High-temperature Ball Milling Research Articles

Preparation of M-type barium ferrite submicron absorbing powder by one-step high-temperature ball milling and its particle structure regulation

This study investigates a simple and rapid process for directly preparing M-type barium ferrite using high-temperature ball milling. By adjusting the rotation speed of the high-temperature ball milling, the morphology and size of the powder can be altered to regulate its electromagnetic properties, aiming for an overall good absorbing effect. The powder’s morphology, agglomeration properties, elemental valence states, and electromagnetic parameters were characterized using SEM, BET, XPS, EDS, and VNA. The results show that as the milling speed increases, the particle size of the M-type barium ferrite decreases, transitioning from the typical hexagonal flake particles to spherical block particles, forming a porous loose structure with richer dielectric loss mechanisms and enhanced electromagnetic wave loss capacity. Electromagnetic loss performance analysis indicates that at a milling speed of 50 rpm, the powder achieves the best electromagnetic loss of −61.16 dB at a matching thickness of 8.77 mm and a microwave absorption bandwidth of 4.1 GHz.

Preparation of microcrystalline graphite/zinc ferrite composites with enhanced and tunable electromagnetic wave absorption using a high-temperature ball milling method

Microcrystalline graphite (MG)/zinc ferrite (ZFO) composites were prepared by a high-temperature ball milling method. The magnetic and microwave absorption properties of MG/ZFO composites were analyzed in the frequency range of 2.0–18.0 GHz. The results showed that MG has a favorable impact on the microwave absorption capacity of ZFO. The composites containing 10 wt% MG had a minimum reflection loss of −62.90 dB, which is almost a factor of 12 higher than for pure ZFO, and their effective absorption bandwidth (EAB, RL<−10 dB) covers frequency range of 5.84–7.92 GHz for a matching thickness of 3.9 mm, and for a matching thickness of 1.8 mm, the EAB covers frequency range of 12.87–17.70 GHz. A probable mechanism of microwave absorption for MG/ZFO composites is based on a synergistic combination of dielectric and magnetic losses. The attractive properties of prepared composites indicate that they are promising and competitive materials for use in microwave absorption.

Sustainable Synthesis of Diamondoid Ethers by High-Temperature Ball Milling

Diamondoids have emerged as promising carbon-based nanomaterial building blocks because of their unique combination of exceptional properties and availability for selective functionalization. Until now, the chemical functionalization of diamondoids was primarily based on solution methods. However, the limited solubility of diamondoid derivatives and their tendency to sublimate at even slightly elevated temperatures made it difficult to prepare more extensive diamondoid scaffolds. Here, we present the first mechanochemical synthesis of several diamondoid ethers differing in the type, size, and number of their hydrocarbon cage subunits. We found that the efficient preparation of these ethers is enabled solely by high-temperature ball milling conditions and does not proceed under ambient conditions. When compared to the conventional synthesis of the same ether derivatives, the calculated green chemistry metrics showed the enormous sustainability benefits of the mechanochemical synthesis. The mechanochemical approach includes shorter reaction times, a green inorganic base, a simplified workup procedure, comparable or superior reaction yields, and the elimination of solvents in the synthesis. Furthermore, crystal structures obtained from single-crystal X-ray diffraction experiments confirmed the molecular structures of the target products and gave insight into their intermolecular interactions in the solid state. From the perspective of the future applicability of these materials in nanotechnology, the cost and sustainability of their preparation are paramount. We demonstrated herein that mechanochemistry is a viable option for this challenge.

Effect of particle morphology on the flowability of HDH Ti powders treated by high temperature ball milling

• Morphology of low cost HDH titanium powder seriously affects its flowability. • A novel technique to improve powder morphology for enhancing its flowability. • Quantitative correlation of powder flowability and morphology was established. • Flowability increases with a smaller fractal dimension and/or larger circularity. The metal powder flowability determined by powder characteristics significantly influences on the final parts manufactured by additive manufacturing (AM). Among the characteristics, the individually effect of morphology on its flowability still is not comprehensively evaluated. In this study, the effect of morphology on the flowability of hydride-dehydrate titanium (HDH Ti) powder treated by high temperature ball milling (HTBM) was investigated systematically using the fractal dimension and shape factors, i.e., circularity, elongation, compactness and convexity. The results of HTBM show that the modified HDH Ti powder with a mass flow rate of 48.1 ± 0.3 s/50 g and the angle of repose (AOR) of 38.88 ± 0.5°. The fractal dimension of powder plays a main role on the flowability, which increase in the decrease of it. The box plot and Pearson correlation coefficient of shape factors indicate that only circularity is strong correlation with flowability, which increases with it. The regression model of flowability expressed with fractal dimension and circularity shows the adjusted R 2 value of 0.991, which is good agreement with the experiment. Taken together, this study provides a general guide to evaluate the powder flowability based on the morphology.

