Ziwei Tang

Synthesis, characterization and luminescence study of Eu(III) tungstates and molybdates nanotubes using carbon nanotubes as templates

Eu(III) tungstates and molybdates nanotubes have been successfully synthesized by the solvothermal method using carbon nanotubes (CNTs) as removable templates. The products were characterized by X-ray diffraction spectroscopy, transmission electron microscopy, energy-dispersive X-ray spectrometry, thermogravimetric and differential thermalanalysis. It is demonstrated that CNTs are fully coated with an amorphous Eu(2)(MO(4))(3) (M=W, Mo) layer, which is about 10nm thick and almost continuous and uniform. After the Eu(2)(MO(4))(3) (M=W, Mo)/CNTs composites have been calcined at 700 degrees C, Eu(2)(MO(4))(3) (M=W, Mo) nanotubes are obtained by removing the CNTs templates. The diameter of the Eu(2)(MO(4))(3) (M=W, Mo) nanotubes is 40-60 nm, which is consistent with that of CNTs. The luminescence properties of the Eu(2)(MO(4))(3) (M=W, Mo) nanotubes calcined at various temperatures have been investigated. The result shows that the Eu(2)(MO(4))(3) (M=W, Mo) nanotubes obtained from the Eu(2)(MO(4))(3) (M=W, Mo)/CNTs composites calcined at 700 degrees C display a strong red emission peak at around 611 nm.

Synthesis and Spectroscopic Study of a Terbium(III) 2,6-Pyridinedicarboxylate Complex

ABSTRACT The terbium(III) 2,6-pyridinedicarboxylate complex Na3Tb(PDA)3·8H2O with intense green luminescence was synthesized by liquid phase reaction and characterized by means of infrared (IR), ultraviolet (UV), 1H nuclear magnetic resonance (1HNMR), 13C nuclear magnetic resonance (13CNMR), and fluorescence spectra. In this complex, the coordination function of each PDA2− group with terbium(III) center is tridentate chelate from two carboxyl oxygen and one heterocyclic nitrogen atoms while carboxylate group in a monodentate fashion. Terbium(III) is in nine-coordination configuration. Due to the high paramagnetic character and strong electron attraction ability of Tb3+ ion, the chemical shifts of 1HNMR and 13CNMR spectra on the complex heterocycle to lower field compared with free H2PDA, while that of C7 and C8 of the complex move to higher fields probably due to shielding effects of the carboxyl group as well as conjugation system of two five-membered chelate cycles. Moreover, the 1HNMR and 13CNMR spectra of the complex have broader peak width than that of free H2PDA. The excitation and emission spectra of the complex show that the energy of the π(n)-π* excited state of can be effectively transferred to Tb3+ ion, resulting in emission from the 5 D 4 → 7 F j(j = 3–6) electronic transitions of Tb3+ ion. Because of the low symmetric center and strong coordination field that were affected, 5 D 4 and 7 F j(j = 6,5,4) energy levels of Tb3+ have split. In addition, the complex exhibits thermal stability below 460°C in air.

Ag-catalyzed Synthesis of Tb(BO2)3 Nanorods

Well-crystallized with excellent luminescent properties, Tb(BO2)3 nanorods were first successfully synthesized by a simple solid-state method with Ag as catalyst. The result of X-ray diffraction showed that the Tb(BO2)3 nanorods could be well-crystallized at 700 °C. As-prepared straight nanorods of Tb(BO2)3 had the typical diameters in the range of 100–200 nm, the thickness of 30–50 nm and the lengths up to 3 μm by transmission electron microscopy and the corresponding selected area electron diffraction indicated that the nanorod calcined at 700 °C was single-crystalline. Based on the fact that Ag nanoparticles attached to the tips and middles of the Tb(BO2)3 nanorods, a growth model of the Tb(BO2)3 nanorods was proposed. Photoluminescence spectra under excitation at 369 nm showed that these Tb(BO2)3 phosphors had a green emission at 546 nm, which is ascribed to 5D4→7F5 transition. The effect of calcining temperature on the structures, morphologies, and luminescent properties of Tb(BO2)3 phosphors were studied.