Rare Earth Materials Research Articles

“There is plenty of energy at the bottom”: A spectral conversion approach for upconversion-powered water-splitting PEC cell

An avant-garde step towards the use of the long infrared tail of the incident solar radiation with untapped and crucial applications in photocatalysis and energy harvesting schemes is presented: “there is plenty of energy at the bottom”. In detail, a pure photonic approach to enhance titanium dioxide (TiO2) photocatalytic activity is proposed, by using rare-earth doped luminescent glassy materials, capable of performing NIR-to-UV-VIS spectral conversion (up-conversion). Therefore we report infrared-driven boosting of green hydrogen production in a photo-electrochemical water-splitting cell using TiO2 electrodes, revisiting the original design of Fujishima and Honda fifty years later. This proof-of-concept comprises infrared-induced hydrogen and oxygen evolution via water-splitting and determines univocally the role of a solely photonic effect to split water. Thus, the conversion of the incident NIR radiation, before its interaction with the photocatalyst, emerges as a significant contribution to the state-of-the-art for an effective harvest of the near-infrared portions of sunlight.

Unraveling Magnet Structural Defects in Permanent Magnet Synchronous Machines—Harmonic Diagnosis and Performance Signatures

Rare-earth-based permanent magnets (PMs) have a vital role in numerous sustainable energy systems, such as electrical machines (EMs). However, their production can greatly harm the environment and their supply chain monopoly presents economic threats. Alternative materials are emerging, but the use of rare-earth PMs remains dominant due to their exceptional performance. Damage to magnet structure can cause loss of performance and efficiency, and propagation of cracks in PMs can result in breaking. In this context, prolonging the service life of PMs and ensuring that they remain damage-free and suitable for re-use is important both for sustainability reasons and cost management. This paper presents a new harmonic content diagnosis and motor performance analysis caused by various magnet structure defects or faults, such as cracked or broken magnets. The proposed method is used for modeling the successive physical failure of the magnet structure in the form of crack formation, crack growth, and magnet breakage. A surface-mounted permanent magnet synchronous motor (PMSM) is studied using simulation in Ansys Maxwell software (Version 2023), and different cracks and PM faults are modeled using the two-dimensional finite element method (FEM). The frequency domain simulation results demonstrate the influence of magnet cracks and their propagation on EM performance measures, such as stator current, distribution of magnetic flux density, back EMF, flux linkage, losses, and efficiency. The results show strong potential for application in health monitoring systems, which could be used to reduce the occurrence of in-service failures, thus reducing the usage of rare-earth magnet materials as well as cost.

Machine learning assisted search for Fe–Co–C ternary compounds with high magnetic anisotropy

We employ a machine learning (ML)-guided framework to explore rare earth free magnetic materials, specifically focusing on Fe–Co–C ternary compounds for potential use in permanent magnets. Utilizing a specifically trained crystal graph convolutional neural network model, we efficiently screen a vast space of nearly a million substitutional structures to select 620 promising structures for further investigation by first-principles calculation. We predict five low-energy metastable Fe–Co–C compounds with formation energy less than 150 meV/atom above the convex hull. These compounds exhibit high magnetization (Js > 1.0 T) and significant magnetic anisotropy (K1 > 1.0 MJ/m3), making them promising candidates for permanent magnet applications. The phonon calculations indicate these compounds are dynamically stable. Our ML-guided framework demonstrates the utility of rapidly identifying novel materials with tailored magnetic properties.

Tunning Pr to achieve ultra-high magnetic properties of anisotropic nanocrystalline (Sm,Pr)Co5 magnets

