Applications and functions of rare-earth ions in perovskite solar cells

The emerging perovskite solar cells have been recognized as one of the most promising new-generation photovoltaic technologies owing to their potential of high efficiency and low production cost. However, the current perovskite solar cells suffer from some obstacles such as non-radiative charge recombination, mismatched absorption, light induced degradation for the further improvement of the power conversion efficiency and operational stability towards practical application. The rare-earth elements have been recently employed to effectively overcome these drawbacks according to their unique photophysical properties. Herein, the recent progress of the application of rare-earth ions and their functions in perovskite solar cells were systematically reviewed. As it was revealed that the rare-earth ions can be coupled with both charge transport metal oxides and photosensitive perovskites to regulate the thin film formation, and the rare-earth ions are embedded either substitutionally into the crystal lattices to adjust the optoelectronic properties and phase structure, or interstitially at grain boundaries and surface for effective defect passivation. In addition, the reversible oxidation and reduction potential of rare-earth ions can prevent the reduction and oxidation of the targeted materials. Moreover, owing to the presence of numerous energetic transition orbits, the rare-earth elements can convert low-energy infrared photons or high-energy ultraviolet photons into perovskite responsive visible light, to extend spectral response range and avoid high-energy light damage. Therefore, the incorporation of rare-earth elements into the perovskite solar cells have demonstrated promising potentials to simultaneously boost the device efficiency and stability.

Influence of rare-earth ions on structural and magnetic properties of CdFe_2O_4 ferrites

Nano-sized powders of rare-earth ions added CdFe2O4 ferrites were synthesized by oxalate co-precipitation method.The influence of R ions（R = Sm3＋, Y3＋, and La3＋） on the microstructure and magnetic properties of CdFe2O4 ferrites was studied.XRD, SEM, FTIR, and magnetic hysteresis loops were used for analyzing the samples.The addition of R ions alters the structure of the powders and decreases the crystalline size, lattice constant, and grain size.The magnetic properties such as saturation magnetization, remanent magnetization, and magnetic moment increased due to addition of rare-earth ions in CdFe2O4 ferrite.The formation of secondary phase on the grain boundaries supports the abnormal growth.FTIR spectra show two absorption bands.Results suggest that the magnetic properties depend on the particular method of preparation and additives.

Simulating resonance-mediated two-photon absorption enhancement in rare-earth ions by a rectangle phase modulation

Improving the up-conversion luminescence efficiency crucial in several related application areas. In this work, of rare-earth ions via the multi-photon absorption process is we theoretically propose a feasible scheme to enhance the resonance-mediated two-photon absorption in Er3＋ ions by shaping the femtosecond laser field with a rectangle phase modulation. Our theoretical results show that the resonance-mediated two-photon absorption can be decomposed into the on-resonant and near-resonant parts, and the on-resonant part mainly comes from the contribution of laser central frequency components, while the near-resonant part mainly results from the excitation of low and high laser frequency components. So, the rectangle phase modulation can induce a constructive interference between the two parts by properly designing the modulation depth and width, and finally realizes the resonance-mediated two-photon absorption enhancement. More- over, our results also show that the enhancement efficiency of resonance-mediated two-photon absorption depends on the laser pulse width （or laser spectral bandwidth）, final state transition frequency, and intermediate and final state absorption bandwidths. The enhancement efficiency modulation can be attributed to the relative weight manipulation of on-resonant and near-resonant two-photon absorption in the whole excitation process. This study presents a clear physical insight for the quantum control of resonance-mediated two-photon absorption in the rare-earth ions, and there will be an important significance for improving the up-conversion luminescence efficiency of rare-earth ions.

Simulation of Intermediate State Absorption Enhancement in Rare-Earth Ions by Polarization Modulated Femtosecond Laser Field

We extend the third perturbation theory to study the polarization control behavior of the intermediate state absorption in Nd^（3＋）ions. The results show that coherent interference can occur between the single-photon and three-photon excitation pathways, and depends on the central frequency of the femtosecond laser field. Moreover,single-photon and three-photon absorptions have different polarization control efficiencies, and the relative weight of three-photon absorption in the whole excitation processes can increase with increasing the laser intensity.Therefore, the enhancement or suppression of the intermediate state absorption can be realized and manipulated by properly designing the intensity and central frequency of the polarization modulated femtosecond laser field.This research can not only enrich theoretical research methods for the up-conversion luminescence manipulation of rare-earth ions, but also can provide a clear physical picture for understanding and controlling multi-photon absorption in a multiple energy level system.

