Preparation,Properties And Mechanics Sensing Of ZnS:Mn²⁺ Mechanoluminescent Materials

Triboluminescence is the phenomenon that materials could emit light when stimulated by mechanical behaviors,such as friction,scratching,squeezing,impacting,stretching,compression,etc.It can also be called mechanoluminescence.However,since this phenomenon has been discovered,it is more like the expression of triboluminescence.Triboluminescent materials have great application value in lighting,display systems,mechanical sensors,aerospace and military damage detection,ceramic material crack monitoring,etc.In recent years,the research on triboluminescent materials has become more and more extensive and profound.However,the current research on triboluminescence still lacks the depth of theoretical and the breadth of application development.Based on the most typical triboluminescent material ZnS:Mn²⁺,this thesis studies the luminescence characteristics,luminescence mechanism and application of triboluminescent material.The main contents of this paper can be divided into the following three aspects:?1?ZnS:Mn²⁺triboluminescence powder of zinc blende structure was synthesized by high temperature solid phase method,and the doping concentration of Mn²⁺was 0.6%-2.8%.The UV-Vis absorption spectrum test confirmed that Mn²⁺has been incorporated into the ZnS crystal and replaced the Zn²⁺lattice.The photoluminescence spectrum shows that in addition to the orange-yellow light emission at 585 nm of the ⁴T₁?⁶A₁ electron transition of Mn²⁺,there is also light emission at 470 nm due to zinc vacancy.ZnS:Mn²⁺was further compounded with epoxy resin material to prepare a hard triboluminescent elastomer.Under the effect of applied stress,the hard elastomer only exhibited orange-yellow triboluminescence at585 nm.And the optimal Mn²⁺doping concentration of ZnS:Mn²⁺for photoluminescence and triboluminescence is 1.8%and 0.9%,respectively.Through the thermoluminescence test,the changes of traps and carriers before and after mechanical stimulation of ZnS:Mn²⁺were analyzed,and the triboluminescent mechanism of ZnS:Mn²⁺was discussed in detail.?2?ZnS:Mn²⁺triboluminescent powders of sphalerite and wurtzite were synthesized by high-temperature solid-phase method,and the doping concentration of Mn²⁺was 1.0%.Composite ZnS:Mn²⁺of sphalerite structure with epoxy resin was used to prepare hard triboluminescent material.Two different mechanical stimuli were respectively applied to the ZnS:Mn²⁺/epoxy composite material:when a load of1-10N was applied to the composite material on the rotating friction test machine,the triboluminous intensity was linear with the load in a certain load range;on the universal testing machine,gradually increase the pressure on the composite material to 2000N.It is found that the triboluminous intensity increases linearly with the pressure in the range of 0-1300N.In addition,ZnS:Mn²⁺of wurtzite is compounded with PDMS to prepare a soft triboluminescent materials.Two different mechanical stimuli?friction force and compression stress?were applied to the ZnS:Mn²⁺/PDMS composite respectively.It can also be seen that the triboluminous intensity is increases linearly with the mechanical stimulus.Studying the relationship between the mechanical stimulation and the triboluminous intensity of ZnS:Mn²⁺triboluminescent materials can guide the application development of the triboluminescent materials in the field of mechanical sensors.?3?This work designed a mechanical sensor with a completely new structure.Through the design of the sandwich structure composed of stripes and sponges,three different mechanical stimuli?friction force,tensile stress,and pressing stress?were distributed to the three different layers of the device.Then,BSSON:Eu²⁺?green triboluminescence?composite material which is sensitive to friction is selected as the friction sensing layer,and MCP:Eu²⁺?blue triboluminescence?composite materia which is sensitive to tensile stress is used as the tensile/bending sensing layer.The ZnS:Mn²⁺?orange-yellow triboluminescence?composite material which is sensitive to pressure is used as the pressure sensing layer.The luminous response of the device under different mechanical stimuli was tested,and it was found that the mechanical sensor device can clearly distinguish different mechanical stimuli and monitor the trajectory of the mechanical stimuli.The sensor device is installed on the finger of the prosthesis as a smart skin or placed under water to work,it can still perform perfectly,and has good resistance to mechanical fatigue.It is believed that this excellent multifunctional mechanical sensor device has strong application prospects in wearable medical systems,intelligent robots and other fields.