Microwave absorption properties of ZnFe2O4/graphite composites prepared by high-temperature ball milling

ZnFe2O4/graphite composites were synthesized by a high temperature ball milling method. Magnetic properties, electromagnetic response, and microwave absorption properties of the ZnFe2O4/graphite composites with different graphite were investigated by a vibrating sample magnetometer and a vector network analyzer in the 2–18 GHz frequency range. The minimum reflection loss of ZnFe2O4 reached − 19.72 dB at 13.04 GHz at the absorbent layer thickness of 2 mm, and the effective absorption bandwidth (RL<−10 dB) is 3.52 GHz covering a frequency range from 11.44 to 14.96 GHz. The composite with 10 wt% graphite (ZFO/C10) showed excellent electromagnetic impedance matching performance. The minimum reflection loss of ZFO/C10 composite reached − 29.85 dB at 17.52 GHz at the absorbent layer thickness of 1.3 mm, and the effective absorption bandwidth (RL<−10 dB) reached 4 GHz covering a frequency range from 13.12 to 17.12 GHz at a thin thickness of 1.5 mm. Compared to the ZnFe2O4, the ZnFe2O4/graphite composites exhibited better microwave absorbing performance and wider effective absorption bandwidth. A possible microwave absorption mechanism for the ZnFe2O4/graphite composites was proposed.

Electrochemical aptasensor based on Mo2C/Mo2N and gold nanoparticles for determination of chlorpyrifos.

Two-dimensional Mo2C/Mo2N composites were synthesized by high temperature ball milling and used as support materials for fabricating achlorpyrifos (CPF) aptasensor. Gold nanoparticles (Au NPs) were electrodeposited on the surface of aMo2C/Mo2N-modified electrode to connect with the ferrocene (Fc) probe via Au-S bonds. The Fc probe can hybridize with the aptamer probe to form a double-stranded structure. The addition of CPF made the double strands melt and the Fc probe approached the surface of the electrode, thereby resulting in amplification of the electrochemical response. The current response of the aptasensor for detecting CPF in solutions linearly varied from 0 to 400ngmL-1 (with a maximum at 0.98V vs. Ag/AgCl). The Au NPs/Mo2C/Mo2N composites exhibited satisfactory electrochemical behavior due to their excellent electrical conductivity and large surface area. This ultrasensitive aptasensor showed a low limit of detection of 0.036ngmL-1. It was applied to determine CPF in real samples with acceptable recoveries from 94.7 to 116.7%, and the relative standard deviation was from 2.57 to 7.08%.Graphical abstract Schematic diagram of the manufacturing process of the aptasensor. Electrochemical aptasensor based on Mo2C/Mo2N/Au NP composites show excellent performance in detecting CPF.

Effects of mixing processes on the property of the LiFePO4/C cathode material via high-temperature ball milling route

[Formula: see text] samples were obtained via high-temperature ball milling route with different mixing processes. Ultrasonic radiation and wet mechanical agitation were used as mixing processes, respectively. The effects of different mixing processes on the structure and electrochemical performance of [Formula: see text] were investigated. The results exhibited that [Formula: see text] prepared by high-temperature ball milling with ultrasonic irradiation as mixing processes displayed the best rate capability and cycle stability among all the samples: it delivered discharge capacities of [Formula: see text] (0.1 C), [Formula: see text] (5.0 C) and [Formula: see text] (10 C) [Formula: see text], respectively. The discharge capacity was [Formula: see text] [Formula: see text] at 0.5 C-rate over 100 cycles with capacity retention of 95.0%. It is concluded that ultrasonic irradiation is an effective mixing process for the preparation of [Formula: see text] cathode material via high-temperature ball milling route.

