Rare Earth Research Articles

Tailoring the Use of 8-Hydroxyquinolines for the Facile Separation of Iron, Dysprosium and Neodymium.

Permanent magnets (PMs) containing rare earth elements (REEs) can generate energy in a sustainable manner. With an anticipated tenfold increase in REEs demand by 2050, one of the crucial strategies to meet the demand is developing of efficient recycling methods. NdFeB PMs are the most widely employed, however, the similar chemical properties of Nd (20-30 % wt.) and Dy (0-10 % wt.) make their recycling challenging, but possible using appropriate ligands. In this work, we investigated commercially available 8-hydroxyquinolines (HQs) as potential Fe/Nd/Dy complexing agents enabling metal separation by selective precipitation playing on specific structure/property (solubility) relationship. Specifically, test ethanolic solutions of nitrate salts, prepared to mimic the main components of a PM leachate, were treated with functionalized HQs. We demonstrated that Fe3+ can be separated as insoluble [Fe(QCl,I)3] from soluble [REE(QCl,I)4]- complexes (QCl,I -: 5-Cl-7-I-8-hydoxyquinolinate). Following that, QCl - (5-Cl-8-hydroxyquinolinate) formed insoluble [Nd3(QCl)9] and soluble (Bu4N)[Dy(QCl)4]. The process ultimately gave a solution phase containing Dy with only traces of Nd. In a preliminary attempt to assess the potentiality of a low environmental impact process, REEs were recovered as oxalates, while the ligands as well as Bu4N+ ions, were regenerated and internally reused, thus contributing to the sustainability of a possible metal recovery process.

How do seasonal, significant events, and policies affect China's REE export prices? Based on deep learning perspective

This paper aims to accurately predict China's rare earth export prices and reveal the impact of variables such as seasonality, significant events, finance, and supply and demand on rare earth price volatility. Daily datasets of light and heavy rare earths from 2011 to 2023 were used, and the Tree-structured Parzen Estimator-Temporal Fusion Transformer model was employed to predict rare earth prices. Complete Ensemble Empirical Mode Decomposition with Adaptive Noise and partial dependence plots were used to reveal the factors affecting price volatility. The following conclusions were drawn: (1) The Tree-structured Parzen Estimator-Temporal Fusion Transformer deep learning model can provide more accurate rare earth price prediction information; (2) Light rare earth prices are more susceptible to cyclical influences, while heavy rare earth prices are more affected by significant events. The outbreak of COVID-19 has had a long-term impact on both light and heavy rare earth prices; (3) The fluctuations in heavy rare earth prices are mainly influenced by financial factors, while the fluctuations in light rare earth prices are influenced by multiple factors such as finance, supply and demand, and macroeconomics; (4) An increase in resource tax rates may lead to a decrease in rare earth prices, while an increase in restrictions on rare earth mining may lead to an increase in rare earth prices.

Weathering-induced organic matter enrichment in marine-continental transitional shale: A case study on the early Permian Taiyuan Formation in the Ordos Basin, China

