Nano-sized Magnesium Research Articles

The effects of MgO nanofiller to the physicochemical and ionic liquid retention properties of PEMA‐MgTf2‐EMITFSI nanocomposite polymer electrolytes

Nanocomposite polymer electrolytes were prepared by dispersing different compositions of nanosized magnesium oxide (MgO) as ceramic nanofiller in poly(ethyl methacrylate) (PEMA)−20 wt% magnesium triflate (MgTf2)−40 wt% 1‐ethyl‐3‐methylimidazolium bis(trifluoromethylsulfonyl) imide (EMITFSI) electrolytes. The role of ionic liquid, magnesium salt, and ceramic nanofiller were visualized by various physical and electrochemical analyses including scanning electron microscopy, thermogravimetric analysis, electrical impedance spectroscopy, and linear sweep voltammetry. The improvement of ionic liquid retention property has been observed by formation of free standing films of PEMA–40 wt% EMITFSI–20 wt% MgTf2 dispersed with MgO. The smoothness of the films’ surface observed in SEM images suggested the amorphous nature of the films. The room temperature ionic conductivity was improved up to 10−5 S/cm by the incorporation of 1 wt% of MgO nanofiller in the polymer electrolytes. Temperature dependent ionic conductivity showed the Arrhenius‐like behavior with ionic conductivity of 3.78 × 10−4 S/cm at 100°C. The polymer electrolyte also showed enhanced electrochemical stability window. POLYM. COMPOS., 39:1500–1506, 2018. © 2016 Society of Plastics Engineers

Electrical and magnetic properties of nano-sized magnesium ferrite

Nano-sized magnesium ferrite was synthesized using sol-gel techniques. Structural characterization was done using X-ray diffractometer and Fourier Transform Infrared Spectrometer. Vibration Sample Magnetometer was used to record the magnetic measurements. XRD analysis reveals the prepared sample is single phasic without any impurity. Particle size calculation shows the average crystallite size of the sample is 19nm. FTIR analysis confirmed spinel structure of the prepared samples. Magnetic measurement study shows that the sample is ferromagnetic with high degree of isotropy. Hysterisis loop was traced at temperatures 100K and 300K. DC electrical resistivity measurements show semiconducting nature of the sample.

A study of nanosized magnesium ferrite particles with high magnetic moment

Nano-sized magnesium ferrite particles were prepared by sol gel combustion synthesis and were either furnace cooled or quenched after calcining at various temperatures ranging from 300 to 800°C. A magnetisation value of 61emu/g was obtained at 5K for sample calcined at 800°C and quenched in liquid nitrogen temperature. This is one of the highest reported values of magnetisation obtained from quenching at such a lower temperature. An estimate of the number of Fe3+ ions on A and B sites was made after applying Néel Model on the magnetisation values measured at 5K. It was estimated that Fe3+ ions segregates out from both sites disproportionately so as to cause a net decrease in the overall moment. The resultant cation distribution is found to be consistent with the coercivity data.

Tuning the Thermodynamic Properties of MgH2 at the Nanoscale via a Catalyst or Destabilizing Element Coating Strategy

Magnesium nanoparticles as small as 7 nm have been synthesized by reducing di-n-buytlmagnesium with lithium and individually coated with elements including Co, Fe, Ni, Si, or Ti for further tuning of their thermodynamic and kinetic properties. Coating was achieved via a transmetalation process whereby precursors were directly deposited at the surface of the magnesium nanoparticles acting as a reducing agent. Studies of hydrogen storage properties showed that these coated magnesium nanoparticles were capable of absorbing hydrogen at low temperatures <140 °C and partially formed transition metal complex hydrides at temperatures above 350 °C. These complex hydrides, assumed to form a shell around the magnesium core, were found to control hydrogen desorption kinetics to some extent. More remarkably, thermodynamics of nanosize magnesium were significantly altered through this coating process. In particular, upon Ni coating a significant decrease of the plateau pressure occurred while achieving fast kinetics. This demonstrates the possibility of tuning both the thermodynamic and kinetic properties of magnesium at the nanoscale and provides a new tool for achieving enhanced hydrogen storage properties for nanosize magnesium.

