Lanthanide Cations Research Articles

On the potential of Transparent Rare-Earth-Free ZnAl2O4 Ceramics targeted at the UV-C to UV-B emission

Materials capable of emitting in the ultraviolet UV-C to UV-B spectral range have received considerable attention due to their potential applications in biophotonics, plant lighting, optical cleaning, sterilization, and disinfection. However, progress in the development of phosphors that emit in this short-wavelength range has been relatively sluggish. Most UV-C phosphors developed to date are based on hosts doped with the rare-earth cation Pr3+ due to its bright UV luminescence originating from the 4f15d1 → 4f2 interconfigurational transitions. In this study, we explore how the UV emission can be tailored to different wavelength ranges by developing rare-earth-free materials. Specifically, we demonstrate that UV-C to UV-B emission can be achieved in transparent ZnAl2O4 – based ceramics. For the first time, such transparent ceramics have been successfully produced with the help of reactive spark plasma sintering with SiO2 or LiF additives, which modified the process of grain growth resulting in an increase in the average grain size from 250 nm to 4 µm. Moreover, these additives also improved the optical transmission properties, with in-line transmission measurements at a wavelength of 550 nm reaching values of 50 % and nearly 65 % in the infrared region. Depending on the addition of SiO2 and LiF, the excitation by photons with energy exceeding 6.2 eV has generated the deep UV emission peaks in the range from 230 to 300 nm. Based on the analysis of the results of luminescence spectroscopy and EPR studies, the observed UV-C emission is suggested to originate from the excitons localised near oxygen vacancies. The number of vacancies is the highest in undoped ZnAl2O4 ceramics, whereas adding SiO2 and LiF suppresses their number and modifies their local environment due to changes in charge compensation, which in turn allows tuning the spectral position of the UV-C band. The quantum yield of the UV-C emission reached 5 % for undoped ZnAl2O4 ceramics. The sintered ZnAl2O4 transparent ceramic shows a versatile solution for next-generation rare-earth-free deep-UV devices.

Synthesis of cationic lanthanoid tetraphenylborate crown ether complexes

The efficacy of Me3NHBPh4 as a protolytic agent in the generation of reactive lanthanoid cations has been further explored. Reaction of [Nd(BH4)3(thf)4] with Me3NHBPh4 in a 1:3 mole ratio, and dibenzo-18-crown-6 (DB18C6) in thf did not yield [Nd(thf)n][BPh4]3, but [Nd(BH4)2(DB18C6)][BPh4]⋅2THF (1), a complex primed for further functionalisation, was isolated. The structure has an eight coordinate Nd atom with two trans tridentate BH4− ligands. Redox transmetallation/protolysis (RTP) reactions between Yb metal, PhHgC6F5, and Me3NHBPh4 in the presence of 18-crown-6 (18C6) or DB18C6 in MeCN or in thf followed by work up with MeCN yields [Yb(CE)(MeCN)3][BPh4]2⋅nMeCN (CE = 18C6, n = 0 (2), and DB18C6 n = 3 (3)), the structures of which have nine coordinate Yb atoms. Two pairs of MeCN ligands are transoid, whereas the third pair have a small cis NYbN angle. In the absence of a crown ether ligand, the RTP reaction in MeCN yields the known [Yb(MeCN)8] [BPh4]2.

Cycloheptatrienyl-Bridged Triple-Decker Complexes.

The first structurally characterized organometallic multidecker sandwich complexes featuring a cycloheptatrienyl ring (Cht, C7H73-) in the coordination sphere are presented. The synthesis of inverse sandwich complexes of the rare earth elements YIII and ErIII with a bridging cycloheptatrienyl ligand of the type [(thf)(BH4)2LnIII(μ-η7:η7-Cht)LnIII(BH4)(thf)2] is described first. The subsequent introduction of the CotTIPS ligand (CotTIPS = 1,4-(iPr3Si)2C8H62-) into the coordination sphere of the rare earth cations resulted in the isolation of unprecedented triple-decker compounds with the formula [(thf)3K{(η8-CotTIPS)LnIII}2(μ-η7:η7-Cht)], bearing a seven-membered aromatic carbon ring as a middle deck. These compounds are also the first examples of rare earth triple-decker complexes not bridged by a Cot derivative, based on purely carbon-based ligands. The magnetic properties of the respective ErIII congeners were investigated in detail, leading to the observation of antiferromagnetic coupling of the ErIII cations and a blocking temperature of 13.5 K. The conversion of the YIII compound [(thf)3K{(η8-CotTIPS)YIII}2(μ-η7:η7-Cht)] with [YIII(Cot)I(thf)2] resulted in ligand rearrangement and the selective formation of the first triple-decker complex ([(η8-CotTIPSYIII)2(μ-η8:η8-Cot)]) featuring two Cot ligands with different substituents in its coordination sphere.

