硅酸盐学报2025，Vol.53Issue(2)：267-279,13.DOI:10.14062/j.issn.0454-5648.20240119
Cl-/F-取代及增加Na+位调控Eu2+在α-堇青石中占位发光
Regulation of Eu2+Occupancy Luminescence in α-cordierite by Cl-/F Substitution and Na+Site Addition
摘要
Abstract
With the development of technology and the increasing emphasis on patent protection,anti-counterfeiting technologies are emerging one after another.Among numerous anti-counterfeiting technologies,photoluminescence anti-counterfeiting technology is widely used in the field of anti-counterfeiting due to its excellent optical properties.However,traditional fluorescent powder anti-counterfeiting only changes its color when the UV excitation light source is changed,lacking dynamic changes in the time dimension.Therefore,it is necessary to develop an efficient anti-counterfeiting new luminescent material.Currently,the use of cation substitution and multiple occupied sites has become a popular strategy for tunable emission.Due to the interaction between activators and anions,the energy difference between the energy levels of the luminescent center ion can be altered.Therefore,anion substitution can also be an effective strategy to adjust the photoluminescence performance.This article describes the preparation of Mg2-xNaxAl4Si5O18-xQx∶1％Eu2+(Q=C1,F)by glass relaxation crystallization method,which introduces Na+sites and replaces lO2-with 2F-/2C1-to achieve the opening of the[Al/Si]6O18 hexagonal ring structure,providing a rich field environment for the central ion Eu2+to enter the α-Mg2Al4Si5O18 structure:Na+sites,Mg2+sites,and hexagonal ring channel sites.By regulating the Eu2+occupation,Euvac2+,EuMg2+and EuNa2+structures are formed,achieving blue to yellow light emission. Methods Based on the composition of 2MgO-2Al2O3-5SiO2,a series of Mg2-xNaxAlSiO18-xQx∶1％Eu2+(Q=Cl,F)fluorescent powders(abbreviated as 1Eu2+,1Eu2+-xNaCl and 1Eu2+-xNaF)were prepared by introducing NaCl(A.R.),NaF(A.R.),and Eu2O3(A.R.),and glass crystallization after quenching the reactants in ice water.Doping concentration:NaCl are 0,1％,2％,3％,and 5％molar fraction and NaF are 1％,2.0％,2.5％,and 3.0％.Weigh according to the set reactant stoichiometry,and grind the mixture thoroughly in an agate mortar for 30 minutes to ensure even mixing.Transfer it to a graphite crucible,place it in a well furnace,heat it up to 1550 ℃ at a heating rate of 5°/min,and keep it in an argon atmosphere for 30 minutes.Then,pour the molten reactants into ice water for rapid cooling,dry and grind to obtain the precursor glass sample PG.Finally,the precursor glass sample PG will be kept in a reducing atmosphere at 1100 ℃ for 1 hour,and then ground into a crystalline sample after cooling in the furnace. Results and discussion When single doped with Eu2+,Eu2+occupies the Mg2+and channel sites in the α-cordierite structure,forming EuMg2+and Euvac2+luminescent structural units.When NaF is introduced,Eu2+occupies the Na+site to form a new luminescent structural unit EuNa2+.Introducing NaCl/NaF can enhance the occupation of channel sites by Eu2+.When F-/Cl-replaces O2 and partially opens the hexagonal ring of the channel,the channel sites can accommodate more Eu2+,which makes it easier to explain the increased Eu2+structure formed when NaCl/NaF is introduced.When NaCl is introduced,Eu2+hardly occupies the Na+sites,while when NaF is introduced,as the amount of NaF introduced increases,Eu2+occupies more Na+sites.That is because the stronger electronegativity of O2-than Cl-,replacing O2-with Cl-can introduce more covalences in the lattice,that means Eu2+-Cl-has stronger contradiction and polarization than Eu2+-O2-.Moreover,the ionic radius of Cl-differs significantly from that of O2-,making the formation of Eu2+-Cl-more difficult.Therefore,when Cl-is introduced,Eu2+does not occupy the Na+sites.Similarly,when F-is introduced,Eu2+is more likely to occupy Na+sites.In addition,the amount of Eu2+introduced is constant,and when Na+-Cl-is introduced,Eu2+does not occupy the Na+sites.As the Euvac2+structure increases,the corresponding generated EuMg2+structure will decrease.As a ligand,compared to Mg2+-O2-,the introduction of Na+-F has a smaller steric hindrance and greater bonding ability due to the smaller radius and greater electronegativity of F-(compared to O2-)ions.Eu2+will preferentially occupy Na+sites with similar radii and then occupy Mg2+sites.As the amount of NaF introduced increases,more EuNa2+structures are formed while the corresponding EuMg2+structures decrease. Conclusions The main conclusions of this paper are summarized as following.This article mainly studies the effect of introducing Na+sites and Cl-/F-substituted O2-on the occupancy of Eu2+in the α-cordierite structure.Exploring the mechanism of distinguishing subgrain structure evolution for luminescent structural probes.By introducing Na+sites and anionic Cl-/F-substituted O2-to regulate the selective occupancy of Eu2+,temperature sensitive emission from blue white to yellow light is achieved.Cl-/F-substituted O2-opens the hexagonal ring structure of the channel,which facilitates the occupation of channel sites by Eu2+.The proportion of the formed structure increases from 33.32％to 64.89％.When introducing Na+sites,the presence of F increases the proportion of Eu2+occupying Na+sites to form structures to 18.63％.This series of fluorescent powders can significantly improve their thermal quenching performance when NaF is introduced,and have superior thermal stability at 150 ℃.This series of fluorescent powders can be widely used in the fields of adjustable luminescence,detection,and anti-counterfeiting.关键词
选择性占位/取代/发光结构/六元环通道位/可调发光Key words
selective occupancy/substitution/luminescent structure/six element ring channel position/tunable luminescence分类
化学化工引用本文复制引用
邓文娇,朱伟华,张志峰,刘建,曹发斌,申星梅..Cl-/F-取代及增加Na+位调控Eu2+在α-堇青石中占位发光[J].硅酸盐学报,2025,53(2):267-279,13.基金项目
安徽省自然科学基金项目(1808085ME136). （1808085ME136）
