Rare Earth Ions Research Articles

Fabrication of sodium alginate doped phosphoric acid composite hydrogel and its application of the adsorption of La (III) in wastewater

Recycling rare earth ions from wastewater is an important task, as rare earth elements have a wide range of applications and can cause harm to the environment if discharged arbitrarily. In this work, a simple and inexpensive hydroxyethylidene diphosphate-based adsorbent (SA@HEDP) for adsorbing lanthanum was designed and fabricated. The adsorbent SA@HEDP with the surface rich in phosphate and hydroxyl functional groups provided active sites for adsorption of lanthanum. Research on adsorption performance was conducted by testing the amount of HEDP added, the amount of adsorbent used, the effect of initial pH of La (III), adsorption time, and temperature. The results showed that the adsorption capacity of the adsorbent was 158.0 mg/g. Adsorption of La (III) in real wastewater was tested, when the initial concentration of La (III) was 319.2 mg/L, it could be basically all recovered through three adsorption processes. SEM, EDS mapping, XPS, FTIR, and Zeta potential were used to characterize and analyze the mechanism, and mass transfer kinetics was used to analyze the adsorption process of the adsorbent for La (III).

Judd-Ofelt analysis and temperature sensing properties of polyethylmethacrylate (PEMA) networks doped with CdNb2O6: Er3+/Yb3+ phosphors

Research on the sensitivity of temperature measurements and optical thermometry involving rare earth ions has been an area of interest in the field of photonics and materials science. Introducing polymer networks as a new host material has an important role due to their properties including a versatile and stable environment for rare earth ions and rapid response in temperature detection. In this work, linear and crosslinked polyethylmethacrylate (PEMA) networks doped with Er3+/Yb3+ (1.5 mol % Er3+, 2 mol% Yb3+) synthesized by free-radical crosslinking polymerization with 0.1 EMA (weight %) at 60 °C were used to investigate direct and indirect optical bandgap energies and Urbach energy from UV–Visible spectra. The Judd-Ofelt (JO) approach was employed to analyze parameters Ωt (t = 2,4,6), spontaneous transition probabilities (Α), branching ratios (β) and radiative lifetimes (τ) as a function of linear and crosslinked PEMA doped nano-crystalline CdNb2O6: Er3+/Yb3+. The stimulated emission cross-sections of the transitions 2H11/2⟶4I15/2, 2S3/2⟶4I15/2 and 2F9/2⟶4I15/2 of Er3+/Yb3+ were calculated by two different methods; Fuchtbauer-Ladenburg formula and modified theory, respectively. The gain bandwidth cross-section product for the 2H11/2⟶4I15/2 was found to be 162.06. 10−28cm3, 260.94. 10−28cm3 and 461.20. 10−28cm3 of Er3+/Yb3+ embedded in linear, low and high crosslinked PEMA samples, respectively. JO parameters and stimulated emission cross-sections increased; therefore, radiative lifetimes decreased by increasing crosslinking content. In addition, the temperature dependence of upconversion (UC) luminescence was monitored under 975 nm excitation. The fluorescence intensity ratio (FIR) method examined the temperature sensing under two thermally coupled levels at 525 and 548 nm. The maximum sensitivities obtained from the FIR technique within the 300–650 K temperature range shifted to lower temperatures with increasing crosslinker content. Hence, linear and crosslinked polymer hosts doped rare-earth ions can be candidates for remote temperature sensors across various fields.

Influence of Different Alkali Fluorides (LiF/NaF/KF) on Photoluminescence Properties of Dy3+ and Eu3+ Rare Earth Ion Co-Doped Borate Glasses

Influence of Different Alkali Fluorides (LiF/NaF/KF) on Photoluminescence Properties of Dy3+ and Eu3+ Rare Earth Ion Co-Doped Borate Glasses

Structural, magnetic, and magnetocaloric characterizations of geometrically-frustrated SrRE2O4 (RE = Gd, Dy, Ho, Er) oxides for low-temperature cooling applications

