High-energy Ball Milling Process Research Articles

Unlocking the Power of Magnesium Batteries: Synergistic Effect of InSb-C Composites to Achieve Superior Electrochemical Performance.

Pure magnesium anode used in rechargeable magnesium batteries (RMB) exhibits high theoretical capacity but has been challenged by the passivation issue with conventional electrolytes. Alloy-type anodes have the potential to surpass this issue and have attracted increasing attention. However, the kinetic performance and stabilities of conventional alloy anodes are still constrained. In this study, the InSb-10%C anode is synthesized by a two-step high-energy ball milling process. The InSb-10%C anode exhibits a remarkably high capacity of up to 448 mA h g-1, significantly improved cycle performance (234 mA h g-1 at 100 cycles) and rate performance (168 mA h g-1 at 500 mA g-1). The above-mentioned superior performance of the InSb-10%C anode for RMBs is attributed to the cellular graphitized amorphous carbon composite structure (CGA) which effectively refines the particle size and restricts the volume expansion. Additionally, the reduced surface electron density of InSb combined with the high conductivity resulting from graphitization enhances the Mg2+ diffusion performance. Notably, the InSb-10%C anode demonstrates good compatibility with conventional halogen-free salt ether-based electrolytes in the full battery configuration.

A novel nanocomposite-based zeolite for efficient remediation of Cd-contaminated industrial wastewater

Novel nanocomposite sorbent was produced by depositing nanostructured water treatment residual (nWTR) onto zeolite (Ze) using high-energy ball milling process. The physicochemical properties of nanocomposite (Ze-nWTR) prior and after Cd adsorption were analyzed by SEM–EDX, FTIR, BET and XRD. A batch study of cadmium adsorption (Ze-nWTR) was performed at various process parameters (sorbent dose, contact time, solution pH, competing ions, initial concentration and temperature). The obtained data were fitted to various equilibrium and kinetics models. The Langmuir and power function models successfully described Cd adsorption equilibrium and kinetic processes, respectively. The maximum adsorption capacity (qmax) value of Cd by Ze-nWTR nanocomposite (147 mgg−1) was 3 and 5.9 times higher than those of nWTR and zeolite sorbents, respectively. Increasing temperature from 287 to 307 K has resulted in increasing the maximum Cd adsorption capacity (qmax) of the nanocomposite from 147.9 to 270 mgg−1. The calculated thermodynamics parameters suggested physical and chemical attraction between Cd and Ze-nWTR and the association of dissociative mechanism in Cd(II) sorption process. The excellent reusability and Cd removal ability of Ze-nWTR nanocomposite (98%) from industrial wastewater confirm its potential as promising adsorbent for wastewater treatment applications.

Rare-Earth Ion Loss of Er- or Yb-Doped LiNbO3 Crystals Due to Mechanical Destructive Effect of High-Energy Ball Milling

Structural changes of Er- or Yb-ion doped LiNbO3 (LN) nanocrystals were studied in relation to the high-energy ball milling process. The evolution of the size of the particles and the formation of different phases were followed by dynamic light scattering and X-ray diffraction measurements, while the electronic transitions of rare-earth (RE) ions were investigated by absorption spectroscopy in the infrared spectral range. During the milling process, RE ions left the crystal lattice and an RE2O3 phase appeared to an increasing extent next to the LN. The change in the absorption spectra and the phases formed during the grinding process were found to be very similar for both investigated RE ions and were independent of their original concentration in the starting crystal samples. The extent of the RE loss was found to be 90% after 100 min of wet grinding.

Tungsten heavy alloy: Nano-crystallinity and alloying induced low temperature sintering, microstructure and mechanical properties

In this study, a tungsten heavy alloy with a composition of 90 W-4.9Ni-2.1Fe-3.0Cu was processed using powder metallurgy. Pure elements were ball-milled to develop a mechanically alloyed nano-grained solid solution to reduce the required sintering temperature. The alloy was then liquid-phase sintered in a hydrogenated argon atmosphere at 1250 °C. Microstructural characterization revealed that the high-energy ball milling process successfully developed a tungsten solid solution with a reduced tungsten grain size to a level of 15 nm, facilitating effective low-temperature (i.e., 1250 °C) liquid-phase sintering with 88% relative density. The tungsten grains grew mostly in a polygonal shape, coalesced to a large size, and had strong interfacial integrity with the nickel‑iron‑copper matrix. Mechanical properties characterization revealed a significantly high microhardness level of 380 HV, compressive yield strength of 910 MPa, and ultimate compressive strength of 1326 MPa. The applied compressive stress induced intergranular crack propagation leading to the fracture of the sample with a failure strain of 25.6%.