Design and synthesis of Lanthanide(III) complex based luminescence probes for time-resolved luminescence detection of β-galactosidase

β-Galactosidase (β-Gal), confirmed to provide energy and participate in the galactosyl transfer reaction, is primarily over-expressed in ovarian cancer cells. Herein, detecting endogenous β-Gal is essential for the diagnosis and monitoring of primary ovarian cancer cells. In this study, we proposed two structurally related cationic Lanthanide(III) triamide complexes for highly sensitive and rapid detection of β-Gal. Moreover, LDEu02 showed a low detection limit (2.3 × 10−3 U/mL) and high specificity with high affinity for β-Gal, which had great potential to the detection of the β-Gal activity by using time-resolved fluorescence techniques.

Structure and Solution Behavior of Rare-Earth-Metal Complexes with Tripodal N-Donor Ligands.

Rare-earth-metal complexes (Ln=Y, La, Ce, Sm and Lu) of tripodal N-donor ligands respecting the CHON principle have been synthetized and characterized. The selectivity of the ligands through the lanthanide cations was investigated and related to their donor strength.

Non‐Expendable Regulator Enables Durable and Deep Cycling Aqueous Zinc Batteries

AbstractUnstable electrode/electrolyte interface with irreversible Zn deposition and hydrogen reactions have severely damage the cycle life of aqueous zinc‐metal batteries (ZMBs), which is closely related to interfacial environment and deposition behavior of Zn2+. In this work, a series of rare earth chlorides (RCl3) are proposed as non‐expendable regulators to address the above problems. Specifically, rare earth cations (R3+) with high adsorption energy can simultaneously isolate the adsorbed polar H2O molecule layer at the anode interface and regulate uniform Zn deposition behavior by electrostatic shielding. Meanwhile, Cl− binds H2O molecules via the weak hydrogen bonds, thus further inhibiting water‐related side reactions. Consequently, the optimized Zn||Zn symmetric cell can stably cycle for over 8000 cycles at 5 mA cm−2. Surprisingly, the Zn anode with 68.3% zinc utilization also can be operated over 130 h. Even under harsh condition of low N/P ratio of 2.6:1 and high mass‐loading cathode of 12.57 mg cm−2, the NH4V4O10||Zn pouch cell preserves nearly all its capacity after 300 cycles. Further, a low N/P ratio pouch cell with a more respectable capacity of 37.3 mAh preserves deep cycling for 180 cycles. This study sheds light on non‐expendable additives to develop highly durable and deep cycling ZMBs.

Synthesis and Thermal Decomposition of High-Entropy Layered Rare Earth Hydroxychlorides.

The synthesis of multicomponent and high-entropy compounds has become a rapidly developing field in advanced inorganic chemistry, making it possible to combine the properties of multiple elements in a single phase. This paper reports on the synthesis of a series of novel high-entropy layered rare earth hydroxychlorides, namely, (Sm,Eu,Gd,Y,Er)2(OH)5Cl, (Eu,Gd,Tb,Y,Er)2(OH)5Cl, (Eu,Gd,Dy,Y,Er)2(OH)5Cl, and (Eu,Gd,Y,Er,Yb)2(OH)5Cl, using a homogeneous hydrolysis technique under hydrothermal conditions. Elemental mapping proved the even distribution of rare earth elements, while luminescence spectroscopy confirmed efficient energy transfer between europium and other rare earth cations, thus providing additional evidence of the homogeneous distribution of rare earth elements within the crystal lattice. The average rare earth cation radii correlated linearly with the unit cell parameters (0.868 < R2 < 0.982) of the high-entropy layered rare earth hydroxychlorides. The thermal stability of the high-entropy layered rare earth hydroxychlorides was similar to that of individual hydroxychlorides and their binary solid solutions.

