Rare Earth Tb Research Articles

Quantification of trace level rare earth elements in Al matrices by ICP-MS

Abstract A method has been developed for quantification of trace rare earth (Ce, Dy, Er, Eu, Gd, Ho, La, Nd, Pr, Sm, Tb and Yb) impurities in alumina and aluminum by inductively coupled plasma mass spectrometry (ICP-MS) after matrix separation. The matrix separation was achieved by selective precipitation of trace elements. Due to its refractory nature a microwave digestion method was developed and optimized for the quantitative dissolution of Al2O3. The analytical methodology was validated by recovery studies with standard addition as well as with an independent γ-spectrometry technique using 152,154Eu tracers. The observed recovery in the synthetic samples was in the range of 93–100% with precision within 6.1–11.6 (%RSD), while the same in the case of radio tracer technique were found to be >98% and <2% (RSD), respectively. The method detection limit was found within 0.5–8.3 μg kg−1, respectively. The procedure is simple, organic waste free and suitable for routine analysis.

Effect of Co, Cu, Nb, Ti, V on magnetostriction and mechanical properties of TbDyFe alloys

The previous studies have revealed that addition of different elements in TbDyFe alloys have different influences on its microstructure, mechanical and magnetic properties. According to the effects, one can classify elements into different groups. This paper aims to explain the differences by the enthalpy of mixing between the atomic pairs. Various alloys of the type Tb0.3Dy0.7Fe2, (Tb0.3Dy0.7)0.3Fe0.6Co0.1, (Tb0.3Dy0.7)0.3Fe0.6Cu0.1, (Tb0.3Dy0.7)0.3Fe0.6Nb0.1, (Tb0.3Dy0.7)0.3Fe0.6Ti0.1, (Tb0.3Dy0.7)0.3Fe0.6V0.1 were prepared by an arc melting under a high-purity argon atmosphere. The effects of Co, Cu, Nb, Ti, V addition on the microstructure, mechanical properties and magnetic properties of TbDyFe alloys were studied systematically. The results showed that according to the different mixing enthalpy between different atom-pairs, the elements added in TbDyFe alloy could be classified into two different groups. One had a more negative mixing enthalpy with the rare earth element Tb(Dy), such as Co, Cu, which were prone to form phases with rare earth elements; the others possessed a more negative enthalpy of mixing with Fe, such as Nb, Ti, V, which were conducive to react with Fe. With Co, Cu element addition, the alloys exhibited dendritic morphology. While the alloys demonstrated the second phase precipitation morphology with addition of Nb/Ti/V elements. Compared to the Tb0.3Dy0.7Fe2 alloy, the REFe3 phase appeared in the alloys with addition of Co/Cu element. The NbFe2/Fe2Ti/FeV phase precipitated in the alloys with Nb/Ti/V addition, respectively. But the formation of REFe3 phase was effectively suppressed due to the addition of Nb/Ti/V elements. The presence of both REFe3 phases and NbFe2/Fe2Ti/FeV paramagnetic phases all reduced the magnetostriction of (Tb0.3Dy0.7)0.3Fe0.6M0.1 (M = Co, Cu, Nb, Ti, V) alloys compared to the Tb0.3Dy0.7Fe2 alloys.

Exploring structural origin of the enhanced magnetostriction in Tb-doped Fe83Ga17 ribbons: Tuning Tb solubility

Minor rare earth Tb addition greatly enhances the magnetostriction of Fe83Ga17 alloy. However, the structural origin of the enhanced magnetostriction remains unclear, since it is quite difficult to detect Tb element directly. Here, high temperature annealing is designed to tune the Tb solubility for exploring its structure origin in the Tb doped Fe83Ga17 ribbons. It is found during annealing a Tb-rich phase precipitates, leading to the decrease of the tetragonal distortion of the matrix, and the dramatic decrease of the magnetostriction accordingly. These results inversely consolidate that the enhanced magnetostriction is induced by solid soluted Tb element in Fe-Ga alloy.