Enhanced lithium dendrite suppression ability through SiO2 substitution in superionic halogen-rich argyrodites and their application in all-solid-state lithium batteries

Among the inorganic solid electrolytes, it has been reported that argyrodites of sulfide-based electrolyte systems have a number of advantages, including high ionic conductivity and mechanical flexibility. Despite these advantages, their poor compatibility with Li metal still represents a problem. In this work, we prepared a halogen-rich argyrodites Li6-xPS5-xCl1+x solid electrolyte using a high-energy ball milling process. According to the composition test, Li5.3PS4.3Cl1.7 exhibited a high ionic conductivity (9.0 mS cm−1) at room temperature. Thus, we proposed SiO2 doped halogen-rich argyrodites while aiming to achieve improved electrochemical performance and the ionic conductivity. At a value of 9.4 mS cm−1, the ionic conductivity of Li5.34P0.96Si0.04S4.22O0.08Cl1.7 compositions was slightly increased compared to that of Li5.3PS4.3Cl1.7 (9.0 mS cm−1). Moreover, that composition showed a higher critical current density (1.0 mA cm−2) than that of Li5.3PS4.3Cl1.7 (0.35 mA cm−2), indicating that SiO2 doped Li5.3PS4.3Cl1.7 solid electrolyte improved the compatibility of the electrolyte against Li metal by reducing the side reaction with the Li metals. The air stability was also enhanced after SiO2 doping. These results confirmed that metal oxide doping in halogen-rich argyrodites contributed to high ionic conductivity and good electrochemical performance.

Milled graphitic nanoparticle toughened epoxy composites via increased resistance to in-plane crack propagation

Fascinating features of 2D-based carbon materials like graphene have drawn increasing attention to fulfill the desire to enhance the fracture toughness of epoxy composites. However, challenges remain to improve their dispersibility in polymers and increase interaction ability. Thus, work is needed to synthesize alternative cost-effective 2D carbon nanofillers capable of delivering consistent performance as a reinforcer to monitor the fracture toughness of the epoxy composites. The present study demonstrates transforming graphite to ball-milled graphite (BMG) via an effective high-energy wet ball milling process. Herein a noteworthy size reduction is achieved for the BMG ranging from ∼217 to 227 nm. Microscopic investigation spotted an exfoliated 3D networked graphite nanosheet with nanopores. These BMGs were functionalized to attach amine-based silane moieties and were incorporated into the epoxy network. Consequently, even at higher loading levels, they showed their astonishing capability to enhance the crack far field resistance of nanocomposite resulting in significantly improved fracture toughness and energy to ∼2.31 MPa m1/2 and ∼11.30 kJ/m2, respectively. Improvement is ascribed to the better dispersing ability of BMG, which provides a consistent strong interfacial interaction with the epoxy network to modulate material resistance to fracture. Such environmentally friendly nanofillers must be industrially acceptable for synthesizing durable epoxy nanocomposite systems and can be utilized to prepare structural composites.

A Comparative Analysis of Hydrogen Storage Characteristics in AZ31 Magnesium Alloy with the Addition of Graphene and Carbon Nanotubes via Ball Milling Process

