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Extraction of rare earth oxides from discarded compact fluorescent lamps
摘要： Discarded CFL samples are evaluated as a potential source of REEs (Y, Eu, Ce, Tb). The phosphors powder obtained from mechanical separation contains 31% rare earth values. The quantitative XRD analysis of phosphor sample yielded 39.9% red (YOX: Y1.90Eu0.10O3), 14.6% green (CAT: Al11Ce0.67MgO19Tb0.33), and 21.4% blue (BAM: Al10.09Ba0.96Mg0.91O17: Eu2+) phosphor along with 14.1% silica. Planetary ball milling was found promising in the liberation of REEs from given phosphor sample. A short milling of 20–30 min and 3–4 M acid concentration was found adequate for optimal recovery (> 90%) of REEs. Calcination of the precipitates resulted in the formation of REO with Y-Eu purity of > 98% and > 90% recovery rate. Eu, Y phase dissolution behavior was found completely different than Ce, Tb phase due to inert nature of Al11Ce0.67MgO19Tb0.33 till 120 min milling and 6 M acid concentration in leaching. Excessive milling promotes overall dissolution along with impurities dissolution and which further restrict the precipitation process. Based on the complete material balance 13 g of a mixed oxide of Y and Eu can be obtained from 100 units of CFLs.
关键词： Discarded CFL,Phosphor,Rare earth elements,Leaching,Mechanical milling
更新于2025-11-21 11:18:25
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The production of graphene–boron nitride nanosheet heterostructures via liquid phase exfoliation assisted by a milling process
摘要： Graphene–boron nitride (BN) nanosheet heterostructures have become one of the highly interesting matters in recent times owing to their advantages. In this study, the liquid phase exfoliation method was preferred for production of graphene–BN nanosheet heterostructures. However, a pre-milling process was applied to starting materials, instead of the classical liquid phase exfoliation method previously used in the literature. Hexagonal graphite (h-G) and h-BN mixtures were milled for 50 h and the milled powders were subjected to the liquid phase exfoliation process. As a result of the examinations, it was observed that graphene–BN nanosheet heterostructures were successfully synthesized. The widths of the synthesized nanosheets were 300–500 nm and nanosheets were multi-layers. It was seen that a large part of the powder mixture were occurred at high amorphization during the ball milling process. According to X-ray diffraction (XRD) peaks, the amorphization ratio was almost 90%. But, almost all of amorphous structures were removed during acid mixing and the thermal process. But, amorphous structures still existed in samples. In addition, the ball milling process damaged the sheets and defects formed. Despite all these disadvantages, the milling process carried out in this study provided formation of thinner and larger sheets compared with previous similar studies.
关键词： ball milling,BN nanosheets,exfoliation,heterostructures,Graphene
更新于2025-09-23 15:23:52
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Investigation on tool wear process of milling wave-transmitting Si <sub/>3</sub> N <sub/>4</sub> ceramics
摘要： Due to the low fracture toughness of wave-transmitting Si3N4 ceramics, the special material removal mechanism causes the tool wear to be different. The paper presents the tool wear forms and mechanism under different milling depth. The effect of tool wear on cutting force and machined surface morphology is discussed. Tests have been performed under typical conditions of cutting depth of 0.3 mm (in plastic-domain processing) and 0.4 mm (in brittle-domain processing). The results show that the abrasive wear caused by the chips is the main mechanism of the cutting edge wear and the flank wear, the increase of the side edge rear angle with tool wear is the main cause of the chipping phenomenon. The cutting depth is a significant influence parameter to the wear characteristics, and two types have been distinguished. As the material removal volume ascending, the cutting edge wear and the flank face wear has a stable period, and the root-mean-square deviation of processing surface increases to 1.6 μm, while that increase with the material removal volume continuously, and the processing surface decreases to 1.4 μm. It has been proved that the cutting force tends to increase first and then decrease as the material removal volume is about 4320 mm3.
关键词： ceramics,milling,morphology,plastic-domain,chipps,wear,Tool,brittle-domain,surface
更新于2025-09-23 15:23:52
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Chemical imaging of buried interfaces in organic-inorganic devices using FIB-ToF-SIMS
摘要： Organic-inorganic hybrid materials enable the design and fabrication of new materials with enhanced properties. The interface between the organic and inorganic materials is often critical to the device’s performance and therefore chemical characterization is of significant interest. Since the interfaces are often buried, milling by focused ion beams (FIB) to expose the interface is becoming increasingly popular. Chemical imaging can subsequently be obtained using secondary ion mass spectrometry. However, the FIB milling process damages the organic material. In this study, we make an organic-inorganic test structure to develop a detailed understanding of the processes involved in FIB milling and SIMS imaging. We provide an analysis methodology that involves a “clean-up” process using sputtering with an argon gas cluster ion source to remove the FIB induced damage. The methodology is evaluated for two additive manufactured devices, an encapsulated strain sensor containing silver tracks embedded in a polymeric material and a copper track on a flexible polymeric substrate created using a novel nanoparticle sintering technique.
