Rare Earth Pr Research Articles

Long-term open-pit mining activities at the world's largest light rare earth mine significantly affect light rare earth elements in road dust over long distances

The long-term effects of decades of open-pit mining at the Bayan Obo deposit, the world's largest light rare earth mine, on the concentrations of several elements in road dust over long distances are unknown. Here, bulk road dust (BRD) and resuspended road dust (RRD) were collected from different distances from the mine for subsequent analysis of mining impacts. As a result of mining activities, light rare earth elements (LREEs), especially La, Ce, Pr and Nd, show different statistical and spatial variations compared to other elements. These LREEs decrease with increasing distance from the mine, and the values found in RRD are higher than those in other particle sizes. Mining emissions and soil have the most significant influence on these LREEs compared to other factors. Spatially, these four LREEs changed significantly over a large area (up to 60km from the mine) due to mining emissions. However, long-term mining activities affect these elements mainly through mining-contaminated soil as opposed to mining emissions. This study confirms the significant impact of mining activities on LREEs in road dust via a comprehensive data-driven framework, emphasizing the significant environmental effects of long-term open pit mining.

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.

Data Fusion of Acoustic and Optical Emission from Laser-Induced Plasma for In Situ Measurement of Rare Earth Elements in Molten LiCl-KCl.

Molten salts have a significant potential for use as next-generation nuclear reactor coolants and in pyroprocessing for the recycling of used nuclear fuel. However, the molten salt composition needs to be known at all times, and high temperatures and intense ionizing radiation pose challenges for the monitoring instrumentation. Although the technique of laser-induced breakdown spectroscopy (LIBS) has been studied for in situ measurements of molten salts, trials to improve its monitoring accuracy using chemometrics are lacking. In this study, a data fusion technique using the LIBS optical and laser-induced acoustic (LIA) signals was investigated to enhance the measurement accuracy for molten salt monitoring. Prediction models were constructed using the partial least-squares method, and the variable importance in projection scores was analyzed to evaluate the effect of incorporating the LIA signal into the analysis. This study investigates rare earth elements Eu, Er, and Pr found not only in nuclear but also in other settings such as laser and magnetic materials. The analysis of LIBS data without data fusion resulted in a root-mean-square error of prediction (RMSEP) of 0.0774-0.0913 wt %, whereas the prediction model using data fusion led to approximately 18-40% enhanced RMSEP (0.0461-0.0679 wt %). The results suggest that fusing the LIBS data with the simultaneously recorded LIA data can improve the monitoring accuracy of rare earth element composition in molten salts.

Study on the Catalytic Activity Modification of Pr and Nd Doped Ce0.7Zr0.3O2 Catalysts for Simultaneous Removal of PM and NOX

Cerium-zirconium composite oxides (Ce0.7Zr0.3O2) have a remarkable effect on catalytic removal of carbon particles (PM) and nitrogen oxides (NOX) emitted from diesel engine, in order to further improve the thermal stability, oxygen storage capacity and low temperature catalytic REDOX performance of cerium zirconium composite oxides (Ce0.7Zr0.3O2), a small amount of Pr and Nd rare earth elements are doped to improve the catalytic activity of cerium zirconium composite oxides. In this paper, the composite oxide of Pr6O11–Nd2O3–CeO2–ZrO2 is prepared by unsteady co-precipitation method, and the physicochemical properties of the composite oxide catalyst are analyzed by BET, SEM, XRD and ICP. The gas adsorption capacity and catalytic activity of composite oxide catalysts are measured by temperature programmed reaction technology (TPR). The results show that the composite oxide of Pr0.05Nd0.05Ce0.6Zr0.3O2 prepared by using rare earth elements Pr and Nd inhibits the growth process of grain, refining the grain, and improving the sintering phenomenon at high temperature. The addition of Pr and Nd causes lattice defects, increases the number of oxygen vacancies, and improves the mobility of lattice oxygen, namely promotes oxide oxygen storage property, gas adsorption and catalytic oxidation reduction ability. After modification, Pr0.05Nd0.05Ce0.6Zr0.3O2 has good resistance to high temperature aging performance, prolongs the service life, reduces the PM lowest ignition temperature and minimum catalytic activity temperature of nitrogen oxide, and promotes the NOX reduction rate. For Pr0.05Nd0.05Ce0.6Zr0.3O2, the lowest ignition temperature of PM is about 150 °C, and the lowest catalytic activity temperature of NO is about 130 °C. The maximum CO2 production rate is 68.3%, and the maximum NO reduction rate is 45%.