Additive Effects of Rare-Earth Ions in Sodium Aluminoborate Glasses Using ²³Na and ²⁷Al Magic Angle Spinning Nuclear Magnetic Resonance

We conducted structural analysis of xNa2O-yY2O3-5B2O3-3Al2O3 and xNa2O-yLa2O3-5B2O3-3Al2O3 glasses to elucidate the additive effects of rare-earth ions in these sodium aluminoborate glasses, and investigated the local environment surrounding Na+ in them by using 23Na and 27Al magic angle spinning?nuclear magnetic resonance (MAS NMR) spectroscopy. The amount of higher-coordinated Al species ([5]Al and [6]Al) gradually increased in response to an increase in the ratios of Y2O3 to Al2O3 and La2O3 to Al2O3 in each type of glass, respectively. Moreover, the difference in the cation field strength (CFS) between Y3+ and La3+ was observed to affect the generation of [5]Al and [6]Al, especially when the amount of these ions in the glasses increased. In addition to the above, the coordination number of Na+ ions increased with an increase in the number of rare earth ions, confirmed by comparing results with NMR spectra of crystalline Na2Al2B2O7. The latter possibly occurred due to the oxygen concentration on Al[5] and Al[6]. Finally, it was confirmed that the formation of [5]Al and [6]Al decreases molar volume in oxide glasses, which might be partially due to better atomic packing of [5]Al and [6]Al.

Study on the hydrogen absorption properties of a YGdTbDyHo rare-earth high-entropy alloy

This study investigated the microstructure and hydrogen absorption properties of a rare-earth high-entropy alloy(HEA),YGdTbDyHo.Results indicated that the YGdTbDyHo alloy had a microstructure of equiaxed grains,with the alloy elements distributed homogeneously.Upon hydrogen absorption,the phase structure of the HEA changed from a solid solution with an hexagonal-close-packed(HCP)structure to a high-entropy hydride with an faced-centered-cubic(FCC)structure without any secondary phase precipitated.The alloy demonstrated a maximum hydrogen storage capacity of 2.33 H/M(hydrogen atom/metal atom)at 723 K,with an enthalpy change(ΔH)of-141.09 kJ·mol^(-1)and an entropy change(ΔS)of-119.14 J·mol^(-1)·K^(-1).The kinetic mechanism of hydrogen absorption was hydride nucleation and growth,with an apparent activation energy(E_(a))of 20.90 kJ·mol^(-1).Without any activation,the YGdTbDyHo alloy could absorb hydrogen quickly(180 s at 923 K)with nearly no incubation period observed.The reason for the obtained value of 2.33 H/M was that the hydrogen atoms occupied both tetrahedral and octahedral interstices.These results demonstrate the potential application of HEAs as a high-capacity hydrogen storage material with a large H/M ratio,which can be used in the deuterium storage field.

Solid-state quantum nodes based on color centers and rare-earth ions coupled with fiber Fabrye-Pérot microcavities

High-performance optical quantum memories serving as quantum nodes are crucial for the distribution of remote entanglement and the construction of large-scale quantum networks.Notably,quantum systems based on single emitters can achieve deterministic spin–photon entanglement,which greatly simplifies the difficulty of constructing quantum network nodes.Among them,optically interfaced spins embedded in solid-state systems,as atomic-like emitters,are important candidate systems for implementing long-lived quantum memory due to their stable physical properties and robustness to decoherence in scalable and compact hardware.To enhance the strength of light-matter interactions,optical microcavities can be exploited as an important tool to generate high-quality spin–photon entanglement for scalable quantum networks.They can enhance the photon collection probability and photon generation rate of specific optical transitions and improve the coherence and spectral purity of emitted photons.For solid-state systems,open Fabry–Pérot cavities can couple single emitters that are not in proximity to the surface,avoiding significant spectral diffusion induced by the interfaces while maintaining the wide tunability,which enables addressing of multiple single emitters in the frequency and spatial domain within a single device.This review described the characteristics of single emitters as quantum memories with a comparison to atomic ensembles,the cavity-enhancement effect for single emitters and the advantages of different cavities,especially fiber Fabry–Pérot microcavities.Finally,recent experimental progress on solid-state single emitters coupled with fiber Fabry–Pérot microcavities was also reviewed,with a focus on color centers in diamond and silicon carbide,as well as rare-earth dopants.

