Ultra-fine nano-rare earth phosphate fluorescent material synthesis, characterization

Title: Ultra-fine nano-rare earth phosphate fluorescent material synthesis, characterization and properties of
　　Author: Ghauri
　　Degree-granting units: Central South University
　　Keywords: nanoparticles;; nanorods;; LnPO_4;; doping;; LnPO_4: Eu;; YPO_4: (Eu ~ (3 +), Li ~+);; photoluminescence
　　Summary:
　　This paper studies the LaPO4 nanospheres / Neodymium magnets nanorods, lanthanide phosphate LnPO4 (Ln = Yb, Er, Dy, Tb, Gd, Sm, Ce, Y), LnPO4: Eu and YPO4: (Eu3 +, Li +) synthesis, and its optical properties were studied. Specific tasks are as follows:
　　Using La2O3, NH4H2PO4 as the reactants, respectively, by hydrothermal method and sol - gel synthesis of spherical and rod-like structure LaPO4 nanoparticles. Using TG-DSC, XRD, TEM and SEM for the synthesized samples were characterized. The results indicate that the samples to the monoclinic monazite structure, samples of spherical or rod-like structure from the decision of pH during the reaction, low pH conditions tend to generate a rod-like or linear morphology of the product, while at high pH values ​​tend to to generate the spherical morphology of the product. Preliminary study of the crystal morphology control of the reaction mechanism. Simple method of rare earth doped, a preliminary study of crystals of different morphology of their fluorescent properties. The results show that the crystal sphere or ellipsoid launch the strongest, followed by rod-like or linear, irregular aggregates weakest.
　　Ordinary Hydrothermal a series of lanthanide phosphate LnPO4 (Ln = La, Y, Ce, Sm, Gd, Tb, Dy, Er, and Yb) nanoparticles with an average radius of 100 nm. Synthesis process, the first to ethylenediaminetetraacetic acid (EDTA) and citric acid (CA) as a complexing agent to form a uniform, transparent EDTA-metal-CA precursor, and then use water to generate the final thermal nanocrystals. Using XRD, TEM and SEM by means of the synthesized samples were characterized. The results indicate that the samples for the hexagonal structure, good crystallinity, and the sample base for the ball-type structure, with an average particle size of about 20 nm were. With a series of Eu-doped experiments, and the synthesized samples were tested at room temperature fluorescence properties. The results show that lanthanides with atomic number increases, the synthesis of the corresponding emission spectra intensity of the smaller product; sample intensity and symmetry of the emission spectrum of Eu concentration ratio with the increase showing increased first and then cut small process, Eu ion doping concentration of 5%, the highest intensity of emission spectra; ratio of fluorescence intensity and the symmetry and the reaction pH and water temperature is proportional to the thermal reaction.
　　To adopt a common complex of EDTA and CA simple sol - gel prepared by a Li + ions and Eu3 + ion-doped nanoparticles of YPO4. Using XRD, TEM, HRTEM and SEM of the synthesized products were characterized. The results show that the http://www.chinamagnets.biz/Neodymium/Ball-Neodymium-Magnets.php product is pure phase tetragonal structure, crystal ball, the average grain size close to 100 nm. More detailed study of the Li + ion doping concentration, Eu3 + ion concentration of the active center and the calcination temperature on the double-doped YPO4: (Eu3 +, Li +) nanocrystals photoluminescence properties. The results indicate that Li + ions introduced into the YPO4: Eu3 + lattice can significantly improve the PL spectra of luminous intensity, the sample YPO4: (5% Li +, 5% Eu3 +) with the strongest emission intensity, compared to the sample YPO4: 5 % Eu3 +, its emission intensity increased 2.5 times.
　　Degree Year: 2010