Electrosorption-driven selective thorium removal from radioactive wastewater with phosphate – Incorporated g-C3N4 electrode

This research introduces a novel approach for developing an improved method for removing thorium ions (Th(IV)), termed as electrosorption, by fusing the principles of electricity and adsorption. The methodology involves utilizing a phosphate – incorporated graphitic carbon nitride (g-C3N4/P) electrode, synthesized via a hydrothermal – calcination process with urea as a precursor and bis (2-ethylhexyl) phosphoric acid (D2EHPA) as a dopant. Static batch experiments were conducted to explore the influence of various parameters, including voltages, initial Th(IV) concentrations and operational time, on the electrosorption of Th(IV). Characterization analysis including XRD, FT-IR, FESEM-EDS and XPS were conducted to validate the successful integration of phosphate into the g-C3N4 structure. The g-C3N4/P electrode demonstrated impressive adsorption capacity for Th(IV) electrosorption in an aqueous solution containing an initial concentration of Th(IV) at 100 mg.L−1. It was observed that applying a potential as low as −0.2 V resulted in significantly increase in the Th(IV) removal with 92.23 % (> 300 mg.g−1) within 30 minutes of duration, compared to cases without the electrochemical assistance (65.41 mg.g−1). Through FT-IR and XPS analyses, the adsorption mechanism was clarified as follows: (1) the negatively charged g-C3N4/P electrode attracted Th(IV) ions through electrostatic interaction; and (2) Th(IV) ions was coordinated with exposed oxygen (O), nitrogen (N) and phosphorus (P) atoms via complexation. In the context of real wastewater scenarios involving rare earth residue, encompassing Ce(III), La(III), Nd(III) and Pr(III) ions, the g-C3N4/P electrode showcased good capabilities in selectively adsorbing Th(IV). Additionally, the electrode synthesized in this study displayed considerable regenerative capabilities, sustaining a commendable removal ratio of approximately 70 % over five successive cycles. These findings underscore the promising potential of g-C3N4/P electrode for thorium removal through electrosorption applications.

Dual co-doping strategy for prolonged luminescence in laser-sintered BaAl2O4:Eu2+, RE3+ ceramics

This work reports on the influence of co-doping on the luminescence and persistent luminescence properties of BaAl2O4 (BaO·Al2O3) laser-sintered ceramics. The samples were doped with Eu and doubly co-doped with different rare earths (Dy, Er, Nd, Pr, and Tm) followed by laser-sintering without an atmospheric control, at a power density of 1.6 W/mm2. All sintered ceramics contained the hexagonal BaAl2O4 phase and had a homogeneous microstructure. A photoluminescence emission band centered at 495 nm was observed, which was due to the 4f65 d1 → 4f7 Eu2+ transition in the BaAl2O4 matrix. The persistent luminescence emission was monitored for 15 min after charging at 345 nm for 3 min. The combination of Nd and Dy co-doping led to substantial improvements in decay time and persistent luminescence intensity compared to individual co-doping. These results suggested that the two co-dopants interacted by modifying the trap configurations in the BaAl2O4 matrix.

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.

Effect of Pr substitution on structural, electrical and magnetic properties of NiZnCo ferrite for high frequency applications

With the miniaturization, chip, and integration of electronic products, the working frequency of electronic components is also getting higher and higher, which puts forward requirements for us to seek high-frequency materials with higher performance. To enhance NiZnCo ferrite properties, this study introduced the rare earth element Pr for modification and thoroughly examined its impact. The material Ni0.55Zn0.3Co0.15PrxFe2-xO4 (NZCPF, 0 ≤ x ≤ 0.1) was synthesized by sol-gel self-propagating technique. The X-ray diffraction of NZCPF indicates that Pr3+ doped NiZnCo ferrites still keep the cubic spinel structure. With the increasing substitution of Pr3+ ions in NiZnCo ferrite, the average grain size of the sample decreases from 1.05 μm to 0.73 μm. After the addition of Pr3+ ions, the dielectric loss takes its minimum value (0.41@100 Hz), and the DC resistivity ρ takes its maximum value (4×106 Ω·m@30℃). The value of μ' (@10 MHz) monotonically decreases from 11.9 to 5.9 as the doping amount of Pr3+ ions, denoted by x, increases. The saturation magnetization intensity decreases from 68.05 to 58.45 emu/g, and maximum magnetic loss decreases about 30% (0.65@1 GHz). It is worth noting that the resonance frequency fr increases from 343 MHz to 638 MHz with x increases, which is a substantial improvement compared to previous studies. Generally, the introduction of Pr3+ ions into NiZnCo ferrite results in outstanding electromagnetic characteristics, offering a valuable reference to the advancement of compact and high-frequency devices.

