High Energy Planetary Ball Mill Research Articles

Interface-driven microwave absorption enhancement in Mn-optimized Co2FeAl1-xMnx Heusler alloys

To address the urgent need for efficient and stable electromagnetic wave absorbing materials for electromagnetic interference (EMI) protection, we synthesized Co2FeAl1−xMnx Heusler soft magnetic alloys using a high-energy planetary ball milling method. We comprehensively analyzed their structural characteristics, surface morphology, magnetic properties, and electromagnetic parameters to explore their potential in electromagnetic wave absorption. The results show that incorporating manganese (Mn) significantly changes the alloys' crystal structure, surface morphology, and magnetic properties, greatly enhancing their wave absorption performance. The Mn doping specifically alters the surface morphology, which plays a crucial role in influencing the wave absorption characteristics of the Heusler alloys. When the Mn content increased to 25 %, the sample exhibits superior wave absorption, achieving the maximum reflection loss of −44.83 dB at 13.68 GHz with a thickness of 1.5 mm and an effective absorption bandwidth of 5.52 GHz. With a significant increase in the aspect ratio and noticeable changes in surface morphology, the sample with 75 % Mn content shows exceptional performance with an effective absorption bandwidth of 5.68 GHz, representing the highest effective absorption bandwidth in single-phase Heusler alloys. The Mn doping strategy effectively improves the material's impedance matching by adjusting its permittivity and permeability, facilitating multiple polarization relaxation mechanisms and significantly enhancing the alloys' electromagnetic wave absorption efficiency. Our study provides detailed experimental data for optimizing the electromagnetic wave absorption characteristics of Heusler alloys, verifies their practical application potential, and paves the way for developing new high-performance electromagnetic wave absorbing materials.

CO2 capture using red mud & mechanically-activated red mud and its kinetics under ambient conditions

Greenhouse gas emissions and the growing stockpiles of red mud, an alkaline industrial waste with potential for CO2 sequestration, present significant environmental challenges. This article aims to enhance the CO2 sequestration capacity of red mud by mechanically activating its surface using a high-energy planetary ball mill for extended grinding periods. The novelty of the study lies in investigating the CO2 sequestration capacity and evaluating its kinetics includingadsorption and desorption on feed and mechanically-activated red mud under atmospheric temperature and pressure for the first time via a direct gas–solid carbonation route using a fixed bed column. The effect of ball size (10,8 and 6 mm) used in high-energy planetary ball mills while mechanical activation, CO2 flow rate (20–80 ml/min), and reaction time (1–5 h) on the CO2 capture has been studied. Apart from this, experimental data on CO2 sequestered (1–5 h) and the extent of CO2 desorption (7–35 days) are fitted to various kinetic models, including pseudo-first-order, pseudo-second-order, and Avrami’s fractional order models. Results showed that the CO2 sequestration capacity of feed red mud is 3.75 mg/g, while the capacity of mechanically-activated red mud increased to 18.28 mg/g, with an adsorption time of 5 h at ambient temperature and pressure. The most suitable fit is attained with Avrami’s fractional order model, suggesting that both physisorption and chemisorption contribute to enhancing the CO2 sequestration capacity of red mud. The mechanism for this process has also been proposed along with the suitable characterizations.

Microstructural and Thermal Properties of the Mechanically Alloyed Fe3Al Powders Doped with Boron

A nanocrystalline Fe3Al powders free and doped with boron was prepared by mechanical alloying (MA) of Fe and Al elemental powders using a high-energy planetary ball mill. The evolution of microstructure and the thermal behaviour of the MA Fe3Al powders have been studied using X-ray diffraction (XRD), scanning electron microscopy (SEM) with energy dispersive X-ray analysis (EDX) and differential scanning calorimetry (DSC). From these findings, it is clear that the crystallite size was refined and that the lattice parameter was increased by addition of boron. The results obtained by DSC revealed that the addition of boron results a decrease of microstructural parameters and recrystallization take place.