In this study, we reported on the bulk anisotropic nanocrystalline Sm1-xPrxCo5 (x = 0.2–0.6) magnets aimed at achieving excellent energy products. Through a combination of advanced processing techniques, including melt spinning, hot pressing, and hot deformation process, bulk magnets with a fine nanocrystalline structure were successfully synthesized. The results revealed that the substitution of Pr strengthened the c-axis texture and the saturation magnetization, facilitating the enhancement of remanence (Mr) and maximum magnetic energy product [(BH)max]. However, Pr substitution decreased the coercivity (Hci) due to the reduced magnetocrystalline anisotropy field. Excellent magnetic properties are obtained for Sm0.4Pr0.6Co5 magnets with the (BH)max of 23.2 MGOe and Hci of 11.8 kOe. The prepared (Sm,Pr)Co5 magnets with different Pr contents have essentially the same microstructure with RECo5 main phase grains of about 400 nm in diameter and fine dispersed rare earth-rich nanoprecipitates. Our findings can provide reliable reference for manufacturing nanocrystalline permanent magnet materials and promote the development of rare earth permanent magnet new materials.

Synthesis and Luminescent Properties of TiO<sub>2</sub> Materials Single and Triple Doped with Rare Earth Ions (Sm<sup>3+</sup> , Tb <sup>3+</sup> and Eu<sup> 3+</sup>)

Four types of titanium dioxide (TiO2) materials doped with a single kind of rare earth ions Ln3+ (Eu3+, Tb3+, or Sm3+) and three rare earth ions (Eu3+, Tb3+, and Sm3+) were synthesized by the sol-gel method. The compositions, structures, and photophysical properties of these compounds were tested. The structure of the rare earth ion-doped TiO2 samples was characterized by X-ray powder diffraction (XRD) and Fourier-transform infrared spectroscopy (FT-IR). Optical absorption and fluorescence information was obtained using UV-Vis spectroscopy and fluorescence spectroscopy. The surface morphology of rare earth ion-doped TiO2 materials was observed using scanning electron microscopy (SEM). To further explore the photoluminescent properties of rare earth-doped TiO2 materials for practical applications, small-scale LED light-emitting devices were fabricated.

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.

Elucidating correlation-driven insulating state in an effective spin—½ antiferromagnet NdVO4

TheJeff= ½ state: a result of interplay of strong electronic correlations (U) with spin-orbit coupling (SOC) and crystal field splitting, offers a platform in the research of quantum materials. In this context, 4frare-earth based materials offer a fertile playground. Here, strong experimental and theoretical evidences for aJeff= ½ state is established in a three-dimensional spin system NdVO4. Magnetic measurements show the signatures of a SOC drivenJeff= ½ state along with the presence of antiferromagnetic (AFM) interaction between Nd3+moments, whereas, heat capacity reveals the presence of an AFM ordering around 0.8 K, within this state. An entropy of Rln2 (equivalent toJ= ½) is released around 4 K which implies the presence ofJeff= ½ state at low temperatures. Total energy calculations within the density functional theory (DFT) framework reflect the central role of SOC in driving the Nd3+ions to host such a state with AFM correlations between them, which is in agreement with experimental results. Further, DFT + SOC calculations with and without the inclusion ofU, points that electron-electron correlations give rise to the insulating state making NdVO4a potential candidate forU-driven correlated Mott insulator.

F-π* Back Bonding Orbital Induced by Lutetium-Based Conducting MOF Promotes Highly Selective CO 2 to CH 4 at Low Potential.

The research on electrocatalytic carbon dioxide reduction (ECR) catalysts using renewable energy is particularly crucial in energy conversion studies, especially for viable hydrocarbon production. This study employs density functional theory calculations to screen a series of non-radioactive lanthanide two-dimensional metal-organic frameworks (MOFs) for product selectivity in ECR. Based on theoretical screening, our focus is on a lutetium (Lu)-based conducting MOF (Lu-HHTP), which exhibits a Faradaicefficiency of approximately 77% for methane (CH4) production and maintains a stable current density of -280 mA/cm2at -1.1 V vs. RHE. In situ electrochemical experiments and material characterization demonstrate that the Lu sites possess high coordination stability and structural recoverability during catalytic CO2reduction, attributed to the overlap between Lu's f-orbitalsand the π*-orbitals of the ligand O, and the formation of back bonding orbitals between the f-orbitals of Lu and the π* orbitals of CO contribute increasing CH₄selectivity and lowering the potential. This study leverages rare-earth MOF-type materials, offering a novel approach to addressing low conductivity and stabilizing rare-earth materials, thereby establishing a theoretical framework for the conversion of linearly adsorbed *CO into hydrocarbons.