Effect of Si precursor on structural and catalytic properties of nanosize magnesium silicates

Two Si precursors, inorganic (sodium silicate) and organic (tetraethoxy silane), were used to synthesize magnesium silicate (MgSil) nanomaterials. The effect exerted by the nature of Si precursors on the morphology and structural properties of the samples was studied by chemical analyses, X-ray diffraction, HRTEM, FTIR spectroscopy, XPS, N2 adsorption, solid-state NMR spectroscopy and TPD of CO2 and NH3 techniques. The characterization results show that MgSil-org sample possessed hollow nanospheres which are composed of small platelets and sheets; in contrast, MgSil-inorg sample showed nanotubular structure due to more alkaline nature of the inorganic Si precursor. Additionally, MgSil-org sample have different textural characteristics, acidic and basic properties. MgSil-org sample have higher surface areas, more uniform mesoporous pores, and more number of acidic and basic sites as well as higher activities in transesterification of tributyrin and esterification of palmitic acid with methanol than MgSil-inorg sample. MgSil-org sample is stable and showed excellent reusability for more than five cycles without any loss of activity in transesterification and esterification reactions.

Improvements in the sintering behavior and microwave dielectric properties of fergusonite-type NdNbO4 ceramics

Microwave dielectric ceramics based on fergusonite-type NdNbO4 were prepared by an aqueous sol–gel process. The precursor powders and dielectric ceramics were characterized by X-ray diffraction, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and microwave methods. Highly reactive nano-sized magnesium titanate powders with particle sizes of 20–40nm were successfully obtained at 900°C as precursors. The sintering characteristics and microwave dielectric properties of NdNbO4 ceramics were studied depending on sintering temperatures ranging from 950°C to 1300°C. With the increase of sintering temperature, density, εr and Qƒ values increased and saturated at 1150°C with excellent microwave properties of εr=29.8, Qƒ=49,010GHz and τƒ=53ppm/°C. The correlations of microstructure and dielectric properties for NdNbO4 ceramics were also investigated.

Progress in Preparation of Nano-Sized Magnesium Hydroxide from Concentrated Seawater and Brine

The nanosized magnesium hydroxide is a valuable intermediate for chemical industry materials. This review covers the preparation methods of nanosized magnesium hydroxide using concentrated seawater or brine as raw material, including alkaline method, calcium method, ammonia method and other new methods. Additionally, the development trend of preparing nanosized magnesium hydroxide from concentrated seawater or brine was analyzed.

Explosion characteristics of micron- and nano-size magnesium powders

Explosion characteristics of micron- and nano-size magnesium powders were determined using CSIR-CBRI 20-L Sphere, Hartmann apparatus and Godbert-Greenwald furnace to study influence of particle size reduction to nano-range on these. The explosion parameters investigated are: maximum explosion pressure (Pmax), maximum rate of pressure-rise (dP/dt)max, dust explosibility index (KSt), minimum explosible concentration (MEC), minimum ignition energy (MIE), minimum ignition temperature (MIT), limiting oxygen concentration (LOC) and effect of reduced oxygen level on explosion severity. Magnesium particle sizes are: 125, 74, 38, 22, 10 and 1 μm; and 400, 200, 150, 100, 50 and 30 nm. Experimental results indicate significant increase in explosion severity (Pmax: 7–14 bar, KSt: 98–510 bar·m/s) as particle size decreases from 125 to 1 μm, it is maximum for 400 nm (Pmax: 14.6 bar, KSt: 528 bar·m/s) and decreases with further decrease of particle size to nano-range 200–30 nm (Pmax: 12.4–9.4 bar, KSt: 460–262 bar·m/s) as it is affected by agglomeration of nano-particles. MEC decreases from 160 to 30 g/m3 on decreasing particle size from 125 to 1 μm, its value is 30 g/m3 for 400 and 200 nm and 20 g/m3 for further decrease in nano-range (150–30 nm). MIE reduces from 120 to 2 mJ on decreasing the particle size from 125 to 1 μm, its value is 1 mJ for 400, 200, 150 nm size and <1 mJ for 50 and 30 nm. Minimum ignition temperature is 600 °C for 125 μm magnesium, it varies between 570 and 450 °C for sizes 38–1 μm and 400–350 °C for size range 400–30 nm. Magnesium powders in nano-range (30–200 nm) explode less violently than micron-range powder. However, likelihood of explosion increases significantly for nano-range magnesium. LOC is 5% for magnesium size range 125–38 μm, 4% for 22–1 μm, 3% for 400 nm, 4% for 200, 150 and 100 nm, and 5% for 50 and 30 nm. Reduction in oxygen levels to 9% results in decrease in Pmax and KSt by a factor of 2–3 and 4–5, respectively, for micron as well as nano-sizes. The experimental data presented will be useful for industries producing or handling similar size range micron- and nano-magnesium in order to evaluate explosibility of their magnesium powders and propose/design adequate safety measures.