Heterophase synthesis of rare-earth zirconates

This study focuses on developing a heterophase process for synthesizing rare-earth zirconates, specifically R2Zr2O7 /R2O3·2ZrO2 (R = La, Sm, Gd, Dy). We investigated the sorption properties of low-hydrated zirconium hydroxide, a precursor for complex-oxide phases, towards rare-earth elements' ions (La, Sm, Gd, Dy). The results indicate that sorption by low-hydrated zirconium hydroxide is a multifaceted process, involving the incorporation of rare-earth cations into the pores of low-hydrated hydroxide and ion exchange. The paper details the synthesis of R2Zr2O7 /R2O3·2ZrO2 (R = La, Sm, Gd, Dy), considering both «light» and «heavy» elements. The process process involves the interaction between Zr(OH)3÷1O0.5÷1.5·(1.6÷2.6)H2O, low-hydrated zirconium hydroxide, and an aqueous solution of rare-earth acetate (С(La3+) = 0.155 mol/l, С(Sm3+) = 0.136 mol/l, С(Gd3+) = 0.141 mol/l, С(Dy3+) = 0.120 mol/l) followed by heat treatment. The resulting phases and their thermolysis products were analyzed using differential thermal analysis and X-ray phase analysis. Single-phase rare-earth zirconates R2Zr2O7 (R = La, Sm, Gd) and the Dy2O3·2ZrO2 solid solution were only obtained at 800 °С. The lattice parameters are calculated for each phase. Lanthanum, samarium, and gadolinium zirconates exibited a cubic pyrochlore structure (Fd3–m), while dysprosium displayed a fluorite structure (Fm3–m). The average particle size of all zirconates was 1.14 ± 0.02 μm.

High-pressure/high-temperature synthesis of a new polymorphic series of lanthanoid cadmium borates, LnCdB6O10(OH)3 (Ln = Sm–Er)

Abstract We report on the synthesis, structure determination, and characterization of a new series of compounds LnCdB6O10(OH)3 (Ln = Sm–Er). Syntheses were carried out in a Walker-type multianvil device at 7 GPa and 650 °C. Structure determinations revealed the coexistence of an orthorhombic and a monoclinic polymorph, depending on the ionic radius of the lanthanoid cation. The orthorhombic structural variants crystallize non-centrosymmetrically in the space group Pna21 (no. 33), while the monoclinic modifications crystallize in space group P21/c (no. 14). Both modifications display a layered crystal structure built up by a repeating [B6O13]8− building block as their main structural feature.

Tailored (La0.2Pr0.2Nd0.2Tb0.2Dy0.2)2Ce2O7 as a Highly Active and Stable Nanocatalyst for the Oxygen Evolution Reaction.

Designing highly active and robust catalysts for the oxygen evolution reaction is key to improving the overall efficiency of the water splitting reaction. It has been previously demonstrated that evaporation induced self-assembly (EISA) can be used to synthesize highly porous and high surface area cerate-based fluorite nanocatalysts, and that substitution of Ce with 50% rare earth (RE) cations significantly improves electrocatalyst activity. Herein, the defect structure of the best performing nanocatalyst in the series are further explored, Nd2Ce2O7, with a combination of neutron diffraction and neutron pair distribution function analysis. It is found that Nd3 + cation substitution for Ce in the CeO2 fluorite lattice introduces higher levels of oxygen Frenkel defects and induces a partially reduced RE1.5Ce1.5O5 + x phase with oxygen vacancy ordering. Significantly, it is demonstrated that the concentration of oxygen Frenkel defects and improved electrocatalytic activity can be further enhanced by increasing the compositional complexity (number of RE cations involved) in the substitution. The resulting novel compositionally-complex fluorite- (La0.2Pr0.2Nd0.2Tb0.2Dy0.2)2Ce2O7 is shown to display a low OER overpotential of 210 mV at a current density of 10 mAcm-2 in 1M KOH, and excellent cycling stability. It is suggested that increasing the compositional complexity of fluorite nanocatalysts expands the ability to tailor catalystdesign.