The magnetocaloric (MC) properties of many rare earth (RE)-based magnetic solids have been intensively investigated. This research aims to develop suitable MC materials for low-temperature cooling application and to better elucidate their intrinsic properties. We have fabricated four single-phase SrRE2O4 (RE = Gd, Dy, Ho, Er) oxides and conducted a systematic experimental investigation into their structural, magnetic, and low-temperature MC properties. All these SrRE2O4 oxides crystallize in an orthorhombic structure (space group Pnma) and exhibit typical geometrical frustration. This frustration arises from the one-dimensional RE ion zigzag ladders along the c-axis, which link the two-dimensional honeycomb lattice in the ab plane. The elements in SrRE2O4 oxides are uniformly distributed and present with valence states of Sr2+, RE3+, and O2−, respectively. Large low-temperature MC effects and notable performances are realized in these SrRE2O4 oxides, determined by the MC parameters of magnetic entropy change, refrigerant capacity, and temperature-averaged entropy change (with a lift of 5 K). These MC parameters under a magnetic field change of 0–70 kOe are as follows: 34.18 J/kgK, 275.88 J/kg, and 30.74 J/kgK for SrGd2O4; 18.13 J/kgK, 253.83 J/kg, and 17.54 J/kgK for SrDy2O4; 18.81 J/kgK, 354.77 J/kg, and 18.61 J/kgK for SrHo2O4; and 22.63 J/kgK, 284.25 J/kg, and 21.97 J/kgK for SrEr2O4. These values are comparable to those of most recently updated low-temperature MC materials with remarkable performances, making these SrRE2O4 oxides highly interesting for practical cooling applications.

Multicolor luminescent rare-earth-free glass ceramic for thermal information indication

Temperature-dependent multicolor luminescent materials are widely used in optical temperature sensing and related applications. However, most of these materials derive their luminescence from the radiation transition of rare earth (RE) ions. Therefore, the development of RE-free luminescent materials is of great significance for RE resources and environmental protection. Here, we propose a novel RE-free multicolor luminescent glass-ceramic (GC) and offer a color regulation strategy for defect-induced luminescence. As the temperature rises, thermal expansion alters the state of the defects, causing the emission color to gradually shift from cyan-green to dark blue. This color shift is reversible, returning to the original color as the temperature decreases. Moreover, the GC retains 97.2 % of its luminescence intensity after being submerged in water for one year, highlighting its excellent physicochemical stability. A pattern label prepared by this GC, exhibits excellent luminescent color-temperature response, indicating its potential application in high-temperature information indication.

Preparation of large specific surface rare earth oxides from calcium-containing rare earth solution by carbon dioxide carbonization method☆

The calcium-containing rare earth solution is generated during the recovery processes of NdFeB waste, which is treated as wastewater by enterprises. In this paper, the carbon dioxide carbonization method was applied to the separation of rare earths and calcium in the solution, as well as the preparation of rare earth oxides with a large specific surface. It is shown that the process of CO2 carbonization of solution includes reactions such as the dissolution, diffusion and ionization of CO2, the carbonate precipitation of rare earth ions, and the neutralization of hydrogen ions. At a pH of 4.5, the carbonization precipitation rate is effectively controlled, enabling homogeneous precipitation and ensuring both high precipitation yield and rare earth oxides purity. In this way, the crystallization of carbonization products is a process dominated by the oriented attachment theory and coexisting with the Ostwald ripening theory, resulting in abundant pores formed by multiple layers of stacking in the products. With the optimal carbonization conditions, the rare earth precipitation yield solution reaches 99.32%. The obtained carbonization products are crystalline (LaCe)(CO3)3·8H2O, and the purity of the rare earth oxides is as high as 99.22 wt%. The specific surface area of the rare earth oxides reaches 94.7 m2/g, and its adsorption efficiency for tetracycline hydrochloride in solution can reach 92.6% in a short time. The rare earth oxides are expected to be used as an adsorption material for wastewater treatment and other adsorption environments.

Effect of Dopant Concentration on Luminescence Properties of Na3Ca2(SO4)3F: RE (RE = Eu3+, Dy3+) Phosphor for Solid-State Lighting.