A comparative analysis of the factors controlling organic matter (OM) enrichment between marine-continental transitional (transitional hereafter) and marine or lacustrine shales is lacking. The early Permian Taiyuan Formation in the Ordos Basin, deposited during a shift from marine to continental settings in northern China, provides a unique opportunity to unravel the differences in OM enrichment mechanisms among these shales. The Taiyuan Formation is characterized by high TOC content (average 4.50%) and kerogen type II2-III. Most samples are thermally mature with a few high to post-mature samples relating to the Late Jurassic–Early Cretaceous Yanshanian magmatism. Rare earth elements and yttrium (REY) are dominated by light- and medium-types enrichments, with distinctly positive Gd anomaly, likely due to seawater incursion. A warm and humid climate prevailed during deposition of the Taiyuan Formation, consistent with the tropical-subtropical location of the North China Plate in the early Permian. The climatic conditions promoted intense continental weathering as reflected by high Th/Sc ratios, chemical index of alteration values, and feldspar alteration to scaly kaolinite. The V/(V + Ni) ratio is inconsistent with the other redox proxies, presumably due to variations in the redox buffer supply in the transitional facies (e.g., OM and pyrite), varying burial rates and dissimilar redox potential of different elements. Hence, this proxy should be interpreted with caution in such settings. Most redox proxies indicate oxic bottom water during deposition of the Taiyuan Formation transitional shale, in contrast to typical OM enriched marine and lacustrine shales where redox stratification or euxinic conditions are common. Instead, the dominant factor for OM enrichment in transitional shales appears to have been a high influx of terrestrial weathering products, including abundant higher-plants OM, associated with preservation of OM due to rapid burial. This process minimizes the detrimental effects of oxic conditions on OM accumulation in the transitional shale facies. This mechanism may hold relevance for analogous basins elsewhere.

Tracing sources of inorganic suspended particulate matter in the Great Barrier Reef lagoon, Australia

Water clarity on the inshore Great Barrier Reef (GBR) is greatly influenced by terrestrial runoff of suspended particulate matter (SPM). Catchment sediment tracing studies often do not extend into the marine environment, preventing the analysis of preferential marine transport. This study employs novel collection and sediment tracing techniques to examine the transport of the terrigenous ‘mineral’ component of plume SPM within the GBR lagoon for two flood events. Utilising geochemical, radionuclide and clay mineral analysis, we trace terrigenous mineral sediments > 100 km from the river mouth. We show that the SPM geochemistry is highly influenced by particle-size fractionation, desorption, and dilution within the plume, rendering traditional tracing methods unviable. However, the ratios of rare earth elements (REE) to thorium (Th) provide stable tracers of mineral SPM transported across the catchment to marine continuum and allow the identification of discrete catchment sources for each flood event. Plume sediment radionuclides are also stable and consistent with sub-surface erosion sources.

The effect of particles size of Gd2O3 on the radiation protection mechanisms of ZnO

There are two mechanisms established for increasing the radiation resistance of optical properties of micron-sized zinc oxide (mZnO) powder modified by gadolinium oxide (nGd2O3) nanoparticles by means of relaxation of the primary radiation defects (electrons and holes): — in atoms of rare-earth element gadolinium; — on Gd2O3 nanoparticles. During modification with gadolinium oxide micron-sized particles, only one (first) mechanism for radiation resistance increasing is enabled. These results are obtained by recording diffuse reflectance spectra in high vacuum in the range of 0.2–2.5 μm under radiation exposure by accelerated electrons (in situ). The established mechanisms for increasing radiation resistance refer not only to the types of powders under the study, but also to other types of oxide semiconductor powders and rare-earth elements. These mechanisms can also be extended to the photo résistance of oxide powders modified by nanoparticles and solid solutions based on them.

Zr-Based Metal–Organic Framework (UiO-66) Doped with Rare-Earth Element (La, Y)-Supported Polyoxometalate Liquid for Oxidative Desulfurization of Dibenzothiophene Oxidation

Zr-Based Metal–Organic Framework (UiO-66) Doped with Rare-Earth Element (La, Y)-Supported Polyoxometalate Liquid for Oxidative Desulfurization of Dibenzothiophene Oxidation

Effects of Sc–Er Rare Earth on Solidification Microstructure and Mechanical Properties of A360 Alloy

Effects of Sc–Er Rare Earth on Solidification Microstructure and Mechanical Properties of A360 Alloy

Insight into mechanism for remarkable photocatalytic hydrogen evolution of Cu/Pr dual atom co-modified TiO2.