Powder metallurgical processing of novel Al0.5CoCrFeNiNb0.5-Si0.1 high entropy alloys: Phase evolution and nanomechanical properties

In this research, the high entropy alloy (HEA) of Al0.5CoCrFeNiNb0.5-Si0.1 was successfully synthesized through mechanical alloying utilizing a high-energy planetary ball mill. The synthesized HEA powder was subsequently pressed and sintered at 1400 °C with varying holding times. The phase evolution was investigated using X-Ray Diffraction (XRD) technique. Furthermore, the microstructural, morphological, and compositional characteristics of the powders were examined using Transmission Electron Microscopy (TEM) with Selected Area Electron Diffraction (SAED), as well as Scanning Electron Microscopy (SEM) in conjunction with Energy Dispersive Spectroscopy (EDS). The nano-mechanical properties of the HEA compact were evaluated through nanoindentation to determine nano-hardness and elastic modulus.The mechanical alloying process was conducted for a duration of 30 h, resulting in the formation of a single-phase BCC solid solution, as confirmed by XRD and SAED analyses. The study investigated the criteria for phase stability based on the minimum Gibbs free energy and Hume-Rothery rules, which were consistent with the observed microstructural characteristics. Furthermore, the sintering process resulted in porosity levels of 6.01 % and 4.71 %, with corresponding densities of 6.96 g/cm³ and 7.12 g/cm³ for holding times of 3 and 4 h, respectively. It was noted that extended holding times improved the mechanical properties, with the alloy achieving a maximum hardness of 546 HV, nano-hardness of 5.57 GPa, elastic modulus of 265.47 GPa, and yield stress of 1.89 GPa after a holding time of 4 h.

Ball milling and annealing effect in structural and magnetic properties of copper ferrite by ceramic synthesis

This study aims to better understand the relationship between the microstructure and magnetic properties of copper ferrite, which is an inverse spinel that present a body-centered tetragonal structure associated with a remarkable Jahn–Teller (JT) effect. For this goal, a sample has been synthesized by the ceramic route from a stoichiometric mixture of high-purity CuO and Fe2O3 powders activated mechanically in a high-energy planetary ball mill. This sample was calcined in air furnace at 1000 ºC for 6 h. As synthetized sample with a cubic structure was divided into two parts and one of them was annealed at 650 ºC for 3 h and slowly cooled to room temperature to obtain a pure tetragonal spinel sample. Furthermore, these two samples were subjected to the same processes of severe plastic deformation by milling for up to 70 h and subsequent annealing at temperatures ranging between 300 and 600 ºC to obtain samples with a mixture of phases in different proportions. For the cubic one, there is no change in its structure due to milling, always remaining 100 % cubic, and the evolution in the saturation magnetization was related to the changes in the density of defects present. On the other hand, copper cations are always found in the octahedral sites of spinel with a tetragonal structure. The small decrease in the degree of inversion to 0.95 induced by milling in this sample is capable of breaking the JT distortion, giving rise to the appearance of a cubic phase. This work demonstrates how the structure, microstructure, defects like stacking faults and deformation twins, and degree of inversion of the different phases are related to changes in magnetic properties.

Al–B4C-(Gd, Gd2O3) composite materials: Synthesis and characterization for neutron shielding applications

In this study, Al–20%B4C-x%Gd and Al–20%B4C-x%Gd2O3 (x = 1, 3, 5) composite powders were prepared using a high-energy planetary ball milling method to enhance the physical properties of Al–B4C neutron shielding composites. The prepared powders were subjected to uniaxial cold compaction at 500 MPa, resulting in cylindrical specimens. Subsequently, the specimens were sintered in a tube furnace at 600 °C for 1 h under an Ar atmosphere to prevent oxidation. The microstructure of the resulting composites was characterized using X-ray diffraction (XRD) and scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM/EDX). Archimedes density, hardness, and corrosion tests were performed on the compacted samples. Moreover, the composite's thermal and fast neutron absorption rates were calculated using the MCNP6.2 simulation code. The neutron equivalent dose rate was experimentally determined using the Am–Be neutron source. The simulation results demonstrated that the composite materials containing Gd exhibited the highest thermal neutron absorption rate, while those containing Gd2O3 demonstrated the highest fast neutron absorption rate. This research contributes valuable insights into the design and utilization of neutron-absorbing materials with suitable mechanical properties.

Electrochemical determination of dopamine by poly (methyl orange) shape memory alloy modified carbon paste electrode

We have successfully prepared 50Ni-30Ti-20Hf shape memory alloy powders using a high-energy planetary ball mill for 20 h by wet milling. The fabricated shape memory alloy powders were characterized by X-ray diffraction (XRD), and scanning electron microscope (SEM) to investigate the phases present and the morphology of the powders respectively. The use of 50Ni-30Ti-20Hf (nitinol) shape memory alloy powders as electro-catalytic materials is a unique and new idea. We are the first researchers to use nitinol powders as dopamine (DA) electrochemical sensors. For better electrochemical oxidation and higher current response of DA, we have electro-polymerized the surface of nitinol-modified carbon paste electrode (MCPE) with methyl orange (MO). Using poly(MO)-NiTiHf-MCPE, we have determined the DA using cyclic voltammetry (CV) and differential pulse voltammetry (DPV) respectively. The calculated active surface area for BCPE, NiTiHf-MCPE, and the poly(MO)-NiTiHf-MCPE were found to be 0.044, 0.089, and 0.098 cm2 respectively. The electro-polymerized nitinol MCPE not only increased the surface area but also increased the electron transfer kinetics. Our results confirmed the participation of 2 electrons and 2 protons in the electrochemical redox reaction.