In the present investigation, an examination was conducted on the hydrogen storage performance of industrial waste grade AZ31 magnesium alloy when combined with either Carbon Nanotubes or Graphene. This study aims to understand the enhancement of hydrogen storage properties reinforced with polymer materials, such as Graphene or Carbon Nanotubes. The experimental samples, composed of AZ31 Magnesium Alloy combined with either Carbon Nanotubes or Graphene, were crafted through gravity casting. Thereafter, a high-energy ball milling process was employed to further refine the hydrogen storage material powders. The micrographic structures of all the sample powders were analyzed by x-ray diffraction (XRD), and scanning electron microscopy (SEM) coupled with energy dispersive spectroscopy (EDS). Additionally, the average particle size distributions of the sample powders were quantified for comprehensive characterization. The absorbed and desorbed hydrogen capacity and kinetics was calculated by a Sievert's type apparatus. Overall, the performance of the sample powder AZ31-0.1G showed the highest absorption and desorption at a rate of 0.0036 wt%/s and 0.0084 wt%/s. Moreover, the hydrogen capacity of AZ31-0.1G reached the highest value at 5.32 wt%. The acquired data unveils that with the adding of either Graphene or Carbon Nanotubes as additives significantly improved the hydrogen storage capacity of AZ31 magnesium alloy.

Synthesis of Sb-doped Li10P3S12I solid electrolyte and their electrochemical performance in solid-state batteries

The glass-ceramic Li10P3S12I solid electrolyte exhibited moderate ionic conductivity of ∼3 mS cm−1, but it shows low interface stability with lithium, poor moisture stability, and the electrochemical performance is not well established with respect to lithium. In this work, we enhance the ionic conductivity, interface stability, and air stability using Sb-substitution in Li10P3S12I glass-ceramic solid electrolyte using a high-energy ball milling process followed by a low heat treatment process. The ionic conductivity analysis reveals that the prepared Li10.1P2.95Sb0.05S12I glass ceramic composition shows a higher ionic conductivity of 5.9 mS cm−1 at 25 °C than Li10.1P2.95Sb0.05S12I (5.06 mS cm−1). The Li10.1P2.95Sb0.05S12I glass ceramic symmetric cell exhibits a better critical current density of 1 mA cm−2 than bare (0.7 mA cm−2). Also, it demonstrates better DC cyclability at 0.25 mA cm−2 without internal short circuits after 80 cycles. The Sb-substitution not only enhanced the ionic conductivity, also increased the moisture stability according to HSAB theory. The lithium solid-state battery is constructed using the Li10.1P2.95Sb0.05S12I electrolyte that demonstrates a high discharge capacity of 146 mAh g−1 at 0.1C rate than bare electrolyte (126 mAh g−1).

Enhancing the Microhardness of Coatings Produced by Cold Gas Dynamic Spraying through Multi-Reinforcement with Aluminum Powders Containing Fullerenes and Aluminum Nitride

Coatings with high hardness were successfully obtained using low-pressure cold spray (LPCS) technology from nanocrystalline powders based on the aluminum alloy AlMg6, which were multi-reinforced with 0.3 wt.% fullerenes and 10–50 wt.% AlN. The powders were synthesized through a two-stage high-energy ball milling process, resulting in a complex mechanical mixture consisting of agglomerates and micro-sized ceramic particles of AlN. The agglomerates comprise particles of the nanocomposite material AlMg6/C60 with embedded and surface-located, micro-sized ceramic particles of AlN. Scanning electron microscopy and EDS analyses demonstrated a uniform distribution of reinforcing particles throughout the coating volume. An X-ray diffraction (XRD) analysis of the coatings revealed a change in the predominant orientation of matrix alloy grains to a more chaotic state during deformation over the course of cold gas dynamic spraying. A quantitative determination of AlN content in the coating was achieved through the processing of XRD data using the reference intensity ratio (RIR) method. It was found that the proportion of transferred ceramic particles from the multi-reinforced powder to the coating did not exceed ~65%. Experimental evidence indicated that LPCS processing of mono-reinforced nanocrystalline powder composite AlMg6/C60 practically did not lead to the formation of a coating on the substrate and was limited to a monolayer with a thickness of ~10 µm. The microhardness of the monolayer coating obtained from the deposition of AlMg6/C60 powder was 181 ± 12 HV. Additionally, the introduction of 10 to 50 wt.% AlN into the powder mixture contributed to the enhancement of growth efficiency and an increase in coating microhardness by ~1.4–1.7 times. The obtained results demonstrate that the utilization of agglomerated multi-reinforced powders for cold gas dynamic spraying can be an effective strategy for producing coatings and bulk materials based on aluminum and its alloys with high microhardness.

