Rare Earth Tb Research Articles

Impact of rare earth Tb3+ substitution in cobalt ferrites: Tuning structural, dielectric, magnetic properties and photocatalytic activity

Nanocrystalline CoTbyFe2-yO4 (0 ≤ y ≤ 0.025) ferrites were prepared through the citrate-gel combustion method. X-ray diffraction confirmed the formation of a single-phase spinel structure with crystalline sizes ranging between 19 and 48 nm. The experimental and theoretical lattice parameters correlated well and were found to be ranging between 8.510 and 8.367 Å. SEM images revealed a large aggregation of spherical-shaped nanoparticles with non-uniform shape and distribution. Magnetization measurements revealed the dependance of both Ms, Mr, and HC with increasing Tb3+ content. The evolution of MS and HC upon reducing the measuring temperature indicates the thermal instability of the blocked magnetic moments, which increased for the different compositions. The dielectric properties obtained for CoTbyFe2-yO4 as a function of frequency. The Tb-doped cobalt ferrite catalysts exhibit superior photocatalytic efficiency for crystal violet (CV) degradation as compared to cobalt ferrite nanoferrite catalysts.

Selective exposure of (1 1 1) crystal plane in Pd49Ag30Te4 by Tb doping to weaken Pd − C bond and promote electroreduction of CO2 to CO

Employing electric energy to convert carbon dioxide (CO2) into valuable small molecules is a potentially practical method in energy storage and greenhouse gas alleviation. A huge challenge for electrocatalytic CO2 reduction is to reduce overpotential to improve energy efficiency. Herein, we demonstrate that doping alloy Pd49Ag30Te4 (PAT) with rare-earth element Tb is beneficial for selective exposure of (111) crystal plane, which is a highly active crystal plane for producing carbon monoxide (CO). The as-prepared Tb2.9PAT exhibited high electrocatalytic performance with 95.7 % CO faradic efficiency at − 0.8 V (vs RHE), far exceeding that of PAT, and coupled with good durability. In situ spectral study and theoretical calculations disclose that the introduction of Tb regulates the d-band center of PAT alloy, weakens the Pd − C bonding ability, and promotes the desorption of *CO in the rate-determining step. This study provides a method for doping induced selective exposure of crystal face, which provides new idea for improving catalytic performance.

Fabrication of rare earth (Tb+3) and alkaline earth metal (Mg+2) Co-doped CdAl2O4@MXene composite: A unique approach to tune bandgap energy through quantum confinement effect for photocatalytic applications

The present work includes the use of effective strategy to improve the photocatalytic degradation activity of CdAl2O4 via dopant assimilation to enhance the bandgap energy (Eg) and to influence the light-sensitive activity of this spinel mixed oxide. In this study, CdAl2O4 (CA), Mg–CdAl2O4 (MCA), and Tb-doped Mg–CdAl2O4 (TMCA) were fabricated by the facile co-precipitation route and an ultra-sonication approach was used to prepare a composite of Tb-doped Mg–CdAl2O4 with MXene (TMCA@MXene). The obtained results from UV–Visible analysis deduce that there is an increase in Eg of MCA (2.51 eV) and TMCA (2.67 eV) as compared to pure CA (2.45 eV) which follows the quantum confinement effect accompanying the decrease in crystallite sizes of doped samples as compared to CA. The significant increase in bandgap energy of TMCA is due to the confinement of electrons in a small area and also due to the conversion of continuous energy levels into discrete energy levels. Moreover, UV–Visible spectroscopic analysis was made to evaluate the catalytic performance of fabricated photocatalysts against harmful organic pollutants. The photocatalytic study showed that the co-doped CdAl2O4 (TMCA) is a better photocatalyst than MCA and CA for the degradation of selected pollutants. Among all synthesized catalysts i.e. CA, MCA, TMCA, and TMCA@MXene, the highest photocatalytic activity was shown by MXene based nanocomposite. TMCA@MXene showed ∼86 % degradation of Rhodamine B (RhB) and 79.6 % degradation of Aspirin (acetylsalicylic acid). The outstanding photocatalytic efficacy of TMCA@MXene could be accredited to the quantum confinement effect produced by co-doping of alkaline earth metal (Mg+2) and rare earth metal (Tb+3) and large surface area, high conductivity, and excellent light harvesting capability provided by MXene sheets. Hence, TMCA@MXene could be an effective photocatalyst in future for the removal of toxic organic pollutants.