Fe-doped ZnO nanoparticles prepared by high energy ball milling with enhanced sonophotocatalytic performance

Zinc oxidenanostructures were synthesized using a thermal decomposition method and subsequently doped with Fe (III)in this study. Techniques such as X-ray diffraction, Field emission scanning electron microscopy, and Fourier transform infrared spectroscopy were used to investigate the structural and chemical composition of nanomaterials. Fe-doped ZnO was synthesized using a simple, low-cost planetary high-energy ball milling process. The sonophotocatalytic activity of Fe-doped ZnO under visible light and ultrasonic waves was then studied. Another aspect of this study is the utilization of visible light, which is far more accessible and cost-effective than UV light. Malachite green (MG) and phenol were applied as water-soluble contaminants. MG degraded about 87.65% after 1 h in the presence of a Fe-doped ZnO catalyst under visible light and ultrasonic waves simultaneously. Phenolwas degraded by approximately 64.50% under the same conditions.

Synthesis of rGO-reinforced MgAl2O4 spinel composites by solid-state powder route mechanism: A comparative analysis between non-reinforced and rGO-reinforced spinel composites

Reduced Graphene Oxide (rGO)-reinforced MgAl2O4 spinel composite was successfully synthesized by a solid-state powder route mechanism via high-energy planetary ball milling of corresponding metal oxide precursors followed by a high-temperature single-stage sintering process. The effect of rGO on the homogeneity, phase development, morphology, chemical composition, rate of formation of spinel, and cation anti-site formation of the composites was methodically investigated. For comparison, a stoichiometric non-reinforced MgAl2O4 spinel was also synthesized. The addition of 0.2 wt% and 0.4 wt% of rGO as reinforcement increased the homogeneity of the ball-milled composite powder, with Polydispersity Index (PDI) values of 0.19 and 0.15 respectively, as compared to 0.24 obtained in non-reinforced spinel composite. The X-ray diffraction pattern and IR spectrum of 1650 °C sintered composites confirmed the formation of highly crystalline phases with spinel structure. The microstructural analysis revealed that the addition of rGO led to a reduction in porosity and improved the process of sintering. Calorimetric studies showed that spinelization started to occur at 858 °C and 880 °C for 0.2 wt% and 0.4 wt% rGO-reinforced composites respectively, which was faster than non-reinforced composite. 27Al solid-sate nuclear magnetic resonance (SS-NMR) analysis depicted that ceramic composite reinforced with rGO exhibited lesser inversion parameter of 0.09 (for 0.2 wt% rGO) and 0.055 (for 0.4 wt% rGO), as compared to 0.145 obtained in non-reinforced composite, indicating lesser cation anti-sites formation in rGO-reinforced spinel composite.

Effect of milling time on structural, mechanical and tribological behavior of a newly developed Ti-Ni alloy for biomedical applications

Ti-Ni alloy is the most attractive material in the medical field for orthopedic implants like total hip replacement due to its special properties. The purpose of this study was to examine the impact of grinding/milling times on the characteristics of the nanostructured Ti50-Ni50 alloys produced via the mechanical alloying process (MA), utilizing a planetary high-energy ball mill at different grinding times (2, 6, 12, and 18 h). The grinding time causes grain refinement and a decrease in the porosity of materials, which allows for the improvement of a material’s mechanical properties and wears resistance. The structural, physical and tribological behavior of Ti50-Ni50 alloy was characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), nanoindentation test, and ball-on-disk tribometer operated under varying applied loads of 2, 10, and 20 N. The findings demonstrated that the crystallite size was reduced and the microstrain increased reaching values of 29 nm, and 0.99%, respectively, at higher grinding times. The percentage of porosity in the Ti50-Ni50 alloy was 11%, while the density attained was 89% after 18 h of grinding. Moreover, as the grinding duration increased up to 18 h, the hardness increased (341 HV) owing to the refinement of the grains. It was also noted that the Ti50-Ni50 alloy that was milled at 2 h exhibited the lowest elastic modulus (89 GPa). In addition, it was found that wear rates and the coefficient of friction were decreased reaching the values of 29.67 µm3/N.μm, and 0.31, respectively, for the samples milled at 18 h and examined under 2 N. Enhanced structural and mechanical qualities are responsible for this improvement in tribological properties. These properties make Ti50-Ni50 alloys clinically relevant for human biomedical implantation.

