Study On Preparation Of Aluminosilicate Luminescent Materials And Its Luminescent Properties By Rare Earth Doped High Alumina Blast Furnace Slag

Blast furnace slag is a side product of the ironmaking process,but most of the blast furnace slag resource utilization in our country is still in the low added value period.The structure of blast furnace slag is unstable,and its quaternary components will form an aluminosilicate structure after heat treatment,which can be used as the matrix of glassy and crystalline rare earth luminescent materials.In this paper,starting from high-aluminum blast furnace slag,the high-temperature water quenching sintering method is used to prepare aluminosilicate luminescent materials to realize the functional material utilization of high-aluminum blast furnace slag.By studying the relationship between the change of the matrix structure and the luminescence performance under different doping concentrations of rare earth ions and heat treatment temperature,the single doping or co-doping of rare earth ions is used to find high-performance luminescent materials.The main research content is divided into the following three parts:1.The high-temperature molten water quenching method is used to prepare the Tb³⁺-doped aluminosilicate glass luminescent material with high alumina blast furnace slag.According to the DSC thermal analysis,the glass transition point and crystallization temperature are found,and the crystallization kinetics is calculated.The structure and luminescence performance of glassy luminescent materials before and after heat treatment were compared by XRD phase analysis and photoluminescence spectroscopy.The results show that Tb³⁺single-doped aluminosilicate glass forms Ca₂(Mg_0.5Al_0.5)(Si_1.5Al_0.5O₇)crystals through surface crystallization during heat treatment at 1000?,and the luminescence performance is significantly lower than that before heat treatment.After the introduction of Ce³⁺,energy transfer occurs between Ce³⁺and Tb³⁺ions through multipolar interaction,and the process can be described as 5d(Ce³⁺)+⁷F₆(Tb³⁺)?²F_5/2(Ce³⁺)+⁵D₃(Tb³⁺).The energy transfer improves the luminous intensity of the glass luminescent material,which can reach 6 times that of Tb³⁺single-doped under the excitation of near ultraviolet 362 nm.The 4 mol%Tb³⁺/1 mol%Ce³⁺doped aluminosilicate luminescent glass sample has good thermal stability at 150?,and can be used as a green solid luminescent material for near-ultraviolet LED excitation.The high-aluminum blast furnace slag from steel mills was used to replace part of the raw materials to prepare glass luminescent materials and to test the luminescent properties.When the replaced mass fraction reached about 50%,the luminous intensity decreased to less than half due to the influence of impurities.2.The Eu²⁺/Eu³⁺-doped Ca₂(Mg_0.5Al_0.5)(Si_1.5Al_0.5O₇)tunable luminescent material with high aluminum blast furnace slag was prepared by high-temperature water quenching sintering.According to DSC thermal analysis,the glass transition point temperature and crystallization temperature are obtained,and the crystallization kinetics calculation is performed.The luminescence in the water-quenched glass sample exhibits concentration quenching with the increase of Eu²⁺doping concentration,and is accompanied by a red shift of the peak value.In the process of heat treatment at 900?1000?to form Ca₂(Mg_0.5Al_0.5)(Si_1.5Al_0.5O₇)phase,the larger Mg O₄tetrahedrons and the smaller Si O₄tetrahedrons both replaced the Al O₄tetrahedrons with similar volume,which changed the environment around Eu²⁺ions resulting into the split of the 5d energy level.The emission spectra of Eu²⁺ions are decomposed into a combination of blue(421 nm)and green(516 nm)broad peaks,and Eu²⁺is partially oxidized to Eu³⁺emitting red light(618 nm)during the heat treatment process,and using the principle of three primary colors to achieve tunable white light emission.The emission peak of light-emitting luminescent materials in the red region has better thermal stability,followed by the blue region,and due to the intervalence charge transfer between Eu²⁺/Eu³⁺,the emission spectrum of Eu²⁺has the worst thermal stability in the green region.To prepare Ca₂(Mg_0.5Al_0.5)(Si_1.5Al_0.5O₇)luminescent materials by partially replacing raw materials with high aluminum blast furnace slag from steel mills,the presence of impurities not only affects the crystallization of the matrix,but also is not conducive to the absorption and emission of energy by rare earth ions.As a result,the emission peak intensity of the green region and the red region in the emission spectrum is significantly reduced,and the luminescence performance is greatly weakened.3.Introducing Tb³⁺into Eu²⁺/Eu³⁺doping and preparing Eu²⁺/Tb³⁺/Eu³⁺doped high aluminum blast furnace slag Ca₂(Mg_0.5Al_0.5)(Si_1.5Al_0.5O₇)tunable emission luminescent material by high-temperature water quenching sintering method.The phase structure changes and luminescence properties of samples with high Eu3+doping concentration after heat treatment at different temperatures are analyzed,and control experiments are designed according to the results.When the sample is heat-treated to form the Ca₂(Mg_0.5Al_0.5)(Si_1.5Al_0.5O₇)phase,a small part of Eu Ca Al₃O₇phase is formed due to the substitution of Ca²⁺?Eu³⁺and Si⁴⁺?Al³⁺,which distorts the local symmetry of Eu³⁺,resulting in enhanced emission of ⁵D₀?⁷F₄.The Eu²⁺green region in the Ca₂(Mg_0.5Al_0.5)(Si_1.5Al_0.5O₇)phase has poor thermal stability of the emission spectrum,while Tb³⁺has a strong luminous intensity and good thermal stability in the green region.At the same time,there is an energy transfer process of⁵D₄(Tb³⁺)+⁷F₀(Eu³⁺)?⁷F₅(Tb³⁺)+⁵D₁(Eu³⁺)between Tb³⁺and Eu³⁺,which can further enhance the red light emission.Therefore,the introduction of Tb³⁺into the matrix can achieve enhanced emission of three-primary tunable white light.When the ambient temperature rises from 30°C to 150°C,although the luminous intensity decreases,the chromaticity coordinates always remain in the white light region.