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Preparation and Spectroscopic Properties of Y2O3:Re （Re=Nd,Er,Ce） Nano-powders and Transparent Ceramics

Author: WangXiaoChun
Tutor: YinMin；ZhangWeiPing
School: University of Science and Technology of China
Course: Condensed Matter Physics
Keywords: Y2O3: Nd Y2O3: Er Ce Nano powder Transparent ceramics
CLC: TB383.1
Type: Master's thesis
Year: 2010
Downloads: 179
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Abstract


This dissertation consists of four chapters, introduction describes the background of the thesis work, Chapter II Chapter reported the Y- 2 O 3 : Re (Re = Nd Er, Ce) material preparation, structural characterization and luminescence properties results. Introduction First introduced in recent years, the focus on types of rare earth luminescent materials, and then elaborated on the characteristics of the rare-earth ions and their glowing, given the development of transparent ceramics and related preparation process, and finally a brief introduction of the solid-phase method, sol-gel method and nano powder prepared by coprecipitation. In the second chapter, respectively, using the solid-phase method, the sol-gel method and coprecipitation prepared Y 2 O 3 : Nd powder XRD and SEM powder chemical structure and particle morphology were characterized and 808nm semiconductor laser excited samples, the differences in the nature of the morphology and luminescence to study the structure of the sample under different methods. Prepared by solid samples, the operation is simple, but the reaction to the desired temperature, 800 ° C calcined Nd 3 ion is not enough time to diffusion, sample almost no luminescence; prepared powder particles than large, and the pores. Samples of sol-gel method, agglomeration more serious porous structure, morphology, complexing agents and metal complexation reactions affected by pH, the luminous intensity of the product obtained in the different pH values. Prepared by coprecipitation sample, the smaller the particle size around 20 nm particles knot dense lamellar structure, the basic conditions for the preparation of transparent ceramics. Y 2 O 3 : Nd nano-powder lattice constant of 808 nm laser excitation emission spectrum intensity with Nd concentration changes in the further study of the different doping concentration. When the doping concentration is higher than 1%, the sample emitting start generating quenching, quenching is caused by the energy levels between the pair of cross-relaxation. In the third chapter, the precipitating agent ammonium bicarbonate, changing the preparation conditions, the use of the coprecipitation prepared Y 2 O 3 : Er 3 nano powder and transparent ceramics by FTIR, elemental analysis, XRF and other means to study the structure and composition of the precursor chemical precursors in the heating process of weightlessness analyzed by TG-DTA, XRD and SEM of the powder phase situation and to characterize particle morphology. Er 3 of the spectral characteristics of the ion, and the pH value of in-depth analysis of powder light. Made of ceramic powder samples of the experimental system to analyze the impact of different precursor conditions on ceramic transparency, and analyze the similarities and differences of the luminescence properties of the powder and ceramic. the pH value is changed, the chemical structure of the precursor is substantially constant, but the precipitate Y, Er the ratio will change the pH value of 9.5, the actual content of the precursor in the ER 8.5 0.5% higher than the pH value, and nanoparticles of particle size distribution range of different pH are not identical, the resulting differences in the nature of the sample emitting. Added 1% of dispersing agent on the chemical structure of the precursor product substantially no effect, but will change the proportion of Y, Er precipitate; dispersant at different pH values ??of the powder particles impact, pH value 8.5, and the product particles becomes small, the particle size distribution range widened, the sheet-like structure of the surface is very smooth, the pH value of 9.0, the role played by the dispersant opposite surface debris increased. Y 2 O 3 : 1% Er 300 800nm ??range were characterized absorbed the corresponding 4f ground state to the 4f excited states, respectively. 380nm wavelength light excitation, the main emission peaks at 500 600nm range, corresponding 2 H 11/2 / 4 S 3/2 → 4 I 15/2 transition, the strongest emission peak at 563 nm. 980nm and 808nm laser excitation, monitoring the sample of two-photon conversion green emission phenomenon; Er doping concentration the existence 4 S 3/2 → 4 I 9/2 4 I 4 →> I between 13/2 level on the cross-relaxation, the red emission enhancements. 980nm excitation, red upconversion luminescence is also a two-photon process. XRD diffraction peak position and a powder sample of the ceramic samples consistent, but the peak intensity distribution changes, (400) crystal faces grow preferentially, resulting in the corresponding diffraction peak intensity is greatly enhanced. transparency of the ceramic, the pH value, and a dispersing agent affects both the pH value of 8.5 ceramic better transparency. After a dispersing agent has been added, is not the same degree of change of ceramic transparency, pH value of 8.0 and 8.5, the effects of the dispersing agent is preferably; the same pH value, excess dispersant hired contrary. High-temperature sintering grain growth better ceramic sample luminescence enhancement of about one order of magnitude. In the fourth chapter, prepared by coprecipitation (Y 0.95 La 0.05 ) 2 O 3 : Ce powder luminescence properties of the analysis of samples, and La Ce ions. First X-ray diffraction results show that the Y 2 O 3 matrix introduced 5% La does not change Y 2 O 3 < / sub> itself, the basic structure of the solid solution (Y- 0.95 La 0.05 ) 2 O 3 Remaining cubic phase . The excitation and emission spectra test results indicate that the matrix to the introduction of the 5% of La and sample obtained after calcination at 800 ℃ broadband emission in the visible wavelengths in the ultraviolet 271nm/368nm excitation; combined XPS Ce 3d spectrum in the different samples and analysis of the O 1s spectra can be determined, the light-emitting originated Ce 3 ions exist further infer matrix introduced La certain conditions from the Ce 3 ion stabilizing role.

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