Electroluminescence color tuning between green and red from metal–oxide–semiconductor devices fabricated by spin-coating of rare-earth (terbium + europium) organic compounds on silicon

Color tunable electroluminescence (EL) from metal–oxide–semiconductor devices with the rare-earth elements Tb and Eu is reported. Organic compound liquid sources of (Tb + Ba) and Eu with various Eu/Tb ratios from 0.001 to 0.4 were spin-coated on an n+-Si substrate and annealed to form an oxide insulator layer. The EL spectra had only peaks corresponding to the intrashell Tb3+/Eu3+ transitions in the spectral range from green to red, and the intensity ratio of the peaks was appropriately tuned using the appropriate Eu/Tb ratios in liquid sources. Consequently, the EL emission colors linearly changed from yellowish green to yellowish orange and eventually to reddish orange on the CIE chromaticity diagram. The gate current +IG current also affected the EL colors for the medium-Eu/Tb-ratio device. The structure of the surface insulator films analyzed by cross-sectional transmission electron microscopy (TEM), X-ray diffraction (XRD) analysis, and X-ray photoelectron spectroscopy (XPS) has four layers, namely, (Tb4O7 + Eu2O3), [Tb4O7 + Eu2O3 + (Tb/Eu/Ba)SiOx], (Tb/Eu/Ba)SiOx, and SiOx-rich oxide. The EL mechanism proposed is that electrons injected from the Si substrate into the SiOx-rich oxide and Tb/Eu/Ba-silicate layers become hot electrons accelerated in a high electric field, and then these hot electrons excite Tb3+ and Eu3+ ions in the Tb4O7/Eu2O3 layers resulting in EL emission from Tb3+ and Eu3+ intrashell transitions.

Spin-orbit torque-induced switching in ferrimagnetic alloys: Experiments and modeling

We investigate spin-orbit torque (SOT)-induced switching in rare-earth-transition metal ferrimagnetic alloys using W/CoTb bilayers. The switching current is found to vary continuously with the alloy concentration, and no reduction in the switching current is observed at the magnetic compensation point despite a very large SOT efficiency. A model based on coupled Landau-Lifschitz-Gilbert (LLG) equations shows that the switching current density scales with the effective perpendicular anisotropy which does not exhibit strong reduction at the magnetic compensation, explaining the behavior of the switching current density. This model also suggests that conventional SOT effective field measurements do not allow one to conclude whether the spins are transferred to one sublattice or just simply to the net magnetization. The effective spin Hall angle measurement shows an enhancement of the spin Hall angle with the Tb concentration which suggests an additional SOT contribution from the rare earth Tb atoms.

New La1−xTbxMnO3 nanoparticles: fabrication via wet chemical route for enhanced structural, electrical and dielectric parameters

Rare earth Tb3+ doped LaMnO3 nanoparticles were fabricated via cheap facile wet chemical micro emulsion route. X-ray diffraction and spectral analysis by Fourier transform infrared radiation spectroscopy confirmed the formation of orthorhombic structure of La1−xTbxMnO3 nanoparticles. The crystallite size was found in the range 10–50 nm. The lattice parameters (a)–(c) and cell volume were decreased as the La3+ was replaced with Tb3+. This was attributed to the smaller ionic radius of Tb3+ (0.92 Å) as compared to that of La3+ (1.03 Å). Scanning electron microscopic images showed that the La1−xTbxMnO3 grains are well structured and have no cracks. They are non-homogeneous in size with occasionally aggregation. The dielectric measurements of La1−xTbxMnO3 nanoparticles performed in the frequency range 1 × 106 to 3 × 109 Hz showed that both Tb3+ contents and frequency decreased the dielectric parameters. At high frequency, the dipoles could not follow the alternating field and thus resulted in decreased dielectric parameters. The Tb3+ in LaMnO3 decreased the internal viscosity of the system that affected the dielectric parameters. DC-electrical resistivity was enhanced with the increased Tb3+ contents. This might be due to f–d orbital coupling between rare earth and transition metal cations in La1−xTbxMnO3 nanoparticles.

