State Of Tb Research Articles

Dispersion of Exciton Polaritons in Terbium Nitrate Hexahydrate

The dispersion relations of exciton polariton waves in terbium nitrate hexahydrate are determined based on the model of the interaction of electromagnetic waves with resonant electronic states of Tb3+ ions at the 5D4–7F6 transition. Frequencies of unitary polaritons characterized by refractive indices equal to unity are determined. It is shown that the group velocity of electromagnetic waves in the region of unitary polaritons is lower than the speed of light in vacuum by several orders of magnitude. A sharp increase in the efficiency of photoluminescence and Raman scattering is predicted in the case where the excitation radiation frequency approaches the unitary polaritons frequency.

Synthesis of new fluorite-related rare earth oxides Ln $${\text{Ln}}_{2}^{\prime }$$ Ln 2 ′ MO7 (Ln, Ln′ = rare earths; M = Nb, Sb, Ta), their structures and magnetic properties by calorimetry measurements

New fluorite-related quaternary rare earth oxides Ln $${\text{Ln}}_{2}^{\prime }$$ MO7 (Ln = Nd, Gd, Tb; Ln′ = Lu and Y; M = Nb, Sb, Ta) were prepared. They crystallize in an orthorhombic superstructure of cubic fluorite with space group C2221. The results of the Rietveld analysis indicate that there exists some disordering of the Ln and Ln′ atoms at the eight-coordinate site and the seven-coordinate site. These compounds are paramagnetic down to 1.8 K except for TbLu2SbO7. Magnetic susceptibility measurements show that TbLu2SbO7 antiferromagnetically orders at 3.0 K. Specific heat measurements also show a λ-type anomaly at the same temperature. The analysis of the magnetic specific heat for TbLu2SbO7 indicates that the magnetic transitions are due to the ground doublet state of Tb3+ ions.

Technological aspects for Tb3+-doped luminescent sol–gel nanomaterials

Luminescent properties of silica sol–gel nanomaterials doped with Tb3+ ions were studied and the results are presented. Compositions of the studied materials were varied while the terbium ions concentration was kept constant. Some technological parameters were analyzed and their pronounced effect on the photoluminescence properties is observed. Spectroscopic parameters of Tb3+ ions were determined basing on excitation and emission measurements as well as on luminescence decay analysis before and after heat treatment process. The registered emission bands in the visible spectral range correspond to the 5D4→7FJ (J=3−6) transitions of Tb3+ ions. Intensities of the emission bands and luminescence decay curves of Tb3+ ions depend on the excitation wavelength. Also, enhancement of the emission bands intensities and a significant increase of luminescence lifetime for the 5D4 excited state of Tb3+ ions after heat treatment process was observed. The structure of obtained glasses was examined using X-ray diffraction (XRD), as well as FT-IR and Raman spectroscopic techniques. The obtained results indicate the incorporation of Tb3+ ions into nanocrystalline phase during ceramization process.

Blue-green luminescence in Hg free excited Sr2P2O7:Tb3+ pyrophosphate phosphor for NUV excited LEDs

Tb3+ activated Sr2P2O7 phosphor was prepared by modified solid state diffusion technique at 700°C. The XRD pattern of Sr2P2O7 is in well argument with the standard ICDD File (24-1011) available. Surface morphology of the present phosphor has been studied by scanning electron microscope (SEM). In photoluminescence investigation, the excitation spectra of the phosphor extends from 200 to 400 nm gives optimum absorption at 352 nm, which is mercury free excitation and characteristics of NUV excited LED. Under the excitation of 352 nm, Sr2P2O7 doped with trivalent terbium ions produces weak blue emission between 400-500 nm owing to the 5D3 to the 7FJ transitions of Tb3+ and strong green emission in 500650 nm region of the visible spectrum due to the 4f-4f transitions from the 5D4 to 7FJ (J=6, 5, 4, 3) states of Tb3+. The entire study reveals that the present phosphor have promising applications in the lamp industry especially for solid state lighting (mercury free excited lamp phosphor) and NUV LEDs.

Electrospinning preparation and luminescence properties of terbium complex/polymer composite fibers.

The terbium complex Tb(acac)2AA (acac: acetyl acetone, AA: acrylic acid) was incorporated into polystyrene (PS) matrix and electrospun into various composite fibers. The mass ratios of rare-earth complex to polymer were fixed in all composite fibers. The diameters of the composite fibers decrease with increase in the collection distance during electrospinning. The luminescence properties of the Tb(acac)2AA/PS composite fibers were studied in comparison to those of the pure Tb complex. The excitation bands became narrower and blue-shifted compared with that of the pure complex in all of the Tb(acac)2AA/PS composite fibers. The fluorescence lifetime of the 5D4 state of Tb3+ ion in the composite fibers was shorter than that of the Tb complex. The effect of the fiber diameter on the luminescence properties was also studied. As a result, the fluorescence lifetimes of the 5D4 state in all of the Tb(acac)2AA/PS composite fibers decreased gradually with decrease in diameter.

