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The Dy2Co17 compound series has garnered considerable attention due to its high saturation magnetization and Curie temperature, making it a promising candidate for microwave absorption applications. The ideal electromagnetic wave absorbing material should possess exceptional electromagnetic wave attenuation and optimal impedance matching. Doping the material can improve its electromagnetic wave attenuation and impedance matching value, thereby enhancing its electromagnetic wave absorbing ability. In this study, Dy2Co17−xNix samples were designed to increase their attenuation capability. The addition of Ni elements caused lattice distortion, which modulated the relaxation polarization and resonance loss capability, resulting in the best impedance matching value. The data on attenuation constant, impedance matching value, electromagnetic parameters, magnetism, eddy current loss, and reflection loss of Dy2Co17−xNix were investigated and analyzed. The results revealed that the samples have a plate-like morphology, and at a frequency of 7.12 GHz and a thickness of 2 mm, the RLmin of Dy2Co16.7Ni0.3 reached − 44.50 dB, indicating good impedance matching. Furthermore, based on CST simulation, the samples demonstrated an effective reduction in the RCS value, highlighting its excellent electromagnetic wave attenuation ability. [ABSTRACT FROM AUTHOR]

Palladium (Pd) is widely used in catalyst, aerospace, and medical applications, but only 1% of its reserves are found in nature. So, the recovery of Pd(II) is very important. Natural fibers are a good adsorption material, and the abundant functional groups in bamboo shoot shell (BSS) fibers can form interactions with metal particles. However, few studies on Pd(II) adsorption using BSS fibers exist. In the present work, waste bamboo shoot shells were doped with titanium dioxide (TiO2) particles, and the surface activation of BSS-TiO2@CA by citric acid (CA) was carried out to prepare an efficient and recyclable adsorbent BSS-TiO2@CA for the adsorption of Pd(II). The adsorption performance, adsorption mechanism, and regeneration performance of BSS-TiO2@CA on Pd(II) were systematically analyzed by continuous adsorption experiments, characterization, and response surface method. It was found that the surface-activated waste bamboo shoot shells had an outstanding adsorption capacity of Pd(II), and the maximum adsorption rate of BSS-TiO2@CA reached 85% with a maximum adsorption capacity (Qm) of 175.74 mg/g. The functionalized use of waste bamboo shoot shells provides a new idea for the development of sustainable, cost-effective, and environmentally friendly adsorbents. [ABSTRACT FROM AUTHOR]

Due to the frequent use of electronic equipment, electromagnetic radiation pollution has become a prominent problem. The use of microwave-absorbing materials can effectively solve this phenomenon. In this study, flaky Dy2-xCo17Tbx alloy powders were prepared by vacuum smelting, and the microwave absorption performance was investigated by changing the Tb doping amount and matching thickness. The results show that the magnetic loss and dielectric loss are improved to a certain extent with the doping of Tb, and the absorption peak value moves to the low-frequency region. At the same time, the saturation magnetization (Ms) decreases with the increase in Tb doping. When x = 0.2 and the matching thickness is 1.6 mm, the minimum reflection loss (RLmin) value is −40.9 dB at 10.08 GHz, and the effective absorption bandwidth (EAB) is 1.6 GHz (9.28~10.88 GHz). In general, Dy2-xCo17Tbx alloy powders have good microwave absorption performance in the X band. [ABSTRACT FROM AUTHOR]

The RE-Ni (RE = La, Ce, Nd, Tb and Ho) binary systems have been optimized thermodynamically using the CALPHAD (CALculation of PhAse Diagram) method based on experimental phase equilibrium and thermodynamic property data. The solution phases including the liquid phase and terminal solid solution phases were modeled by the substitutional solution model with the excess Gibbs energy being described by the Redlich–Kister polynomials. The binary intermetallic compounds REaNib were treated either as stoichiometric phases or by using the two-sublattice model to consider the homogeneity ranges of the compounds. A set of self-consistent thermodynamic parameters of the RE-Ni (RE = La, Ce, Nd, Tb and Ho) binary systems was obtained, which can be used to reproduce well the experimental data. Furthermore, in combination with the reported assessments of the RE-Ni (RE = Pr, Sm, Gd, Dy, Er and Y) binary systems, the phase equilibria and thermodynamic properties of the RE-Ni (RE = La, Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er and Y) binary systems were examined systematically. A trend was shown for the variation of phase equilibria and thermodynamic properties as a function of the RE atomic number. In general, as the atomic number of the rare earth metals increases, the phase transition/reaction temperatures of the RE-Ni intermetallic compounds become higher and higher, and the enthalpies of mixing of liquid RE-Ni (except for Sm-Ni) alloys as well as the enthalpies of formation of the RE-Ni (except for Y-Ni and Sm-Ni) intermetallic compounds become increasingly negative. This trend demonstrates stronger RE-Ni bonds in binary systems containing heavier rare earth elements. [ABSTRACT FROM AUTHOR]