High ionic conducting NaSICON enabled by mechanical activation enhanced reaction

NaSICON-type materials have been investigated since 70s and become an attractive candidate for energy storage and many other emerging applications owing to their good ionic conductivity. However, further enhancement in ionic conductivity at room temperature (RT) and facile processing methods to synthesize NaSICON in an energy efficient and low cost manner are required to enable various emerging applications. This study reports a new processing method, termed as mechanical-activation-enhanced reactions, to address these challenges simultaneously. It is shown that Na3Zr2Si2PO12 membranes with little or no impurity, relative densities ∼95 %, and total ionic conductivity of 1.53 × 10−3 S/cm at RT can be synthesized through one high-energy ball milling process followed by one step of high-temperature reaction(s) and sintering at the same time, greatly simplifying the procedure for synthesizing NaSICON membranes while achieving the outstanding ionic conductivity reported in the literature. It is found that mechanical activation at RT has significantly increased the reactivity of the reactants, accelerated the reaction kinetics in forming NaSICON, and increased the bottleneck size of the NaSICON crystal for Na ion transport. This study has provided a new direction to synthesize high performance, low cost NaSICON membranes and offered guidelines for achieving NaSICON membranes with superior ionic conductivity in the future.

Modification of 316L steel powders with bronze using high energy ball milling for use as a binder component in PBF-LB/M printing of diamond-metal matrix composites

For the processing of diamond-metal matrix composites, the powder bed fusion using a laser for metals (PBF-LB/M), represents a new promising method for the additive manufacturing of diamond tools for concrete and rock machining, even with more complicated geometries. Previous research activities show a strong tendency for cracking and delamination during the construction process of the samples. This behavior is caused by thermal residual stresses associated with the embedded diamonds. To control these negative effects on the process side, the volume energy density is reduced accordingly, which, however, led to increased pore formation. This publication deals with an approach on the material side to modify a 316L stainless steel base powder with an addition of 20 wt% bronze via a high energy ball milling (HEBM) process in such a way that a homogeneous solid solution phase is created. A significantly increasing of the melting interval and a decreasing of both solidus and liquidus temperature was observed, which can reduce pore formation in the PBF-LB/M-process. In addition, XRD-diffractometry and SEM/EDS-analysis showed that the homogeneous solid solution phase of this alloyed powder segregates again into Fe- and Cu-rich phases when heated up to the melting point.

Tuning intrinsic defects of Pt-based carbon supports by high-energy ball-milling for enhanced alkaline hydrogen evolution

Carbon materials are significant supports for catalysts, in which surface properties play a crucial role in catalytic performances. However, the correlation between the intrinsic defects of carbon supports and the alkaline hydrogen evolution reaction (HER) performance of catalysts is still unclear. Herein, graphite (G) was used as a model support to study the effect of intrinsic defects of carbon support on the HER performance. To this end, defect-enriched graphite supports were obtained by a simple high-energy ball-milling process. The affluent intrinsic defects (edge surfaces) in graphite supports served as active sites for the dispersion and anchoring of Pt nanoparticles for better electron transfer from Pt species to the support, leading to strong metal-support interactions. The resulting Pt-loaded on defect-enriched DG-30 (Pt/DG-30) delivered a lower overpotential of 46 mV at 10 mA cm−2 when compared to undecorated Pt/G (177 mV), indicating an excellent HER activity. Pt/DG-30 also showed superior stability due to the strong metal-support interactions between Pt nanoparticles and carbon support. In sum, significant insights into the rational optimization and regulation of intrinsic defects of carbon supports were provided for the preparation of new catalysts-modified carbon supports with enhanced HER performances.

