Tb Glass Research Articles

High-resolution Tb3+-doped Gd-based oxyfluoride glass scintillators for X-ray imaging

SiBNaBaGd–5.0Tb glass scintillators with a high spatial resolution of 20 lp mm−1 and high XEL intensity are reported.

Gamma radiation attenuation characteristics, acoustic and mechanical properties of TeO2/TiO2/B2O3 glasses using Monte carlo code and Phy-X/PSD software

This study, aims to investigate on non-traditional tellurite glasses and conducted to study structural, mechanical, acoustic and parameters of gamma radiation shielding (eg. Liner Attenuation Coefficient (LAC), Half Value Layer (HVL), micro-hardness (H)), for the Ternary TeO2/TiO2/B2O3 glasses with different molar composition. Important parameters used for radiation shielding of the glass samples were investigated by both Monte Carlo simulation codes (MCNP and Geant4) and Phy-X/PSD software, in the 0.284, 0.347, 0.511, 0.662, 0.826, and 1.173 MeV photon energies. As a result, the values of Elastic module, structural, acoustic parameters and fractal Bond were found in this paper. Our calculation confirmed that samples (with the most TeO2 content almost 80 mol% and the least B2O3 amount around 10 mol%) represented the least Molar oxygen volume (11.980 cm3/mol) and the most Oxygen packing density (83.465 mol/L). The simulated results, show that the HVL for the TT and TB glass samples are below the level of other examples, and the TTB2 has the highest HVL at high energy (1.173 MeV). Also, TT and TB have higher MAC and TTB2 has lower MAC.

Structural and spectroscopic properties of phosphate–tungsten glasses doped with Nd3+ and Tb3+

Glasses of composition 90NaPO3-10WO3-xNd2O3, (0 ≤ x ≤ 1.7 mol%) and 90NaPO3-10WO3-yTbF3, (0 ≤ y ≤ 5.0 mol%) have been prepared and characterized. 31P and 23Na magic-angle spinning (MAS) NMR and 23Na{31P} rotational echo double resonance results are consistent with previously published data, indicating the presence of Q(2) and Q(1)1 W units. In addition, linear dependences of 31P MAS-NMR linewidths and spin-lattice relaxation rates and the electron spin-spin relaxation behavior (in the case of Nd2O3 doping) are consistent with a random dopant distribution, For Nd2O3- doped glass samples, absorption spectra in the visible and infrared regions were collected and analysed, and photoluminescence excitation and emission spectra were obtained under 575 nm excitation. Using the Judd-Ofelt formalism, the Ω2, Ω4 and Ω6 parameters were determined and by using them, the radiative lifetime (τr) were calculated for the 4F3/2 excited state. The fluorescence quantum efficiency value for this level (QE = τf/τr) of 13% was determined for glass with x = 1.0. The photophysical properties of Tb- doped glasses were also studied and upon UV excitation (372 nm) the glasses show emissions in the green (540 nm, 5D4 → 7F5 transition) and blue (434 nm, 5D3 → 7F4). The relative luminescence intensity ratio 5D3 → 7F5/5D4 → 7F5 is higher for lower Tb3+ content (0.5 Tb glass sample), because for higher Tb3+ contents, a cross-relaxation energy transfer process takes place favoring the green emission.

Radio, cathodo and photoluminescence investigations of high density WO3-Gd2O3-B2O3 glass doped with Tb3+

The Tb3+ doped tungsten-gadolinium-borate glasses (WGB:Tb) were prepared by the melt-quenching technique with different Tb2O3 concentration (0.0, 0.1, 0.5, 1.0 and 2.0 mol%). Properties of glasses were characterized by such techniques as Archimedes´ method, XRD, absorption spectroscopy, various types of luminescence spectroscopy and decay curves. Glass performs the enhanced compaction with increment of Tb2O3 content. XRD pattern represents the amorphous nature of glass system. Tb3+ in glass absorbs photons in visible light and near infrared region. The strong green emission around 544 nm via 5D4 → 7F5 transition of Tb3+ were generated under three types of excitation such as ultraviolet–visible light (photoluminescence), X-ray (radioluminescence) and electron (cathodoluminescence). The Gd3+ - Tb3+ energy transfer plays an important role for strong green emission of glass. The intensity of this luminescence increases with increment of Tb2O3 concentration. All luminescence decay curves represent in the forms of non-single/multi-component exponential functions. The values of all decay time are in the order of millisecond. Moreover, the emission intensity of Tb3+ reduced with temperature increment (thermal quenching) proved by the temperature-dependent luminescence. In this work, the WGB:Tb glass doped with 2.0 mol% of Tb2O3 is a versatile glass. It is suitable and can be developed for using as a photonic materials in the green light source, laser, display/screen, X-ray detector and scanning/transmission electron microscope.

The structural and warm light emission properties of Sm3+/Tb3+ doubly doped strontium bismuth borosilicate glasses for LED applications.