Effect of Doping Trace Rare Earth Elements on Corrosion Behavior of EH36 Offshore Platform Steel

EH36 offshore platform steel, La (0.0031%) steel, Ce (0.0027%) steel, and Pr (0.0001%) steel were selected as the research objects. The corrosion of four groups of steel was simulated by immersion experiments. In the presence of Cl− the effect of rare earth elements (La, Ce, Pr) on corrosion was investigated by the weight loss method. The morphology of the corrosion products and the apparent morphology after the removal of the corrosion products were observed by scanning electron microscopy (SEM); the main components of four steel corrosion products were analyzed by X-ray diffraction (XRD). The electrochemical behavior and the influence of temperature and Cl− concentration on the corrosion of the four kinds of steel were analyzed by an electrochemical polarization curve and Nyquist diagram. The results showed that the addition of trace rare earth elements, La, Ce, and Pr, to EH36 offshore platform steel can reduce the corrosion rate and the corrosion current density (Icorr), and increase the charge transfer resistance during the corrosion process. The Icorr of La steel, Ce steel, and Pr steel is 6.59 × 10−5 A·cm−2, 7.57 × 10−5 A·cm−2, and 9.53 × 10−5 A·cm−2, respectively, which is lower than that of EH36 steel (Icorr = 1.82 × 10−4 A·cm−2). The influence of Cl− concentration and temperature on the four steels showed the same trend; that is, with the increase in Cl− concentration, the corrosion rate first rises and then slows down, and with the increase in temperature, the corrosion rate gradually accelerates. Rare earth elements promote the production of more α-FeOOH in the rust layer, and the compactness of this product plays a certain role in protecting the steel matrix. The addition of trace rare earth elements, La, Ce, and Pr (less than 0.004%), improves the corrosion resistance of EH36 steel.

Effects of rare-earth Pr3+-Dy3+ doping on structural, magnetic, optical and dielectric properties of Zn2Y hexaferrite

This study was conducted to investigate the properties of Pr3+-Dy3+ doped Zn2Y-type hexaferrite for potential technological applications. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and field-emission scanning electron microscopy (FESEM) were used to analyze structural properties. The crystallite size in the synthesized samples varies between 57.54 and 68.57 nm. The vibrational bands at 400 and 600 cm−1, common to all hexaferrites, were confirmed through FTIR. The FESEM analysis reveals an agglomeration of magnetic grains and a decrease in the average grain size from 1.24 to 1.06 μm. The M-H loops show that, with x values of 0.0, 0.1, and 0.2, the saturation magnetization is determined to be 34.76, 34.23, and 32.52 emu/g, respectively. The corresponding coercivity values are 21.24, 30.39, and 33.99 Oe. UV–visible spectroscopy using Tauc theory reveals an increase in the optical band gap from 2.32 to 2.50 eV, indicating a tunable energy band structure by incorporating Pr3+-Dy3+ ions. The dielectric constant increases, whereas AC conductivity decreases with increased Pr3+-Dy3+ concentration. The obtained results suggest the potential suitability of these materials for various technological applications.

A clean process for the recovery of rare earth and transition metals from NiMH battery based on primary amine and lauric acid

A novel rare earth separation system composed of lauric acid (LA) and primary ammonium (RNH2) was studied. Compared with individual LA and RNH2, the mixed extraction system can significantly improve the extraction and separation ability of rare earth (RE). When LA and RNH2 are mixed in an equal molar ratio, the synergistic coefficient for extracting Nd(III) in the system reaches 136.85. Effective separation of Nd from Co and Ni can be achieved, with the separation coefficients of 1503 and 2762 for Nd/Co and Nd/Ni, respectively. The ion association mechanism of developed extraction system can avoid the generation of saponification wastewater. Thus, the negative impact of saponification wastewater on the economy and environment can be reduced. The extraction system is simple to be prepared and easy to be stripped, which helps to reduce acid and alkali consumption. Application of this extraction system can effectively realize the separation of RE elements La, Ce, Pr, Nd and transition metals Co, Ni, Mn in nickel-metal hydride (NiMH) battery. This paper provides a new strategy for the development of ionic liquid saponification technology without saponified wastewater.