Critical current degradation in an epoxy-impregnated rare-earth Ba_(2)Cu_(3)O_(7-x)coated conductor caused by damage during a quench

High-temperature superconducting(HTS)rare-earth Ba_(2)Cu_(3)O_(7-x)(REBCO)coated conductors(CCs)have significant potential in high-current and high-field applications.However,owing to the weak interface strength of the laminated composite REBCO CCs,the damage induced by the thermal mismatch stress under a combination of epoxy impregnation,cooling,and quenching can cause premature degradation of the critical current.In this study,a three-dimensional(3D)electromagnetic-thermal-mechanical model based on the H-formulation and cohesive zone model(CZM)is developed to study the critical current degradation characteristics in an epoxy-impregnated REBCO CC caused by the damage during a quench.The temperature variation,critical current degradation of the REBCO CC,and its degradation onset temperature calculated by the numerical model are in agreement with the experimental data taken from the literature.The delamination of the REBCO CC predicted by the numerical model is consistent with the experimental result.The numerical results also indicate that the shear stress is the main contributor to the damage propagation inside the REBCO CC.The premature degradation of the critical current during a quench is closely related to the interface shear strength inside the REBCO CC.Finally,the effects of the coefficient of thermal expansion(CTE)of the epoxy resin,thickness of the substrate,and substrate material on the critical current degradation characteristics of the epoxy-impregnated REBCO CC during a quench are also discussed.These results help us understand the relationship between the current-carrying degradation and damage in the HTS applications.

Recent Advances in Fibrous Materials for Hydroelectricity Generation

Depleting fossil energy sources and conventional polluting power generation pose a threat to sustainable development.Hydroelectricity generation from ubiquitous and spontaneous phase transitions between liquid and gaseous water has been considered a promising strategy for mitigating the energy crisis.Fibrous materials with unique flexibility,processability,multifunctionality,and practicability have been widely applied for fibrous materials-based hydroelectricity generation(FHG).In this review,the power generation mechanisms,design principles,and electricity enhancement factors of FHG are first introduced.Then,the fabrication strategies and characteristics of varied constructions including 1D fiber,1D yarn,2D fabric,2D membrane,3D fibrous framework,and 3D fibrous gel are demonstrated.Afterward,the advanced functions of FHG during water harvesting,proton dissociation,ion separation,and charge accumulation processes are analyzed in detail.Moreover,the potential applications including power supply,energy storage,electrical sensor,and information expression are also discussed.Finally,some existing challenges are considered and prospects for future development are sincerely proposed.

Aligned Ion Conduction Pathway of Polyrotaxane‑Based Electrolyte with Dispersed Hydrophobic Chains for Solid‑State Lithium–Oxygen Batteries

A critical challenge hindering the practical application of lithium–oxygen batteries(LOBs)is the inevitable problems associated with liquid electrolytes,such as evaporation and safety problems.Our study addresses these problems by proposing a modified polyrotaxane(mPR)-based solid polymer electrolyte(SPE)design that simultaneously mitigates solvent-related problems and improves conductivity.mPR-SPE exhibits high ion conductivity(2.8×10^(−3)S cm^(−1)at 25℃)through aligned ion conduction pathways and provides electrode protection ability through hydrophobic chain dispersion.Integrating this mPR-SPE into solid-state LOBs resulted in stable potentials over 300 cycles.In situ Raman spectroscopy reveals the presence of an LiO_(2)intermediate alongside Li_(2)O_(2)during oxygen reactions.Ex situ X-ray diffraction confirm the ability of the SPE to hinder the permeation of oxygen and moisture,as demonstrated by the air permeability tests.The present study suggests that maintaining a low residual solvent while achieving high ionic conductivity is crucial for restricting the sub-reactions of solid-state LOBs.

