Preparation And Spectral Controllable Behavior Of Tri-doped Garnet Transparent Ceramics For High Power LD Lighting

With the increasing demand for high-brightness warm white light-emitting devices,the blue-driven solid-state lighting technology which combines blue laser diode（Laser Diode,LD）with fluorescent transparent ceramics arises at the historic moment.Transparent ceramic packaged laser diode has low thermal expansion coefficient and high thermal conductivity,but the current transparent ceramics have the problem of low color rendering index（CRI）due to the lack of red components.In order to obtain high quality white light for laser illumination,it is necessary to synthesize high performance red light emitting transparent ceramics.In this paper,Mn and Sm were doped into Y₃Al₅O₁₂（YAG）ceramics to improve the lack of red light in fluorescent transparent ceramics.Red light emitting transparent ceramics with high performance were prepared by a certain sintering process.The properties of the ceramics were tested by scanning electron microscope（SEM）,fluorescence spectrophotometer and other characterization methods,and their spectral controllability was studied.The specific contents and results of the work are as follows:（1）Spectral regulated behavior of Mn²⁺Doped garnet transparent ceramicsSeveral groups of Y₃Al₅O₁₂ transparent fluorescent ceramics with different concentrations of Y₃Al₅O₁₂ were prepared by solid state reaction-vacuum sintering.Its transmittance is 78.6%at 800 nm.Two main emission peaks of the ceramic were detected at 590 and 749 nm.Due to the charge compensation effect,electron cloud expansion effect and effective energy transfer,the luminescence properties of the ceramics were improved satisfactorily.The LD system made of the prepared ceramics and blue LD shows a high color rendering index of 80,a low correlation color temperature of 4098 K and a good luminous efficiency of 96.9 lm/W.（2）Preparation and Spectral controllable behavior of Sm³⁺doped Garnet transparent CeramicsTaking advantage of the multi-component doping property of ceramics,the red light components Ce³⁺and Sm³⁺in the main body of Sm³⁺,YAG matrix replaced the Y³⁺ion site in dodecahedron lattice site,and Mn²⁺replaced the Al³⁺ion site in octahedral lattice site on the basis of YAG:Ce³⁺,Mn²⁺.Under the excitation of 450 nm blue light,the characteristic emission peaks of three kinds of doped elements appeared at 540,571,593,600,619,653,668,715 and 749 nm.Due to the effective energy transfer between Ce³⁺and Mn²⁺and between Ce³⁺and Sm³⁺,the color rendering index of the prepared ceramics is increased to82.3.In addition,the lowest color temperature can reach 3894 K,which greatly improves the deficiency of lack of red light in traditional ceramics,combined with the advantages of excellent heat resistance,thermal conductivity,electrical safety and high quality luminescent properties of fluorescent transparent ceramics.The prepared high-performance red-emitting fluorescent transparent ceramics for high-power laser lighting will have a broader application prospect in the future.