Enhancing RDX Thermal Decomposition in Al@RDX Composites with Co Transition Metal Interfacial Layer

In this study, an Al/Co@RDX composite was meticulously prepared through a combination of planetary high-energy ball-milling and a spray-drying technique. The thermal reactivity of these Al/Co@RDX composites was comprehensively investigated and compared using the TG/DSC technique. It is shown that the initial decomposition temperature of RDX in the DSC curve was decreased by 26.3 °C in the presence of Al/Co, which could be attributed to the nano-sized Co transition metal catalyzing the decomposition reaction of nitrogen oxides in RDX decomposition products. The decomposition peak temperature of RDX and the heat released by the thermal decomposition of RDX in the Al/Co@RDX composite were decreased by 26.3 °C and increased by 74.5 J·g−1, respectively, in comparison with those of pure RDX. The types of major gaseous products released from Al/Co@RDX were found to be identical to those of pure RDX, encompassing N2O, CH2O, CO2 and HCN. However, the concentrations of those gaseous products for Al/Co@RDX were higher than those observed for pure RDX, which may owe to the fact that the Al/Co composite can interact with the –CH2 and –NO2 within RDX molecules, which leads to the weakening of the C-N and N-N bonds. In addition, the decomposition of RDX in the Al/Co@RDX composite was observed as a one-step process with an apparent activation energy (Ea) of 115.6 kJ·cm−3. The decomposition mechanism of the RDX in the Al/Co@RDX composite was identified to follow the chain scission model (L2), whereas the two-step decomposition physical models observed for pure RDX were found to closely resemble the L2 and autocatalytic models.

All solid-state fabrication strategy of CdS@ZnS nanocomposites and their photocatalytic performance in water purification

Herein a systematic study of two-step solid-phase synthesis of CdS@ZnS nanocomposites and their photocatalytic activity is presented. First, CdS nanoparticles were synthesized in a planetary ball mill through a solid-state ion exchange reaction. In the second step, Cd2+ ions were partially replaced by Zn2+ ions at the surface of the nanoparticles using solvent free long-term activation in a high-energy planetary ball mill. The optimal activation time in a ball mill was determined to be 45 min. Spherical CdS nanoparticles with a diameter of 10 nm and modified CdS@ZnS (45 min) nanocomposites were characterized by X-ray diffraction analysis, Raman and UV-vis spectroscopy, and scanning electron microscopy. The ability of nanocomposites for photocatalytic water purification was tested on the degradation of the model organic dye Orange II in an aqueous solution under the visible light irradation. The modified CdS@ZnS nanocomposites showed higher photocatalytic activity compared to the original CdS nanoparticles.

NiO:Cu+2 mesoporous nanoparticles with enhanced oxidative sonophotocatalytic performance for visible-light driven organic pollutants remediation

Mesoporous nickel oxide nanostructures were synthesized using a solvothermal method. and then doped with Cu2+ via high energy planetary ball milling technique. crystallinity, morphology, porosity, size, and composition of the nanoparticles were evaluated using XRD, BET, TEM, and EDX techniques. The as-prepared doped nanoparticles were used for the first time in the oxidative sonophotocatalytic removing of organic pollutants in low-frequency and low-energy ultrasound waves at room temperature in the presence of visible light. After 60 min of double irradiation (ultrasound + Visible light) in the presence of doped nanoparticles, more than 86 % of the pollutants were removed; reaching a constant rate of 0.0363 min−1. integration ultrasonic and visible light in the oxidative sonophotocatalytic remediation process resulted in a synergistic effect of about 72 %. Above all, the results showed the high reusability and stability of the doped nanoparticles in consecutive runs with minor fading in their sonophotocatalytic performance. To investigate the mechanism, the performance of the oxidative sonophotocatalytic removing process was examined by the addition of different types of trapping and enhancer agents. Finally, the generality of the process was evaluated by the remediation of commercially available antibiotics from water.