Crystal structure refinement, morphological, and magnetic properties of ternary nanohybrid PrxMn0.5Co0.5Fe2−xO4 (0.00 < x < 0.04) spinel ferrite

Rare earth Pr3+ ion substituted in the Mn - Co spinel ferrite was prepared via. sol–gel route. The phase composition of the prepared samples was analyzed by X-ray diffraction (XRD). Rietveld refinement confirms the single phase for the samples (x = 0.0, 0.01, 0.02) and shows a secondary phase for the samples with higher concentrations of Pr3+ (x = 0.03 and 0.04). The absorption band occurs within 400–600 cm−1 which affirms the formation of spinel ferrite by the Fourier transform infrared (FTIR) spectra. Field emission scanning electron microscopy (FESEM) micrograph reveals the presence of porous morphology and non-uniform grain growth inhomogeneous in size and shape due to the agglomeration present in the prepared sample. A vibrating sample magnetometer (VSM) study reveals all the samples exhibit a ferromagnetic nature. The coercivity (Hc) increases from 441.78 to 557.32 Oe and then decreases to 503.48 Oe. Owing to the basis of large surface area, presence of pore size, and soft magnetic nature synthesized spinel ferrites are best suitable for supercapacitor electrode material.

Harnessing the composition of dissolved organic matter in lagoon sediment in association with rare earth elements using fluorescence and UV–visible absorption spectroscopy

Dissolved Organic Matter (DOM) plays a pivotal role in influencing metal binding and mobility within lagoon sediments. However, there exists a gap in understanding the compositional alterations of DOM concerning Rare Earth Elements (REEs) across varying pollution gradients. This study aimed to characterize DOM and examine its relationship with REEs in sediment cores from different pollution levels in Yundang Lagoon, China using excitation-emission matrix-parallel factor analysis (EEM-PARAFAC). The results raveled four distinct fluorescent components. Among these, two correspond to humic-like substances, while the remaining two are attributed to protein-like substances. Remarkably, the prevalence of protein-like compounds was observed to exceed 58% of the total fluorescence intensity across all the investigated sites. Furthermore, a substantial discrepancy in total fluorescence intensity was detected between the Songbai Lake and the Inner and Outer Lagoon, indicating a variance in DOM content. In terms of REEs, the average concentration of total REEs was notably elevated within the Songbai Lake sediments (318.36 mg/kg) as compared to the Inner and Outer Lagoon sediments (296.36 and 278.05 mg/kg, respectively). Of significance is the enrichment of Light Rare Earth Elements (LREEs), particularly Ce, La, Pr, and Nd, over Heavy REEs (HREEs) across all surveyed locations. Intriguingly, a coherent trend emerged wherein the fluorescence intensity and LREE concentrations exhibited a synchronized increase from Outer to Inner to Songbai Lake core sediments. This observation substantiates a strong correlation between DOM content and pollution levels (p < 0.05). By shedding light on the intricate interplay between DOM and REEs within urban aquatic sediments, this study imparts novel insights which enrich our comprehension of urban environmental dynamics.

Ab initio studies of Electronic Structure and magnetic properties of RAl(Mg)3 (R= Ce, Pr, Nd, Sm and Gd) alloys

We report the magnetic behaviour of RAl3 and R(Mg)3 (R= Ce, Pr, Nd, Sm and Gd) alloys studied through ab initio calculations based on density functional theory (DFT). The magnetic moments obtained from the all electron full potential calculations suggest strong magnetic instability in Ce compounds. The compounds with heavier rare earths (Pr, Nd, and Gd) exhibit local moment with high orbital moment, consistent with crystal field splitting of the 4fn ground state. The results obtained for SmAl3 and SmMg3 suggest possible valence fluctuation. Our calculated magnetic moments closely agree with experimental results reported in literature. We have also calculated the magnetic hyperfine field and its spin and orbital contributions. While, the total hyperfine field is dominated by the contribution from orbital magnetic moment, the Fermi contact contribution to the hyperfine field is found to scale with the spin projection factor (gJ−1)J. The calculated hyperfine field values are found to show good agreement with available experimental results.