Effect of mixed rare earth cations on structure, optical, mechanical and radiation shielding parameters of Na2O–B2O3 glass

The value of rare earth-containing glasses continues to increase, resulting in a higher cost for producing such glasses. The reduction in rare earth content reduces the cost of the production process. Investigating whether it is possible to prepare glasses with low rare earth (such as Dy and Sm) contents is valuable. In this work, the impacts of Dy2O3/ Sm2O3 substitutions on borate glass's structural, optical, and mechanical features were investigated. The optical studies reflected the structural modifications. For example, Urbach tail increased from 0.39 to 0.69 eV with further Dy2O3/ Sm2O3 substitutions. This increasing behavior refers to a less stable glass matrix. This outcome was substantiated by the diminished values of all elastic parameters in the current glasses upon additional Dy2O3/ Sm2O3 substitutions. Nonlinear optical parameters were examined across various wavelengths and compositions, revealing negligible variations within the visible and near-infrared (Vis-NIR) spans. However, a notable decrease was observed in the UV region, exhibiting a rapid decline with increasing substitutions. Furthermore, induced defects within the internal structure of the glassy network, notably non-bridging oxygens with additional Dy2O3/ Sm2O3 substitution, resulted in heightened nonlinear optical parameters. Simultaneously, all elasticity moduli decreased with further Dy2O3 additions in the current glassy system, attributed to increased disorder caused by defect production, dangling bonds, and non-bridging oxygens in the glassy matrix.In addition, the half-value layers of all glass samples were compared to those of typical and widely used shielding materials. Through this analysis, certain glass samples demonstrated superior qualities compared to conventional shielding materials. Notably, the glass sample with the highest Sm2O3 level (and correspondingly the lowest Dy2O3 value) exhibited particularly favorable attributes. Consequently, our glass samples show potential as effective shields in nuclear radiation environments.

Achieving high open-circuit voltage in efficient kesterite solar cells via lanthanide europium ion induced carrier lifetime enhancement

Short carrier lifetimes is a key challenge limiting the open-circuit voltage (VOC) and power conversion efficiency (PCE) of kesterite Cu2ZnSn(S,Se)4 (CZTSSe) solar cells. In this work, for the first time, lanthanide europium (Eu) ions have been introduced into Ag-incorporated CZTSSe absorber layer, which can modify the selenization reaction pathway during the initial selenization process, leading to high-quality (Ag, Eu)-CZTSSe absorber with large compact crystal grains and benign surface potential fluctuations. This innovative absorber engineering can also optimize defects dynamics with less detrimental defects and defects-assisted non-radiative recombination. Thus, significantly enhanced minority carrier lifetimes from 0.97 to 3.15 ns can be achieved, representing one of the top values among various bulk and/or interface engineering treated CZTSSe. The champion CZTSSe thin-film solar cell exhibits an impressive VOC of 545.6 mV, accompanied with a stimulating increase in PCE from 10.68% to 13.30%. These findings underscore the potential of lanthanide cation doping to drive significant advancements in CZTSSe photovoltaic technology, and therefore promoting its further development and future applications.

Effect of raw material pretreatment and ionic radius on the preparation and microwave dielectric properties of Re2TiO5 ceramics

The present study focuses on the synthesis and characterization of rare-earth titanates, specifically Re2TiO5 (ReLa, Nd, Sm), with a particular emphasis on their microwave dielectric properties. The factors influencing the synthesis of La2TiO5 compound through the traditional solid-state method were thoroughly investigated, with a significant finding being the notable impact of moisture absorption in La2O3. The impact of variations in rare-earth cation radii on the structure and dielectric properties was systematically analyzed. Re2TiO5 (ReLa, Nd, Sm) ceramics crystallized into an orthorhombic structure with space group Pnam, which was confirmed through Rietveld refinement. The resulting materials demonstrated exceptional microwave dielectric properties characterized by a low permittivity range of 13.72–17.39, high-quality factors ranging from 8331 to 17,795 GHz, and a significantly reduced temperature coefficient of resonance frequency (−33.2∼-12.6 ppm/°C). The correlation between microwave dielectric properties and structural characteristics (including ionic polarizability, packing fraction, and bond valence) was investigated. The exceptional potential of these rare-earth titanates lies in their ability to meet the stringent requirements for low signal transmission delay in wireless communication systems, owing to their advantageous low permittivity within the microwave frequency spectrum.