Correlation between nutrients, rare earth elements and heavy metals in O. Sativa rice plant organs by instrumentation neutron activation analysis and proton induced x-ray emission techniques

The accumulation of halogens and metals from roots to stems, leaves and grains of Oryza sativa rice plant collected in Northern Senegal (St Louis region) at the same stages of growth but at different salinity soil levels was investigated by measuring their elemental concentration by invasive instrumental techniques of neutron activation analysis and proton induced x-ray emission. The normalized elemental concentration of Na, Cl, K, (Cs, Rb, Sr, Sb, Ba Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Cu, Zn, As, Se, Br, Rb, Sb was correlated with one of rare earth elements, La, Ce, Sm, Yb, Nd, Eu, Tb, Tm, and Lu) and the one of the heavy metals Hf, Ta and Th and to assess their subsequent distribution within the Oryza sativa rice plant in a particular salinity environment. The exploration of the experimental data was performed by applying machine learning techniques with Python to find their elemental correlations. This study shows that the accumulation of iron is highly correlated with the amount of rare earth elements and heavy metals investigated. We observe an inverse correlation between Fe and Cl concentrations in the roots and stems of the Oryza sativa rice plant, in which higher levels of Fe in the roots relative to stems correspond to lower levels of Cl. We also remark that there is no accumulation of rare earth elements in the root tissues of the different Oryza sativa rice plants studied. Whereas, in the stem, leaf, and grain organs there is a strong correlation between metal contents and rare earth elements.

Understanding the coercivity enhancement mechanism of grain boundary diffused Nd-Fe-B magnets by comparing with commercial equivalent coercivity magnets

The grain boundary diffusion (GBD) technology effectively utilizes heavy rare earth (HRE) elements to improve the coercivity of sintered Nd-Fe-B magnet. Significantly, clarifying its coercivity improvement mechanism is essential for further optimizing the process and performance. Through comparative analysis with commercial conventional magnets (CSH) processing equivalent coercivity, this study investigated the specific mechanism by which the GBD method enhances the coercivity of HRE elements in an efficient manner. To achieve the same coercivity (∼21.4 kOe), GBD magnets contained only 0.25 wt% Tb, whereas CSH magnets had 1.17 wt% Dy and 1.18 wt% Tb. The microstructure analysis revealed that the Tb element in the GBD magnet was concentrated in the outer layer of the grain, constituting 17.37 wt% of the total rare earth content. While, in CSH magnets, the HRE element in the main phase grains accounted for only 9.58 wt% of the total rare earth elements, including Dy (3.83 wt%) and Tb (5.75 wt%). The characteristic core-shell structural grains in GBD magnet also endowed it with an uneven magnetic domain structure and a more concentrated “abrupt” magnetization reversal. Based on the characterization results the nucleation positions of the two types of magnets were analyzed by fitting Hci/Ms and Ha/Ms. The results can serve as a guide for enhancing coercivity in grain boundary diffusion sintered Nd-Fe-B magnets, aiding in process and property optimization, and advancing the understanding of nucleation type mechanisms.

Structural and Magnetic Impressions of Rare Earth Tb Doping on Ba–In Based Hexaferrites Prepared Through Sol–Gel Route for Magnetic Aspects

Structural and Magnetic Impressions of Rare Earth Tb Doping on Ba–In Based Hexaferrites Prepared Through Sol–Gel Route for Magnetic Aspects

Spatial confinement of styryl pyridine salt derivative in MCM-22 molecular sieve network for boosted fluorescence emission and stable ratiometric sensing of bacillus anthracis biomarkers

