Study On Preparation And Thermoluminescence Properties Of Mn:CaF₂ Transparent Ceramics

Mn:CaF₂ materials play a very important role radiation dosimetry and other fields,because of its excellent thermoluminescence properties.Recently,the research on Mn:CaF₂ thermoluminescent materials is mostly limited to polycrystalline powder or monocrystalline materials,but there are only few reports on Mn:CaF₂ transparent ceramics.Transparent ceramics have been widely studied for its extended advantages,such as larger doping concentration with controllable distribution in the material olume,scalability to large size,low fabrication cost,good mechanical and thermal properties.Therefore,it is of great theoretical and practical value to study the abrication and thermoluminescence properties of Mn:CaF₂ transparent ceramics.In the paper,Mn:CaF₂ nanopowders doped with different Mn²⁺concentrations were irstly synthesized by chemical precipitation.The nanopowders exhibited good ispersion.Then Mn:CaF₂ transparent ceramics with better optical properties were prepared by hot pressing method in the vacuum.The mainly points of this work were summarized as follows:?1?The Mn:CaF2 nanopowders were synthesized by chemical precipitation.The effects of Mn²⁺doping content on structure,morphology and particle size of Mn:CaF₂nanopowders were analysised by XRD,SEM,TEM etc.The results show that Mn:CaF₂ nanopowders with fluorite-type structure were no any second phase appeared.It exhibited good dispersion and rare agglomeration.The doping of Mn²⁺ions leaded to the formation of the lattice distortion of CaF₂,which makes the crystallinity worse.With the increase of Mn²⁺ions,the lattice constant and grain size of Mn:CaF₂ nanopowders decreased.In addition,the particles gradually changed from ellipsoid to spherical,and the particle size tended to be consistent.?2?Mn:CaF2 transparent ceramics were prepared by hot pressing method.The effects of sintering temperature on the densification,microstructure and transmittance of the ceramics were discussed.The results show that Mn:CaF₂ transparent ceramics sintered at 900?exhibiting a more dense microstructure and best transmittance.When the temperature was below 900?,the ceramic with some residual pores was not dense enough,and the grain size was not uniform.When the temperature was above 900?,the transmittance and relative density of obtained ceramics decreased.?3?The effect of Mn²⁺doping content on the microstructure and optical properties of ceramics was investigated.It was found that with the increase of Mn²⁺doping content,the transmittance of ceramics continued to increase,while the emission intensity of ceramics first increased and then decreased,and the strongest emission intensity was obtained when doping 5%Mn.The transparent ceramics doped with 7%Mn had a higher transmittance,which reached about 54.69%at 660nm and 91.1%at 2000 nm respectively.In addition,the ceramic with a better optical transparency of showd a more compact microstructure,less residual pores,more uniform grain size.?4?Studying on the thermoluminescence properties of Mn:CaF₂ nanopowders and its transparent ceramics.The results showed that the thermoluminescence sensitivity of Mn:CaF₂ transparent ceramics was much better than that of nanopowders,the fading was smaller,and thermoluminescence signal tended to be stable after a month,which showed the better application advantage.