Synthesis and luminescent properties of BaLn2(1−x)ZnO5:2xTb3+ (Ln = Y, Gd) nanophosphors

The synthesis of BaLn2(1−x)ZnO5:2xTb3+ (Ln = Y, Gd) nanophosphors using solution combustion method with an aim to study the effect of sintering temperature and Tb3+ ions concentration on the luminescent properties has been investigated. Under UV excitation, BaY2(1−x)ZnO5 and BaGd2(1−x)ZnO5 nanoparticles exhibit apparent characteristic green emission from 5D4 state to 7F6−3 states of Tb3+ ions with the strongest at 544 nm. Luminescence concentration quenching could be observed when the Tb3+ ions contents were more than 4 mol% in both nanophosphors. The luminescence decay curves suggest monoexponential behavior of both nanophosphors. X-ray diffraction results confirmed the single-phased orthorhombic structure of both powders belonging to space group Pbnm. TEM analysis indicates the spherical morphology of nanoparticles with average grain size in the range of 85–95 nm. BaY2(1−x)Tb2x ZnO5 and BaGd2(1−x)Tb2x ZnO5 nanophosphors may have potential applications in field emission displays based on their uniform shape, low-cost synthetic route, and diverse luminescent properties.

Optical absorption and X-ray luminescence of glassy lithium tetraborate activated by terbium oxide

It has been demonstrated on the basis of absorption spectra measurements that the activation of glassy lithium tetraborate by terbium results in the formation of band of localized electronic states in the pseudo-band gap, which correspond to the energy levels of rare earth element ions. As follows from the analysis of the X-ray luminescence spectra, the activator ion plays the most important role in the emergence of luminescent properties of glassy lithium tetraborate. It has been established that X-ray luminescence in glassy lithium tetraborate activated by terbium is mostly realized due to transitions from excited 5D3- and 5D4-states to the levels of spin-orbital splitting of the main 7FJ state of Tb3+ ion.

Optical absorption spectra and magnetic phase transitions in TbFe3(BO3)4

Optical absorption spectra of the trigonal crystal of TbFe3(BO3)4 in the vicinity of the 7F6 → 5D4 transition in a Tb3+ ion were studied as a function of temperature (2–70 K) and magnetic field strength (0–60 kOe) at 2 K. The splitting of the excited states of Tb3+ due to both the magnetic ordering of iron and an external magnetic field was determined. Abrupt splitting of the absorption lines of Tb3+ at temperature TN of the magnetic ordering of the subsystem of iron was revealed, suggesting that the nature of such splitting is not entirely magnetic.

Ferromagnetic Interaction between Copper and Terbium Ions in Pentanuclear Cluster [Cu3Tb2(ClCH2COO)12(H2O)8] · 2H2O

For the first time the exchange interaction between copper and non-Kramers Tb3+ ions was studied by means of electron paramagnetic resonance (EPR). Features of the manifestation of this interaction in the EPR spectra of dimer fragments Cu–Tb and pentanuclear fragments Cu–Tb–Cu–Tb–Cu are analyzed. The possibility to determine the sign and value of this interaction from EPR spectra for the case when the lowest states of Tb3+ are the states |0〉, | ± 1〉 is shown. The exchange interaction between copper and trivalent terbium ions in the studied pentanuclear complex is ferromagnetic.

Emission spectra of Cs2KTbCl6 and Cs2KEuCl6, and Tb3+→Eu3+ non-radiative energy transfer in Cs2KTb0.9Eu0.1Cl6

A spectral assignment of the first excited states of Tb3+ in Cs2KTbC16 and Eu3+ in Cs2KEuCl6 obtained from excitation and emission spectra is presented. A non-radiative energy transfer process from Tb3+ to Eu3+ ions was found to occur in Cs2KTb0.99Eu0.1Cl6. This process is strongly temperature dependent, such that it becomes quenched at low temperature. The most probable mechanisms responsible for such energy transfer are suggested for the case in which the Tb3+5D4 state is excited.

Study on state of terbium ion in liposome by one-order derivative fluorescence quenching method

The state of Tb3+ is investigated in liposome. When the concentration of PC is below CMC (critical micell concentration), most of Tb3+ is associated with PC, the binding constant is about 3.35×103 L/mol. When the concentration of PC is beyond CMC, most of Tb3+ is dimerized, the dimerization constant is about 3.92×104L/mol. In PC−CH−H2O system, the binding constant of Tb3+−CH complex 2.93×104L/mol is obtained.