Enhanced properties of LiFePO4/C cathode materials co-doped with V and F ions via high-temperature ball milling route

V and F ions co-doped LiFePO4/C (LFP-VF) cathode material is prepared via high-temperature ball milling route. Effects of V and F ions co-doped on the structure, morphology and electrochemical property of LiFePO4 are investigated in this work, and some analysis of X-ray diffraction, scanning electron microscope, transmission electron microscope, charge-discharge tests, electrochemical impedance spectroscopy and cyclic voltammetry are employed. The results confirm that prepared LFP-VF exhibits excellent electrochemical property. The specific capacities are 165.7 (0.1 C), 154.9 (1.0 C) and 124.9 (10 C) mAhg−1. Moreover, over 500 cycles at 1.0 C-rate, the discharge capacity is 148.2 mAhg−1 with a capacity retention rate of 95.7%. Experimental results indicate that the electrochemical performance of LiFePO4 can be greatly enhanced by co-doping with V and F ions.

Effects of Tween 80 dispersant on LiFePO4/C cathode material prepared by sonochemical high-temperature ball milling method

Li-ion batteries have drawn increasing attention because of attractive characteristics such as high operating voltage, high particle density, long cycle life, low self-discharge, and not showing a memory effect. LiFePO4/C cathode material was prepared via a sonochemical high-temperature ball milling method using Tween 80 dispersant. The effects of the Tween 80 on the electrochemical properties of LiFePO4/C were investigated. The experimental results showed that the Tween 80 improved the surface area of LiFePO4/C, and the prepared cathode material showed a better electrochemical performance: it delivered discharge capacities of 159.0 mAh g−1 at 0.1 C and 110.4 mAh g−1 at 10 C, which were higher than for Tween 80-free samples. Moreover, the discharge capacity was 119.6 mAh g−1 at a rate of 5.0 C over 100 cycles while the capacity retention was 94.2%.

Enhancement of Nb-doping on the properties of LiFePO4/C prepared via a high-temperature ball milling–based method

Li1-xNbxFePO4/C has been prepared by wet mechanical stirring–assisted high-temperature ball milling route. Wet mechanical stirring was considered to be effective to promote the dispersion of the precursor in solution. Effect of Nb-doping amount was explored for enhancing the properties of LiFePO4/C. The experimental results showed that Li0.98Nb0.02FePO4/C displayed a well-crystallized structure of LiFePO4 and excellent electrochemical performance. It exhibited that the initial discharge capacities were 164.9 mAhg−1 at 0.1 C and 118.8 mAhg−1 at a rate of 10 C, respectively. Moreover, it achieved a specific capacity of 114.3 mAhg−1 at a 10 C rate after 200 cycles with a capacity fading rate of 3.8%. Thus, Nb-doping is recommended as a beneficial technique to improve the electrochemical properties of LiFePO4.

A facile ultrasound assisted high temperature ball milling synthesis of LiFePO4/graphene with enhanced electrochemical performance

LiFePO4/graphene (LiFePO4/G) cathode material was prepared by a facile ultrasound assisted high temperature ball milling method. Ultrasound assisted was found to be effective to promote the dispersing of the precursor in solution. Physical and electrochemical properties of LiFePO4/G were studied. The results exhibited that graphene combined with the LiFePO4 clusters giving rise to a conductive network. LiFePO4/G displayed a well-crystallized LiFePO4 structure and excellent electrochemical performance. The initial discharge capacities of LiFePO4/G were 162.8, 156.8, 151.9, 145.8, 137.5 and 121.6 mAhg−1 at rates of 0.1, 0.5, 1.0, 2.0, 5.0 and 10 C, respectively. Moreover, at 0.1 C-rate, the capacity was 160.4 mAhg−1 over 100 cycles with a capacity retention of 98.5%. It is concluded that graphene is a conductive additive which can enhance the electrochemical properties of LiFePO4.