The phase relationships of the CeCo5-SmCo5 pseudobinary system have been studied by means of x-ray powder diffraction (XRD), differential thermal analysis (DTA), thermogravimetric measurements (TGM), and scanning electron microscopy equipped with energy dispersive x-ray spectroscopy (SEM–EDS). The XRD results show that continuous solid solutions were formed in this CeCo5-SmCo5 pseudobinary system, and all the (Ce, Sm)Co5 solid solutions belong to a hexagonal structure with space group P6/mmm. With the increase of Sm content x, the lattice parameter, a, and the cell volume, V, of (Ce1−xSmx)Co5 solid solutions increase linearly, but its lattice parameter, c, decreases linearly. The DTA measurements show that the temperature of the peritectic reaction L + (Ce, Sm)2Co17 → (Ce, Sm)Co5, the liquid phase transition temperature of the reaction L → L + (Ce, Sm)2Co17, and the Curie temperature of the (Ce1−xSmx)Co5 alloys increase almost linearly as x increases from 0 to 1.0. Based on the XRD results and DTA data, the tentative vertical section of the CeCo5-SmCo5 pseudobinary phase diagram has been constructed. [ABSTRACT FROM AUTHOR]

The structure, magnetic and magnetocaloric effect of Pr1−xDyxNi2 (x = 0.0, 0.2, 0.4, 0.6, 0.8, 1.0) compounds have been systematically studied. According to X-ray diffraction data, all samples exhibit MgCu2 laves cubic structure. Despite the addition of Dy element, Pr1−xDyxNi2 series compounds remains second-order magnetic phase transition throughout, but both the maximum magnetic entropy change (ΔSM) and the width at half-maximum of the ΔSM peak (δTFWHM) increase and reach 19.4 J/(kg·K) and 30 K (x = 0.8), respectively, resulting in an increase in the relative cooling power (RCP). Pr1−xDyxNi2 compounds show the potential application of magnetic refrigeration materials. [ABSTRACT FROM AUTHOR]

Potassium-ion batteries (PIBs) are promising next-generation energy storage candidates due to abundant resources and low cost. Sb-based materials with high theoretical capacity (660 mAh·g−1) and low working potential are considered as promising anode for PIBs. The remaining challenge is poor stability and slow kinetics. In this work, FeSb@N-doped carbon quantum dots anchored in three-dimensional (3D) porous N-doped carbon (FeSb@C/N⊂3DC/N), a Sb-based material with a particular structure, is designed and constructed by a green salt-template method. As an anode for PIBs, it exhibits extraordinarily high-rate and long-cycle stability (a capacity of 245 mAh·g−1 at 3,080 mA·g−1 after 1,000 cycles). The pseudocapacitance contribution (83%) is demonstrated as the origin of high-rate performance of the FeSb@C/N⊂3DC/N electrode. Furthermore, the potassium storage mechanism in the electrode is systematically investigated through ex-situ characterization techniques including ex-situ transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). Overall, this study could provide a useful guidance for future design of high-performance electrode materials for PIBs. [ABSTRACT FROM AUTHOR]