Isothermal compressibility, internal pressure studies of aqueous rare earth nitrate solutions at 298.15 K: An attempt to estimate ionic radii and understand inner– and outer–sphere exchange water structural interactions

In this communication, we report our analysis and results concerning the determination of ionic radii in aqueous solution phase for Lanthanum (La+3), Neodymium (Nd+3), Erbium (Er+3) and Ytterbium (Yb+3) ions in presence of nitrate (NO3-) anion at 298.15 K. The literature data for density, adiabatic compressibility, and specific heat capacity of solutions at constant pressure have been used to compute isothermal compressibility, internal pressure of solutions in limiting concentration range. The apparent molar isothermal compressibility of electrolytes and hydration numbers have been obtained. The electrostriction for rare earth cations and intrinsic volumes have been calculated using thermodynamic equations. The ionic radii of cations have been obtained using the ionic partial molar volume data of NO3- ions and the results are compared with those obtained for rare earth chlorides. The two series affect is also observed for ionic radii and internal pressure. The results have been explained on the basis of water structural effects due to electrostatic field and water dipole interaction between the inner– and outer–sphere water exchange reaction.

On-Off Ratiometric Fluorescence Europium(III) Metal-Organic Framework for Quantitative Detection of the Inflammatory Marker Neopterin.

Benefiting from the unique photoluminescence behavior of the lanthanide(III) ions and organic ligands, a lanthanide(III) metal-organic framework (Ln-MOF) material can simultaneously demonstrate photoluminescence of lanthanide(III) cations and organic molecules and endow its superior applications of fluorescence sensing behaviors. Herein, we present a europium(III) MOF material {[Eu2(BPTA)·(CH3COO)2·3DMA]·0.5DMA·3H2O}n (1) (where H4BPTA is 3,3',5,5'-biphenyltetracarboxylic acid) for photoluminescence performance of quantitatively sensing the inflammatory marker neopterin (Neo). The obtained 1 comprises Eu2(COO)4 paddlewheel secondary building units, which could be bridged by BPTA4- ligands to extend a 2D framework. The fluorescence titration indicates 1 can achieve simultaneous fluorescence behavior of Eu3+ ions and Neo via on-off ratiometric effects and thus could be exploited as the ratiometric fluorescence sensor matrix. Such a fluorescence phenomenon of 1 as a ratiometric sensor for quantitative detection of Neo via an on-off ratiometric effect is never observed in MOF chemistry. Moreover, naked-eye visible color variations of the fluorescence for 1 could be observed from red to blue with increasing concentrations of Neo, confirmed by fluorescent test strips as well as portable fluorescent hydrogels. And 1 also shows a low detection limit of 15.11 nM. A synergetic contribution of the competitive absorption, fluorescence resonance energy-transfer, and photoinduced electron-transfer mechanisms between Neo and the framework of 1 realizes the on-off ratiometric fluorescence behavior for Neo detection, supported by the UV-vis spectral overlap experiment and DFT calculations.

Lanthanide Organic-Inorganic Hybrids for X-ray Scintillation and Imaging.

Two X-ray scintillators based on organic-inorganic hybrids were constructed by judiciously incorporating lanthanide cations and organic ligands within a single material. The obtained Eu-pba and Tb-pba not only feature excellent radiation, hydrolytic, and thermal stabilities but also exhibit a linear response to the X-ray dose rate with detection limits of 4.92 and 3.17 μGy s-1, respectively. We further present a flexible scintillator film fabricated by embedding Tb-pba in a polydimethylsiloxane (PDMS) polymer. Their incorporation enables X-ray imaging with a spatial resolution of approximately 10 lp mm-1. These results emphasize the potential of lanthanide organic-inorganic hybrids to achieve outstanding performance in X-ray scintillation and imaging.

Mesoporous RE0.5Ce0.5O2-x Fluorite Electrocatalysts for the Oxygen Evolution Reaction.