A fluoride material phosphor doped with rare earth ions Eu3+ and Dy3+ was studied for its photoluminescence (PL) properties. The material was synthesized using a combustion method and characterized using X-ray diffraction (XRD) and PL techniques. The Na3Ca2(SO4)3F: Eu3+ phosphor exhibits two distinct peaks at 593 nm (orange) and 615 nm (red) at an excitation wavelength of 395 nm. The PL excitation spectrum of the Na3Ca2(SO4)3F: Dy3+ phosphor showed series of peaks, corresponding to the 4f → 4f transitions of Dy3+ ions. Under 350-nm excitation, the PL emission spectrum revealed two prominent bands one at 483 nm (blue region) due to the 4F₉/₂ → 6H₁₅/₂ transition, and another at 573 nm (yellow region) resulting from the 4F₉/₂ → 6H₁₃/₂ transition. These blue and yellow emissions suggest potential applications in solid-state lighting, particularly for mercury-free excitation sources. Rare earth-doped Eu3+/Dy3+ materials exhibit highly efficient PL properties, making them suitable candidates for white light-emitting diodes (LEDs) or other solid-state lighting phosphors.

Effect of Mg and rare earth ions co-doping on the structural and optical properties of ZnO nanorods

Effect of Mg and rare earth ions co-doping on the structural and optical properties of ZnO nanorods

Low-loss and low-temperature Al2O3 thin films for integrated photonics and optical coatings

Amorphous aluminum oxide (Al2O3) is a key material in optical coatings due to its notable properties, including a broad transparency window (ultraviolet to mid-infrared) and excellent durability. Moreover, its higher refractive index contrast relative to silica cladding layers and high solubility of rare-earth ions make it well suited for optical waveguides and the development of various functionalities in integrated photonics. In many coatings and integrated photonics applications, the substrates are temperature and stress sensitive, while relatively thick (∼1 μm) alumina layers are required; thus, it is crucial to fabricate low optical loss alumina thin films at low deposition temperatures, while maintaining high deposition rates. In this study, plasma-assisted reactive magnetron sputtering, operated in an alternating current mode, is investigated as a reliable, straightforward, and wafer-scale compatible technique for the deposition of high optical quality and uniform Al2O3 thin films at low temperature. One-micrometer-thick amorphous Al2O3 planar waveguides, deposited at 150 °C and a rate of 23.3 nm/min, exhibit optical losses below 1 dB/cm at 638 nm and as low as 0.1 dB/cm in the conventional optical communication band.

Hexagonal-inner-cladding fluorotellurite fiber based on hot-extrusion

Laser output power can be significantly enhanced by a double-cladding fiber, as it possesses a large area of inner-cladding for pumping. However, the coupling efficiency of the double-cladding fiber (DCF) is impacted by the shape of the inner cladding. In this study, the simulation results showed that, the hexagonal inner cladding fiber exhibits the highest absorption efficiency of 94.07 % among the fibers with various typical shapes using the three-dimensional ray tracing method at a length of 100 mm. For the experiments, a type of fluorotellurite (TBY, TeO2-BaF2-Y2O3) glass was chosen for its high capacity of rare-earth ions adoption. Subsequently, a finely structured erbium-doped hexagonal DCF was fabricated based on the hot-extrusion method for the first time, with a minimum loss of 1.25 dB/m at 1310 nm. Additionally, the coupling efficiency of the hexagonal DCF was recorded to be 39.47 % at a fiber length of 53 cm, based on the energy distribution experiment. The damage threshold of the hexagonal DCF at 980 nm could be increased to above 26.5 W, nearly doubling that of the single-cladding fiber. Furthermore, a wider fluorescence spectrum with a full width at half maximum (FWHM) of 30 nm was demonstrated by the hexagonal double-cladding fiber, which indicates its potential for high-power laser applications.

