The Optical Properties Of One-dimensional Long Persistence Luminescent Nanomaterials:Synthesized By Low-temperature Precipitation Method

Long persistent luminescence nanomaterials are widely used in the field of biomedicine due to their special delayed luminescence properties.Many excellent research results have been obtained in the research of material composition and preparation technology.However,the current synthetic process cannot meet the controllable adjustment requirements of morphology and afterglow performance.One-dimensional nanomaterials often have unique photochemical properties.Therefore,this paper proposes three low-temperature precipitation synthesis methods and new lanthanum hydroxide long afterglow materials to solve the above problems.We believe that this research result will expand the matrix composition and application of long persistent luminescence nanomaterials.This thesis is divided into seven chapters.The first chapter mainly describes the long persistent luminescence nanomaterials systematically,and presents the existing achievements,problems and solutions.The second chapter is the synthesis of long persistent luminescence nanomaterials.The methods and characterization methods are described in detail;the remaining chapters take the improvement and optimization of the preparation process as clues,and describe the obtained three types of low-temperature precipitation methods:conventional precipitation method,one-step precipitation method and hot-injection precipitation method,new long persistent luminescence nanomaterials(La₂O₂CO₃and La(OH)₃)with excellent properties as matrix.The main research results obtained are summarized as follows:(1)Conventional precipitation method:In Chapter 3,first,according to the conventional precipitation method in the existing synthesis method of long afterglow nanomaterials,the first step is to obtain the precursor La(OH)₃:1%Tb³⁺nanorods.In the second step,high temperature(600?)post-treatment was performed to obtain La₂O₂CO₃:1%Tb³⁺one-dimensional green long afterglow nanorods with good dispersibility.The strongest emission peak is 542 nm(⁵D₄-⁷F₅).The afterglow time is about 1800 s.The shallow trap depth is 0.848 e V.The possibility of synthesizing the target product La₂O₂CO₃with excellent biocompatibility was verified by this method.Secondly,in order to achieve the controlled adjustment of the morphology and afterglow properties of La₂O₂CO₃host long afterglow nanomaterials,the possibility of its application in the biological field was verified.In Chapter 4,we prepared long afterglow nanomaterials with La(OH)₃:Eu³⁺,Ho³⁺nanorods as precursors and post-treatment products of La₂O₂CO₃:Eu³⁺,Ho³⁺.The experimental results show that by simply changing the post-treatment conditions(The heat treatment time t and the post-heat treatment process M)realize the morphological evolution from nanorods to bamboo-like nanorods to nanoparticles and the coordinated regulation of afterglow time.In addition,the prepared long afterglow nanomaterials exhibit excellent water stability and can be suspended in mouse plasma and 10%glucose for more than 10 days.This material also has H₂O₂detection capability,which proves that La₂O₂CO₃based materials have the application potential of real-time monitoring of H₂O₂and glucose without in-situ excitation.However,long afterglow nanomaterials after sintering after treatment often have the disadvantages of agglomeration,particle growth,and poor dispersibility,which limits their development in biological applications.Therefore,we will consider verifying the hydroxide precursors has long afterglow or not.(2)One-step precipitation method:First verify that the precursor product La(OH)₃:20%Eu³⁺nanorods obtained after one-step precipitation in the above study have a weak afterglow phenomenon with a duration of about 600 s.The fifth chapter of this paper mainly emphasizes the optimization and improvement of the afterglow properties of long afterglow nanomaterials which prepared via one-step precipitation method.The afterglow performance was optimized by adjusting the doped ion concentration,co-doped ions,changed doped ions,and improved preparation process.The experimental results show that the optimal doping ion is 20%Sm³⁺,and the optimal preparation process is hot-injection precipitation method.The afterglow intensity of the target product is greatly improved,and the afterglow duration is extended to>600 s.This discovery has far-reaching implications for exploring the synthetic methods of long afterglow nanomaterials,and optimizing the afterglow performance of La(OH)₃:20%Sm³⁺is also the focus of our subsequent research.(3)Hot-injection precipitation method:Chapter 6 mainly emphasizes the adjustment of the afterglow properties of La(OH)₃:20%Sm³⁺long afterglow nanorods by adjusting the synthesis conditions of the hot-injection precipitation method.During the experiment we found that when the preparation conditions When the p H value of the middle precipitation solution is 10 and the reaction temperature is T=90?,the obtained La(OH)₃:20%Sm³⁺long afterglow nanorods have good dispersibility,uniform size,uniform morphology and good afterglow performance relatively.When examining its optical properties,we prepared undoped La(OH)₃samples and La(OH)₃:20%Sm³⁺as a control group for research.The optical properties and afterglow properties of the two prepared samples are basically the same.Both belong to the 455 nm blue afterglow caused by crystal defects,which means that it is necessary to the study the afterglow mechanism of the La(OH)₃.In Chapter 7,we systematically discuss the structure and morphology,optical properties(excitation wavelength 397 nm,emission wavelength 467 nm),and afterglow properties of La(OH)₃,which synthesized by the hot-injection precipitation method.(Afterglow emission peak 455nm,afterglow decay time is far greater than 600 s),and the afterglow mechanism(defect afterglow)of this material is discussed.Finally,we also prepared a sample Y(OH)₃,Yb(OH)₃and Gd(OH)₃prepared by the same synthesis method.The afterglow spectrum show that they also have long persistent luminescence,so as the raw material Na OH.Which proved that long persistent luminescence nanomaterials can be successfully synthesized without high temperature and high pressure.Moreover,an in-depth study of why OH^-containing crystal materials have long persistent luminescence is also essential,it also important to study the principle of such long afterglow phenomenon,which will also be a focus of our subsequent research.