Effect of F-doping on the properties of LiFePO4-x/3Fx/C cathode materials via wet mechanical agitation-assisted high-temperature ball milling method

LiFePO4-x/3Fx/C (x = 0, 0.03, 0.06, 0.09) were obtained via wet mechanical agitation-assisted high-temperature ball milling method. XRD, SEM, TEM, galvanostatic testing, EIS, and CV were applied to study the effects of the amount of F-doping on the structure and electrochemical performance of LiFePO4/C. The results showed that LiFePO3.98F0.06/C displayed the best electrochemical performance: its initial discharge capacities were 162.6 (0.1 C), 156.6 (0.5 C), 150.2 (1.0 C), 144.5 (2.0 C), 131.6 (5.0 C), and 115.8 mAhg−1 (10 C), respectively. Moreover, its discharge capacity was 110.5 mAhg−1 over 100 cycles with a capacity retention rate of 95.4% at 10 C-rate. F-doping is suggested to be an effective approach to enhance the electrochemical performance of LiFePO4.

Modification effect of high-temperature ball milling condition to iron oxide corrosion protective coating

Abstract Grinding time and grinding rotation speed of iron oxide surface modification using high-temperature ball milling method were studied on the basis of the optimal grinding temperature. The modification effect of iron oxide improved with the grinding time extended from 1 h to 5 h and with the grinding rotation speed increased from 300 r/min to 516 r/min. The content of iron oxide to the corrosion performance of epoxy coatings was also investigated. The results show that the modified iron oxide can improve the corrosion performance of epoxy coating, and the optimal content of modified iron oxide in epoxy coating is about 10 wt.%.

Synthesis of LiMn2O4 via high-temperature ball milling process

ABSTRACTSpinel LiMn2O4 powder was prepared by a novel process of high-temperature ball milling. For comparison, the spinel LiMn2O4 powder was also synthesized by the traditional method of solid state reaction. It was found that high-temperature ball milling significantly decreased the synthesis temperature and time. LiMn2O4 with pure spinel phase could be successfully synthesized only by 2 h high-temperature ball milling at 500°C and 600°C. However, pure spinel LiMn2O4 could not be completely synthesized by 2 h solid state reaction at 800°C. The LiMn2O4 particles prepared by high-temperature ball milling are nano-sized (<100 nm) and much smaller than that prepared using solid state reaction. The electrochemical tests results indicated that the as-synthesized LiMn2O4 by 2 h high-temperature ball milling at 600°C showed a favorable initial discharge capacity of 124.2 mAh g−1 at current rate of 0.1 C and still retained a capacity of 119.8 mAh g−1 at 0.1 C after 80 continuous cycles from 0.1 to 2.0 C.

Pretreatments-assisted high temperature ball milling route to Li4Ti5O12 and its electrochemical performance

Spinel Li4Ti5O12 was synthesized via a high temperature ball milling route with the assistance of ultrasonic dispersion, mechanical agitation, and glucose monohydrate solid phase dispersant, respectively. The crystal structures and the electrochemical properties of the as-prepared Li4Ti5O12 were systematically investigated. The results showed the as-prepared samples were highly-crystalline and exhibited high capacities and good cycle stabilities. The initial discharge capacity of sample C5 mixed with 5% glucose monohydrate reached 187.003mAh/g at 0.1C-rate, and retained at 183.509mAh/g after 20 cycles. This facile solid phase dispersant-assisted high temperature ball milling method could be an excellent way to synthesize Li4Ti5O12 for practical applications.

Using high-temperature mechanochemistry treatment to modify iron oxide and improve the corrosion performance of epoxy coating – I. High-temperature ball milling treatment

This study achieved the surface modification of iron oxide pigment by using epoxy resin with high-temperature ball milling device. The compatibility of the modified iron oxide with the epoxy resin and the corrosion protection of epoxy coatings containing the modified iron oxide were investigated. The results show that the epoxy resin molecules grafted on the surface of the iron oxide, and the improved compatibility of the modified iron oxide with the epoxy resin lessens the interface defects between the iron oxide particles and the epoxy resin and enhances the corrosion resistance of the coating.