关键词： FIB,additive manufacturing,hybrid interfaces,ToF-SIMS,polymer,Argon cluster,milling
更新于2025-09-23 15:22:29
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Phase Evaluation of Pure Nanocrystalline Barium Stannate by Two Different Milling Activations
摘要： Pure nanocrystalline BaSnO3 is prepared by two methods: mechanical activation (planetary ball milling) and mechanical hand mixing in agate mortar followed by sintering for both at 1350 °C/ 2 h. The phase formations during synthesis are analyzed by x-ray diffraction (XRD) studies and the crystallite size is measured by Scherrer’s formula from the major peaks of the diffractogram. The nanocrystalline barium stannate having single phase simple cubic perovskite structure is synthesized with a crystallite size about 50 nm. Fourier transform infrared spectroscopy (FTIR) is done to determine symmetric and asymmetric stretching of the bonds formed and co-ordination of the ions within crystal structure. FTIR studies justify the phases developed by XRD since the molecular signature and co-ordination of cations are verified. Microstructure and morphology are observed by scanning electron microscopy (SEM), while energy dispersive x-ray analysis (EDX) is done to determine the presence of the required element of composition formation. Ultra violet-visible spectroscopy (UV-VIS) shows absorption spectra of the sample within the UV region, while the band gap is calculated using the Tauc relation. The band gap evaluated for nanocrystalline barium stannate is about 2–2.78 eV for indirect transition, while for direct transition it is about 2.78–3.14 eV. The value is observed to be close to that of semiconductor-based materials.
关键词： FTIR,UV-VIS,nanocrystalline barium stannate,EDX,high energy planetary milling,XRD,SEM
更新于2025-09-23 15:22:29
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Microstructural interpretation of charge transport dynamics of chemically derived ZnCo2O4 under mechanical milling
摘要： In this work, milling effect on chemically synthesized nanocrystalline Zinc Cobaltite (ZnCo2O4) has been investigated and we report how the structural and electrical properties vary with the milling span. Phase pure ZnCo2O4 has been successfully synthesized via simple and cost-effective co-precipitation method and then it has been milled for one, four and eight hours respectively. XRD confirms formation of single phase cubic structure for both milled and unmilled nano-powders. Different microstructural parameters has been estimated from Rietveld analysis, which shows particle size reduction from ~29.64 nm for unmilled sample to ~18.13 nm for eight hour milled sample. TGA-DSC curve of as prepared sample shows good temperature stability that helps to estimate the appropriate sintering temperature for the samples. TEM analysis also gives values of grain size in agreement with Reitveld analysis. Frequency dependent ac conductivity curve obeys universal Jonscher power law and temperature dependence of frequency exponent is explained by small polaron transaction. Comparable activation energies from hopping mechanism and relaxation process indicates similar transport mechanism. Superimposed scaling spectra obeys TTSP principle. AC conductivity increases with frequency as a result of hopping of the charge carriers. Smaller particles with reduced strain gives enhanced conductivity as well as enhanced value of hopping frequency. This further suggests creation of excess charge carriers in milled samples. Cole-Cole plot shows non-Debye type behavior of the samples. The dielectric loss factor increases with lowering of particle size since smaller grains contributes to faster charge conduction.
关键词： TGA-DSC,Mechanical milling,Electrical characterisation,dielectric loss factor,Microstructure
更新于2025-09-23 15:22:29
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[IEEE 2018 31st International Vacuum Nanoelectronics Conference (IVNC) - Kyoto, Japan (2018.7.9-2018.7.13)] 2018 31st International Vacuum Nanoelectronics Conference (IVNC) - High-performance carbon nanotube paste emitters by using the optimal size distribution of SiC nanometer-fillers aggregates
摘要： We improved carbon nanotube (CNT) paste field emitter by optimizing the size distribution of SiC aggregates as inorganic fillers using a novel milling process. The average size of SiC aggregates was reduced to sub-micrometer with a relatively narrow distribution. The CNT paste emitter with the optimized small SiC fillers of 1 μm in D50, by the milling process, exhibited better adhesive property and more uniform surface morphology than that with large fillers from the as-purchased SiC. Furthermore, the optimized small fillers shows superior field emission performance even under a high current density, making the CNT paste technology very useful for a variety of field emission devices.