The development of high-activity photocatalysts is crucial for the current large-scale development of photocatalytic hydrogen applications. Herein, we have developed a strategy to significantly enhance the hydrogen photocatalytic activity of Cu/Pr di-atom co-modified TiO2 architectures by selectively anchoring Cu single atoms on the oxygen vacancies of the TiO2 surface and replacing a trace of Ti atoms in the bulk with rare earth Pr atoms. Calculation results demonstrated that the synergistic effect between Cu single atoms and Pr atoms regulates the electronic structure of Cu/Pr-TiO2, thus promoting the separation of photogenerated carriers and their directional migration to Cu single atoms for the photocatalytic reaction. Furthermore, the d-band center of Cu/Pr-TiO2, which is located at -4.70 eV, optimizes the adsorption and desorption behavior of H*. Compared to TiO2, Pr-TiO2, and Cu/TiO2, Cu/Pr-TiO2 displays the best H* adsorption Gibbs free energy (-0.047 eV). Furthermore, experimental results confirmed that the photogenerated carrier lifetime of Cu/Pr-TiO2 is not only the longest (2.45 ns), but its hydrogen production rate (34.90 mmol g-1 h-1) also significantly surpasses those of Cu/TiO2 (13.39 mmol g-1 h-1) and Pr-TiO2 (0.89 mmol g-1 h-1). These findings open up a novel atomic perspective for the development of optimal hydrogen activity in dual-atom-modified TiO2 photocatalysts.

Approaching scalable quantum memory with integrated atomic devices

Quantum memory, which maps photonic quantum information into a stationary medium and retrieves it at a chosen time, plays a vital role in the advancement of quantum information science. In particular, the scalability of a quantum memory is a central challenge for quantum network that can be overcome by using integrated devices. Quantum memory with an integrated device is highly appealing since it not only expands the number of memories to increase data rates, but also offers seamless compatibility with other on-chip devices and existing fiber network, enabling scalable and convenient applications. Over the past few decades, substantial efforts have been dedicated to achieving integrated quantum memory using rare earth ions doped solid-state materials, color centers, and atomic gases. These physical platforms are the primary candidates for such devices, where remarkable advantages have been demonstrated in achieving high-performance integrated quantum memory, paving the way for efficiently establishing robust and scalable quantum network with integrated quantum devices. In this paper, we aim to provide a comprehensive review of integrated quantum memory, encompassing its background and significance, advancement with bulky memory system, fabrication of integrated device, and its memory function considering various performance metrics. Additionally, we will address the challenges associated with integrated quantum memory and explore its potential applications. By analyzing the current state of the field, this review will make a valuable contribution by offering illustrative examples and providing helpful guidance for future achievements in practical integrated quantum memory.

Comprehensive impact assessment on resource and environment of emerging recycling technologies for waste materials: Evidence from waste rare earth phosphors recycling

The recycling of waste materials has dual attributes of resource and environment, and current technical evaluation methods are difficult to balance the comprehensive impact of resource and environment, failing to meet the selection requirements of emerging recycling technologies. Focusing on the emerging recycling technology for rare earth phosphors, we developed a resource and environment composite assessment model, employing emergy accounting principles to uniformly quantify resource inputs and environmental impacts. The results indicated that the composite emergy of resource and environment of the recycling technologies is reduced by over 89.05 % compared to that of natural ores development technology. Moreover, the synergistic recycling of zinc (Zn) along with yttrium oxide (Y2O3) achieves an additional emergy reduction by 88.37 %. The resource emergy of natural ores development technology accounts for 95.15 %, indicating its heavy reliance on resource depletion. Due to the utilization of various chemicals, the recycling technologies exhibit stronger environment attribute.