Broadband nanotubes-based nonlinear modulators for erbium- and thulium-doped lasers

Carbon-based nanomaterials have become a long-term research hotspot in the fields of material science and nanotechnology. Carbon nanotubes as one-dimensional nanomaterials have shown great application value in the fields of electronics and optoelectronics. Herein, stable mode-locked pulsed lasers in both 1.5- and 2-μm bands were achieved by combining and balancing the stimulated emission effect of rare-earth ions and saturable absorption effect of carbon nanotubes. In the Er-doped fiber laser, pulses with a SNR of 61 dB and a peak power of 2.97 W were achieved at the wavelength of 1565.8 nm. Meanwhile, bound states were observed in the same laser, where the time delay of pulses was adjustable from 9.84 to 21.77 ps by tuning the pump power and polarization state. In the Tm-doped laser, output pulses were obtained at the wavelength of 1921.0 nm with a 60-dB SNR and a 12.82-W peak power. These results demonstrate that carbon nanotubes are ideal candidates for saturable absorber in mode-locked fiber lasers, which can be applied to a variety of applications, including fiber optic sensing, optical communication, and nanoscale processing.

Effect of Rare Earth Ion Doping on the Performance of Lithium-Rich Cathode Materials for Lithium-Ion Batteries

Lithium-rich layered oxide cathode materials have the advantages of a high voltage and a high specific capacity. Their commercial applications have however been impeded by some disadvantages such as low initial coulombic efficiency and low cycle life. To overcome these issues, rare earth ion-doped lithium-rich layered oxide cathode materials are investigated in this work. The irreversible release of O2- in Li2MnO3 is suppressed by rare earth ions doping, which enhanced the initial coulombic efficiency of the materials. Meanwhile, the rare-earth ion radius used for doping is larger than the Mn4+ radius, which enlarges the (003)-crystalline plane spacing, resulting in a significant enhancement of the rate performance of the material.

A lanthanide luminescent sensor doped polymer dots for ratiometric fluorescence detection of hydrogen sulfide

As one of the indexes of food freshness, hydrogen sulfide content is closely related to food spoilage. A dual-emission sensor for H2S detection was reported in this paper. Poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene] Polymer dots (MEH-PPV-Pdots) were prepared by copolymer of poly [2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene] and styrene-maleic anhydride. The sensor was obtained by embedding purple MEH-PPV-Pdots in a green MOF. The accommodated MEH-PPV-Pdots were considered as the reference signal, while copper ions on the host skeleton served as accessible reaction sites, allowing MEH-PPV-Pdots/Tb0.99Cu0.01-MOF to selectively sense H2S. The sensor exhibited reduced green fluorescence and proportional response to H2S. Because H2S can transfer charge on copper ions and thus affect the green light emitted by rare earth ions. The results showed that the sensor had good stability to H2S in HEPES buffer, fast response, obvious color change, high selectivity and sensitivity. The sensor has been applied to the detection of aquatic products, showing good visualization effect.

Influence of gadolinium doping on structural, optical, and magnetic properties of CuS nanostructures

To examine the effect of rare earth ions on CuS nanostructures, a series of Gadolinium-doped copper sulphide (Cu1-xGdxS) nanostructures were synthesized through the hydrothermal method. These nanostructures were prepared at x = 0, 1, 3, 5, and 7 at. % concentrations. The prepared samples’ structural, optical, and magnetic characteristics were investigated. Powder X-ray diffraction and Raman analysis were performed to examine the structural analysis of the samples and confirm the existence of a covellite phase hexagonal structure. XPS analysis was conducted to study the valence states. Observations of the surface morphology study from FESEM reveal the formation of flower-shaped structures resembling nanospheres, while at lower magnification nanoflakes were observed. Optical reflectance spectra were recorded using UV–Vis spectroscopy, which showed the increase in bandgap as the concentration of Gd rises. The fluorescence spectrophotometer was utilized for the analysis of room-temperature photoluminescence. The prepared samples showed significant emission peaks at 435 nm. Fluorescence lifetime studies were carried out to confirm the fluorescence decay of CuS nanostructures doped with Gd. Magnetic measurements revealed that prepared samples exhibit an unexpected superparamagnetic nature at room temperature.