Developing highly active and stable electrocatalysts for the oxygen evolution reaction (OER) is key to improving the efficiency and practical application of various sustainable energy technologies including water electrolysis, CO2 reduction, and metal air batteries. Here, we use evaporation-induced self-assembly (EISA) to synthesize highly porous fluorite nanocatalysts with a high surface area. In this study, we demonstrate that a 50% rare-earth cation substitution for Ce in the CeO2 fluorite lattice improves the OER activity and stability by introducing oxygen vacancies into the host lattice, which results in a decrease in the adsorption energy of the OH* intermediate in the OER. Among the binary fluorite compositions investigated, Nd2Ce2O7 is shown to display the lowest OER overpotential of 243 mV, achieved at a current density of 10 mA cm-2, and excellent cycling stability in an alkaline medium. Importantly, we demonstrate that rare-earth oxide OER electrocatalysts with high activity and stability can be achieved using the EISA synthesis route without the incorporation of transition and noble metals.

Alloying effect of rare-earth tritellurides on the charge density wave and magnetic properties

Among many van der Waals materials rare-earth tritellurides (RTe3) allow studying several phenomena like magnetic, superconducting, and charge density wave (CDW). These studies show the effect of cationic alloying of antiferromagnetic RTe3 for fully tunable near room-temperature CDW properties. DyxGd1−xTe3 and DyxTb1−xTe3 alloys were synthesized through a chemical vapor transport technique, and the rare-earth element composition was controlled by changing the ratio of rare-earth metal reagents. The results show that the lattice parameters can be continuously tuned with the composition of the rare-earth cations leading to the variation of the internal chemical pressure. Temperature-dependent Raman spectroscopy and electric transport measurement show that the CDW transition temperature (TCDW) of RTe3 alloys varies with lattice parameters/chemical pressure spanning across 300–380 K. Additional magnetism studies offer the first insights into the magnetic ordering in RTe3 alloys. The emergence of multiple magnetic transitions implies complex magnetic interactions that arise from interactions between different rare-earth elements. Overall findings introduce ways to control the CDW behavior and provide valuable insights into the magnetic ordering in RTe3 alloys, contributing to further investigation and a better understanding of their properties.

Cellulose modified to host functionalities via facile cation exchange approach

Properties of cellulose are typically functionalized by organic chemistry means. We progress an alternative facile way to functionalize cellulose by functional group counter-cation exchange. While ion-exchange is established for cellulose, it is far from exploited and understood beyond the most common cation, sodium. We build on our work that established the cation exchange for go-to alkali metal cations. We expand and further demonstrate the introduction of functional cations, namely, lanthanides. We show that cellulose nanocrystals (CNCs) carrying sulfate-half ester groups can acquire properties through the counter-cation exchange. Trivalent lanthanide cations europium (Eu3+), dysprosium (Dy3+) and gadolinium (Gd3+) were employed. The respective ions showed distinct differences in their ability of being coordinated by the sulfate groups; with Eu3+ fully saturating the sulfate groups while for Gd3+ and Dy3+, values of 82 and 41 % were determined by compositional analysis. CNCs functionalized with Eu3+ displayed red emission, those containing Dy3+ exhibited no optical functionality, while those with Gd3+ revealed significantly altered magnetic relaxation times. Using cation exchange to alter cellulose properties in various ways is a tremendous opportunity for modification of the abundant cellulose raw materials for a renewable future.

Modeling Lanthanide Ions in Solution: A Versatile Force Field in Aqueous and Organic Solvents.

In this paper, we propose a new nonpolarizable force field for describing the Ln3+ (Ln = lanthanide) series based on a 12-6-4 Lennard-Jones potential. The development of the force field was performed in pure water by adjusting both the ion-oxygen distance and the hydration free energy. This force field accurately reproduces the Ln3+ hydration properties through the series, especially the coordination number that is hardly accessible using a nonpolarizable force field. Then, the validity and the transferability of the current force field were evaluated for two different systems containing Ln3+ in various solvents, namely, 0.1 mol L-1 La(NO3)3 salts in methanol and Eu(NO3)3 salts in solvent organic phases composed of DMDOHEMA molecules in n-heptane. The good agreement between our simulations and the data available in the literature confirms the accuracy of the force field for describing the lanthanide cations in both aqueous and nonaqueous media.