La-Modified SBA-15 Prepared by Direct Synthesis: Importance of Determining Actual Composition

Lanthanum (La) integration (at various nominal contents) in SBA-15 prepared under acidic medium was intended from corresponding direct nitrate addition during mesoporous silica formation. Materials were impregnated with Pt (1.5 wt%) and studied through several textural (N2 physisorption), structural (XRD, TG-DTG), and surface (FTIR, STEM-HAADF, SEM-EDS, NH3, and CO2 TPD) instrumental techniques. Pt-impregnated solids were tested in phenol hydrodeoxygenation (HDO, T = 250 °C, 3.2 MPa, batch reactor, n-decane as solvent). Catalytic activity (in pseudo-first-order kinetic constant, kHDO basis) was not directly related to Pt dispersion, which was not determined by nominal rare earth content. Determining the actual composition of modified SBA-15 materials is crucial in reaching sound conclusions regarding their physicochemical properties, especially when La modifier is directly added during mesoporous matrix formation, where efficient interaction among constituents could be difficult to get. Otherwise, results from some characterization techniques (N2 physisorption and FTIR, for instance) could be misleading and even contradictory. Indeed, extant modifier precursors, when under SBA-15 synthesis conditions, could affect the properties of prepared materials even though they were absent in obtained formulations. Performing simple compositional analysis could eliminate uncertainties regarding the role of various modifiers on characteristics of final catalysts. However, several groups have failed in doing so.

Tunable dielectric characteristics of the nanocomposite diode based on functionalized graphene quantum dots with and without gadolinium

In this study, we have separately synthesized and characterized solutions of gadolinium (Gd)-free and Gd-doped polyethyleneimine (PEI)-functionalized graphene quantum dots (GQDs) due to the excellent properties of Gd, a rare earth element, in fluorescence and magnetic resonance imaging (MRI). The dielectric properties of Gd-free/doped nanocomposite-based diodes have been compared using impedance spectroscopy (IS) in the frequency range from 1 kHz to 500 kHz and voltage range from −3 V to +5 V at 300 K. From our experimental results, the Gd-free diode was found to have a negative dielectric constant (ε′). In contrast, the Gd-doped nanocomposite diode exhibited positive ε′. The ε′ of the Gd-free diode is −80, while the ε′ of the Gd-doped diode is 35 at 5 V for 1 kHz. The experimental results showed that the dielectric properties of both structures were strongly dependent on the applied voltage and frequency. The Gd doping in the interface has prevented the domination of loss mechanisms within the structure, eliminated negative dielectric at lower frequencies, and conferred a unique micro-capacitor characteristic to the structure. All these efforts will contribute to the development of functional carbon-based materials and the creation of new electronic devices and tunable dielectric properties.

What are the different biomolecules involved in the selective recovery of REEs from mining wastewater using FeNPs synthesized from two plant extracts?

Extracting rare earth elements (REEs) from wastewater is crucial for saving the environment, sustainable use of natural resources and economic growth. Reported here is a simple, low cost and one-step synthesis of Fe nanoparticles (FeNPs) based on two plant extracts having the ability to recover REEs. The synthesis of FeNPs using Excoecaria cochinchinensis leaves extract (Ec-FeNPs) exhibited high selectivity for heavy rare earth due to unique biomolecules, achieving separation coefficients (Kd) of 3.16 × 103–4.04 × 106 mL/g and recovery efficiencies ranging from 71.7 to 100 %. Conversely, the synthesis of FeNPs using Pinus massoniana lamb extract (PML-FeNPs) revealed poorer REE recovery efficiencies of 7.2–86.7 %. To understand the differences between Ec-FeNPs and PML-FeNPs in terms of selectivity and efficiency, LC-QTOF-MS served to analyze the biomolecules differences of two plant extracts. In addition, various types of characterization were carried out to identify the different functional groups encapsulated on the surface of FeNPs. These results reveal the source of the difference in the selectivity of Ec-FeNPs and PML-FeNPs for REEs. Furthermore, during DFT calculations, it was found that biomolecules with varying affinities for the surface of FeNPs interact with each other, leading to the formation of structures that exhibit high reactivity towards REEs. Finally, incorporating Spearman correlation analysis demonstrates that the selective removal efficiency of REEs was closely linked to surface complexation, ion exchange, and electrostatic adsorption. Consequently, this work strongly highlights the potential for the practical application of novel adsorbents in this field.