Electro-Physical Properties of Composites with Nano-Sized Oxides

Polymer matrix nano-sized oxide composites were fabricated by using a modified injection molding in which nano-sized silicon oxide and nano-sized magnesium oxide were contained. Thermal decomposition and evaporation of organic resin depended on the composition of the composites. Nano-sized oxides were uniformly distributed in the composites produced by a modified injection molding combining vacuum degassing and curing at a moderate temperature. 0.2 wt.% of silicon oxide addition to epoxy resin showed the maximum electric field of 3.6, whereas, 2.0 wt.% of magnesium oxide addition was required to reach the same value of electrical field. Both of thermal conductivity and thermal diffusivity of the nano-sized silicon oxide-epoxy composites tended to be increased with silicon oxide content. The relative permittivity of the nano-sized silicon oxide-epoxy composites increased from 5.16 to 5.31 by adding 0.6 wt.% silicon oxide, whereas, magnesium oxide addition up to 2.0 wt.% little influenced to the permittivity. Epoxy matrix-nano-sized silicon oxide composites were more suitable than magnesium oxide for the high performance capacitance.

Optimization of synthesis conditions and the study of magnetic and dielectric properties for MgFe2O4 ferrite

Abstract Nano-sized magnesium ferrites were synthesized by the sol-gel auto-combustion method using a variety of chelating/combustion agents: tartaric acid, citric acid, cellulose, glycine, urea and hexamethylenetetramine. The original purpose of this work was the synthesis of nano-sized magnesium ferrite by using, for the first time, cellulose and hexamethylenetetramine as chelating/combustion agents. Synthesized samples were subjected to different heat treatments at 773 K, 973 K and, respectively 1173 K in air. The disappearance of the organic phase and nitrate phase with the spinel structure formation was monitored by infrared absorption spectroscopy. Spinel structure, crystallite size and cation distribution were evaluated by X-ray diffraction data. The morphology of as-prepared powders was studied using scanning electron microscopy. The magnetic and dielectric properties were studied for the obtained samples.

Influence of Microwave Synthesis Parameters on the Size and Morphology of the Resulting MgAl2O4 Nanoparticles

In the present study, Nano-sized magnesium aluminate powders were successfully synthesized via microwave process based on the reaction between Mg (NO3)2·6H2O and Al (NO3)3·9H2O in distilled water, at various conditions. The products were characterized by X-ray diffraction, scanning electron microscopy (SEM), transmission electron microscopy, photoluminescence (PL) spectroscopy, and EDAX analysis. The effects of different parameters such as reaction time and microwave power on the morphology, particle size, and PL properties of the product were studied by SEM images and the PL.

입자크기 변화에 따른 마그네슘 분진의 폭발특성

We conducted experiments to examine the explosion characteristics of different sizes of micro-sized and nano-sized magnesium dust. These explosion characteristics, such as the maximum explosion pressure and maximum rate of pressure rise, depend on the dust concentration. Changes in the particle sizes do not cause clear differences in the explosion characteristics of nano-sized magnesium dust. However, the explosion characteristic values of micro-sized magnesium dust decrease with increasing particle size. Furthermore, nano-sized magnesium dust showed greater explosion characteristics than micro-sized magnesium dust. The calculated flame propagation velocity showed the same trend as the maximum explosion pressure and maximum rate of the pressure rise. The results of classifying the explosion intensity hazards of a magnesium dust explosion showed that the explosion index increased with the decrease of particle size.

A comparative study of structural, electrical and magnetic properties of magnesium ferrite nanoparticles synthesised by sol-gel and co-precipitation techniques

Nano-sized magnesium ferrite was synthesised using co-precipitation and sol-gel techniques. Structural characterisation was performed using X-ray diffractometer (XRD), Fourier transform infrared (FTIR) spectrometer and scanning electron microscope. XRD analysis reveals the prepared samples are single phasic without any impurity. Particle size calculation shows that the crystallite size of sol-gel prepared samples is 9 nm and co-precipitation sample is 11 nm. FTIR analysis confirmed spinel structure of the prepared samples. Magnetic measurements show that both the samples are ferromagnetic with a high degree of isotropy in co-precipitation derived sample. The frequency dependence of the dielectric constant in the range 100 Hz–20 MHz was also investigated in the temperature range 303–533 K. The results of both the samples followed Maxwell–Wagner model based on interfacial polarisation in consonance with Koops theory.