Microstructure and magnetic properties are systematically investigated to figure out what effect does the Cu content have on (Pr0.25Nd0.75)2Fe13.85-xCo0.1Ti0.05CuxB alloys in this work. The experimental result shows the optimal magnetic properties that the remanent magnetization Jr = 1.13 T, the coercivity Hcj = 588.56 kA/m, and the maximum magnetic energy product (BH)max = 260.66 kJ/m3 at the Cu content x = 0.6. However, it shows that Cu addition can promote the formation of the amorphous phase, which is an important reason for the coercivity decrease. Microstructure observation indicates that the reason for the magnetic property decrease is that the hard 2:14:1 magnetic phases and soft α-Fe phases display a state of irregular distribution with Cu content increasing. [ABSTRACT FROM AUTHOR]

Using published and presently calculated diffusivities, a reliable and self-consistent atomic mobility description of the liquid and fcc phases in a Nd-Fe-B system is established by DIffusion-Controlled TRAnsformation software. Based on the obtained atomic mobility-coupled thermodynamic descriptions of the Nd-Fe-B system, a wheel speed-dependent solidification diagram for a model Nd2Fe14B alloy is constructed, which allows us to examine the influence of wheel speed on the solidification behavior of the quenching Nd2Fe14B alloy. According to the theoretically obtained solidified microstructures and their relationship with the magnetic properties, the optimal wheel speed when melt-spinning the quenching Nd2Fe14B ribbons is determined to be 35 m/s. The experimental microstructural characterizations and magnetic hysteresis loop measurements confirm that the ribbon prepared at a wheel speed of 35 m/s exhibits the best comprehensive magnetic properties because the remaining bcc-Fe phase is significantly suppressed and the main Nd2Fe14B phase was well refined to an ultrafine-grained microstructure. The grain refinement mechanism of the main phase in the ribbons is also described. [ABSTRACT FROM AUTHOR]

The Pr2Fe17−xCrx (x = 0.0, 0.1, 0.2, 0.4) powders were successfully prepared by arc melting and high-energy ball milling. The crystal structure, morphology, magnetic properties, and microwave absorption performance of the Pr2Fe17−xCrx alloys was studied by X-ray diffraction (XRD), scanning electron microscopy (SEM), vibrating sample magnetometer (VSM), and vector network analyzer (VNA), respectively. The results show that the saturation magnetization increases with the increase of Cr doping amount. The average particle sizes of Pr2Fe17−xCrx particulates are 1.56, 1.47, 1.67, and 1.71 μm, which correspond to x = 0.0, 0.1, 0.2, and 0.4, respectively, and the average particle size decreases first and then increases. The minimum absorption peak frequency of Pr2Fe17−xCrx shifts towards a lower frequency region with the increase of Cr doping amount. The minimum reflection loss (RL) of the Pr2Fe17−xCrx composite absorbers decreases first and then increases with the increase of Cr doping amount. The Pr2Fe16.9Cr0.1 composite absorber exhibits excellent microwave absorption properties, its minimum reflection loss value can reach up to − 33.81 dB at 7.28 GHz, and its effective absorption bandwidth (RL < − 10 dB) is 2.24 GHz with the best matching thickness of 2.2 mm. [ABSTRACT FROM AUTHOR]

Mn doping of BiFeO3 for microstructure and electromagnetic characteristics was investigated in BiFe1–xMnxO3 (x = 0.0, 0.05, 0.10, 0.15) nanoparticles synthesized by sol-gel preparation technique. XRD and HR-TEM research reveals that the phase structure of nanoparticles changes from rhombohedral (R3c) for BiFeO3 to cubic (Pm 3 ¯ m) for BiFe0.9Mn0.1O3. The morphological characteristics show that the average particle sizes of the Mn-doped BiFeO3 nanoparticles were decreased as compared with that of the original BiFeO3. XPS spectroscopy analysis showed that Fe and Mn elements exist in the nanoparticles in the form of Fe2+/Fe3+ and Mn3+/Mn4+ valence states, respectively. PPMS-VSM and VAN analysis showed that a certain content of Mn doping can significantly improve the magnetic and microwave absorbing property of BiFeO3. At room temperature, the remnant magnetization and coercive field of the BiFe0.95Mn0.05FeO3 nanopowders were 0.08 emu/g and 6216 Oe, respectively. The minimum RL of BiFe0.95Mn0.05FeO3 can reach about − 29.41 dB at 10.39 GHz at 2.20 mm thickness. [ABSTRACT FROM AUTHOR]