Separation and purification of light rare earth elements from chloride media using P204 and Cyanex272 in sulfonated kerosene under non-saponification conditions

The extraction of light rare earths (Pr and Nd) from chloride medium was investigated using a mixture of di(2-ethylhexyl) phosphoric acid (P204) and bis(2,4,4-trimethylpentyl) phosphinic acid (Cyanex272) in sulfonated kerosene. The P204+Cyanex272 system exerted a synergistic effect on the separation of light rare earths, and the separation coefficient was higher than when P204 and Cyanex272 were used as extractants alone. The separation coefficient of Pr and Nd in the extraction system reached 1.75 when the pH of the aqueous phase material solution was approximately 2.5, and 1.5 mol/L hydrochloric acid as a stripping agent effectively eluted the rare earth ions in the loaded organic phase. Combining the slope method, infrared spectroscopy, and nuclear magnetic resonance spectroscopy, we explored the mechanism of the extracted Nd and Pr into the organic phase complex, and finally entered the organic phase with Re(HA&lt;sub&gt;2&lt;/sub&gt;)&lt;sub&gt;2&lt;/sub&gt;B. The P-O-H bond and P=O bond in the extractant P204 and Cyanex272 formed a coordination bond with Re&lt;sup&gt;3+&lt;/sup&gt;. Therefore, this extraction method also provides a reference for a more environmentally friendly and efficient procedure for separation and purification of light rare earth elements Pr and Nd.

Rare earth-doped Ni/MgAl2O4 catalysts prepared via a one-step sol–gel method for steam reforming of volatile organic solvents at low temperatures

To develop efficient steam reforming catalysts that are widely applicable to various volatile organic solvents under low temperatures, rare earth (La, Ce or Pr)-doped Ni/MgAl2O4 were prepared via a novel one-step sol–gel method. Through various characterizations and DFT calculations, it demonstrated that the rare earths not only improved the catalyst structure, but also promoted the dispersion, electron density and d-band center of Ni. Consequently, all the rare earth-doped Ni/MgAl2O4 catalysts exhibited higher catalytic activity in steam reforming of different volatile organic solvents than the Ni/MgAl2O4 in 500–550 °C. Thereinto, the 10Ni-2La/MgAl2O4 performed the best, achieving a conversion efficiency of 97.3% at 550 °C for the mixture of toluene, acetone, tetrahydrofuran, and n-hexane. The outstanding performance of Ni-La/MgAl2O4 catalyst arises from the structural compatibility between low-spin La atom and Ni cluster, which enables La to modify Ni dispersion and electronic structure more significantly than Ce or Pr.

Nebulizer-assisted spray pyrolysis development of rare earth (Pr3+) doped In2S3 thin films for an intense ultraviolet photocurrent response

Developing In2S3nanolayers using the cost-effective approach for light-current conversion has grown last decades. In this work, we report the high photo-current of indium sulfide (In2S3) thin films having different praseodymium (Pr) contents (0, 1, 2, 3, 4, and 5 wt %) using high-purity indium chloride and thiourea as the sources. The optical absorption, crystal structure, surface appearance, defect-related emission, and photoconductivity of the prepared In2S3: Pr thin films were examined by several characterization techniques. X-ray Diffraction (XRD) measurements demonstrate a cubic structure of the polycrystalline nature of the synthesized films with a preferential (220) growth orientation. The selected Pr dopant enhances the grain size of the In2S3 thin film from 46 to 65 nm and hence, benefits the photosensor properties. Field emission scanning electron microscope (FESEM) images confirms the development of interconnected ball-shaped nanograins. The room temperature photoluminescence (PL) spectra exemplify the presence of violet and green emission at 470 and 521 nm. The developed In2S3:Pr thin films exhibited good absorption in the UV region. Pr addition helped in narrowing the bandgap values from 2.91 to 2.83 eV. Among the different doping yields, the 3%Pr doped In2S3 film shows excellent I–V characteristics and offered a satisfactory external quantum efficiency (495%), pronounced photo responsivity (2.12 A/W) and impressive detectivity (1.54 × 1011 Jones) due to the enhanced light-matter interactions. The present results provide a new platform for future photosensor applications.