Facile room-temperature coprecipitation of uniform barium chlorapatite nanoassemblies as a host photoluminescent material

As an emerging host phosphor material, barium chlorapatite (Ba5(PO4)3Cl), is attracting growing attention. However, rare earth-doped Ba5(PO4)3Cl phosphors have mainly been obtained via high temperature-based, energy-consuming techniques. In this contribution, we developed a straightforward, facile room-temperature coprecipitation method in the presence of a specific amount of ethylenediaminetetraacetic acid disodium salt that provided Ba5(PO4)3Cl nanoparticles self-assembled to construct uniform Ba5(PO4)3Cl nanoassemblies (diameter: 80–120nm) as well as rare earth Tb3+-doped Ba5(PO4)3Cl:xTb3+ nanophosphors. The nanoassemblies were transparent within the ultraviolet and visible spectral range. The Ba5(PO4)3Cl:xTb3+ nanophosphors exhibited four emission peaks under 228-nm excitation, and the optimal doping amount of Tb3+ was 4.0%. In contrast to traditional energy-consuming, high-temperature techniques, the facile room-temperature coprecipitation method developed here represents an attractive alternative route to obtain uniform Ba5(PO4)3Cl nanoassemblies and Ba5(PO4)3Cl:xTb3+ nanophosphors that are candidate luminescent hosts.

Red and green emitting CTAB assisted CdSiO3:Tb3+/Eu3+ nanopowders as fluorescent labeling agents used in forensic and display applications

Nano technology created numerous applications in surface based science due to their reduced size and larger surface area. This offers new promises in surface-based science containing latent fingerprints (LFPs) on porous and non-porous surfaces and anticounterfeiting applications. Conversely, currently used traditional fluorescent powders have several shortcomings due to low sensitivity, high background hindrance and high toxicity. To overcome with these difficulties, we reported rare earth (Tb or Eu) doped cadmium silicate nanopowders synthesized via eco-friendly ultrasound assisted sonochemical route as a substitute for the commercially available fluorescent powders. The obtained products were well characterized by XRD, SEM, DRS, TEM etc. The optimized CdSiO3: Tb3+/Eu3+ (5 mol %) nanopowders (NPs) were used for the visualization of LFPs on various porous and non-porous surfaces. CIE and CCT results revealed that the phosphor was highly useful for the fabrication of red and green emitting diodes in display device and WLED applications. The optimized NPs will create a fangled prospect to visualize LFPs and anti-counterfeiting applications.

Syntheses and Structures of Four Pairs of Coordination Polymers Based on 2,2′-((5-(Methoxycarbonyl)-1,3-phenylene)bis(oxy))dipropanoic Acid

Hydrothermal reactions of rare earth (Nd, Sm, Eu, and Tb) and l- or d-lactic acid are used to construct four pairs of homochiral metal–organic frameworks (HMOFs) with polymetallic building blocks, namely, {[Nd2(L)2(H2O)3]·4H2O}n (1-r)/(1-s) and {[Ln2(L)2(H2O)2]·4H2O}n {Ln = Sm (2), Eu (3), Tb (4)} (n-r)/(n-s). The eight complexes were characterized by single-crystal X-ray diffraction, infrared spectra, elemental analysis, thermogravimetric analysis, electronic circular dichroism (ECD) spectra, and powder X-ray diffraction measurements. The complexes 1–4 featuring a 3D porous metal–organic framework crystallize in chiral space groups, and their chirality is proven by the solid-state ECD spectra. Moreover, the second-harmonic generation (SHG) investigation reveals that the complexes 1-r, 2-r, 3-r, and 4-r have medium SHG eficiencies. The complexes 2, 3, and 4 exhibit relatively high luminescence properties, which could be ascribed to ligand-centered emission. The luminescence of complex 4-r could be quenched by nitrobenzaldehyde, which may be used for molecular sensing and recognition.