Tailored microwave absorption performance through interface evolution by in-situ reduced Fe nanoparticles on the surface of FeSiAl microflake

Poor impedance matching and low-frequency magnetic resonance are great challenge for Fe-based micron-scale materials as microwave absorber in GHz range. Here, we propose in situ interface engineer strategy for tailoring the interface through in situ reduced Fe nanoparticles and introduce planar anisotropy for flattening particles with high aspect ratio during high-energy vertical ball milling process, which can synchronously enhance impedance matching and exceed Snoke’s limit. With increasing milling time, the interface experiences the following in situ evolution: the nano oxide layer-micro particles interface, the partial interface between nano oxide layer and Fe nanoparticles, the integrity Fe nanoparticles-oxide layer interface, the nano oxide layer-microflake interface. Meanwhile, the aspect ratio is up to 74.93. The evolution of interface and high aspect ratio can effectively tailor permittivity and permeability. Due to the novel microstructure that FeSiAl flake are covered by ∼ 30 nm oxide layer containing ∼ 10 nm Fe nanoparticles, natural resonance induced by planar anisotropy, eddy current loss of metallic microflake, relaxation loss induced by interface polarization, conductive loss from electric resistivity together led to good microwave absorption performance (effective absorbing bandwidth of 3.12 GHz at 3.2 mm and minimal reflection loss of −44.47 dB at 7.44 GHz and 3.3 mm). The present finding might highlight for developing the composite absorbers with multi loss type coupling across nano-micro scales.

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.

Hydrolysis hydrogen generation behavior of Mg10Ni10Ce alloy catalytic modified by isomeric carbon materials

Hydrolysis hydrogen generation from Mg-based alloys is considered as a potential energy carrier for global low-carbon and growing energy challenges. At present, it is a key problem to explore an efficient modification method for Mg-based alloys to obtain rapid initial hydrolysis kinetics and high H2 yield in short time. In this work, carbon-based isomeric catalysts were creatively employed to activate Mg10Ni10Ce alloy. Based on the rapid initial hydrolysis kinetics, the effects of carbon nanostructured catalysts on the hydrogen production of Mg10Ni10Ce were studied. Herein, the catalytically modified Mg10Ni10Ce samples with point-like carbon black (SP), one-dimensional tubular carbon nanotubes (CNTs) and two-dimensional layered graphite (GP) are simply prepared by short-time high-energy ball milling process. Due to the significant structural characteristics, the catalytically modified Mg10Ni10Ce samples have higher H2 yields at the initial hydrolysis stage, Mg10Ni10Ce-SP, Mg10Ni10Ce-CNTs and Mg10Ni10Ce-GP samples are 17.3%, 25.2% and 36.2% at 313 K for 30 s, which are higher than that of Mg10Ni10Ce (10.4%). The above work provides an effective strategy for hydrogen production by modifying Mg-based alloys with nanostructured catalysts, and lays a foundation for the application of portable hydrogen production devices.

Study on the arc erosion resistance and mechanism of Cr- doped W[sbnd]Cu composites

WCu composites have been widely used in electrical contacts and arc resistance electrodes. To improve the arc erosion resistance, the WCu composites doping Cr was fabricated by high energy ball milling and SPS process. The arc erosion characteristics of W-Cu-Cr composites under 1000, 5000 and 10,000 electric contact operations were studied, and the mechanism of arc erosion resistance of WCu composites doped with Cr was revealed. The results indicated that the average arc energy of W-Cu-1Cr composites decreased by 35.7%, 53.7%, and 63.8% respectively after 1000, 5000, and 10,000 electrical contact tests compared with WCu composites undoped Cr phase. After 10,000 operations, the average welding force of W-Cu-1Cr composites is 24.3% lower than that WCu composites undoped Cr phase, and had lower arc erosion loss (0.57 mg). In addition, the strong oxygen absorption of Cr phase results in the formation of an oxide film on the surface of WCu composites. The arc root moves smoothly and continuously along the Cr2O3 oxide film at the grain boundary, thereby reducing arc energy and improving the arc erosion resistance of WCu composites.

Effect of ball milling time on the formation and thermal properties of Ag2Se and Cu2Se compounds