In this work, a stable ratiometric nanofluorescent probe for the detection of 2,6-dipicolinic acid (DPA), a Bacillus anthracis biomarker, was developed based on confinement-induced emission enhancement of cationic styrylpyridine salt derivative L in MCM-22 molecular sieve pores. The cationic L and the lanthanide Tb3+ were loaded into the pores of the molecular sieve by electrostatic interaction with the negatively charged AlO4 tetrahedron unit, and L exhibited enhanced red fluorescence emission as a stable fluorescence reference mark in the nanoprobe platform due to the restricted molecular torsion of L in the pores of MCM-22. At the same time, the characteristic green fluorescence emission of Tb3+ can be excited by energy transfer due to the “antenna effect” of DPA. The prepared Tb-L@MCM-22 nanoprobe showed specific selectivity and stable fluorescence ratiometric detection of DPA in tap water, lake water, bovine serum and actual bacterial spores. Benefiting from the confinement-induced fluorescence enhancement effect of L in the MCM-22 molecular sieve pores, the obtained Tb-L@MCM-22 can provide a stable reference signal for the fluorescence ratiometric detection of DPA with a limit of detection (LOD) of 78.6 nM and 1.310 × 104 spores per mL. More importantly, combining of the Tb-L@MCM-22 based DPA detection test strips with a smartphone app demonstrated a stable, convenient and rapid method for detecting of anthrax biomarkers.

Spin–Orbit Torque and Current‐Driven Switching in Pt100‐yTby/Co/AlOx Trilayers

AbstractTo decrease the energy consumption for the electrical manipulation of magnetization, the enhancement of the spin Hall effect through alloying is widely investigated, but the use of rare earth elements is rarely mentioned. This work reports the modification of the spin Hall effect on Pt by doping rare earth Tb atoms. The spin–orbit torque (SOT) performance is significantly enhanced in Pt100‐yTby alloyed heavy metal (HM) layer. Compared with the Tb‐free sample, the damping‐like effective field per unit current density increases to 1.9 times in the samples with Tb content between 5% and 10%. The critical current density for magnetization reversal is greatly reduced by 65% in a device with Pt87Tb13 HM layer and the in‐plane assistant field as small as ±20 Oe is sufficient for the deterministic switching in the same device. By magneto‐optical Kerr effect imaging, it is confirmed that the increased in‐plane field can effectively compensate the Dzyaloshinskii–Moriya interaction (DMI), which not only helps to reduce the critical current, but also facilitates the domain wall motion and is beneficial for the switching process. All results show that the Pt‐Tb alloy is a competitive candidate for low‐power spintronic devices.

Waterborne rare earth complexes/polyurethane systems with UV shielding and tunable fluorescence for anti-counterfeiting

Fluorescent polymer materials integrated with rare-earth complexes demonstrate promising multifunctional capabilities. However, their complex synthesis procedures and prohibitive cost currently constrain large-scale utilization. Herein, rare earth complexes Eu(PBA)3Phen and Tb(PBA)3Phen were synthesized by coordinating Eu3+, Tb3+ with p-hydroxybenzoic acid and phenanthroline, which were then physically incorporated into waterborne polyurethane (WPU) to obtain Eu-WPU and Eu/Tb-WPU composites. The as-prepared Eu/Tb-WPU had tunable fluorescence, whose fluorescent colors from green to red were achieved under ultraviolet excitation. Compared to Eu(PBA)3Phen (0.27 ms; 0.22 %), the Eu-WPU exhibited a prolonged fluorescence lifetime(1.08 ms) and high fluorescence quantum yield (10.7 %). In addition, Eu-WPU had a wider UV shielding range of 200–289 nm than WPU (200–222 nm). The prepared Eu/Tb-WPU exhibited rich fluorescent emission colors and can be used for information security encryption. Therefore, these Eu-WPU and Eu/Tb-WPU have good application prospects in ultraviolet shielding and fluorescence anti-counterfeiting.