Double carbon-embedded Na3V2(PO4)3 (DC-NVP) nanocomposites were prepared via in situ growth of NVP@C nanoparticles on carbon nanotubes (CNTs). Beneficial of a high electronic conductivity network and structure stability, the DC-NVP nanocomposite as an anode of sodium ion batteries (SIBs) reveals outstanding electrochemical properties, delivering ultra-long cycle life with a first charge capacity of 78 mA h g−1 at 50 C and a capacity loss of 0.006%/cycle over 8000 cycles. The NVP//NVP full cells, fabricated by the DC-NVP nanocomposites as bipolar electrode, exhibit a discharge capacity of 72.1 mA h g−1 at 20 C after 5000 cycles and a corresponding capacity retention of 81%. The remarkable performance of DC-NVP nanocomposites is ascribed to that of the unique double carbon-embedded nanostructure, which possesses good electronic conductivity, larger electrode-electrolyte contact area, fast electron and ion transportation, and structural stability. [ABSTRACT FROM AUTHOR]

Sn-based alloy materials are considered as a promising anode candidate for lithium-ion batteries (LIBs) and sodium-ion batteries (SIBs), whereas they suffer from severe volume change during the discharge/charge process. To address the issue, double core—shell structured Sn-Cu@SnO2@C nanocomposites have been prepared by a simple co-precipitation method combined with carbon coating approach. The double core—shell structure consists of Sn-Cu multiphase alloy nanoparticles as the inner core, intermediate SnO2 layer anchored on the surface of Sn-Cu nanoparticle and outer carbon layer. The Sn-Cu@SnO2@C electrode exhibits outstanding electrochemical performances, delivering a reversible capacity of 396 mA·h·g−1 at 100 mA·g−1 after 100 cycles for LIBs and a high initial reversible capacity of 463 mA·h·g−1 at 50 mA·g−1 and a capacity retention of 86% after 100 cycles, along with a remarkable rate capability (193 mA·h·g−1 at 5000 mA·g−1) for SIBs. This work provides a viable strategy to fabricate double core—shell structured Sn-based alloy anodes for high energy density LIBs and SIBs. [ABSTRACT FROM AUTHOR]

The phase relationships of the Ce-Pr-Fe ternary system at 600 °C were experimentally investigated using equilibrated alloys and diffusion junction samples with the use of electron probe microanalysis, x-ray diffraction, and scanning electron microscopy. The isothermal section of the Ce-Pr-Fe system at 600 °C consists of 7 single-phase, 11 two-phase, and 5 three-phase regions. No ternary compound was found. The PrFe2 phase was observed in both ternary alloys and diffusion samples at normal pressure. The solid solubility of Ce in PrFe2 and Pr2Fe17 is 1.76 and 3.75 at.%, respectively. The solid solubility of Pr in CeFe2 and Ce2Fe17 is 13.21 and 0.77 at.%, respectively. [ABSTRACT FROM AUTHOR]

In order to understand the intrinsic properties of high abundance permanent magnet materials, effects of Co element on the structure, magnetic, and microwave absorption properties of La12.5(Fe1-xCox)81.3B6.2 alloys have been investigated with x = 0, 0.1, 0.2, 0.3. The X-ray diffraction results revealed that compounds of La12.5(Fe1-xCox)81.3B6.2 crystallized the Nd2Fe14B-type structure with the space group P42/mnm. The saturation magnetization of the powders increases with the Co content increasing, 97.7 emu/g for x = 0.3. The minimum absorption peak value of La12.5(Fe1-xCox)81.3B6.2 alloy reaches about − 18.69 dB at 10.56 GHz with the matching thickness of 2.5 mm. [ABSTRACT FROM AUTHOR]

Based on the highly efficient diffusion couple and equilibrated alloy methods, phase relations in La-Fe-B ternary system were experimentally investigated by scanning electron microscopy, electron probe microanalysis and electron backscatter diffraction techniques. Isothermal sections of the La-Fe-B system at both 600 and 800 °C were constructed. One ternary phase (LaFe4B4-τ2) was detected at 600 °C and two ternary compounds (τ2 and La2Fe14B-τ1) were determined at 800 °C. Seven three-phase zones were found at 600 °C and ten three-phase regions were found at 800 °C. Liquid phase was found in the La-rich corner at 800 °C. The solid solubility of both binary and ternary compounds in the system is negligible. The present experimental results are important for the design of multi-main-phase Nd-La-Ce-Fe-B magnets. [ABSTRACT FROM AUTHOR]