The thermoelectric materials community has made significant progress on nanostructured and processable materials to improve efficiency and flexibility, reducing manufacturing costs. Selenide compounds, such as Ag2Se and Cu2Se, have received a lot of attention because of their promising capabilities in thermoelectric applications. Additionally, Se is significantly more abundant than Te, with approximately ten times higher availability. High-energy ball milling (HEBM) process is a powerful solid-state synthesis/powder mechanical alloying method. The objective of this work is to form selenide compounds at different milling times (1–20 h) by HEBM process. The structural characterization of the compounds was studied by X-ray Diffraction and X-ray Photoelectron Spectroscopy, while the thermal stability of the prepared samples was examined by Thermogravimetric Analysis. The experimental results show that the Ag2Se sample synthesized at 20 h presents lower thermal stability because of the higher specific surface area and the increased porosity as a result of the hardening effect. Additionally, Cu2Se presents Cu2O(SeO3) as the main phase at low temperatures, while at higher temperatures, CuO is the dominant phase. Therefore, as the heating temperature increases, there is a complete evaporation of Se and a conversion of the remaining copper into copper oxide. The present study demonstrates a simple method for the synthesis of Ag2Se and Cu2Se thermoelectric materials with high oxidation resistance.

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.

The influence of Dy3+ ions doping and annealing temperature on structural, morphological, and spectroscopic properties of lanthanum orthovanadate (LaVO4) material

In the current work, we present the results of nanocrystalline lanthanum orthovanadate (LaVO4) doped with dysprosium ions, which was synthesized by a high-energy ball milling (HEBM) process. Lanthanum, vanadium, and dysprosium oxides were employed as starting reagents. These materials were turned into LaVO4:Dy3+ powder with two polymorphic phases after HEBM and subsequent heating that was carried out in the air in the temperature range from 800 °C to 1200 °C. X-ray powder diffraction (XRD), scanning electron microscopy (SEM), and DRS (UV–vis) spectroscopy were used to characterize the obtained Dy-doped LaVO4 powders. The excitation and photoluminescence (PL) emission spectra, and time decay (lifetime) curves of the dysprosium (III) ions in LaVO4 material were measured and analyzed. The influence of annealing temperature and the concentration of dysprosium (III) ions (1%, 2%, and 3% at.) on spectroscopic properties was discussed. The qualitative phase analysis of Dy-doped LaVO4 powders indicated the dominant presence of a monoclinic LaVO4 structure. The presence of the tetragonal solid-solution (La, Dy)VO4 phase was also revealed. The structural transformation consists of an increase of Zr type LaVO4:Dy3+ phase, resulting in a higher structure and site symmetry of t-LaVO4:Dy3+. With increasing Dy3+ content, the relative fraction of the tetragonal (La, Dy)VO4 phase was also increased in all samples. Furthermore, XRD investigations showed that Dy3+ ions were incorporated mainly into the t-(La, Dy)VO4 structure. The increase of the amount of tetragonal phase in polymorphic LaVO4:Dy3+ material results in higher emission intensity caused by more efficient energy transfer from VO43− vanadate group to Dy3+ ions. The average sizes of the m-LaVO4 crystallites, estimated using the Rietveld method, were in a narrow range from 53 to 77 nm. Two main intense emission peaks were observed in the blue (466–495 nm) and yellow (557–594 nm) wavelength ranges and can be ascribed to transitions involving 4F9/2 to the stark split sublevels of 6H15/2 and 6H13/2, respectively. The overall intensity of the emission strongly depends on the annealing temperature. The best results were achieved for powder heated at 1200 °C. The values of the calculated average decay lifetime τavg of the LaVO4 powders doped with 1%, 2%, and 3% at. Dy heated at 800 °C, 1000 °C and 1200 °C were very similar, but one can observe that with increasing heating temperature the average decay lifetime of LaVO4:Dy powders slightly decreased regardless of the Dy concentration.

Morphology transformation of stainless steel 316L powder from spheres to flakes using high-energy ball milling and the investigation of transformation behaviour

ABSTRACT Today, microfiltration plays the most significant role in removing fine particulate impurities in gas streams used in high-tech industries. However, the current SS316L gas filter has a limitation in enhancing performance due to the trade-off relationship between filterability and permeability. This limitation can be overcome by the geometrical effect of the gas filter that maximises inertial impaction and diffusion interception due to complex flow channels using small flake particles. However, since the smaller the particle size, the yield strength higher, there are few reports of preparing the small flake particles by plastic deformation. This study used a high-energy ball milling process to demonstrate the preparation method for small stainless steel 316L flake particles. Furthermore, the process parameters are systematically optimised to fully transform the spherical particles into thin platelets without fracture and cold welding, and the transformation behaviour is discussed in detail.