Microstructure and properties of brazed diamond with Pr-modified Ni[sbnd]Cr filler metals

The aim of this study is to improve the mechanical properties of diamond tools by brazing diamonds with a modified NiCr filler alloy to achieve the reduction of thermal damage. In this paper, rare earth Pr doping into NiCr filler alloy is brazed at 1080 °C under vacuum and tested for organization and properties. The results show that the doping of Pr refines the grain size and carbide. Moreover, Cr7C3 and Cr3C2 are generated at the brazed interface, which realizes the chemical metallurgical bonding and improves the bonding strength of the diamond. The generation of the NiPr phase reduces the thermal damage of brazed diamonds. When the addition of Pr is 1 wt%, the diamond grits have a more complete morphology. The exposed height reaches 46.6 % of its own height and the carbonized layer is thinner. The thermal damage is reduced. In addition, the frictional wear experiments and strength tests also shows that the performance of this filler alloy brazed diamond is better than the unmodified filler alloy brazed diamond.

Developing N,N,N’,N’-tetra (2-ethylhexyl) diglycolamide encapsulated polymeric beads as promising rare earth extracting agents

ABSTRACT The multi-faceted applications of rare earth elements (REE) in science and technology are not unknown. Scarcity in the primary sources of RE makes it necessary to explore different secondary sources available. Availability of REE in significant amount in spent NdFeB magnetic scrap makes the recycling of REE from this scrap, a lucrative option. In this work, synthetic solutions of 10 g/L (containing the rare earths Nd, Pr and Dy along with Fe) were equilibrated with the organic extractant N,N,N,’N’-tetra (2-ethylhexyl) diglycolamide (TEHDGA) encapsulated in polyethersulfone beads to study the extraction behavior of the REEs from nitric acid medium. Iron (Fe), the major component present in NdFeB scrap, poses the biggest challenge for rare earth extraction from the scraps. The TEHDGA impregnated polymeric beads were found to selectively extract the REEs, leaving Fe(III) in the feed solution. TEHDGA displayed higher selectivity towards the heavier rare earth Dy followed by Nd and Pr. The loading capacity of the beads was measured to be > 1700 ppm. The effect of different experimental parameters, such as contact time, solid-liquid ratio, TEHDGA concentration, feed acidity, were investigated. Contact time of 24 h, TEHDGA concentration of 0.75 M, solid-liquid ratio either 1:5 or 1:10 and feed acidity between 2 and 5 M have been found to suitable for quantitative extraction of REE particularly Dy(III). The recovery of the REEs from the loaded TEHDGA beads was > 90%. Furthermore, the experiment was carried out with higher quantity of beads and feed solution to study applicability of the same in bulk scale. A novel, easy and single-step separation of REE from Fe has been presented in this work.

Long persistent luminescence and photostimulated luminescence in Y3GaO6:Pr3+ phosphor

Long persistent luminescence (LPL) phosphors have a wide range of potential applications, including multi-color anticounterfeiting and long-term continuous detection of short-wavelength ultra-violet (UV) radiation. However, developing a stable carrier container that can provide ultra-long carrier storage for activators and visible multi-color LPL is a challenging task. In this work, we presented a series of Pr3+-doped Y3GaO6 (YGO) LPL phosphors that take full advantage of the synergistic relationship between the host lattice, emitters, and carrier traps. The host provides a suitable lattice site for rare-earth Pr3+ and offers a broad band gap of 5.69 eV to hold traps with depths ranging from 1.01 to 2.17 eV. We observed LPL that was visible to the naked eye for 6 h after excitation, and strong thermoluminescence (TL) spectra could be detected after the phosphor was placed in darkness for 20 days at room temperature. Additionally, we observed photostimulated luminescence under 980 nm and 808 nm laser irradiation with a power density of 5 W cm-2, indicating that low-energy excitation not only leads to LPL but also accelerates the elimination of previously stored carriers. After investigating the crystal structure and possible defects generated in the materials, we proposed a mechanism for LPL. Our findings demonstrate the potential of Pr3+-doped YGO LPL phosphors for a range of applications, such as multi-color anticounterfeiting and long-term continuous detection of short-wavelength UV radiation.