Levels of Rare Earth Elements in Food and Human Dietary Exposure: A Review.

Rare earth elements (REEs) are a group consisting of the following 17 metals: Ce, Dy, Er, Eu, Gd, Ho, La, Lu, Nd, Pr, Pm, Sc, Sm, Tb, Tm, Y and Yb. In the current century, the number of applications of REEs has significantly increased. They are being used as components in high technology devices of great importance industrial/economic. However, information on the risk of human exposure to REEs, as well as the potential toxic effects of these elements is still limited. In general terms, dietary intake is the main route of exposure to metals for non-occupationally exposed individuals, which should be also expected for REEs. The current paper aimed at reviewing the studies -conducted over the world- that focused on determining the levels of REEs in foods, as well as the dietary intake of these elements. Most studies do not suggest potential health risk for consumers of freshwater and marine species of higher consumption, or derived from the intake of a number of vegetables, fruits, mushrooms, as well as other various foodstuffs (honey, tea, rice, etc.). The current estimated daily intake (EDI) of REEs does not seem to be of concern. However, considering the expected wide use of these elements in the next years, it seems to be clearly recommendable to assess periodically the potential health risk of the dietary exposure to REEs. This is already being done with well-known toxic elements such as As, Cd, Pb and Hg, among other potentially toxic metals.

Synergetic recycling of permanent magnet and Li-ion battery cathode material for metals recovery

Rare earth elements (REEs)-based (NdFeB) magnets and lithium−ion batteries (LIBs) are critical for a low−carbon economy. Their production depends on critical elements like REEs, Li, Co and Ni. Recycling of these products have been explored separately as a potential solution. Conventional methods for recycling NdFeB magnets and LIBs face challenges like high energy consumption, lengthy processing, excessive reagent usage, and waste generation. In this study, a novel synergetic recycling methodology is proposed to minimize these challenges. The idea is based on using waste ferrous sulfate solution generated during magnet leaching as a reducing and leaching reagent for battery recycling thereby eliminating the need for additional reagents for oxidation of iron in NdFeB and reduction of cathode material in LIBs. The magnet is leached in diluted H2SO4 at 70 °C followed by double sulfate precipitation for REEs with Na2SO4. The REE-depleted but acidic ferrous solution is then used for reductive leaching of cathode material at 90 °C. The overall recovery rates of REEs, Li, Co, Ni, and Mn in this process are >95%. The iron from magnet material is recovered as crystalline and easily-filterable iron compound that can be converted to goethite and used as a byproduct. This synergetic approach not only reduces reagent consumption and waste generation aligning with the principles of circular economy but also offers improved efficiency, resource conservation, and environmental sustainability.