关键词： milling process,Field emission,Carbon nanotube (CNT),paste formulation,SiC
更新于2025-09-23 15:21:21
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Linear and non linear optical properties of Sb2Se3 thin films elaborated from nano-crystalline mechanically alloyed powder
摘要： Sb2Se3 powder is achieved by mechanical milling of Sb and Se elements. X-ray diffraction analysis indicated the formation of Sb2Se3 orthorhombic phase. The latter finding is confirmed by both X-ray photoelectron spectroscopy characterization and Raman spectroscopy. Magnetic measurement revealed the ferromagnetic character of Sb2Se3 powder. Thin films were obtained by thermal deposition using Sb2Se3 powder as a precursor. Optical measurements carried out on thin films showed a high absorption coefficient and a direct band gap of 1.61 eV. The material has then potential application in photovoltaic conversion. Thin film refractive index dispersion (n) obeys Cauchy dispersion equation. n is investigated and found to comply with Wemple–DiDomenico single oscillator dispersion model. The energy E0 of the oscillator and Ed dispersion energy are derived from the refractive index investigation. Spitzer–Fan model exploitation was allowed to derive the high-frequency dielectric constant ε∞ and the carrier density N/m* ratio. Additionally, Verdet constant V is determined based on the refractive index dispersion study. Furthermore, the nonlinear susceptibility χ(3) as well as nonlinear refractive index are determined for Sb2Se3 thin films. The nanostructure of the material is likely responsible not only for the high nonlinear characteristics but also for the low magnetic character in Sb2Se3.
关键词： Nonlinear optical properties,Optical properties,Thermal deposition,Sb2Se3,Mechanical milling
更新于2025-09-23 15:21:21
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Influence of ion species of AuSi liquid metal alloy source-focused ion beam on SiO2/Si nanopatterning
摘要： This work investigates the influence of the ion source (Au+ and Si+2 ions) of liquid metal alloy source-focused ion beam on the nanopattering. Two sets of SiO2/Si nanopatterns with a width of 450 nm on Silicon on insulator (SOI) substrate are fabricated by 30 keV Au+ and Si+2 ions, respectively. To study this effect, the sputtering yield is calculated using the volume loss method from atomic force microscopy (AFM) profiles obtained for each set. The results of the sputtering yield were compared with theoretical results calculated from Yamamura model for normal incidence for validation. The comparison showed a good agreement between the two results with a relative difference of about 5.3 % obtained using Si+2 ions.
关键词： Liquid metal alloy source-focused ion beam,Milling,Sputtering yield,Nanopattering
更新于2025-09-23 15:21:01
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Application of a suitable particle engineering technique by pulsed laser ablation in liquid (PLAL) to modify the physicochemical properties of poorly soluble drugs
摘要： Several disintegration procedures are well known in the field of pharmaceutical technology to improve the solubility, dissolution rate and bioavailability. Only a few, organic materials were applied for micro/nanoparticle generation by pulsed laser ablation in liquid (PLAL), however in the last decade, several studies presented successful production from different active agents. PLAL could be a non-conventional approach by the preformulation of the drug, as a simple, clean (no additional chemicals are needed) and a rapid wet grinding method. It can be stated about the novelty of the work that a poorly water-soluble meloxicam was milled first time by pulsed laser ablation in liquid, where the effect of three different wavelengths, fluence values (energy density) and polymer type (PVP, PVA, Poloxamer) on the habit, structure, solubility and in vitro properties of the drug were investigated. Nearly spherical amorphous micro- and nanoparticles could be reached in a size range between 60-700 nm. Fourier-transform infrared spectroscopy (FT-IR) was applied to check the purity, secondary interaction and High performance liquid chromatography (HPLC) method was used for the determination of the presence of the meloxicam content and the final yield. The results suggest that laser ablation a useful approach to modify the physicochemical properties of the active agents, introduced a novel preparation method in drug preformulation with improved solubility (from 0.0203 mg/mL to 0.0797 mg/mL), dissolution rate (~85%) and also to produce a suitable intermediate product for traditional and alternative drug administration (e.g. pulmonary, nasal, transdermal).
关键词： physicochemical characterization,novel wet-milling,meloxicam,in vitro dissolution,nanosuspension,laser fragmentation
更新于2025-09-23 15:21:01