Formulating the Relationship Between Intermolecular Interactions and Photodynamic Effects Based on the Optical Regularity Exhibited by Rare Earth‐BODIPY Crystalline Frameworks System

AbstractThis research commenced with an exploration of how metal nodes in metal‐organic frameworks (MOFs) influence photodynamic therapy (PDT) outcomes. Ultimately, it is revealed that intermolecular interactions are the core mechanism determining the optical properties and PDT efficacy of MOFs. An advanced system of MOFs based on the integration of twelve rare earth ions (RE3+) with boron dipyrromethene (BODIPY)‐derived ligands is reported. Intriguingly, this series of MOFs exhibits a reverse relationship between the radius of RE3+ and PDT efficacy. Single‐crystal X‐ray diffraction analyses along with theoretical calculations indicate that varying RE3+ results in a spatial displacement of the ligands along the dipole direction, diminishing electrostatic (dipole–dipole) interactions while enhancing dispersion (π–π) interactions, thereby enhancing the generation of triplet excitons. Consequently, a novel parameter, Ae‐v = EvdW / Eint × 100%, is proposed to quantify the interplay between non‐radiative energy dissipation via electrostatic interactions and efficient energy utilization in generating singlet oxygen through dispersion interactions. Furthermore, with consistent acoustic sensitivity aligned with the sonoluminescence mechanism, RE‐DCBs are employed in sono‐photodynamic cancer therapy, attaining significant therapeutic results in tumor treatment during in vivo experiments.

Ratiometric optical temperature sensing properties based on up-conversion luminescence of novel NaLaTi2O6:Yb3+,Er3+/Ho3+ phosphors

To satisfy the increasing necessity of contactless optical thermometry, utilizing both thermally coupled (TCLs) or non-thermally-coupled (NTCLs) energy levels of rare earth ions in novel phosphors has significant potential for devising the optical thermometers with high temperature sensitivity. Herein, a sequence of novel Yb3+,Er3+/Ho3+ doped NaLaTi2O6 (NLTO) phosphors were sintered using a high-temperature solid-state reaction approach. Structure, phase component and luminescence performance were identified in detail. Upon 980 nm near-infrared (NIR) excitation, the obtained materials presented typical Er3+/Ho3+ characteristic emission wavelengths in visible region, which include two green emission bands around 522 and 543 nm, as well as a weaker red band around 661 nm for Er3+ doped NLTO, a green emission band around 545 nm and a red band around 657 nm for Ho3+ doped NLTO. Besides, a unusual emission band around 757 nm of Ho3+ in visible edge region was also clearly found. The temperature sensing properties of representative NLTO:Yb3+,Er3+/Ho3+ samples were assessed based on the fluorescence intensity ratio (FIR) technique of TCLs or NTCLs energy levels. The maximal absolute sensitivity (Sa) and relative sensitivity (Sr) were determined to be 0.0374 K-1 (293 K) and 0.970% K-1 (293 K) by taking the FIR of NTCLs 2H11/2→4I15/2 and 4F9/2→4I15/2 transitions in NLTO:Yb3+,Er3+. Simultaneously, the maximal Sa and Sr were 0.0306 K-1 (573 K) and 0.776% K-1 (373 K) using the FIR of NTCLs 5F5→5I8 and 5F4,5S2→5I7 transitions in NLTO:Yb3+,Ho3+. Consequently, the temperature sensitivities above can be compared to reported results, which indicate that as-prepared materials have a promising application in optical temperature sensors field.

Luminescent Ln-MOFs for Chemical Sensing Application on Biomolecules.

At present, the application of rare-earth organic frameworks (Ln-MOFs) in fluorescence sensing has entered rapid development and shown great potential in various analytical fields, such as environmental analysis, food analysis, drug analysis, and biological and clinical analysis by utilizing their internal porosity, tunable structural size, and energy transfer between rare-earth ions, ligands, and photosensitizer molecules. In addition, because the luminescence properties of rare-earth ions are highly dependent on the structural details of the coordination environment surrounding the rare-earth ions, and although their excitation lifetimes are long, they are usually not burst by oxygen and can provide an effective platform for chemical sensing. In order to further promote the development of fluorescence sensing technology based on Ln-MOFs, we summarize and review in detail the latest progress of the construction of Ln-MOF materials for fluorescence sensing applications and related sensor components, including design strategies, preparation methods, and modification considerations and initially propose the future development prospects and prospects.

