Research On The Construction Of Melilite Structure And Luminescent Properties Base Of Blast Furnace Slag By Doping Eu²⁺/Tb³⁺/Ce³⁺/Mn²⁺

Complex aluminosilicate high value-added functional materials have become a research hotspot.For example,high alumina blast furnace slag has ideal matrix components of solid-state photoluminescence materials,which can provide an ideal place for the luminescence center.Based on the high alumina blast furnace slag of a steel plant as the main raw material,the structure of Ca₂(Al_1-xMg_x)(Al_1-xSi_1+x)O₇melilite is studied by means of kinetics and thermodynamics,which provides an ideal micro environment for the luminous center ion and gives it photoluminescence function,and provides theoretical support and research scheme for the realization of high alumina and high value-added materials of complex aluminosilicate such as high alumina blast furnace slag.In this paper,the phase structure and luminescence characteristics of phosphors with different matrix(CM_0.25AS,CM_0.75AS and CM_0.5AS)were studied by XRD,SEM and fluorescence spectra.The structure of luminescent micro region was optimized by Eu²⁺/Tb³⁺,Eu²⁺/Ce³⁺,Eu²⁺/Mn²⁺doped Ca₂(Al_1-xMg_x)(Al_1-xSi_1+x)O₇,and the relationship between its structure and luminescence characteristics was established.1.CM_0.25AS:Eu²⁺/Tb³⁺green phosphor was prepared by high temperature melting-ice quenching-heat treatment method.According to the results of DSC thermal analysis,The crystallization temperature range of CM_0.25AS matrix is 880℃-1010℃.Compared with the luminescence properties under different heat treatment temperatures,1000℃is the best preparation temperature of crystalline phosphor.The crystal form of CM_0.25AS is layered structure,and the band gap is 3.21 ev.CM_0.25AS:Eu²⁺phosphor emits green light with a peak of about 530 nm under the excitation of 380 nm.The quenching concentration and critical distance of Eu²⁺are 0.3 mol%and 7.8?,respectively,and the thermal quenching energy barrier is 0.225 ev.CM_0.25AS:Tb³⁺Phosphor produces strong ⁵D₄→⁷F₅ electron transition emission at 542 nm excited by239 nm.The quenching concentration and critical distance of Tb³⁺ions are 1.5 mol%and 4.56?,respectively.The luminescence intensity of CM_0.25AS:1.5Tb³⁺phosphor at150℃is 89.28%of that at 30℃,and the thermal quenching energy barrier is 0.295 ev,which has good luminescence thermal stability.Blast furnace slag of steel mill was introduced into CM_0.25AS:1.5Tb³⁺as raw material to prepare luminescent materials.Through the test,it is considered that the recovery and addition amount of blast furnace slag should be controlled at about 10%2.CM_0.75AS:Eu²⁺/Ce³⁺phosphor was prepared by high temperature melting-ice quenching-heat treatment method.According to the results of DSC thermal analysis,The crystallization temperature range of CM_0.75AS matrix is 842℃-1000℃.Compared with the luminescence properties under different heat treatment temperatures,950℃is the best preparation temperature of crystalline phosphor.The crystal form of CM_0.75AS is layered structure.CM_0.75AS:Eu²⁺phosphor emits green light with a peak of about532 nm under the excitation of 385 nm.The quenching concentration and critical distance of Eu²⁺were 0.4 mol%and 7.09?,respectively.CM_0.75AS:Eu²⁺,Ce³⁺phosphor was prepared by codoping Ce³⁺ions,the quenching concentration of Ce³⁺is0.4 mol%.The energy transfer from Ce³⁺to Eu²⁺ions is studied.The main mechanism is electric dipole electric quadrupole interaction.Under the excitation of 343 nm,adjusting the doping ratio of Eu²⁺/Ce³⁺ions can make the phosphor glow from blue to green.The blast furnace slag of steel mill was introduced into CM_0.75AS:0.4Eu²⁺,0.4Ce³⁺phosphors to prepare luminescent materials.Through the test,it is considered that the recovery and addition amount of blast furnace slag should be controlled at about 10%.3.CM_0.5AS:Eu²⁺/Mn²⁺phosphor was prepared by high temperature melting-ice quenching-heat treatment method.Crystalline phosphors were prepared by heat treatment at 975℃according to DSC thermal analysis curve.Through chemical unit substitution of[Mg²⁺-Si⁴⁺]for[Al³⁺（Ⅰ）-Al³⁺（Ⅱ）]in Ca₂Al₂Si O₇,the structure unit 1(Mg²⁺→Al³⁺（Ⅰ）)and structure unit 2((Si⁴⁺→Al³⁺（Ⅱ）)are formed to constitute CM_0.5AS matrix.Upon excitation of 324 nm,the PL spectrum is a combination of blue-light emission band from Eu²⁺（I）in microstructure 1 and green-light emission band from Eu²⁺（Ⅱ）in microstructure 2.The quenching concentration of Eu²⁺ion is 0.2mol%.CM_0.5AS:Eu²⁺,Mn²⁺phosphor was prepared by codoping Mn²⁺ions,the quenching concentration of Mn²⁺ion is 0.1 mol%.The energy transfer from Mn²⁺to Eu²⁺is studied.Mn²⁺can enhance the emission,and the critical distance of energy transfer from Mn²⁺to Eu²⁺（I）is 7.8?.The fluorescence spectra of heat treatment at different temperatures were analyzed.It was found that Eu²⁺（I）was formed at 850℃and Eu²⁺（Ⅱ）was formed at more than 900℃.When the temperature increases from900℃→950℃→975℃,the luminescence thermal stability of Eu²⁺（I）and Eu²⁺（Ⅱ）also increases,indicating that 975℃is the best heat treatment temperature for phosphors.The blast furnace slag at steel mill was introduced into CM_0.5AS:0.2Eu²⁺,0.1Mn²⁺phosphors to prepare luminescent materials.Through the test,it is considered that the recovery and addition amount of blast furnace slag should be controlled at about 30%.