Exploring rare-earth Kitaev magnets by massive-scale computational analysis

The Kitaev honeycomb model plays a pivotal role in the quest for quantum spin liquids, in which fractional quasiparticles would provide applications in decoherence-free topological quantum computing. The key ingredient is the bond-dependent Ising-type interactions, dubbed the Kitaev interactions, which require strong entanglement between spin and orbital degrees of freedom. Here we investigate the identification and design of rare-earth materials displaying robust Kitaev interactions. We scrutinize all possible 4f electron configurations, which require up to 6+ million intermediate states in the perturbation processes, by developing a parallel computational program designed for massive-scale calculations. Our analysis reveals a predominant interplay between the isotropic Heisenberg J and anisotropic Kitaev K interactions across all realizations of the Kramers doublets. Remarkably, instances featuring 4f3 and 4f11 configurations showcase the prevalence of K over J, presenting unexpected prospects for exploring the Kitaev quantum spin liquids in compounds, including Nd3+ and Er3+, respectively.

Exploring the effect of exchange coupling in (SrFe9.8Al2La0.2O19)1-x/(Co0.7Zn0.3Fe2O4)x nanocomposites synthesised by sol–gel auto combustion method

Extensive research has been conducted over the last decade to develop permanent magnets utilizing less rare earth materials. Exchange-coupled nanocomposite magnets are a fascinating development in the field of permanent magnets. They involve the combination of hard and soft ferrites, resulting in a unique and evolving magnet. Here we present an in-depth structural, morphological and magnetic characterization of ferrite-based nanostructures obtained through a bottom-up sol−gel approach. The combination of high coercivity of a hard phase SrFe9.8Al2La0.2O19 (SFALO) and high saturation magnetization of a soft phase, Co0.7Zn0.3Fe2O4 (CZFO), allowed us to develop exchange-coupled bi-magnetic nanocomposites by varying the mass percentage (x = 0, 0.1, 0.2, 0.3, 0.4, 1). Thermogravimetric analysis (TGA) up to 1200 °C was used to investigate the material’s thermal properties with the phase formation temperature. Detailed atomic/nano-scale structural characterizations of these nanocomposites were performed by X-ray diffraction and Transmission Electron Microscopy. The average particle size was calculated from the SEM analysis and it was observed that most of the composites with ratio x = 0.1, 0.3 & 0.4 was 145 nm and x = 0.2 was 165 nm. The Switching Field Distribution (SFD) curve revealed the exchange coupling between soft and hard magnetic particles. The findings indicate that the inclusion of a soft magnetic phase has a considerable impact on the exchange coupling between the hard and soft ferrite phases. As the spinel concentration increased, in the composite the saturation magnetization increased from 18 emu/g to 48 emu/g. From the stroner-wholfrathmodel, the decrease in the remanence ratio below 0.5 concludes the crystallites are randomly oriented. The nanocomposite with the ratio x = 0.1 was observed with the high magneto crystalline anisotropy of 2183.23 × 102 (J/m3) and a high energy product (BH)max of 5.5 kJ/m3. The aforementioned features of nanocomposites demonstrate their potential for use in permanent magnet applications.

Dual-Mechanism Design Strategy for High-Efficiency and Long-Lived Organic Afterglow Materials.