Preparation and Characterization of Nano-Sized Magnesium Ferrite Powders By a Starch-Gel Process and Corresponding Ceramics

The synthesis and characterization of nano-sized MgFe2O4 by a starch-gel method is described herein. A phase-pure nano-sized MgFe2O4 powder (1a) was obtained after calcining a (MgFe) starch gel at 550 °C. The powder has a specific surface area of 60.6 m2/g and a crystallite size of 9 nm. TEM investigations reveal particles in the range of 7 to 15 nm. The activation energy of the crystallite growth process was calculated as 89 ± 14 kJ/mol. The shrinkage and sintering behaviour of resulting compacts were studied. UV−VIS investigations of the nano-sized powder 1a reveal an optical band gap of 2.38 eV, whereas calcination at 1100 °C (powder 1g) leads to a crystallite size of 129 nm and a band gap of 2.16 eV. Magnetization loops at 300 K and the temperature dependence of both the field-cooled (FC) and the zero-field-cooled (ZFC) agnetization indicate a superparamagnetic behaviour. The blocking temperature for powder 1a was determined as 140 K at a field of H = 500 Oe. We found different saturation magnetizations (Ms) depending on the calcination temperature. Calcination at 550 °C (1a) results in Ms = 20.0 emu/g which increases with calcination temperature to a maximum of 37.7 emu/g for powder 1e calcined at 900 °C. Ceramic bodies sintered between 1450 and 1600 °C exhibit Ms values of 25−28 emu/g. Magnetic investigations at 10 K on powders 1a−1g show hysteresis loops with coercivities up to 950 Oe, remanences to 10 emu/g and Ms values to 50.4 emu/g. Additionally, the nano-scaled powders show a shift of the hysteresis loops.

Effect of Nanosize MgO Addition on the Texture and Mechanical Strength of Bi-2212 Superconductor Compound

The Bi2Sr2CaCu2O8 (Bi-2212) high-temperature ceramic superconductor has the potential to be applied in power system applications due to its low thermal conductivity. However due to the material’s brittle nature and low strength, reinforcement of the Bi-2212 superconductor is necessary for such applications. Due to its high melting point and lower heat capacity, magnesium oxide (MgO) is an excellent candidate as the reinforcement material. In this study, 3% to 8% weight percentage of nanosize MgO powder was added to Bi-2212 superconductor. The Bi-2212/MgO compounds were palletized and heat treated, followed by partial melting and slow-cooling. X-ray diffraction (XRD) was used to study the phases present in the samples. Scanning electron microscopy (SEM) with energy dispersive X-ray (EDAX) analysis was performed to investigate the microstructure, and for identifying the elemental composition of the samples. Electrical resistance and critical current density (Jc) measurements were carried out using the standard four-probe dc method. The degree of texturing of the microstructure was determined using the texture coefficient calculations. In addition, the mechanical strength of the samples was studied by conducting compression test. The results show that the addition of small amount of MgO particles has improved the texture of the Bi-2212/MgO compound. The compound with 5% MgO addition shows significantly higher strength. Addition of higher than 8% of MgO has resulted in highly porous microstructure and subsequently decreasing the strength of the Bi-2212/MgO compound.

Defluoridation of water using nano-magnesium oxide

Nano-sized magnesium oxide (nano-MgO) was investigated for adsorption of fluoride from water. The pure and fluoride adsorbed nano-MgO were characterised by Brunauer–Emmett–Teller, high resolution transmission electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy and energy dispersive X-ray analyses. The surface area of the adsorbent was found to be 92.46 m2/g. Maximum (90%) fluoride removal was obtained with 0.6 g/L dosage of nano-MgO. Fluoride adsorption by nano-MgO was found to be less sensitive to pH variations. Fluoride sorption was mainly influenced by the presence of OH− ion. The presence of other ions studied did not affect the fluoride adsorption capacity of nano-MgO significantly. It has been observed that Freundlich model was better fitted as compared to Langmuir model which indicated the multilayer adsorption of the adsorbent following a pseudo-second order kinetics. Regeneration study showed that 1 M HCl was the best eluent with 95% desorption capacity towards fluoride removal followed by NaOH (2 M) with 25% regeneration of the adsorbent.

