The Preparation,Performance Control And Luminescence Mechanism Of Mg₂SiO₄ Thermoluminescence Dosimetry Materials

Silicates are an attractive class of materials among inorganic phosphors,especially Mg₂SiO₄ which has good thermoluminescence sensitivity after doping with rare earth ions,and can be prepared into thermoluminescence dose materials with good performance.In this paper,Mg₂SiO₄:RE?RE=Ce,Pr,Nd,Sm,Eu,Tb,Dy,Er,Tm,Yb?samples were firstly prepared by high temperature solid state reaction method,comparing the thermoluminescence spectra of pure Mg₂SiO₄ and Mg₂SiO₄:RE samples,with the incorporation of rare earth,the lattice distortion produces crystal defects which are related to the particle size of the rare earth;Two different lattice sites of Mg²⁺in Mg₂SiO₄ can be replaced by rare earth ions,so that the thermoluminescence peak position of the sample is changed;The thermoluminescence peak shifts with the wavelength in the same sample which indicating that there is a closely relationship between the rare earth luminescence and the defects;After comparing the thermoluminescence of Mg₂SiO₄:RE,the thermoluminescence of Mg₂SiO₄:Tb has the best performance,so Tb is selected as doped ion.Secondly,Mg₂SiO₄:x mol%Tb?x=0.5,1,3,5,7?were prepared by changing the preparation methods?high temperature solid state reaction method and microwave heating method?.It is found that the samples synthesized by the two methods are magnesium silicate phases from the X-ray diffraction?XRD?,and the photoluminescence and the thermoluminescencce are the f-f transition of Tb³⁺which is not easily affected by the surrounding crystal field;The luminescence intensity is stronger and the thermoluminescence response to X-rays is more sensitive which samples synthesized by high temperature solid state reaction method;The electron paramagnetic resonance spectrum measurements show that there are unpaired electrons in the lattice,and its g tensor is 1.9986.Thirdly,Mg₂SiO₄:x mol%Tb?x=0.5,1,3,5,7?were prepared by changing the starting materials?MgO and Mg?OH?₂?4MgCO₃?5H₂O as magnesium sources?.It is found that the samples synthesized using high temperature solid state reaction method and magnesium oxide as the magnesium source have better crystalline intensity from the XRD;The photoluminescence spectra of all Mg₂SiO₄ samples synthesized by two raw materials are emission of Tb³⁺;The samples synthesized with MgO have two main thermoluminescence peaks at 196?and 317?,and the thermoluminescence peaks are at 196?,245?,and 317?which samples producted by Mg?OH?₂?4MgCO₃?5H₂O respectively,it shows that the difference of the initial raw materials will affect the distribution of defects in the sample,thus affecting the peak position of thermoluminescence;Mg₂SiO₄:3 mol%Tb has the best thermoluminescence properties.Fourthly,Mg₂SiO₄:Tb,M?M=Li,Na,Ca,Al,Ga?were also prepared using two methods?high temperature solid state reaction method and microwave heating method?.Comparing the metal ion and Tb co-doped samples,it was found that the co-doping have not changed the Mg₂SiO₄ crystal phase from the results of XRD;After scanning electron microscope?SEM?testing,the microstructure of the sample synthesized by the microwave method changed from the aggregated spherical to the bulk structure;Co-doping can effectively improve the luminescence efficiency;The thermoluminescence intensity of the co-doped samples synthesized by different synthesis methods is different,Mg2SiO4:3 mol%Tb,3 mol%Na have the highest thermoluminescence sensitivity made by the microwave method,and Mg2SiO4:3 mol%Tb,3 mol%Al has the highest thermoluminescence sensitivity synthesized by high temperature solid state reaction method,and the peak intensity of 190?is the strongest and basically single peak which can be used for the development of thermoluminescence dosimeters.In summary,this paper has achieved the research on the preparation,performance control and luminescence mechanism of magnesium silicate thermoluminescence dose materials by adjusting the preparation method and raw materials,doping elements,doping concentration and co-doped metal ions.The results shown that the Mg₂SiO₄doped sample is a high-quality thermoluminescence dosing material and has potential application prospects in the field of thermoluminescence dosimetry.