Arc building and maturation of the Lombok Island, East Sunda Arc

Intra-oceanic subduction zones are major sites of crust–mantle material exchange and crustal growth; however, the processes responsible for the magmatic evolution and transformation of nascent arcs into mature oceanic arcs with thicker crust are debated. We present mineral chemistry, zircon UPb age and Hf isotopic data, and whole-rock chemical and Sr–Nd–Hf–Pb isotopic data for Cenozoic volcanic rocks on Lombok in the East Sunda Arc, Indonesia, to investigate their petrogenesis and arc maturation. SIMS zircon UPb analyses of lavas from southern Lombok yield an early Oligocene age of ∼30 Ma. The lavas can be divided into three groups based on their ages and geochemical characteristics: group I (late Eocene) and II (∼30 Ma) lavas from southern Lombok, and group III lavas (∼3–0 Ma) from northern Lombok. The lavas are characterized by a progressive enrichment in K2O and incompatible element contents, and NdHf isotopic compositions with time. Group I lavas are tholeiitic basalts with low K2O contents (0.15–0.17 wt%) and Indian-MORB like rare earth element (REE) patterns and NdHf isotopic compositions (εNd = +7.4; εHf = +14.5), enrichment in large-ion lithophile elements (e.g., Rb, U, and K), and typical forearc basalt (FAB) geochemical characteristics. Group II lavas are low-K basaltic andesites to dacites that yield flat chondrite-normalized REE patterns [(La/Sm)N = 0.9–1.4], uniform initial 87Sr/86Sr ratios (0.7038–0.7042), and positive εNd(t) (+5.9 to +6.8) and εHf(t) (+13.9 to +14.4) values. Group III lavas are typically medium- to high-K calc-alkaline basalt to andesite and are enriched in light REEs [(La/Sm)N = 1.6–3.3] with uniform initial 87Sr/86Sr ratios (0.7038–0.7042) and slightly low εNd(t) (+3.9 to +5.4) and εHf(t) (+10.5 to +12.5) values. Progressive enrichment in incompatible element contents and NdHf isotopic compositions over time, from FAB to high-K calc-alkaline lavas, reflect the maturation of the East Sunda Arc. Sr–Nd–Pb–Hf isotopic mixing models, along with trace element ratios (e.g., Ba/Th, La/Yb, Th/Yb), suggest that increasing amounts of sediments were incorporated into the mantle sources of the magmas from group I (∼0%) to group II (<0.5%) and group III (0.5%–1.0%) lavas. Partial melting models show that the formation of group I and II lavas can be reproduced by high-degree (∼10%) partial melting of spinel peridotite, whereas the group III lavas were formed by low-degree (∼5%) partial melting of spinel peridotite. We propose that the evolution of Lombok arc magmas was controlled mainly by the fluxes of subducted slab material, along with decreasing degrees of partial melting as a result of crustal thickening over time.

Compressive stress reduction in sputter-deposited yttrium aluminum nitride (Y0.2Al0.8N) thin films for BAW resonators with high electromechanical coupling

In the past decade, rare earth elements have found increasing interest in enhancing the piezoelectric coefficient of aluminum nitride (AlN) thin films. Until now, scandium has been the most successful rare earth element to enhance the piezoelectric coefficient (d33) up to 600 %. In this research paper, we present a 250 % increase in d33 to 12.5 pC/N for sputter-deposited yttrium alloyed aluminum nitride (Y0.2Al0.8N) thin films compared to pure AlN. However, this increase in d33 comes with a substantial increase in compressive layer stress well above 1 GPa. Therefore, a chamber pressure sweep technique is introduced, resulting in a 40 % reduction in the stress level without significantly affecting the crystallographic film parameters to facilitate device integration. Even more, high compressive stress in thin films is a critical concern in piezoelectric MEMS devices such as bulk acoustic wave (BAW) resonators, as it can adversely affect the piezoelectric material properties and hence, the electromechanical performance. For this purpose, we demonstrate that the pressure sweep technique improves the electromechanical coupling factor of Y0.2Al0.8N to 7.02 %, being substantially above the reference value of 6.02 % set by pure AlN. In summary, the findings from this study may stimulate further effort to integrate YxAl1-xN thin films in BAW filter devices for future telecommunication applications.

(Fe-Ca-Al)-phosphate mineralization enriched with rare earth elements in the sediments of the middle Jurassic paleovalley (Shankinka Occurrence, Moscow Region, central part of the Russian Plate)

(Fe-Ca-Al)-phosphate mineralization enriched with rare earth elements in the sediments of the middle Jurassic paleovalley (Shankinka Occurrence, Moscow Region, central part of the Russian Plate)

Exploring electroacoustic conversion in a standing-wave thermo-acoustic generator: An experimental study