Organic room-temperature phosphorescence (RTP) and afterglow materials hold great potential for various applications, but there remain inherent trade-offs between the afterglow efficiency and the lifetime. Here, we propose a dual-mechanism design strategy, leveraging the RTP or thermally activated delayed fluorescence (TADF) mechanism for a high afterglow efficiency and the organic long-persistent luminescence (OLPL) mechanism for a prolonged afterglow duration. The intramolecular charge transfer (ICT)-type difluoroboron β-diketonate molecules with a large S1 dipole moment are doped as the luminescent component into the organic matrix with a large dipole moment, and a series of TADF-type afterglow materials can be achieved with an afterglow efficiency of up to 88.7% and an afterglow lifetime of 200 ms. To prolong the afterglow duration, an electron donor is introduced as the third component to generate traps and facilitate charge separation. The obtained materials exhibit a dual afterglow mechanism, first exhibiting a TADF/RTP afterglow with an afterglow efficiency of up to 50.9%, followed by an hours-long OLPL afterglow emission with an afterglow efficiency of up to 13.1%. Further investigations reveal that an appropriate heavy-atom effect can facilitate the intersystem crossing process, which can promote the charge separation process and thus improve the OLPL afterglow performance. Additionally, rare-earth upconversion materials are introduced into OLPL materials to enable their near-infrared excitation properties, showcasing their potential applications in bioimaging.

Study on the effects of preparation processes on OSL and TL properties of NaMgF3:Dy,Eu

OSL fading with storage time after irradiation remains a major obstacle in the development of ideal OSL materials. Dy and Eu co-doped NaMgF3 are attractive candidates for various rare earth doped matrix materials. In this study, NaMgF3:Dy,Eu was synthesized by a solid-state reaction, and the effects of heating temperature, duration, atmosphere, and cooling rate on XRD, TL and OSL properties were studied. A simple, safe, efficient, and time-saving solid-state reaction was identified as a potential method for the preparation of NaMgF3:Dy,Eu, which could be optimally prepared by heating at 750 °C for 2 h under nitrogen atmosphere (2 l/min) followed by rapid cooling. The results show that NaMgF3:Dy,Eu has a more stable OSL response and an excellent TL glow curve, with only a 0.4% decrease in the OSL signal read after 1 d of dose irradiation compared to that immediately after irradiation, and a high main TL peak at ∼320 °C. It has been indicated the OSL signal in this material seems to be strongly related to the main TL peak. The material has a considerable OSL sensitivity and decay rate than the Luxel Detector. NaMgF3:Dy,Eu will have a promising future in the field of OSL dosimetry due to its near tissue equivalence, low OSL fading without preheating, fast OSL decay rate, and predictable and easily reusable dose elimination.

Rare earth based photocatalysts for hydrogen peroxide production☆

Hydrogen peroxide (H2O2) is a versatile compound with widespread applications in various industries. In addition, it has attracted interest as a potential energy carrier due to its high energy density and ability to release oxygen upon decomposition. The development of photocatalytic technology has enabled sustainable production of H2O2. Various structural materials, including organic molecules, polymers, and metal coordination compounds, have been synthesized for investigating photocatalytic H2O2 production. Rare earth materials, in particular, are of interest due to their adjustable porosity and controllable metal active sites, making them valuable for research in this field. These materials have excellent photoelectric properties, making them promise for the photocatalytic synthesis of H2O2. Despite limited reports on systematic reviews of photocatalytic H2O2 production using rare earth materials, this study introduces the principles and advancements in this area. It reviews different methods of photocatalytic synthesis of H2O2, focusing on rare earth elements. Through comprehensive analysis and systematic studies in the existing literature, a deeper understanding of enhanced photocatalytic performance has been achieved. This research not only contributes to advancing fundamental knowledge but also provides a solid foundation for practical applications.

PMSM Design for Elevators: Determination of the Basic Topology Affecting Performance