Gyroscopic g factor of rare earth metals

We develop the in situ magnetization measurement apparatus for observing the Barnett effect consisting of a fluxgate sensor, a high speed rotor with frequencies of up to 1.5 kHz, and a magnetic shield at room temperature. The effective magnetic field (Barnett field) in a sample arising from rotation magnetizes the sample and is proportional to the rotational frequency. The gyroscopic g factor, g′, of rare earth metals, in particular, Gd, Tb, and Dy, was estimated to be 2.00 ± 0.08, 1.53 ± 0.17, and 1.15 ± 0.32, respectively, from the slopes of the rotation dependence of the Barnett field. This study provides a technique to determine the g′ factor even in samples where the spectroscopic method may not be available.

Comparative study on gas sensing properties of rare earth (Tb, Dy and Er) doped ZnO sensor

Zinc oxide and rare earth (Tb, Dy and Er) doped zinc oxide has been synthesized chemically by facile and cost effective co-precipitation method. Effect of dopant on structural, optical and morphological properties of ZnO has been studied by using various characterization techniques. Synthesized powder samples were deposited as thick films on alumina substrate and their gas sensing characteristics have been investigated for various gases at different operable temperatures. Doped ZnO samples have exhibited significant enhancement in sensor response to ethanol and reduction in optimum operable temperature as well. The study also revealed temperature dependent selectivity behavior of Tb and Er doped ZnO sensors towards ethanol and acetone. Significant increase in the gas sensor response of doped samples has been corroborated to their high surface basicity, increased surface area, morphological changes and oxygen vacancies present.

Magnetic entropy change and electrical transport properties of rare earth Tb doped manganites La4/3Sr5/3Mn2O7

The magnetic transition process in double-layer perovskite manganites is rather different from that in the counterpart compound with standard perovskite structure. In this paper, the magnetic phases below room temperature as well as the order of magnetic phase transition in terbium (Tb) doped La4/3Sr5/3Mn2O7 are studied by analyzing the magnetization curves, including thermal hysteresis, magnetic entropy change and its universal curve. The electrical conductivities with and without applied magnetic field are also discussed. Both the undoped and the doped samples (La1-xTbx)4/3Sr5/3Mn2O7 (x=0, 0.025) are prepared through the conventional solid-state reaction of mixed La2O3, Tb2O3, MnCO3 and SrCO3 whose purities are all higher than 99.9%. The mixture is calcined twice at 1000℃ for 12 h. Subsequently, the compactly compressed tablet of the calcined mixture is sintered in air at 1350℃ for 24 h. The data of X-ray diffraction show that the crystallographic structures of both samples are in the Sr3Ti2O7-type tetragonal phase with the space group I4/mmm. The refinement result indicates that the smaller radius of doped Tb3+ reduces all three lattice parameters as well as the c/a ratio, which is attributed to the preferential occupation of Tb3+ on the R site in rocksalt layer instead of the P site in perovskite layer. The temperature and field dependence of magnetization M(T, H), are recorded using the vibrating sample magnetometer of physical property measurement system (Quantum Design). Upon reducing the temperature, both samples exhibit two magnetic phase transitions from the paramagnetic phase at high temperature to the two-dimensional shortrange-ordered ferromagnetic state at the intermediate temperature, and finally the three-dimensional long-range-ordered antiferromagnetic state at low temperature. The zero-field-cooling and field-cooling curves display the characteristics of spin-glass behavior which may be due to the competition between B-site ferromagnetic and antiferromagnetic interactions associated with the randomly distributed A-site ions. The magnetic entropy changes of the samples are obtained through analyzing the magnetization data. The maximal magnetic entropy changes under 7 T magnetic field of the two samples are -4.60 J/(kgK) and -4.18 J/(kgK), respectively. The doped Tb ions reduce the transition temperatures, Tc2D and Tc3D, as well as the maximal value of magnetic entropy change, and increases the transition temperature range. The re-scaling curves of magnetic entropy change at different magnetic fields do not fall into a universal one, rather disperse in a wide interval, which suggests that the system undergoes a weak first-order transition at Tc3D. This conclusion is supported by the thermal hysteresis observed in the magnetization data. In addition, the electrical resistivity of the doped sample can be explained by using the small polaron model, which is different from three-dimensional variable-range hopping mechanism of undoped sample. On reducing temperature, the doped sample undergoes metal-insulator transition at temperature TP about 115 K, which is different from the undoped sample that shows the shoulder-shaped MI transition peaks. Under finite fields, the magnetoresistance value of intrinsic nature is about 56% near Tc3D.

