Studies On Preparation And Luminescence Characteristics Of Ca₃Sc₂Si₃O₁₂ Silicate Materials Excited By Blue Light

Solid-state lighting technology has been vigorously developed for decades,many of fluorescent materials have been continuously researched.As one of the light conversion matrix materials to be studied at early time,the silicate material with garnet structure has been continuously received by researchers since its introduction.Its family has grown continuously for decades,and it has become a fluorescent material matrix with in-depth research and wide application.The composition of the silicate garnet material has considerable flexibility.Many elements can be doped in them.The lattice parameters will change correspondingly by doping different elements,which will make certain lattice sensitive The performance of the luminescent center in this type of matrix becomes more flexible.When doped with different rare earth element ions or transition metal ions,the material will show different luminescence characteristics,and it has great performance in various wavelength bands from visible to infrared.With the development of blue excitation light sources,the study of rare earth/transition metal ion doped silicate garnet materials that can be excited by blue light has very important practical significance.The research in this article is carried out under this background.In this thesis,the garnet structure silicate Ca₃Sc₂Si₃O₁₂is used as the matrix,and the rare earth ion Ce³⁺ion and transition metal ion Cr³⁺and Mn²⁺are selected as the luminescence center to dope,supplemented by Lu-Mg modification and other methods to adjust the matrix,obtained a series of phosphors and fluorescent ceramics.Studies of the luminescence characteristics of the matrix doped with rare earth ions and transition metal ions,and the possibility of transparent ceramicization of related materials had been discussed.The specific research content and results are as follows:（1）A series of Ca_3-xLu_xSc_2-xMg_xSi₃O₁₂:y Cr³⁺near-infrared phosphors were prepared by high-temperature solid-phase method.The Ca_3-xLu_xSc_2-xMg_xSi₃O₁₂materials was completed by the Lu-Mg modification of Ca₃Sc₂Si₃O₁₂.After adding Cr³⁺ions into this material,a high-efficiency near-infrared phosphor was obtained,and its luminescence characteristics were studied.Its possible applications have been boldly speculated based on relevant data.This kind of material can be effectively excited by 450 nm blue light and emit deep red-near infrared light with a peak at 750nm～780 nm.By fixing the Cr³⁺ion concentration and fixing the degree of modification of the substrate Lu-Mg,the highest luminous efficiency Ca_1.08Lu_1.92Mg_1.92Si₃O₁₂:0.08Cr³⁺was obtained.The deep red-near infrared part of the pc-LED packaged with this material has achieved an emission power of～70 m W@100 m A and an electro-optical conversion efficiency over 30%@10 m A,which is the highest value in existing reports.At the same time,the temperature characteristics of this material are also quite excellent.If the fluorescence intensity at room temperature is used as the benchmark,when the temperature reaches～600 K,the fluorescence intensity emitted by the material can still be maintained at 50%.The material can adapt to the high temperature enviro nment that may exist in the working.（2）Using a normal camera and an infrared camera observed the illumination of specific glass sheets by a pc-LED packaged with Ca_1.08Lu_1.92Mg_1.92Si₃O₁₂:0.08Cr³⁺phosphor and the chip CHAOYUE 5730（450 nm）.By comparing the similarities and differences between different images and analyzing the characteristics of the processed images,the application potentials in machine vision and other fields are discussed.（3）Ca₃Sc₂Si₃O₁₂:Ce³⁺,Mn²⁺fluorescent ceramics were prepared by high temperature solid phase method combined with vacuum sintering method.The emission band of Ca₃Sc₂Si₃O₁₂:Ce³⁺is in the green part,and the red part is supplemented by doping Mn²⁺ions,so as to achieve higher color rendering fluorescence emission while maintaining the excellent luminescence characteristics of fluorescent ceramics.Ca₃Sc₂Si₃O₁₂:Ce³⁺,Mn²⁺series fluorescent ceramics can be effectively excited by blue light around 450 nm,and the excitation source can be either a blue chip or blue laser.Excessive Ce³⁺ions found during the excitation process are not helpful to the final fluorescence intensity,but may inhibit the emission of Mn²⁺.In the case of fixed Ce³⁺ions with a small doping amount,as the doping amount of Mn²⁺ions increases,the red light part of the sample is correspondingly enhanced.Through the combination of fluorescent ceramics and blue chip/laser,the emission spectrum under the working conditions of the simulated device was obtained,and the emission with a lumen efficiency of up to 46 lm/W and a color rendering index of Ra up to 87 was obtained.At the same time,the emission of the blue laser was adjusted.The excitation power realizes the control of the color coordinates,and emits white light with color coordinates（0.3218,0.3354）and（0.3063,0.3253）.It shows that the fluorescent ceramic has the potential to be applied to white light LED/LD lighting.Through the relationship between the emission of different peak of the sample shows potentials in measurement of temperature.（4）On the basis of work（3）,the transparency process of Ca₃Sc₂Si₃O₁₂:Ce³⁺,Mn²⁺fluorescent ceramics is further explored.As a prerequisite for high-power excitation,the transparency of fluorescent ceramics is practical significance in applications.Ca₃Sc₂Si₃O₁₂,as a cubic matrix,has a structural basis for preparing transparent ceramics.By introducing the Y element into the Ca₃Sc₂Si₃O₁₂:Ce³⁺,Mn²⁺fluorescent ceramics and using the re-firing process,the transmittance of the fluorescent ceramics with Ca_2.98Sc_1.98Si₃O₁₂:0.005Ce³⁺,0.02Mn²⁺,0.015Y³⁺has been improved.Then after polishing and other post-treatment processes,a linear transmittance of～4%translucent fluorescent ceramic sheet was getted.A 450 nm blue chip and a 455 nm laser were used to excite it,and its luminescence characteristics were studied.When using a blue light chip for excitation,the lumen efficiency of the translucent fluorescent ceramic chip can reach 104.85 lm/W@10m A,but the blue light band is obviously missing;when a 455 nm laser is used for high-power excitation(P_laser=2.19W),its lumen efficiency can also be maintained at59.13 lm/W without material damage.This proves that Ca_2.98Sc_1.98Si₃O₁₂:0.005Ce³⁺,0.02Mn²⁺,0.015Y³⁺translucent fluorescent ceramics have the conditions for high-power laser illumination regardless of their mechanical strength and luminescence characteristics.