In recent years, with the increase in high-rise building construction, there has been a rise in demand for elevators. This demand has spurred mutual growth between the vertical transportation sector and high-rise building construction. Both sectors are improving technology, security, and comfort standards. Traditional elevator traction machines typically employ asynchronous motors coupled with geared reducers, despite their low energy efficiency and requirement for large machine rooms. However, with the proliferation of rare-earth magnet materials and advancements in driver technologies, the use of Permanent Magnet Synchronous Motors (PMSMs) in elevator traction machines has increased. PMSMs operate with direct drive, eliminating the need for reducers. High efficiency and passenger comfort are crucial parameters for elevator traction machines. This study focuses on identifying the fundamental topology that could influence the performance of PMSMs for gearless elevator machines. Factors such as stator materials, rotor structures, permanent magnets, winding configurations, slot/pole combinations, cogging torque and torque ripple have been examined to select suitable design topologies for elevator motors. Important topics such as the magnetic properties of grain-oriented silicon steel sheets used in stator construction, B-H curves, lamination forming and stacking factors have been addressed. Two different rotor topologies and magnet arrangements, namely internal and external, have been investigated in PMSM designs. Additionally, the use of four different magnet materials, namely AlNiCo, Ferrite, NdFeB, and SmCo have been compared for PMSM traction motors in elevators. Single-layer and double-layer winding configurations, distributed and concentrated winding configurations have been compared. Fractional slot/pole combinations, which directly affect the performance and comfort of PMSMs, have also been examined based on information obtained from the literature. Particularly, structures with high winding factors, such as 12/10, 12/14, 18/16, 18/20, 24/22, and 24/26 have been identified. Finally, studies on skewing to reduce cogging torque and torque ripple have been addressed.

Ca9-yMgyNaGd0.667(PO4)7:Eu2+: A Single Eu2+-Doped Full-Spectrum White Light Emission Phosphor with High Color Rendering Index.

The multi-cationic site occupation control of rare earth doped phosphor materials is one of the key factors in achieving single-phase full-spectrum emission. In this work, the site distribution of Eu2+ in Ca9NaGd0.667(PO4)7 (CNGP):x%Eu2+ phosphors with multi-cationic sites was determined. Under 385 nm excitation, CNGP:x%Eu2+ samples exhibited a cyan emission composed of three sub-Gaussian components. The CNGP:1.5%Eu2+ phosphor was structurally modified through the partial substitution of Mg2+ for Ca2+ according to the crystallographic site engineering theory, and corresponding luminescent properties had been adjusted. When the concentration of Mg2+ changed, the Ca9-yMgyNaGd0.667(PO4)7:1.5%Eu2+ (CNGPE:yMg2+) phosphors exhibited a tunable emission from cyan to orange and achieved white light emission at y = 0.6. Based on the change of the crystal field environment, the mechanism of Mg2+ substitution affecting the luminescence characteristics of CNGP:x%Eu2+ phosphors was researched in detail. The light-emitting diode device consisted of a CNGPE:0.6Mg2+ phosphor and a 385 nm chip and had a high color rendering index (CRI = 91.9), low correlated color temperature (CCT = 4852 K), and excellent color stability. The optical performance of this device makes it promising to be used in full spectrum lighting.

Enhanced electron transfer kinetics via constructing co-catalytic system of cerium oxide and carbon dots enabling efficient electrosynthesis of hydrogen peroxide in neutral media

The sluggish kinetics coupled with the competition of four-electron pathway in neutral media diminishes the production efficiency of hydrogen peroxide (H2O2) via the two-electron oxygen reduction reaction (2e− ORR). To address this dilemma, this contribution proposes one electron modulation strategy to expedite the charge transfer capability by integrating carbon dots with CeO2 (CDs/CeO2) for the efficient neutral electrosynthesis of H2O2. It was found that the integration could effectively bolster both the activity and selectivity of 2e− ORR on CDs and CeO2. Remarkably, the highest 2e− selectivity could reach up to 92 % for the optimized CDs/CeO2, substantially surpassing that (77 %) of pristine CeO2, together with about 1.5 times enhancement of activity. Meanwhile, it also delivered a superior long durability at 20 mA cm−2 for 24 h and a high Faraday efficiency of 97 %. Further in-situ transient potential scanning (TPS) technique revealed that the pseudo-capacitance and charge storage capacity of CeO2 were significantly tuned by CDs during dynamic ORR process, being conducive to the reaction kinetics and the 2e− selectivity. The findings in this work not only extends the co-catalytic system based on CDs and rare earth materials for 2e− ORR, but also offers novel insights into correlation between their electron distribution dynamics and 2e− ORR performance.