Studies on the flame retardant, mechanical and thermal properties of ternary magnesium hydroxide/clay/EVA nanocomposites

Ethylene vinyl acetate copolymer (EVA) nanocomposites were prepared by melt blending of EVA with nano-sized magnesium hydroxide [Mg(OH)2] and modified montmorilonite clay. Nano Mg(OH)2 was synthesized in the laboratory by matrix-mediated growth and controlled technique. Particle size of Mg(OH)2 crystals was performed using X-ray diffraction technique and was found to be in nanometer range. Ternary EVA, clay and Mg(OH)2 nanocomposites were prepared by melt blending using Brabender Plastograph EC. The prepared samples were characterized by flame test, tensile tests and thermogravimetric analysis (TGA). Morphological study of the composites was studied by scanning electron microscopy (SEM). Flame retardant properties of samples were significantly improved in the EVA/clay/Mg(OH)2 nanocomposites without losing its mechanical properties. Ternary system showed better thermal, flame retardant and mechanical properties compared with nanocomposites of EVA filled only with the nano Mg(OH)2.

Layer-by-layer chemical deposition technique for thin film assembly of deposited nano-sized magnesium(II)–5,7-dinitro-8-hydroxyquinolate: Characterization and spectral–optical–electrical properties

Layer-by-layer (LBL) chemical deposition technique was implemented as a low cost and efficient methodology for rapid synthesis and assembly of deposited thin films of nano-sized magnesium(II)–5,7-dinitro-8-hydroxyquinolate complex, Mg[(( NO 2) 2- 8HQ) 2]. The stoichiometry of deposited nano-sized complex was characterized as a 1:2 ratio based on metal to ligand without contribution of the nitro-group. Further structural characterization and identification were also monitored by using Fourier Transform infrared spectroscopy (FT-IR) in order to confirm the possible mode of bonding in the deposited nano-sized Mg[(( NO 2) 2- 8HQ) 2] complex. Thermal gravimetric analysis (TGA) of the ligand and complex were studied and compared to evaluate the possible incorporated thermal stability characteristics. Surface imaging of assembled thin film was performed by using scanning electron microscopy (SEM) to confirm high homogeneity in surface particles distribution with average particle size in the range of 30–50 nm. The absorption spectrum of Mg[(( NO 2) 2- 8HQ) 2] thin film was recorded in the spectral region 250–1000 nm. The optical transmission and reflection spectra of the films have been recorded within the wavelength range 250–2500 nm. The optical parameters of the films, such as absorption index, α, refractive index, n, band gap, E g , dielectric constants, ε 1 and ε 2 and dissipation factor, tan δ, have been also determined. Two activation energies were determined from the temperature dependence of the dark electrical conductivity. Hopping conduction parameters of Mg[(( NO 2) 2- 8HQ) 2] have been calculated by employing the variable range hopping model.

Effect of substitution of K + ions on the structural and electrical properties of nanocrystalline MgAl 2O 4 spinel oxide

Potassium substituted nanosized magnesium aluminates having a nominal composition Mg 1 − x K x Al 2 O 4 where x=0.0, 0.25, 0.5, 0.75, 1.0 have been synthesized by the chemical co-precipitation method. The samples have been characterized by means of X-ray diffraction (XRD), scanning electron microscope (SEM), and dc electrical resistivity measurements. The XRD results reveal that the samples are spinel single phase cubic close packed crystalline materials. The calculated crystallite size ranges between 6 and 8 nm. The behaviour of the lattice constant seems to deviate from the Vegard's law. While X-ray density clearly increases, the bulk density and consequently, the percentage porosity do not exhibit a significant change on increasing the K + content. The SEM micrographs suggest homogeneous distribution of the nanocrystallites in the samples. The dc electrical resistivity exhibits a typical semiconducting behaviour. Substitution of a Mg 2+ ion by a K + ion provides an extra hole to the system, which forms small polaron. Thermally activated hopping of these small polarons is believed to be the conduction mechanism in the Mg 1 − x K x Al 2 O 4 . The activation energy of hopping of small polarons has been calculated and found K + ions content dependent.

Surface Modification and Preparation of High Purity Nanometer Magnesium Hydroxide Using Impinging Stream

High purity nanometer magnesium hydroxide is produced by impinging stream reaction crystallization method using bischofite as feedstock. Effects of operation conditions on the impinging stream of Mg (OH)2 are reported and the control factors of purity are confirmed. The morphology of the powder was characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). Result shows that purity of Mg (OH)2 can reach 99% and the mean size of crystal is 13.5nm. Surface modification of nano-sized magnesium hydroxide using four surface modifiers such as sodium steatite, sodium laurylsulfonate, sodium oleate and sodium silicate were investigated in this paper. The modified magnesium hydroxide has smaller particle size, larger powder contact angle, slower sedimentation velocity, the less in-oil capacity than unmodified sample