Thermoacoustic generators (TAGs) present an attractive solution for converting low-grade thermal energy into useable electrical power. Despite their relatively modest fabrication, TAGs face significant efficiency challenges that impede their broader adoption. Current research efforts in thermoacoustics are primarily focused on overcoming these limitations. A critical factor influencing TAG efficiency is the design of the acoustic-to-electric (ATE) device. This component plays a vital role in converting the acoustic energy generated within the thermoacoustic engine (TAE) into electricity. Despite its importance, the impact of ATE design on overall TAG performance has often been overlooked in previous studies. This research aims to address this gap by investigating how different ATE configurations influence the efficiency of power conversion within thermoacoustic systems. Specifically, this study delves into the potential of electromagnetic devices: linear alternators and loudspeakers, as ATE converters in a Standing Wave Thermoacoustic Generator (SWTAG) framework using air at atmospheric conditions. Firstly, a comparative analysis was conducted between two types of linear alternators—moving magnet and moving coil and tested with different magnet types (rare earth and ferrie anisotropic) to evaluate their impact on voltage generation. Secondly, the influence of various factors on energy conversion using loudspeakers was investigated, including loudspeaker type (paper cone vs. polypropylene cone), housing geometry (diameter and length), housing material (galvanized steel vs. PVC), open versus closed ATE housing design and utilizing dual loudspeakers. The generated electricity was utilized to power a light bulb. Linear alternators resultsMoving coil configuration outperformed the moving magnet design due to its lighter weight. Rare earth disc magnets generated higher voltage outputs compared to ferrie anisotropic magnets. The moving coil configuration achieved a maximum voltage output of 454 mV, while the moving magnet design reached a maximum of 312 mV. Both linear alternator configurations displayed low overall efficiencies. This is likely due to a mismatch between the magnet and coil diameters, leading to inefficiencies in capturing the generated magnetic field. Loudspeakers resultsPaper cone loudspeakers demonstrated superior performance due to their greater displacement capability. The Saknyo-Paper cone loudspeaker configuration achieved a voltage output of 4.11 V. Optimal voltage generation was achieved when the loudspeaker diameter matched the ATE device housing diameter. Galvanized steel housing offered better performance than PVC housing due to reduced vibration losses. The voltage outputs for the galvanized steel and PVC configurations were 4.11 V and 2.21 V, respectively. Closing the loudspeaker housing resulted in decreased voltage output due to wave interference. The voltage outputs for the galvanized steel and PVC configurations were 3.33 V and 1.62 V, respectively. Dual loudspeakers significantly enhanced voltage generation compared to a single loudspeaker. The maximum voltage recorded for the dual loudspeaker configuration was 6.5 V.The developed thermoacoustic generator achieved an output voltage exceeding the target of 6 V and thermal-to-electric efficiency of 3.42 % with an output electric power of 10.56 W, surpassing previous air-powered TAGs operating at atmospheric conditions. The generator successfully illuminated a light bulb, demonstrating its ability to generate useable electricity. This study provides valuable insights into optimizing the design of acoustic-to-electric conversion devices in TAGs. The findings highlight the importance of factors such as material selection, housing geometry, and magnet type for maximizing energy conversion efficiency.

Effect of different rare-earth dopings of KNN-based transparent energy storage ceramics

Rare-earth elements [Formula: see text]-, [Formula: see text]-, [Formula: see text]- and [Formula: see text]-doped ([Formula: see text][Formula: see text])[Formula: see text][Formula: see text][Formula: see text][Formula: see text]O3 ceramics (abbreviated as KNLNB-0.1%RE) were prepared by conventional solid-phase sintering method. The structure, transparency, energy storage and photoluminescence properties of the samples are investigated. All ceramics have the pseudo-cubic phase structure without the impurity phase at room temperature. KNLNB-0.1%RE ceramics exhibit excellent optical transmittance, with KNLNB-0.1%Ho achieving 71.8% transmittance in the visible wavelength range (780[Formula: see text]nm) and largest effective energy storage density of 1.45[Formula: see text]J/cm3. In our experiments, rare-earth-doped KNLNB ceramics exhibit photoluminescence effects. This work facilitates the development of transparent energy storage ceramics with fluorescent effects.