The crystal structure, magnetic, and microwave absorption properties of the (Nd1−xLax)2Fe14B system have been investigated. The La2Fe14B compound was successfully synthesized and refined, giving a tetragonal structure, space group P42/mnm with the Nd2Fe14B-type structure. The crystal structure parameters of the (Nd1−xLax)2Fe14B compounds were determined by full-profile Rietveld refinements. The results revealed that all intermediate alloys form a continuous solid solution. The normalized lattice parameters of the (Nd1−xLax)2Fe14B compounds increase linearly with an increase of La concentration. Based on the results of DSC measurements and X-ray powder diffraction examinations, the phase diagram of the Nd2Fe14B-La2Fe14B system has been constructed. The remanence (Mr) and coercivity (Hc) of (Nd1−xLax)2Fe14B (x = 0.00, 0.10, 0.20, 0.30, and 0.40) gradually decrease. The highest reflection loss is − 29.8, − 27.4, − 24.1, − 18.6, and − 14.2 dB at 9.8, 8.9, 7.5, 6.9, and 6.5 GHz, respectively. The absorption peak shifts toward from higher frequency region to lower frequency region and the absorption bandwidth widens with the increase of the La substitution. [ABSTRACT FROM AUTHOR]

The magnetic properties of (Pr1−xSmx)2Fe14B melt-spun ribbons with varying x from 0 to 1.0 have been studied. The optimum magnetic property of Pr2Fe14B ribbon could be obtained with the surface velocity of copper wheel of 30 m/s. By melt spinning method, the formation of α-Fe impurity phase in the (Pr1−xSmx)2Fe14B samples could be inhibited, and the grain could be aligned. Sm element could be incorporated into Pr2Fe14B main crystalline phase and formed (Pr,Sm)2Fe14B phase with space group P42/mnm. The Curie temperature (Tc) of the (Pr1−xSmx)2Fe14B ribbons increases gradually from 555 to 617 K with the increase of Sm content x. Both the coercivity (Hc) and remanence ratio (Mr/Ms) decrease firstly and then increase with the Sm content increasing. As long as the Sm content x does not exceed 0.1, the squareness of demagnetization curve remains good. The critical value of transition from easy c-axis to easy plane for (Pr1−xSmx)2Fe14B ribbons is x= 0.6. When the Sm content x is up to 0.6, all the Hc and Mr/Ms achieved the minimum value, i.e., 243 Oe and 0.346, respectively. [ABSTRACT FROM AUTHOR]

Rhombohedral Li2.4Na0.6V2(PO4)3@C nanoplates are synthesized by a simple sol-gel method. The almost single rhombohedral phase nature of Li2.4Na0.6V2(PO4)3@C along with nanoplate structure leads to high specific capacity and rate capability, and a remarkable cycling performance. As cathode materials for lithium-ion batteries, rhombohedral Li2.4Na0.6V2(PO4)3@C nanoplates deliver a high initial discharge capacity of 121.6 mAh g−1 and an excellent capacity retention of 95.6% after 200 cycles at a rate of 1 C in a potential range of 3.0-4.3 V. Even at a high rate of 10 C, an initial discharge capacity of 115.3 mAh g−1 and a capacity retention of 76.7% after 500 cycles are observed. The outstanding electrochemical performance is attributed to the synergetic effect of stable rhombohedral phase, nanoplate structure and uniform carbon coating layer. [ABSTRACT FROM AUTHOR]