Host sensitization of luminescence of lanthanide activators in NaBi(WO4)2

The synthesis and luminescence of a series of NaBi(WO4)2 activated with trivalent lanthanides Tb, Sm and Nd using the solid-state reaction method is reported. All samples were characterised by X-ray diffraction (XRD), scanning electron microscope (SEM) and photoluminescence (PL). The XRD study confirmed the tetragonal phase without any secondary phase. Particles of irregular shape ranging between 5 and 20 µm were observed. Elemental composition was obtained from EDAX and results were found consistent with the formula NaBi(WO4)2. The formation of single-phase NaBi(WO4)2 was again confirmed through these results. Elemental mapping indicated that all elements were uniformly distributed. The band gap was evaluated using Tauc’s. formula and was found from 5.6 eV to 5.91 eV which is higher than reported values (3.6 eV). For NaBi(WO4)2:Tb, excitation was monitored for 545 nm emission. Emission spectra upon excitation by 488 nm showed prominent lines around 545 and 549 nm. These are due to the transition 5D4 7F5. 5 mol.% Tb yielded maximum PL intensity. When 405 nm excitation is used for Sm3+ doped phosphor, lines can be seen in three groups around 564, 600 and 647 nm. The highest emission intensity is observed for Sm3+ concentration of 5 mol.% and quenching was observed for high values. A weak band could be seen in the excitation spectra which is distinct from the f-f lines. The position of this band is close to that observed in the reflectance spectra. Hence it is proposed that there is host sensitization, even though weak, of the lanthanide luminescence in this host. Sensitization is most probably due to Bi3+ Ln3+ energy transfer.

Antiferromagnetic topological insulating state in Tb0.02Bi1.08Sb0.9Te2S single crystals

Topological insulators are emerging materials with insulating bulk and symmetry protected nontrivial surface states. One of the most fascinating transport behaviors in a topological insulator is the quantized anomalous Hall insulator, which has been observed in magnetic-topological-insulator-based devices. In this work, we report a successful doping of rare earth element Tb into ${\mathrm{Bi}}_{1.08}{\mathrm{Sb}}_{0.9}{\mathrm{Te}}_{2}\mathrm{S}$ topological insulator single crystals, in which the Tb moments are antiferromagnetically ordered below $\ensuremath{\sim}10$ K. Benefiting from the in-bulk-gap Fermi level, transport behavior dominant by the topological surface states is observed below $\ensuremath{\sim}150$ K. At low temperatures, strong Shubnikov--de Haas oscillations are observed, which exhibit 2D-like behavior. The topological insulator with long range magnetic ordering in rare earth doped ${\mathrm{Bi}}_{1.08}{\mathrm{Sb}}_{0.9}{\mathrm{Te}}_{2}\mathrm{S}$ single crystal provides an ideal platform for quantum transport studies and potential applications.

Enhanced electrochemical properties of NASICON-type Na3Zr2Si2PO12 solid electrolytes with Tb3+-ions-assisted sintering

The new-type NZSP solid-state electrolytes with enhanced ion transport properties were synthesized by using lanthanide rare-earth Tb3+ ions assisted-sintering. The Na3+xZr2-xTbxSi2PO12 (x = 0, 0.1, 0.2, 0.3, 0.4) solid-state electrolytes were characterized by X-ray diffraction analysis, scanning electron microscopy, and AC impedance testing. The effects of different Tb3+ contents on the phase composition, microstructure morphology, and electrochemical performance were investigated. The results showed that both Na3Zr2Si2PO12 and Na3Tb(PO4)2 phases are formed in the solid electrolytes by Tb3+-ions-assisted sintering. The formation of a new phosphate phase regulates the Si/P ratio of the dominant electric phase, enhances the Na+ occupation, and helps to enhance the mobility of sodium ions. The introduction of an appropriate amount of Tb3+ ions has a soldering-like effect, which can effectively improve the densification of ceramics and further improve the ionic conductivity by promoting grain fusion and reducing the grain boundary concentration. At room temperature, the ceramic with the composition Na3.2Zr1.8Tb0.2Si2PO12 exhibits a high relative density of 97.03% and the highest ionic conductivity of 6.32 × 10−4 S·cm−1 and with a low activation energy of 0.22 eV. In addition, the Na3Tb(PO4)2 grain boundaries phase with low electronic conductivity can limit the transfer of electrons and reduce the electronic conductivity of the NASICON electrolytes, so that the tolerance of solid-state electrolytes against Na dendrite growth is strongly enhanced. The Tb3+-ion-assisted sintering strategy can provide a valuable reference for improving the electrochemical performance of fast ion conductors.

A Tb3+-anchored Zr(iv)-bipyridine MOF to promote photo-induced electron transfer and simultaneously enhance photoluminescence ability and photocatalytic reduction efficiency towards Cr2O72−

The fluorescence sensing sensitivity, accuracy, and photocatalytic reduction efficiency of a bcu topological Zr-MOF have been effectively improved, by firmly anchoring lanthanide Tb3+ ions in the Zr-MOF.