Strontium Bismuth Borosilicate (SrBiBS as N) glasses doped with Tb3+ ions (N: Tb) and co-doped with Sm3+/Tb3+ (N: SmTb) were synthesized through the process of classical melt quenching. The structural and optical properties are investigated through energy dispersive spectroscopy; X-ray diffraction, Differential thermal analysis (DTA) and Fourier transform infrared spectra (FTIR), Optical absorption (OA) and photoluminescence (PL) spectral studies. X-ray diffraction indicates amorphous nature of glass. DTA curves explained the thermal stability and stress parameters of glasses. FTIR spectrum indicates existing vibrations of borate and silicate units. The absorption spectra have shown nine absorption bands of Tb3+ ions in the visible and NIR regions, due to transitions from ground state 7F6. In visible region, absorption spectra of co-doped glasses exhibited two bands of Tb3+ and three bands of Sm3+ with hyper sensitive transitions at 375 nm (7F6 → 5G6) and 401 nm (6H5/2 → 6P3/2). Photo Luminescence (PL) spectra of N: Tb and N: SmTb glasses is recorded at 375 nm excitation. N: Tb glasses have shown green emission corresponding to 5D4 → 7F5 transition. In all N: SmTb glasses, addition of Tb3+ ions has enhanced Sm3+ emission which is connected to quenching of Tb3+ emission. Moreover, 0.8 mol% of Tb3+ ions in co-doped glass (N: SmTb8) has shown maximum emission. The energy transfer process was inferred from shortening of decay times observed in N: SmTb glasses. The decay profiles fitted with Inokuti-Hirayama model suggests that the electric dipole-dipole interaction(S = 6) between Sm3+ and Tb3+ might dominate in energy transfer mechanism with probability PET and energy transfer parameter Q of 113-173 S-1 and 9.9-12.0 respectively. The color chromaticity (CIE) coordinates from PL emission of N: Tb & N: SmTb glasses have covered Green, Orange red and yellow (warm-light) regions with coordinates in ranges of x = 0.39-0.62 and y = 0.34-0.56.The color temperatures in range of 1713 K-4258 K.

Synthesis and characterization of a BaGdF5:Tb glass ceramic as a nanocomposite scintillator for x-ray imaging

Transparent glass ceramics with embedded light-emitting nanocrystals show great potential as low-cost nanocomposite scintillators in comparison to single crystal and transparent ceramic scintillators. In this study, cubic structure BaGdF5:Tb nanocrystals embedded in an aluminosilicate glass matrix are reported for potential high performance MeV imaging applications. Scintillator samples with systematically varied compositions were prepared by a simple conventional melt-quenching method followed by annealing. Optical, structural and scintillation properties were characterized to guide the design and optimization of selected material systems, aiming at the development of a system with higher crystal volume and larger crystal size for improved luminosity. It is observed that enhanced scintillation performance was achieved by tuning the glass matrix composition and using GdF3 in the raw materials, which served as a nucleation agent. A 26% improvement in light output was observed from a BaGdF5:Tb glass ceramic with addition of GdF3.

Investigation of spectroscopy and the dual energy transfer mechanisms of Sm3+-doped telluroborate glasses

The absorption, luminescence, Raman spectra and lifetimes of Sm-doped alkali telluroborate glasses (TB glasses) TB:Sm3+ have been investigated. The dual energy transfers including energy transfer between Sm3+ - Sm3+ pairs and Sm3+ - non-bridging oxygen (NBO) intrinsic defects were investigated. The concentration quenching of luminescence intensity was explained by the non-radiative energy transfer between the Sm3+ ions through the cross-relaxation mechanism. The decay curves are single exponentials with low concentrations (lower 0.10mol%) and become non-exponentials at higher concentrations. The non-exponential decay curves are fitted to the Inokuti and Hirayama model to give the energy transfer parameters between Sm3+ ions. The dominant interaction mechanism for energy transfer process is dipole–dipole interaction. The energy transfer induced Sm3+ photoluminescence enhancement in tellurite glass was experimentally studied and confirmed.

Local chemical and topological order in Al–Tb and its role in controlling nanocrystal formation

How the chemical and topological short- to medium-range order develops in Al–Tb glass and its ultimate effect on the control of the high number density of face-centered-cubic-Al (fcc-Al) nuclei during devitrification are described. A combined study using high-energy X-ray diffraction (HEXRD), atom probe tomography (APT), transmission electron microscopy and fluctuation electron microscopy (FEM) was conducted in order to resolve the local structure in amorphous Al90Tb10. Reverse Monte Carlo simulations and Voronoi tessellation analysis based on HEXRD experiments revealed a high coordination of Al around Tb atoms in both liquid and amorphous states. APT results show Al-rich and Al-depleted regions within the as-quenched alloy. A network structure of Tb-rich clusters divides the matrix into nanoscale regions where Al-rich clusters are isolated. It is this finely divided network which allows the amorphous structure to form. Al-rich regions are the locus for fcc-Al crystallization, which occurs before the intermetallic crystallization. FEM reveals medium-range ordered regions ∼2nm in diameter, consistent with fcc-Al and trigonal-like Al3Tb crystal structures. We propose that the high coordination of Al around Tb limits diffusion in the intermetallic network, allowing for the isolated Al-rich regions to form at high density. These regions are responsible for the extremely high density of Al nanocrystal nuclei.