Leaching behaviors of iron and aluminum elements of ion-absorbed-rare-earth ore with a new impurity depressant

Ion-absorbed rare-earth ore is an important mineral resource which is widely extracted by in-situ leaching process. And such process generates a significant amount of impurities such as aluminum and iron ions in leaching solution simultaneously. The surface characteristics and interactions by infrared spectroscopy and X-ray diffraction were studied to optimize the leaching conditions. It is found that the environment-friendly depressant LG-01 can react with the impurity ions through the formation of a new complex on the surface of leaching residues. Thus, it reduces significantly the concentration of impurity ions in leaching solution and improves the leaching rate of rare-earth ore. Moreover, a leaching rate of 95.6% and an impurity removal rate of 92% have been achieved under the optimized conditions.

Electrical switching in cadmium ferrite with different rare-earth ions(Sm^(3+), Y^(3+), and La^(3+))

The cadmium ferrite and 5 % rare-earth ions（Sm^3＋, Y^3＋, and La^3＋） added Cd ferrites were synthesized by oxalate co-precipitation method and characterized by X-ray diffraction（XRD）, Fourier transform infrared spectroscopy（FT-IR）, and scanning electron microscope（SEM） techniques. All ferrite samples under investigation exhibit current-controlled negative resistance type I–E characteristics at room temperature. The required electrical-switching field in cadmium ferrite is higher than that for 5 % Sm^3＋, Y^3＋, and La^3＋added cadmium ferrites. The5% addition of Sm^3＋, Y^3＋, and La^3＋ in cadmium ferrite is found to decrease the grain size in this ferrite. This decrement in the grain size makes the required switching field to decrease in cadmium ferrite. No aging effect for electrical switching is observed in these ferrites.

Rare-earth ions coordination enhanced ratiometric fluorescent sensing platform for quantitative visual analysis of antibiotic residues in real samples

Levofloxacin(LVFX)as a representative drug of quinolone antibiotics is widely used in clinical,and its residues enriched in water bodies and sideline products seriously damage human health.It is imperative to develop a real-time/on-site sensing method for monitoring residual antibiotics.Here,we report a portable sensing platform by utilizing a composite fluorescent nanoprobe constructed by the cerium ions(Ce^(3+))coordination functionalized Cd Te quantum dots(QDs)for the visual and quantitative detection of LVFX residues.This fluorescent probe provides a distinct color variation from red to green,which shows a good linear relationship to LVFX residues concentrations in the range of 0-6.0μmol/L with a sensitive limit of detection(LOD)of 16.3 nmol/L.The smartphone platform with Color Analyzer App installed,which could accomplish quantified detection of LVFX in water,milk,and raw pork with a LOD of 27.9nmol/L.The facile sensing method we proposed realizes rapid visualization of antibiotics residual in the environment and provides a practical application pathway in food safety and human health.

Up/down conversion luminescence rare-earth ion-doped Y_2O_3 1D nanocrystals

Multicolor luminescent rare-earth ion-doped Y2O3 nanocrystals （NCs） were prepared by a solvethermal method. The as-synthesized NCs yielded nanosheets, nanowires （NWs） and nanorods （NRs） with the increase of alkali （NaOH） in oleic acid system. Moreover, Y203 nanowires with controllable size have also been obtained. After sintering, the PL intensity of Y2O3：Ln3＋ nanocrystals increased with the changed morphology of the precursor, that is, Y（OH）3 nanocrystals. Both downconversion （red emission for Y2O3：Eu3＋ and green emission for Y2O3：Tb3＋） and upconversion （red emission for Y2O3：Yb/Er3＋） luminescence of the as-prepared nanocrystals have been demonstrated in this work. We also found that the PL intensity of Y2O3：Ln3＋ NCs dispersed in polar solvent was stronger than that in nonpolar solvent. Their up/downconversion fluorescence and controllable morphology might promise further fundamental research and biochemistry such as nanoscale optoelectronics, nanolasers, and ultrasensitive multicolor biolables.

Enhanced Laser Cooling of Rare-Earth-Ion-Doped Glass Containing Nanometer-Sized Metallic Particles

The enhanced laser cooling performance of rare-earth-ions-doped glasses containing small particles is predicted. This is achieved by the enhancement of local field around rare earth ions, owing to the surface plasmon resonance of small metallic particles. The role of energy transfer between ions and the particle is theoretical discussed. Depending on the particle size and the ion emission quantum efficiency, the enhancement of the absorption and the fluorescence is predicted. Moreover, taking Yb^3＋-doped ZBLAN as example, the cooling power and heat-light converting efficiency are calculated. It is finally concluded that the absorption and the fluorescence are greatly enhanced in these composite materials, the cooling power is increased compared to the bulk material.