Prediction of Wear Characteristics for Al-MnO2 Nanocomposites using Artificial Neural Network (ANN)

An Artificial Neural Network (ANN) model was developed to investigate the impact of various ball milling parameters on the wear characteristics of Al-MnO2 nanocomposites. The process involved the synthesis of nano-sized particles through a high-energy planetary ball milling process, followed by the fabrication of nanocomposites using the stir casting method. The synthesized nanoparticles are characterized using X-Ray diffraction (XRD), and the nanocomposites are examined through scanning electron microscopy. To evaluate the wear behavior of the nanocomposites, a pin-on-disc test is conducted, generating a data set used for training the ANN model. The primary objective was to predict the wear rate of the synthesized Al-MnO2 nanocomposites using the ANN. Upon comparing the ANN's predictions with actual experimental results, it became evident that a well-trained ANN model proved to be a highly effective tool for estimating the wear rate of Al-MnO2 nanocomposites.

Corrosion Resistance of Fe-Cr-Si Alloy Powders Prepared by Mechanical Alloying

Powders with nanometric crystallites of two ternary alloys Fe0.90Cr0.05Si0.05 and Fe0.85Cr0.10Si0.05 were prepared by mechanical alloying (MA) in a planetary high-energy ball mill at various milling times followed by annealing in a vacuum at 900 K to induce an oxygen-induced surface segregation of Cr and Si atoms. The prepared powders were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). The obtained results show that all prepared powders crystallize in the body-centered cubic structure and are composed of micrometric particles, which are polycrystalline and consist of many nanometric crystallites. The mean size of the particles as well as the crystallites decreases progressively with milling time. In order to study the anti-corrosion properties of the obtained materials, the powders were exposed to atmospheric gases at 870 K. After each oxidation step, the formation of iron oxides was investigated using 57Fe transmission Mössbauer spectroscopy (TMS). It was found that the powders of Fe0.90Cr0.05Si0.05 and Fe0.85Cr0.10Si0.05 obtained after 10 and 20 h of MA are extremely resistant to oxidation. This result can be connected with the fact that XPS measurements reveal a high concentration of Cr and Si atoms on the surface of powder particles.

An investigation of microstructural basis for corrosion behavior of Al-CNT composites fabricated by SPS

In this research effect of the addition of multi-wall carbon nanotubes (MWCNTs) as additive powder on microstructure and corrosion behavior of fabricated Al-CNT composites was studied. The aluminum powder and CNTs were mixed with high energy planetary ball-mill. It is observed that by increasing milling time, the uniformity of CNTs on aluminum matrix and consequently corrosion resistance of Al-CNT composite is increased. On the other hand, by increasing the volume percentage of CNTs, the uniformity of CNTs on aluminum matrix and corrosion resistance of fabricated Al-CNT composite is reduced. The value of polarization resistance, Rp, for fabricated composites with 2 % CNT is improved from 1.28 to 3.60 Ω/cm2 by increasing milling time. Also, the value of Rp for fabricated composites with 4 h milling time, is reduced from 3.60 to 2.76 Ω/cm2 by increasing the percentage of CNTs from 2 % up to 5 %. Moreover, Cyclic Polarization results showed that the pitting corrosion resistance improves by increasing milling time and deteriorates by increasing the percentage of CNTs. The electrochemical impedance spectroscopy (EIS) results showed that the corrosion mechanism of Al-CNT composites is a combination of uniform and pitting corrosion. Indeed, the CNTs act as preferred cathode regions and cause to formation of micro galvanic couples. The Al-2%CNT-4 h showed better uniformity and the highest corrosion resistance. The Al-5%CNT-2 h presented non-uniform distribution of CNTs and the lowest corrosion resistance.

Particle size-dependent structural and magnetic properties of Pr0.6-xBixSr0.4MnO3 (x = 0.10 and 0.25)

Nanoparticles of Pr0.6-xBixSr0.4MnO3 (x = 0.10 and 0.25) have been prepared using the swift and cost-effective top-down approach in a high-energy planetary ball mill without any chemical processing and environmental impacts resulting due to pollutants arising from nanoparticle synthesis. The work investigates the role of particle size reduction on the structural and magnetic properties. An increase in milling time from 0 to 240 min results in the drastic reduction of particle size which drops significantly in the initial phase of ball milling i.e., 0–60 min while the microstrain and dislocation densities show nearly monotonic increase. Interestingly the magnetism and size reduction demonstrate a clear one to one correspondence. In both compositions, the paramagnetic (PM) to ferromagnetic (FM) transition, TC decreases and the magnetic transitions broaden both as function Bi and size reduction. The Curie–Weiss analysis of the inverse magnetic susceptibility ({chi }^{-1}) shows a deviation from linearity indicating the presence of the short-range FM interactions above TC which has been understood as Griffith’s phase like singularity. The size reduction can effectively reduce TC, enabling a significant control over tuning of transition temperature and net magnetization. The field dependent magnetization for x = 0.10 demonstrate dominant FM state whereas for x = 0.25, metamagnetic magnetization highlights competitive coexistence of FM and antiferromagnetic (AFM) interactions in the system. With ball milling, the net magnetization decreases, and the metamagnetic behaviour is suppressed. The M–H loops of ball milled nanoparticles are highly unsaturated indicating the enhanced surface disorder in the nanoparticles which can be understood using the core–shell structure.