Band Gap Tuning in Transition Metal and Rare-Earth-Ion-Doped TiO2, CeO2, and SnO2 Nanoparticles

The energy gap Eg between the valence and conduction bands is a key characteristic of semiconductors. Semiconductors, such as TiO2, SnO2, and CeO2 have a relatively wide band gap Eg that only allows the material to absorb UV light. Using the s-d microscopic model and the Green's function method, we have shown two possibilities to reduce the band-gap energy Eg-reducing the NP size and/or ion doping with transition metals (Co, Fe, Mn, and Cu) or rare earth (Sm, Tb, and Er) ions. Different strains appear that lead to changes in the exchange-interaction constants, and thus to a decrease in Eg. Moreover, the importance of the s-d interaction, which causes room-temperature ferromagnetism and band-gap energy tuning in dilute magnetic semiconductors, is shown. We tried to clarify some discrepancies in the experimental data.

Opportunities and challenges in CsPbX3@Glasses@Film with High Quality for LCD by Process Optimization towards commercialization

Although backlight display screens based on CdSe quantum dots (QDs) have basically solved the remaining problem of small display gamut, its high preparation cost limits its commercial development. In contrast, perovskite nanocrystals (NCs) with narrow band emission, simple preparation and low cost have made leaps and bounds in next-generation backlit displays luminescent material. However, the instabilities are the main issues to solve before we can apply these materials in modern displays. Researchers have precipitated perovskite NCs in inorganic glass substrates and compounded them with PDMS films for backlighting, but the important factors for commercialization have been ignored: Long-term stability under strong blue light irradiation and preparation cost. In this work, a unique melt-water quenching method combined with composition control was applied to prepare a series of glass powder. The optimal photoluminescence (PL) emission and color coordinates in the color coordinates of glasses powder were elaborately regulated by heat treatment temperature control and the introduction of rare earth Tb. Moreover, the passivation of the glass powder surface through special water treatment greatly improves its stability under long time blue light exposure. After irradiation under 20000 cd/m2 blue light (460 nm) for 500 h, the PL intensity retention rate reaches 85% of commercial CdSe film. The red and green-emitting NCs glasses powder with high photoluminescence quantum yield (PLQY) and stability were combined with PET, PS and PDMS to form a composite film, afterwards, combined with Liquid crystal display (LCD)module shows a fuller color image. Finally, after comparison, PS film was demonstrated to be the most suitable choice for commercialization backlighting.

Synthesis and photoluminescence properties of a novel green-emitting LiYGeO4 :Tb3+ long afterglow phosphor.

A new green luminescent phosphor, Li(Y1-x Tbx )GeO4 , was prepared using a high-temperature solid-phase method. The X-ray diffraction (XRD) measured spectrum agreed well with the standard card JCPDS No. 02-3479, indicating that it is a quaternary compound belonging to the space group of Pnma(62) with an orthogonal crystalline phase; the excitation and emission spectra measured using the phosphor spectrometer showed that it can be effectively excited by near-ultraviolet light at 378 nm and blue light at 482 nm, and produced excellent strong emission of green light at 550 nm. The afterglow test results show that the sample had a good long afterglow effect at lower doping concentrations; the thermal stability test results showed that its thermal burst activation energy ΔE ≈ 0.37 eV had its excellent thermal stability. The rare earth Tb3+ -doped green phosphor, LiYGeO4 :Tb3+ , has potential applications in household lighting, medical therapy, and optical storage.

Grain boundary infiltration in HDDR processed Nd2Fe14B magnets

We investigate the grain boundary infiltration process of various low melting eutectic alloys for the coercivity enhancement of hydrogenation disproportionation desorption recombination (HDDR) processed Nd-Fe-B powders. Nd-based as well as heavy rare earth (Tb) and light rare earth (La, Ce) containing alloys were systematically studied: Nd70Cu30, Nd90Al10, Nd80Ga15Cu5, Nd62Fe14Ga20Cu4, Nd60Tb10Cu30, La71Cu29 and Ce72Cu28. Moreover, the Fe content in the quaternary Nd-Fe-Ga-Cu system was varied to investigate the effect of grain boundary phase magnetism on the resultant coercivity.The largest coercivity enhancement, from 0.42 T in the as-HDDR powder to 1.88 T after infiltration was observed in the case of ternary Nd80Ga15Cu5 composition. Furthermore, it also shows the best temperature stability with the infiltrated sample still exhibiting a coercivity of 0.58 T at 200 °C. Infiltration of light rare earth (La, Ce) based alloy did not increase coercivities due to poor wetting at the grain boundaries. Adding Fe to the grain boundary alloys was shown to enhance magnetization up to a certain extent without significant loss in coercivity. These findings demonstrate the effectiveness of grain boundary infiltration in HDDR-processed magnets without using heavy rare earths. The infiltration with non-magnetic material strongly decreases the intergranular interaction, reflected in a different magnetic domain evolution during the magnetization reversal process.

