Research On The Optical Properties And Applications Of Nd³⁺/Cr³⁺ Doped LiGa₅O₈ Glass-ceramic

Glass-ceramics（GC）is a kind of glass with specific composition.After heat treatment,a large number of tiny crystals can be uniformly precipitated in the glass matrix,which has a unique structure different from traditional glass and also has a direct crystalline phase different from ceramics.GC not only has excellent physical and chemical stability,but also has the optical properties of nanocrystalline,and can obtain the specific optical properties by adjusting the composition.In particular,GC with near-infrared（NIR）luminescent properties have been widely studied.NIR luminescent materials have broad application potential in many fields,including new high-penetration NIR luminescent materials,which have great application prospects in biological imaging,disease treatment,communication,night vision,solar cells and so on.However,most of the existing NIR luminescent materials are fluorescent powder materials with large scattering space,which will cause serious heat accumulation when applied to NIR light-emitting diode（LED）,and can only realize optical information storage on a two-dimensional scale,which seriously limits its application scenarios.However,the GC material is a bulk material with high transparency,no significant scattering space,and is adaptable to harsh service environments,with high softening temperatures,and maintains high mechanical strength even at high temperatures.NIR light-emitting materials coupled with glass can expand their application scenarios,such as higher efficiency in NIR LED and multi-dimensional optical information storage.Therefore,people need to further explore the research of NIR GC materials.Therefore,in this work,the precursor glass was prepared by high-temperature melting and nanocrystals were precipitated by heat treatment.LiGa₅O₈ nanocrystals were precipitated in the original position of silicate glass matrix,and the optical properties of LiGa₅O₈ nanocrystals were optimized by Nd³⁺/Cr³⁺ion doping,so as to obtain high performance near infrared luminescent materials.It is applications in optical information storage and NIR LED are discussed.Specific research contents are as follows:1.LiGa₅O₈ nanocrystals were induced in situ on the glass matrix by high-energy electron beam.The phase separation,nucleation and growth of LiGa₅O₈ nanocrystals in the glass matrix can be directly observed under in situ electron microscopy.A series of uniform LiGa₅O₈:Nd³⁺GC were prepared in amorphous transparent medium by high temperature melting method and later heat treatment.The NIR luminescence peak of the GC was generated at～1060 nm,and the emission intensity at 150°C was 71%of that at room temperature.We designed a portable high-power NIR LED based on its NIR luminescence characteristics and applied it to night vision biological imaging and other fields.In addition,we obtained the LED device with hollow structure through the hollow encapsulation between the microcrystalline glass sample and the excitation chip,which effectively solved the problem of long-term heat accumulation between the luminous material and the chip under the working conditions of high-power LED.Further,we conducted heating tests on the phosphors mixed with GC and epoxy resins,and the results showed that,compared with epoxy resins,the aging and yellowing of GC seriously affected the luminous efficiency,showing almost no change under long-term high temperature conditions,and the advantages of working at high temperature.The portable near infrared LED device has good thermal conductivity and heat dissipation structure,as well as good optical thermal stability.2.LiGa₅O₈:Cr³⁺glass was synthesized by high temperature melting.LiGa₅O₈:Cr³⁺GC exhibit excellent deep trap carrier storage capability under blue light irradiation,enabling optical data writing and reading in three-dimensional space by photon trap/detrap mode.In addition,samples with high transparency and suitable traps are selected through different Cr³⁺doping concentrations and annealing temperatures.The trap depth of Cr³⁺microcrystalline glass is deep enough to maintain the luminescence intensity of photostimulation at more than 75%after 12 days of storage after writing information.In addition,the 405 and 980 nm lasers can be used to achieve controlled write,read and erase combined with transparent medium three-dimensional storage and trap modulation strategy,thus realizing information storage and information encryption in 4D mode.