain mechanical force was applied,all three host composite elastomers showed blue ML peak at 425nm..Through the analysis of the thermoluminescence spectra before and after stress,the mechanoluminescence mechanisms of the three substrates were explained.?2?The blue luminescent material CaYAl₃O₇:Ce³⁺samples with high brightness ML properties were prepared by high temperature solid-state method and were composited with PDMS to prepare CaYAl₃O₇:Ce³⁺/PDMS ML elastomers.After analyzing the fluorescence spectrum,it was found that the blue light emission was mainly attributed to the 5d?4f transition of Ce³⁺.By adjusting the concentration of doped rare earth ions,it was found that when the concentration of Ce³⁺was 4%,the photoluminescence and ML intensity of the sample were the highest.Comparing the luminescence intensity of the sample with the reported ML material ZnS:Cu,the ML intensity of CaYAl₃O₇:Ce³⁺is significantly stronger under the same test conditions.Through the analysis of the thermoluminescence spectra before and after stress,the basic principle of the ML of CaYAl₃O₇:Ce³⁺was explained.The strain response of CaYAl₃O₇:Ce³⁺/PDMS ML elastomers was studied.It was found that the ML intensity showed a tendency of increasing first and then decreasing,and the strain that produced the strongest emission was 10%.In order to obtain greater responsiveness,the CaYAl₃O₇:Ce³⁺is composited with highly elastic silica gel and the mechanical emission tendency obtained is the same as that of the CaYAl₃O₇: Ce³⁺/PDMS composite elastomer,which can produce the strongest emission strain of 150%.?3?CaLaAl₃O₇:Tb³⁺series green ML materials were synthesized by high-temperature solid-state method,and CaLaAl₃O₇:Tb³⁺/PDMS composite elastomers were further prepared.By observing and analyzing the fluorescence spectrum,the experimentally obtained emission peak can correspond well with the characteristic emission peak of Tb³⁺.By adjusting the concentration of doped rare earth ions,it was found that when the concentration of Tb³⁺was 6%,the ML emission intensity of the sample was the highest,which was consistent with the theoretically calculated quenching concentration.The luminescence intensity of the sample was compared with that of the well-characterized green ML material ZnS:Cu.During the experiment,it was found that CaLaAl₃O₇:Tb³⁺/PDMS and CaLaAl₃O₇:Tb³⁺/silica gel composite elastomers exhibited a certain dependence on tensile strain.With the increase of the strain,the ML intensity shows a trend of increasing first and then decreasing.The strains that produce the strongest emission are 25%and250%respectively.The basic principle of mechanical emission of CaLaAl₃O₇:Tb³⁺was explained by analysis of the thermoluminescence spectra before and after stress.Using the difference in the strain response ability of CaYAl₃O₇:Ce³⁺and CaLaAl₃O₇:Tb³⁺,two kinds of ML powders were simultaneously compounded in PDMS or silica gel,the mechanical luminescence color from blue to green was achieved during the whole process of stretching and emitting light of the elastomer.Evolution has led to the development of a stretch-chroma flexible device based on mechanical luminescent materials.