Electrochemical Determination of Ascorbic Acid by Mechanically Alloyed Super Duplex Stainless Steel Powders

SAF-2507 super duplex stainless steel powders (SDSS) were prepared using a high-energy planetary ball milling process. The X-ray diffraction (XRD) shows peak broadening after 20 h of ball milling and revealed a phase transformation resulting in a two-phase alloy mixture containing nearly equal amounts of ferrite (α) and austenite (γ). After 20 h of ball milling the particle size was reduced to ~201 nm. Scanning electron microscope (SEM) micrographs showed small-size irregular grains with an average particle size ranging from 5–7 µm. The high-resolution transmission microscope (HRTEM) analysis confirmed the presence of nanocrystalline particles with sizes ranging from 10 to 50 nm. The presence of ferrite phase is visible in the corresponding diffraction pattern as well. In this paper, we have discussed the electrochemical sensor application of mechanically alloyed nano-structured duplex stainless steel powders. The fabricated 4 mg duplex stainless steel modified carbon paste electrode (SDSS-MCPE) has shown excellent current sensitivity in comparison with 2, 6, 8, and 10 mg SDSS-MCPEs during the detection of ascorbic acid (AA) in a phosphate buffer solution with a pH of 6.8. The calculated electrode active surface area of SDSS-MCPE was found to be almost two times larger than the surface area of the bare carbon paste electrode (BCPE). The limit of detection (LD) and limit of quantification (LQ) were found to be 0.206 × 10−8 M and 0.688 × 10−8 M, respectively, for the fabricated 4 mg SDSS-MCPE.

Nitrogen-Doped Titanium Carbide (Ti3 C2 Tx ) MXene Nanosheet Stack For Long-Term Stability and Efficacy in Au and Ag Recovery.

The development of efficient adsorbents for the practical recovery of precious metals from electronic waste is vital to advanced energy/environment industries. Ti3 C2 Tx MXene-based materials are promising adsorbents for aqueous environments; however, the highly defective and super hydrophilic nature of the MXene surface hinders its practical applications. Here,wereport that nitrogen-doped MXene (N-MXene) nanosheet stacks, prepared via high-energy planetary ball milling under N2 purging, exhibited a long-term stable and excellent recovery capability for Au and Ag ions via the nitrogenation of defective vacancies. Notably, these microscale nanosheets could facilitate the sustainable production of Au and Ag from secondary sources, exhibiting a high recovery rate and capability (1198 mg g-1 for Au and 1528 mg g-1 for Ag), long-term stable storability (21 d), and high selectivity (Kd of 1.67 × 106 for Au and 2.07 × 107 for Ag). Furthermore, the reversible redox chemistry of N-MXene facilitated its repeated use in adsorption/desorption cycles.

Crystallographic and magnetic analysis of ordered-disordered Ni51Mn34Sn15 Heusler alloy obtained by mechanical alloying and annealing

Ni51Mn34Sn15 Heusler alloy was prepared from elemental powders in a high energy planetary ball mill under argon atmosphere for milling times up to 10 h. Alloy formation was checked by X-ray diffraction, and by the means of the Rietveld method, the amount of phases was computed. It was found that by mechanosynthesis, B2 disordered structure was formed after 8 h of milling containing high lattice strains. By scanning electron microscopy, the morphology of the powders through the obtaining process was followed. The elemental powders degree of homogenization and distribution versus milling time was investigated by energy dispersive X-ray spectroscopy. The decrease of the magnetization with alloy formation was observed in connection with the disordered phase formation. Low and short temperature annealing was found to have an important influence on the alloy ordering to L21 structure and to enhance magnetic properties up to a value comparable with the arc-melted sample. The Curie temperature was found to be depended on the iron contamination occurred during milling and an ordering temperature of 60 °C was measured for the phase with L21 structure.