Isotope signature and elemental characteristics of subsurface formations around deep-laying coal seams probed by means of atomic and nuclear-based techniques.

A systematic investigation on the isotopic and elemental signature, for both stable and radioactive elements, and mineral contents was performed to examine the characteristics of subsurface formations collected at different depths between 3.962km and 4.115km around deep-laying coal seams located under the Marmarica plateau in Egypt. Concentrations of major and minor oxides (Na2O, MgO, Al2O3, SiO2, SO3, K2O, CaO, TiO2, MnO, ΣFeO+Fe2O3, SrO, ZrO2, and BaO) were determined by X-ray fluorescence and dependencies among these concentrations revealed the type and sort of the formations. Organic contents were determined by Fourier Transform infrared spectroscopy to investigate the variation of the CO/CC bonding ratio with depth. Rare earth elements (REE), specifically Y, Sc, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu were determined by inductively coupled plasma mass spectrometry while actinoids were detected by the radioactive decay of its daughter nuclei. The results showed a high trapping of REE elements and actinoids in layers above the coal seams which indicates the occurrence of aqueous flow followed by possible sorption in these layers. The mobility of the fluid was investigated using the process radioactive decay series between Ra226 and Ac228 from one side and their daughters from the other side.

Photochromic and Electric Field-Regulating Luminescence in High-Transparent (K,Na)NbO3-Based Ferroelectric Ceramics with Two-Phase Coexistence.

Rare earth Tb3+ doped (K0.465Na0.465Li0.07)(Nb0.93Bi0.07)O3 (KNNLB-x%Tb) lead-free transparent ferroelectric ceramics were designed and prepared. The effects of Tb3+ on phase structure, microstructure, optical transmittance, photoluminescence, and photochromic behaviors were studied. Although two ferroelectric phases coexist, the optical transmittance can reach the high value of 74% in the visible light region because of the fine grains, dense ceramic microstructure, large optical energy band gap, and relatively high symmetry of coexisting ferroelectric phases. In addition, Tb3+ works as a luminescent center, and the reversible photochromic modulation is achieved by alternate stimulation of illumination and heat treatment. Meanwhile, the luminescence contrast can be improved under in situ electric field stimulation due to the easy change of lattice symmetry in coexisting ferroelectric phases. The generation of color centers after illumination and the local crystal field around the luminescent center caused by in situ electric field contributes to above phenomena. These ceramics exhibit the great potential in optical data storage and anticounterfeiting.

The Effect of Grain Size on the Diffusion Efficiency and Microstructure of Sintered Nd-Fe-B Magnets by Tb Grain Boundary Diffusion.

The grain boundary diffusion process (GBDP) of heavy rare earth Tb is an effective method to improve the coercivity of Nd-Fe-B magnets, and the matrix grain size has a crucial effect on the diffusion efficiency and depth of the Tb element. In this work, magnets with different grain sizes have been fabricated using powder metallurgy to investigate the effect of grain size on Tb diffusion efficiency and the microstructure of Nd-Fe-B-type magnets. After the Tb diffusion process, the coercivity increment of the magnet with 4.9 μm large grain is 8.60 kOe, which is much higher than that of the magnet with 3.0 μm small grain (~5.90 kOe), which clearly demonstrates that the coercivity increment decreases as the grain size decreases. Microstructure analysis suggested that grain refinement significantly increases the total surface area, resulting in narrowing and discontinuity of the grain boundary phase (GBP). Therefore, as the channel for diffusion, the narrowing and discontinuity of the GBP are unfavorable for diffusion, resulting in a decrease in diffusion efficiency.