Effective model for rare-earth Kitaev materials and its classical Monte Carlo simulation

Recently,the family of rare-earth chalcohalides were proposed as candidate compounds to realize the Kitaev spin liquid(KSL)[Chin.Phys.Lett.38047502(2021)].In the present work,we firstly propose an effective spin Hamiltonian consistent with the symmetry group of the crystal structure.Then we apply classical Monte Carlo simulations to preliminarily study the model and establish a phase diagram.When approaching to the low temperature limit,several magnetic long range orders are observed,including the stripe,the zigzag,the antiferromagnetic(AFM),the ferromagnetic(FM),the incommensurate spiral(IS),the multi-Q,and the 120°ones.We further calculate the thermodynamic properties of the system,such as the temperature dependence of the magnetic susceptibility and the heat capacity.The ordering transition temperatures reflected in the two quantities agree with each other.For most interaction regions,the system is magnetically more susceptible in the ab-plane than in the c-direction.The stripe phase is special,where the susceptibility is fairly isotropic in the whole temperature region.These features provide useful information to understand the magnetic properties of related materials.

Monolithic crystalline silicon solar cells with SiN_x layers doped with Tb^(3+) and Yb^(3+) rare-earth ions

In this study, we propose the fabrication of monolithic crystalline silicon solar cells with Tb^(3+) and Yb^(3+)-doped silicon nitride(SiN_x) layers by low-cost screen-printing methods. The performances of c-Si solar cells can be enhanced by rare-earth ions doped SiN_x layers via the mechanism of spectrum conversion.These SiN_x doped and codoped thin films were deposited by reactive magnetron co-sputtering and integrated as the antireflection coating layers in c-Si solar cells. The characterizations of SiN_x, SiN_x:Tb^(3+) tand SiN_x:Tb^(3+)-Yb^(3+) thin films were conducted by means of photoluminescence, Rutherford backscattering spectroscopy, Ellipsometry spectroscopy and Fourier transform infrared measurements. Their composition and refractive index was optimized to obtain good anti-reflection coating layer for c-Si solar cells.Transmission electron microscopy performs the uniform coatings on the textured emitter of c-Si solar cells. After the metallization process, we demonstrate monolithic c-Si solar cells with spectrum conversion layers, which lead to a relative increase by 1.34% in the conversion efficiency.

Recent developments and applications on high-performance cast magnesium rare-earth alloys

During the past decades,with the increasing demands in lightweight structural materials,Mg alloys with low density and high performance have been extensively investigated and partly applied in some industries.Especially when rare earth(RE)elements are added as major alloying elements to Mg alloys,the alloy strength and creep resistance are greatly improved,which have promoted several series of Mg-RE alloys.This paper reviews the progress and developments of high-performance Mg-RE alloys in recent years with emphasis on cast alloys.The main contents include the alloy design,melt purification,grain refinement,castability,novel liquid casting and semisolid forming approaches,and the industrial applications or trials made of Mg-RE alloys.The review will provide insights for future developments of new alloys,techniques and applications of Mg alloys.

Quantum light storage in rare-earth-ion-doped solids

The reversible transfer of unknown quantum states between light and matter is essential for constructing large-scale quantum networks. Over the last decade, various physical systems have been proposed to realize such quantum memory for light. The solid-state quantum memory based on rare-earth-ion-doped solids has the advantages of a reduced setup complexity and high robustness for scalable application. We describe the methods used to spectrally prepare the quantum memory and release the photonic excitation on-demand. We will review the state of the art experiments and discuss the perspective applications of this particular system in both quantum information science and fundamental tests of quantum physics.

Component Content Soft-sensor Based on Neural Networks in Rare-earth Countercurrent Extraction Process

Throught fusion of the mechanism modeling and the neural networks modeling,a compo- nent content soft-sensor,which is composed of the equilibrium calculation model for multi-component rare earth extraction and the error compensation model of fuzzy system,is proposed to solve the prob- lem that the component content in countercurrent rare-earth extraction process is hardly measured on-line.An industry experiment in the extraction Y process by HAB using this hybrid soft-sensor proves its effectiveness.