The Sm-Ni-Fe ternary system has been investigated at 773 K by means of powder x-ray diffraction, metallography and scanning electron microscopy equipped with energy dispersive x-ray spectroscopy. The isothermal section consists of 16 single-phase regions, 29 two-phase regions and 14 three-phase regions. The influence of Fe-doping on the structure and the microwave absorption properties of the SmNi compound has been systematically studied. The homogeneity range in SmNiFe was determined as x = 16.67. The lattice parameters were found to gradually increase and the particle size become much finer with the increase of Fe concentration. All the samples exhibited good microwave absorption properties in the X-band (8-12 GHz). The highest reflection loss of the SmNiFe ( x = 0.0, 5.0, 10.0,15.0, 16.67) alloys are −10.12 dB, −10.39 dB, −16.44 dB, −20.69 dB, and −43.05 dB at 6.96 GHz, 7.92 GHz, 8.56 GHz, 10.04 GHz, and 11.08 GHz, respectively. The absorption peak shifted towards the higher frequency region with the increasing amount of Fe substitution. [ABSTRACT FROM AUTHOR]

To study the effect of Ni content on microwave absorption of NdCo alloy. The NdCoNi ( X = 0.0, 0.2, 0.6, 1.0, 1.4) powders were prepared by arc smelting and high energy ball milling method. The structure and morphology of the powder were investigated by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The electromagnetic parameters of the powder were measured by vector network analyzer (VNA) at room temperature. The XRD results indicate that the prepared powder maintain the NdCo phase. The minimum reflectivity value frequency shifts towards the lower frequency with the increase of Ni content. The minimum reflectivity value of NdCoNi alloy reaches about −26.6 dB at 2.9 GHz with the matching thickness of 2.2 mm. And the milled powder was tempered ranging of 50-200 °C for 1 h. The minimum reflectivity frequency shifts to higher frequency region compared to the powder without heat treatment. The absorbing frequency bandwidth increases with the tempering treatment increase. [ABSTRACT FROM AUTHOR]

The PrFeTi (x = 0.0, 0.1, 0.2, 0.3, 0.4) powder were prepared by arc smelting and high energy ball milling method. The phase structure, morphology, magnetic properties and electromagnetic parameters of the powders were characterized by X-ray diffraction, scanning electron microscopy, vibrating sample magnetometer and vector network analyzer, respectively. The results indicate that the lattice parameter a and c and unit-cell volume V increase linearly with the increasing amount of Ti doping. The saturation magnetization of the PrFeTi alloys decreases with the increase of Ti content. The minimum absorption peak frequency shifts towards higher frequency region upon the Ti substitution. And the minimum reflection loss of the PrFeTi alloys increases with the increase of Ti content. The minimum reflection loss of PrFeTi powder reaches about −32.50 dB at 5.36 GHz, and the frequency bandwidth of R < −10 dB reaches about 1.52 GHz with the best matching condition d = 2.5 mm. [ABSTRACT FROM AUTHOR]

The LaMgNiCoMnAl has been treated by the HF and KF etching solution and Ni coating solutions with the different concentrations. The surface structure and the electrochemical properties of the untreated and the treated hydrogen storage alloys have been investigated in details. The results show that the surface oxide layer on the alloys is removed after fluoridation and the surface of the alloy powders becomes smooth with electroless Ni plating. The maximum discharge capacity of the alloy electrodes is increased from 359.5 mA h g (M1) to 370.1 mA h g (M5) and the cycling stability is improved slightly after the surface treatment. At a discharge current density of 900 mA g, the high rate dischargeability (HRD) is enhanced from 38.3% (M1) to 77.0% (M5) and the M5 electrode still keeps at a high value of 55.9% at a discharge current density of 1500 mA g. In addition, the exchange current density I and the hydrogen diffusion coefficient D are also increased by the surface treatment. [ABSTRACT FROM AUTHOR]

The phase equilibria of the Er-Al-Zr ternary system at 500 °C were investigated using a combination of electron probe microanalyzer and x-ray diffraction. The microstructure and diffraction peaks were analyzed to determine the phases and compositions of Er-Al-Zr ternary system. Based on the experimental results, the isothermal phase diagram of the Er-Al-Zr ternary system consists of 14 three-phase equilibrium regions, 15 two-phase equilibrium regions, and 13 stable binary compounds, but no ternary compounds were detected. The solubility of Er in the Al2Zr, Al3Zr2, AlZr, Al3Zr4, Al2Zr3 is 9.9, 5.3, 9.0, 12.4, 6.7 at.%, respectively. The present work could be important for alloy design of Al-based alloys and thermodynamic analysis of the Er-Al-Zr ternary system. [ABSTRACT FROM AUTHOR]