Preparation of red-emitting phosphor (Y,Gd)BO3:Eu3+ by high temperature ball milling

The red-emitting phosphor (Y,Gd)BO3:Eu3+ was prepared by high temperature ball milling in order to improve the color purity and decrease the calcining temperature. The phosphor was characterized by X-ray diffraction (XRD), scanning electron microscope (SEM) and luminescence spectra. The results showed that the phosphor(Y,Gd)BO3:Eu3+ could be obtained at 600 °C, i.e. at a much lower temperature in contrast to conventional solid state reaction. The phosphor can be effectively excited by VUV radiation at 147 nm. In its emission spectrum, the strongest peak at 628 nm correlating to red emission was ascribed to the forced electric dipole transition 5D0→7F2 of Eu3+ ions. Its chromaticity coordinates (CIE) were calculated to be x=0.65, y=0.35. Significantly, the intensity ratio of Y0.65Gd0.1Eu0.25BO3 phosphors of the red (5D0→7F2) to the orange (5D0→7F1) transition (R/O value) is 2.39, which is higher than 2.15 of the phosphor prepared by solid state reaction. The color purity was significantly improved. The particles with narrow distribution range and spherical morphology were approximately 200 nm in size. The luminescent properties of the (Y,Gd)BO3:Eu3+ sample with 25 mol% doping concentration of Eu3+ were optimal. Therefore, high temperature ball milling is of help to (Y,Gd)BO3:Eu3+ phosphor for improving the color purity and decreasing the calcining temperature in the future applications.

Synthesis of LiFe&lt;sub&gt;0.97&lt;/sub&gt;Nb&lt;sub&gt;0.03&lt;/sub&gt;PO&lt;sub&gt;4&lt;/sub&gt;C by High Temperature Ball Milling

LiFe0.97Nb0.03PO4/C was synthesized by the method of high temperature ball milling (HTBM), using raw materials including Fe2O3, LiH2PO4, Nb2O5and glucose, which was used as reductant and carbon source. The samples were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM) and electrochemical performance test. The sample synthesized at 700 °C for 8h showed excellent electrochemical properties, with the discharge capacity as high as 140 mA•h/g at 0.1C rate respectively. The sample also showed an excellent capacity retention as there was no significant capacity fade after 10 cycles.

Structure Analysis and Magnetic Properties of Nano-Sized NbxNiyZn1−x−yFe2O4 Powders Formed by Combustion Synthesis and Mechanical Milling

Nano-sized Nb(x)Ni(y)Zn1-x-yFe2O4 ferrites with average particle size of less than 100 nm were prepared by using self-propagating high-temperature synthesis and mechanical ball milling. Average ferrites size of the SHS products were less than about 100 nm after 20 minutes mechanical milling. The average combustion temperatures and the combustion propagating rates were in the ranges of 1145 to 1543 K and 4.1 to 7.2 mm/s, respectively. Rietveld refinement of the pattern converged to good agreement (chi2 = 4.87). Final product of SHS was Nb0.13Ni0.41Zn0.46Fe2O4 with Fd3m structure and the lattice parameter of 0.83623 nm. Maximum magnetization (Ms), residual magnetization (Mr), coercive force (iHc) and susceptibility of the Nb0.013Ni0.41Zn0.46Fe2O4 ferrites formed at the oxygen pressure of 0.25 MPa were 12.30 Wb/m2 Kg, 1.57 Wb/m2 Kg, 6321 A/m, and 0.02 m3/Kg, respectively. Niobium addition to nickel-zinc ferrites resulted in increasing Ms, Mr and iMc about 59%, 78% and 387%, respectively. Neutron diffractometry revealed that the variation of magnetic properties was related to non-stoichiometric number and oxygen position of the niobium-nickel-zinc ferrites due to the competitive reduction reaction among niobium, nickel and zinc oxides.

New method for preparation of luminescent lanthanide materials BaMoO4:Eu3+

<title/>A new solid state synthesis method, called the high temperature ball milling (HTBM) method, was developed for the production of high performance single phase BaMoO4:Eu3+ phosphor powders. In this work, X-ray diffraction (XRD) and scanning electron microscope (SEM) techniques and emission spectra test were used to characterise the obtained phosphor powders. Compared with chemical precipitation method often employed for the synthesis of phosphors interested, the HTBM method not only decreased the solid synthesis temperature from 1000 to 600°C, but also enhanced the emission intensity of yielded phosphors in the red light region by 48%. Additionally, BaMoO4:Eu3+ red phosphor powders produced by the HTBM method have relatively small and more uniform particle sizes. The HTBM method thus opens a new path to solid state synthesis, especially for the materials difficult to obtain at low temperature.