Tb3+-impregnated, non-porous silica glass possessing intense green luminescence under UV and VUV excitation

A colorless transparent luminescence material was successfully prepared by impregnation of leached, porous glass with Tb3+ ions followed by reductive sintering in a CO atmosphere. Tb3+ emissions under ultraviolet (UV) and vacuum ultraviolet (VUV) excitation clearly showed the most intense emission band to be situated at 543nm, which corresponds to the 5D4→7F5 transition. Sintering of the Tb glass in a reducing atmosphere resulted in a significant enhancement of Tb3+ emission intensity in comparison with sintering in air. The presence of traces of cerium ions was verified in Tb glasses, and more Ce3+ ions were produced as a result of the reductive sintering. The increase in Ce3+ ions was believed to be mainly responsible for the enhancement of 5D3→7Fj and 5D4→7Fj transitions from Tb3+ ions owing to an energy transfer channel. A clearly defined difference in the spectral energy distribution of Tb3+ emissions was found for 231nm UV and 160nm VUV excitation of the Tb glass. The phenomenon of cross relaxation was only observed under 231nm UV excitation. Different excitation mechanisms were taken into account. Direct excitation of Tb3+ ions together with Ce3+ ions occurred in the Tb glass under the 231nm UV light, whereas indirect excitation consisting of host absorption of energy and transfer from host to Tb3+ ions occurred under the 160nm VUV light.

Preparation and luminescent properties of sol–gel derived SiO 2–B 2O 3:Tb glass films

Borosilicate glass films doped with rare-earths were deposited on glass substrates by using a simple sol–gel method. To avoid the undesirable precipitation due to the different hydrolysis rates between silicon and boron alkoxides, two solutions were used for dip-coating separately. One solution consisted of silicon tetraethoxide, ethanol, water and terbium nitrate as the Tb dopant. Another consisted of triethyl borate. Layer-by-layer deposition was applied by dipping into these solutions in sequence. The luminescent properties of Tb 3+ were investigated for the borosilicate samples in relation to the firing effect. After firing at 900 °C, a remarkable increase (≈8 times) of the Tb 3+-ion luminescence was observed for the borosilicate samples, while the silicate sample showed about 3 times increase in luminescence intensity. The boron addition of as low as 1 mol% of B 2O 3 was found to be very effective in increasing the Tb 3+ luminescence intensity.

Random magnetism in amorphous rare-earth alloys (invited)

Several aspects of the magnetic transitions seen in rare-earth metallic glasses are discussed, particularly with reference to recent theoretical work. These include: (a) apparent double transitions observed in Gd glasses where exchange fluctuations are important, (b) evidence for a correlated speromagnetic state recently predicted by Chudnovsky and Serota, and (c) the analysis of a Tb glass with strong random anisotropy in terms of an Ising-type spin-glass transition.

Scintillating Glass, Fiber-Optic Plate Detectors for Active Target and Tracking Applications in High Energy Physics Experiments

We have studied the performance of scintillating glass fiber-optic plates using 10 GeV/c particles at the SLAC test beam. The plates were composed of: (1) Terbium activated cladded-glass cores in a matrix of 15 #x003BC;m spacing; and (2) Cerium activated cladded-glass cores in a matrix of variable spacing 6-10 #x003BC;m. The target plates were viewed with a three-stage, gatable image intensifier. Particle tracks and nuclear interactions were recorded on film for both materials. We observe 5 detected hits/mm for minimum ionizing particles for the Tb glass, and 1-2 hits/mm for the Ce glass. The test results indicate that scintillating glass fiber-optic plates can be used as high spatial resolution tracking detectors for both fixed target and colliding beam experiments.

Effect of anisotropy strength on phase transitions in random anisotropy magnets

ac susceptibility and magnetization measurements are reported for a number of Gd and Tb based glasses. Raman magnetic anisotropy effects are observed in both the Gd and Tb glasses. The Gd glasses show a transition to an infinite susceptibility state and in some cases a further transition to an hysteretic state at low temperatures in which field-cooling and magnetic viscosity effects are observed. The Tb glass shows only a small speromagnetic peak at low temperatures. The ratio of anisotropy strength to exchange was varied in the Gd glasses by alloying, and the effect of this on the resulting magnetic states is discussed.

Electrical and magnetic properties of rare-earth — Gold glasses

We present magnetic and electrical properties of amorphous rare-earth alloys of composition ( R 75Au 25) 100− x B x ( R = Pr, Gd, Tb, Er and x = 0, 10). Low-field susceptibility, electrical resistivity and high-field magnetization measurements were made between 1.6 and 300 K. Resistivity measurements show both positive and negative temperature coefficients and in some cases maxima and minima that are associated with magnetic ordering and Kondo-like scattering respectively. For all the samples except those containing Gd, the local random anisotropy produces asperomagnetic ordering and high coercive fields. Large magnetic after-effects have been observed down to liquid helium temperatures particularly for the Tb glass. Metamagnetic effects have been found in (Er 75Au 25) 90B 10.