Optical Properties of Europium-Doped Silicon-Based Thin Films

The integration of a silicon-based light emitter into existing CMOS technology has long been intriguing due to its optoelectronic compatibility with microelectronics [1]. However, the indirect band gap nature of bulk silicon has hindered its effectiveness as a light emitter. In addressing this limitation, rare earth ions have emerged as significantly interesting candidates owing to their unique optical and electronic properties. Rare earth-doped silicon structures have earned special attention as they exhibit sharp light emission in different spectral regions [2] . This notable feature is attributed to the effective excitation of rare earth ions within the host matrix. Efficiently excited rare earth ions can produce visible emissions ranging from infrared to ultraviolet, presenting possibilities in diverse applications such as solid-state lighting, displays, lasers, photovoltaics, and optical communication. The incorporation of rare earth-doped silicon structures presents a promising solution to overcome the challenges posed by silicon's intrinsic properties, thereby paving the way for improved performance across a diverse range of optoelectronic applications. Europium is a attractive rare earth material with two optically active states, Eu2+ and Eu3+, enabling it to generate a diverse range of color emissions extending from blue to red depending on the surrounding matrix [3].In this study, we investigated the optical properties and compositions of europium (Eu)-doped thin films including silicon oxide, silicon oxynitride, and silicon carbonitride. For this purpose, thin films were fabricated by electron cyclotron resonance plasma-enhanced chemical vapor deposition (ECR-PECVD) with in-situ magnetron sputtering on p-type 3" Si (100) substrates. In-situ Eu doping was performed by a radio frequency (RF) magnetron sputtering gun, using a 0.25 in. thick, 2 in. (diameter) 99.9% pure Eu sputtering target. Precursor gases, including silane (diluted in 90% argon), oxygen (diluted in 90% argon), nitrogen (diluted in 90% argon), and ethane were utilized. Annealing was performed on the as-deposited films over a broad temperature range, from 600° to 1100°C, in a nitrogen (N2) environment. Rutherford backscattering spectrometry (RBS) was performed to determine the atomic concentration of the film constituents. Variable angle spectroscopic ellipsometry (VASE) analysis was conducted to investigate the optical properties of the films. Room temperature photoluminescence (PL) experiments were performed using a laser diode excitation source operating at a wavelength of 375nm. Notably, bright visible emission was observed in some of the thin films. Finally, we discuss the influence of the atomic concentration of Eu and the annealing temperature on the emission properties observed in the photoluminescence experiments.[1] F. Azmi, Y. Gao, Z. Khatami, and P. Mascher, “ Tunable emission from Eu:SiOxNy thin films prepared by integrated magnetron sputtering and plasma enhanced chemical vapor deposition ,” J. Vac. Sci. Technol. A, vol. 40, no. 4, p. 043402, 2022, doi: 10.1116/6.0001761.[2] A. Brik et al., “Annealing Effects on Structural Characteristics of Europium Doped Silicon-Rich Silicon Nitride,” Silicon, vol. 14, no. 14, pp. 8417–8425, 2022, doi: 10.1007/s12633-021-01636-w.[3] D. Li, X. Zhang, L. Jin, and D. Yang, “Structure and luminescence evolution of annealed Europium-doped silicon oxides films,” Opt. Express, vol. 18, no. 26, p. 27191, 2010, doi: 10.1364/oe.18.027191.

(Battery Student Slam 8 Award Winner) Evaluating Electrodeposited Tin and Antimony-Based Anodes for Sodium-Ion Batteries