Solgel-hydrothermal synthesis of Tb/Tourmaline/TiO2 nano tubes and enhanced photocatalytic activity

In this study, we synthesized Tb/Tourmaline/TiO2 nano tubes (NTs) through a solgel-hydrothermal method. The as-prepared samples were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, Raman spectromicroscope, scanning electron microscopy, transmission electron microscopy and UV-vis diffuse reflectance spectroscopy. The resulting Tb/Tourmaline/TiO2 NTs exhibited higher photocatalytic activity than pure TiO2 and TiO2 nano particles (NPs) in the degradation of menthyl orange under UV-light. Results revealed that doping rare earth element Tb could narrow the wide band gap of TiO2 and tourmaline could trap the photogenerated electron of TiO2 to inhibit the recombination of photogenerated electron-hole pairs.

A density functional theory study of electronic and magnetic properties of rare earth doped monolayered molybdenum disulphide

The effects of Rare Earth (RE) atoms Sm, Eu, Gd, Tb, and Dy doping on structural, electronic, and magnetic properties of single layer MoS2 were investigated using first principles calculations. The analysis of electronic properties pointed out the appearance of host-impurity hybrid states on the edges of principal bands of the material, which appeared to cause narrowing of its bandgap. The values of total magnetic moment were calculated as 3.3 μB, 8.1 μB, 8.5 μB, 6.8 μB, and 6.4 μB for Sm-, Eu-, Gd-, Tb-, and Dy-doped MoS2, respectively. The underestimation of magnetic moment in the case of Sm doping is found which is assigned to shielding of 4f moments and quenching of angular momentum caused by Sm 4f–S 3p hybridization. On the other hand, the observed overestimation of magnetic moments for Eu and Gd cases is likely to be due to increase in angular momentum due to indirect exchange interaction of highly localized 4f states via 5d or 6s conduction electrons. The findings of this work point out the possibilities of tuning the band gap and magnetic properties of monolayer MoS2 upon RE doping for realization of p-type ferromagnetic semiconductors.

Charge-transfer-based terbium MOF nanoparticles as fluorescent pH sensor for extreme acidity

Newly emerged metal organic frameworks (MOFs) have aroused the great interest in designing functional materials by means of its flexible structure and component. In this study, we used lanthanide Tb3+ ions and small molecular ligands to design and assemble a kind of pH-sensitive MOF nanoparticle based on intramolecular-charge-transfer effect. This kind of made-to-order MOF nanoparticle for H+ is highly specific and sensitive and could be used to fluorescently indicate pH value of strong acidic solution via preset mechanism through luminescence of Tb3+. The long luminescence lifetime of Tb3+ allows eliminating concomitant non-specific fluorescence by time-revised fluorescence techniques, processing an advantage in sensing H+ in biological media with strong autofluorescence. Our method showed a great potential of MOF structures in designing and constructing sensitive sensing materials for specific analytes directly via the assembly of functional ions/ligands.

Crystal structure and magnetism of BiFeO3 nanoparticles regulated by rare-earth Tb substitution

Tb-doped BiFeO3 nanoparticles were prepared using sol–gel method. The effect of Tb substitution on crystal structure and magnetism of BiFeO3 nanoparticles were investigated. It is shown that the crystal structure and magnetism of BiFeO3 nanoparticles are regulated by rare-earth Tb substitution. Particularly, the sizes of the particles are reduced to smaller than 100 nm after doping with Tb. The magnetization of Tb-doped BiFeO3 nanoparticles has been enhanced in magnitude, which is mainly attributed to the suppression of spin cycloid structure belonging to R3c phase fraction in the process of rhombohedral-to-orthorhombic structural phase transformations. At the meantime, the magnetic hysteresis loops show exchange bias towards negative axis. The exchange bias behaviors originate from the coupling interaction between antiferromagnetic core and ferromagnetic surface. The present work provides a route regulating the magnetization of BiFeO3 particles as well as further promoting its applications in multiferroic materials.