Photocatalytic activation of hydrogen peroxide via a novel CuFe2(PO4)2(OH)2 up-conversion material without rare-earth ions for doxycycline hydrochloride degradation

A novel CuFe2(PO4)2(OH)2 up-conversion material without rare-earth ions was fabricated for hydrogen peroxide (H2O2) activation to degrade doxycycline hydrochloride (DOH) under simulate sunlight irradiation. The CuFe2(PO4)2(OH)2 exhibited superior absorption performance in near-infrared (NIR) region and up-conversion property. The CuFe2(PO4)2(OH)2 can effectively activate H2O2 for DOH degradation under ultraviolet, visible and NIR irradiation. Although H2O2 was more easily adsorbed on monometallic Fe3(PO4)2(OH)2 surface according to the result of density functional theory calculations, the CuFe2(PO4)2(OH)2 showed more superior property for H2O2 activation than Fe3(PO4)2(OH)2 due to its higher photoconversion efficiency. Moreover, the redox cycles of Fe3+/Fe2+ and Cu2+/Cu+ on CuFe2(PO4)2(OH)2 surface further promoted H2O2 activation to degrade DOH with •OH was the main active species. The degradation process and evolution law of intermediates were determined by HPLC/MS/MS and DFT calculations. The Toxicity Estimation Software Tool based on quantitative structure–activity relationship prediction and antibacterial experiment showed that the overall toxicity and antibacterial activity gradually decreased with reaction. The CuFe2(PO4)2(OH)2 existed fine anti-interference property and universality for the removal of other antibiotic pollution.

Metal Propionate Solutions for High-Throughput Liquid-Assisted Manufacturing of Superconducting REBa2Cu3O7-δ (RE = Y, Gd, Sm, and Yb) Films.

The cost-effective synthesis of a series of metal propionate powders (copper, yttrium, barium, samarium, gadolinium, and ytterbium) is developed through single chemical reactions resulting in five novel crystalline forms. These complexes are valuable precursors for the preparation of epitaxial REBa2Cu3O7-δ (REBCO) superconducting films (here, RE = Y, Sm, Gd, and Yb) through the innovative transient liquid-assisted growth (TLAG) process based on chemical solution deposition (CSD). TLAG-CSD shows impressive results with YBa2Cu3O7-δ (YBCO), obtaining critical current densities of 2.6 MA/cm2 (77 K) on 500 nm films at unprecedented growth rates (50-2000 nm/s), boosting unprecedented high-throughput industrial production. With a cardinal concern on designing the pyrolysis toward optimal nanocrystalline films for TLAG, an analysis of the thermal behavior of the synthesized precursors is essential. Decomposition pathways for each metal propionate are established, and compatibility with TLAG-CSD is corroborated. Metal-organic solutions for these REBCO systems are successfully prepared, and their rheological properties and thermal behavior are analyzed. This work demonstrates homogeneous nanocrystalline films through propionate-based REBCO precursor solutions, including several rare-earth ions, which display exemplary chemical and microstructural characteristics crucial for TLAG, and provides a base for a wide variety of CSD-based functional oxides.

Controllable multicolored optical glass-ceramics based on nanostructure strategies and dopants

Novel functional materials that integrate multiple tunable luminescence modes hold significant scientific and application potential. In this study, nanostructure strategies were employed to fabricate a series of microcrystalline glasses doped with rare-earth and transition-metal ions. The crystallization behavior of the nanocrystals (NCs) was revealed through high-resolution transmission electron microscopy (HRTEM), and the photoluminescence spectra of the samples were systematically investigated, demonstrating the achievement of independent and efficient visible light emission. With the further addition of the dopant Mn2+, it can occupy different sites to generate efficient energy transfer for ions, effectively improve the luminous efficiency, and changing the Mn2+ concentration can achieve a wide tunable color gamut. In addition, by exciting the glass samples with different excitation light sources, tunable emission of both red and blue was achieved. The results demonstrated the significant potential of the experimental samples as new multifunctional materials for optical dynamic anti-counterfeiting applications.