The widescale adaption of intermittent renewable energy sources, such as wind and solar, must be accompanied by a grid storage network to store energy when it is abundant and redistribute it as needed for on-demand use. Short-term storage in the form of rechargeable batteries is an attractive avenue for meeting these storage needs. The dominant technology in today’s market, the lithium-ion battery (LIB), is cost-prohibitive due to the need for rare-earth materials. Using the same working principle as LIBs, sodium-ion batteries (NIBs) utilize earth-abundant, low-cost sodium compounds instead of lithium compounds. Tin (Sn) and antimony (Sb) alone are promising anode materials for sodium-ion batteries with high theoretical capacities (847 and 660 mAh/g for Sn and Sb with Na, respectively) relative to current LIB anode chemistry (372 mAh/g) [1,2]. When combined, SnSb has shown to have increased stability relative to Sn or Sb alone [3]. Here, we synthesized Sn-Sb thin films with varied Sn and Sb atomic ratios by co-electrodeposition from a deep eutectic solvent by modifying solution stoichiometry and electrodeposition parameters. Using a combination of X-ray photoelectron spectroscopy (XPS), X-ray diffraction, and energy dispersive X-ray spectroscopy (EDS), phases and compositions of Sn-Sb synthesized by electrodeposition were identified. Once synthesized, we sought to determine the influence of morphology, surface chemistry, and composition on the capacity retention and rate capabilities of Sn and Sb-based anodes in NIBs. An optimized electrode composition was identified using a carbonate-based electrolyte, which resulted in stable capacity retention cycling at a rate of C/2 for 270 cycles.[1] W. T. Jing, C. C. Yang, and Q. Jiang, Journal of Materials Chemistry A, 8, 2913–2933 (2020).[2] S. Megahed and B. Scrosati, Journal of Power Sources, 51, 79–104 (1994).[3] W. P. Kalisvaart, H. Xie, B. C. Olsen, E. J. Luber, and J. M. Buriak, ACS Applied Energy Materials, 2, 5133–5139 (2019).

Influence of Rare-Earth Doping Content and Type on Phase Transformation and Transport Properties in Highly Doped CeO2.

Rare-earth doped CeO2 materials find extensive application in high-temperature energy conversion devices such as solid oxide fuel cells and electrolyzers. However, understanding the complex relationship between structural and electrical properties, particularly concerning rare-earth ionic size and content, remains a subject of ongoing debate, with conflicting published results. In this study, we have conducted comprehensive long-range and local order structural characterization of Ce1-xLnxO2-x/2 samples (x ≤ 0.6; Ln = La, Nd, Sm, Gd, and Yb) using X-ray and neutron powder diffraction, Raman spectroscopy, and electron diffraction. The increase in the rare-earth dopant content leads to a progressive phase transformation from a disordered fluorite structure to a C-type ordered superstructure, accompanied by reduced ionic conductivity. Samples with low dopant content (x = 0.2) exhibit higher ionic conductivity in Gd3+ and Sm3+ series due to lower lattice cell distortion. Conversely, highly doped samples (x = 0.6) exhibit superior conductivity for larger rare-earth dopant cations. Thermogravimetric analysis confirms increased water uptake and proton conductivity with increasing dopant concentration, while the electronic conductivity remains relatively unaffected, resulting in reduced ionic transport numbers. These findings offer insights into the relationship between transport properties and defect-induced local distortions in rare-earth doped CeO2, suggesting the potential for developing new functional materials with mixed ionic oxide, proton, and electronic conductivity for high-temperature energy systems.

Optimization of electromagnetic layout for E-machine in electric vehicles: Achieving high performance, efficiency and NVH

The development of electric vehicles (EVs) presents the challenge of optimising electric machines to enhance efficiency, compactness, noise, vibration, harshness (NVH), and affordability, while reducing the dependence on heavy rare-earth materials to reduce the CO2 footprint of electric powertrains. This paper introduces a comprehensive optimization approach for the electromagnetic design of permanent magnet synchronous machines (PMSMs), employing a combination of Design of Experiment (DoE) and Robust Neural Networks (RNN). The optimization framework is utilised to comprehensively address the multiple objectives of an electric machine, including efficiency, noise, vibration, harshness (NVH), and cost. The integration of Artificial Intelligence (AI)-driven modelling has resulted in significant performance improvements, achieving up to 96% total efficiency over the entire load cycle with substantial NVH reductions of up to 20 dB, while reducing the magnet rare earth materials by 35% compared to the baseline. Furthermore, this methodology reduces the simulation time by up to 90%, demonstrating the potential of combining neural network optimization with conventional finite element simulation techniques. The validation of the AI-driven optimization approach with the measurement of the baseline and optimised electric machines for efficiency and vibration is demonstrated for correlation.