Leaching rare-earth and radioactive elements from alkaline rocks of the Lovozero Massif, Kola Peninsula

The paper presents data on the leaching efficiency of rare-earth (La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu) and radioactive (Th and U) elements by various reagents from alkaline rocks of the Lovozero Massif. Element concentrations were analyzed by ICP-MS and instrumental neutral activation (INAA). A new complex technique is suggested for analyzing elements on the solid phase of polymer hydrogels. This technique makes it possible to enhance the sensitivity and selectivity of INAA when these elements are simultaneously contained in rocks. Data are presented on the selective leaching of trace elements and the application of environmentally safe reagents.

(Invited) XAFS of Rare Earth Elements in Amorphous Silicon Alloys: What Do We Know about the Local Structure?

X-ray absorption spectroscopy (both XANES, X-ray Absorption Near-Edge Spectroscopy and EXAFS, Extended X-ray Absorption Fine Structure) is a powerful tool to determine the chemical environment of selected elements in solids. It is particularly well suited to study rare earth elements in amorphous silicon alloys. In this paper we review the technique and results obtained for different rare earth elements, especially Er, Eu and Tb. Whenever possible, the rare earth elements coordinate to any oxygen present in subcoordinated envitronments that vary with the host and can be very distorted. The details of the environment depend on the technique used to prepare the samples. Annealling above 400C makes the coordination evolve towards oxide-like 6-fold environments. Europium is a special case. It may assume either 2+ or 3+ oxidation states. The X-ray absorption peaks associated with the core electrons binding energy can be used to estimate the relative concentration of each. Annealling in oxidizing atmospheres can modify the Eu3+/Eu2+ ratio, affect the atomic surroundings and change the luminescence spectrum. In general, efficient luminescence of the 3+ ions is associated with low coordination oxygen environments. This environment does not change significantly at the relatively low annealling temperatures (up to 300C) that maximize the photoluminescence. The reason for the increase of the luminescence intensity with annealling not a modification of the local environment of the rare earth ions.

Luminescence of Terbium and Neodymium Ions in Yttrium Aluminum Garnet Xerogels on Porous Anodic Alumina

Luminescent structures of yttrium aluminum garnet doped with rare-earth elements Tb and Nd (YAG:Tb3+ and YAG:Nd3+) were formed by the sol–gel route on films of porous anodic alumina. The morphology, phase composition, and luminescence of the fabricated structures were investigated. Photoluminescence spectra of the YAG:Tb3+ and YAG:Nd3+ structures revealed emission bands due to electronic transitions of the relevant rare-earth elements. Fine structure was observed in the luminescence bands of all fabricated samples and was associated with the manifestation of a Stark effect.

Fabrication, magnetostriction properties and applications of Tb-Dy-Fe alloys: a review

: As an excellent giant-magnetostrictive material, Tb-Dy-Fe alloys (based on Tb0.27-0.30Dy0.73-0.70Fe1.9-2 Laves compound) can be applied In many engineering fields, such as sonar transducer systems, sensors, and micro-actuators. However, the cost of the rare earth elements Tb and Dy is too high to be widely applied for the materials. Nowadays, there are two different ways to substitute for these alloying elements. One is to partially replace Tb or Dy by cheaper rare earth elements, such as Pr, Nd, Sm and Ho; and the other is to use non-rare earth elements, such as Co, Al, Mn, Si, Ce, B, Be and C, to substitute Fe to form single MgCu2-type Laves phase and a certain amount of Re-rich phase, which can reduce the brittleness and improve the corrosion resistance of the alloy. This paper systemically introduces the development, the fabrication methods and the corresponding preferred growth directions of Tb-Dy-Fe alloys. In addition, the effects of alloying elements and heat treatment on magnetostrictive and mechanical properties of Tb-Dy-Fe alloys are also reviewed, respectively. Finally, some possible applications of Tb-Dy-Fe alloys are presented.