Increase Of Mg Content Research Articles

Revolution and Control of Fe-Al-(Mg, Ti)-O Oxide Inclusions in IF Steel during 260t BOF-RH-CC Process

The evolution of inclusions that contain Al, Mg, and Ti was studied through industrial-grade experiments. Field emission scanning electron microscopy, energy dispersive spectrometry, inductively coupled plasma atomic emission spectrometry, and FactSage software were used to analyze the evolution mechanisms of inclusions in Al-killed titanium alloyed interstitial free (IF) steel. The research found that the evolution of inclusions during the smelting process of IF steel is results in ‘large sphere-like SiO2-CaO-FeO-MgO-MnO’ and ‘small cluster spherical FeO-MnO’ change to cluster-like Al2O3 and irregular MgO·Al2O3, then change to Al2O3·TiOx and Al2O3, and finally change to Al2O3. It is difficult for Al2O3·TiOx to stably exist in the IF molten steel. It is the key to extend the holding time properly after Ruhrstahl Heraeus (RH) to ensure the removal of Al2O3 inclusion. With the increase of Mg content, the change path of MgAl2O4 inclusion in IF steel is that Al2O3 changes to MgO·Al2O3, and finally changes to MgO. It is difficult to suppress MgO·Al2O3 spinel formation by controlling the oxygen in the steel, but Ca can modify part of the MgO·Al2O3 spinel inclusions during RH refining. In order to ensure the removal of 6–10 μm inclusions, the holding time is suitable for 19–42 min.

Effect of Mg-substitution in Co–Ni-Ferrites: Cation distribution and magnetic properties

We report the changes in structural and magnetic properties of spinel ferrites by doping magnesium, a cation that occupies the tetrahedral site, in place of nickel that occupies the octahedral site in Co–Ni ferrite (Co0.5Ni0.5Fe2O4) ceramic. We synthesized nano-crystalline Co0.5MgxNi0.5-xFe2O4 (x = 0, 0.1, 0.2, 0.3, 0.4) ceramic powder samples by sol-gel autocombustion method followed by calcination at 600 °C in air for 2 h. X-ray diffraction (XRD) patterns of the synthesized samples confirm crystalline single-phase spinel structure with cubic symmetry (Fd-3m space group). Refined structural parameters were calculated through Rietveld refinement of the XRD patterns. The crystallite sizes for all the samples were found to be in the range of 30–38 nm. Porous morphology of the samples was clearly observed from the scanning electron micrographs. The FTIR spectra confirm the formation of the spinel phase through the observed vibrational bands assigned to the tetrahedral (Td) and octahedral (Oh) interstitial complexes in the spinel structure. Magnetic measurements indicate a decrease of saturation magnetization (Ms) with increase in concentration of Mg. Room temperature 57Fe-Mössbauer spectroscopy in association with XRD results confirmed the ferrimagnetic nature of the samples with Mg occupying the Td site, Ni occupying the Oh site and Co occupying both the Td and Oh sites in the ratio of 2:3. Using the cation occupancies, Néel's two sublattice model could explain the observed magnetic properties in our Mg doped Co–Ni ferrite samples.

Increasing the Magnesium Concentration in Various Dialysate Solutions Differentially Modulates Oxidative Stress in a Human Monocyte Cell Line.

Oxidative stress is exacerbated in hemodialysis patients by several factors, including the uremic environment and the use of dialysis fluids (DFs). Since magnesium (Mg) plays a key role in modulating immune function and in reducing oxidative stress, we aimed to evaluate whether increasing the Mg concentration in different DFs could protect against oxidative stress in immunocompetent cells in vitro. Effect of ADF (acetate 3 mM), CDF (citrate 1 mM), and ACDF (citrate 0.8 mM + acetate 0.3 mM) dialysates with Mg at standard (0.5 mM) or higher (1, 1.25, and 2 mM) concentrations were assessed in THP-1 monocyte cultures. Reactive oxygen species (ROS) and malondialdehyde (MDA) levels were quantified under basal and uremic conditions (indoxyl sulfate (IS) treatment). Under uremic conditions, the three DFs with 0.5 mM Mg promoted higher ROS production and lipid damage than the control solution. However, CDF and ACDF induced lower levels of ROS and MDA, compared to that induced by ADF. High Mg concentration (1.25 and/or 2 mM) in CDF and ACDF protected against oxidative stress, indicated by reduced ROS and MDA levels compared to respective DFs with standard concentration of Mg. Increasing Mg concentrations in ADF promoted high ROS production and MDA content. Thus, an increase in Mg content in DFs has differential effects on the oxidative stress in IS-treated THP-1 cells depending on the dialysate used.

Organic fertilizer application and Mg fertilizer promote banana yield and quality in an Udic Ferralsol.

Low soil fertility, high rates of fertilizer application and low yields and quality are major problems in intensive banana production in acid soils of south China. A field experiment was carried out for two years to determine the optimum management practices for maximizing soil health and banana yield and quality. The experiment consisted of an unamended control (CK) and lime (Lime), calcium magnesium phosphate fertilizer (CMP), organic fertilizer (OF), and organic fertilizer combined with calcium magnesium phosphate fertilizer (OFC) treatments. Soil nutrient concentrations and banana shoot biomass, nutrient uptake, yield and fruit quality were determined. Application of lime and CMP was found to increase soil pH and nutrient availability and increase banana yield. Yet, the banana biomass and yields in the Lime and CMP treatments were significantly lower than those in the OF and OFC treatments in which soil organic matter (SOM) content increased. Total soluble solids and soluble sugar contents increased in the CMP and organic fertilizer treatments. A consistent increase in Mg concentrations in banana leaves over the two years in the CMP and organic fertilizer treatments indicates that Mg is essential for banana production and quality. Short-term adding Mg from banana corms increased total soluble solids and soluble sugar content. The application of organic fertilizer combined with CMP or Mg solution is therefore recommended to increase soil health and promote the yield and quality of banana in intensively managed plantations in subtropical regions.

The Impact of Mg Concentration, Microwave Irradiation Time, and Sintering on Magnesium-Hydroxyapatite Synthesis

Hydroxyapatite synthesis is an inorganic compound that makes up the hard tissues of the human body such as bones. This study aims to substitute Magnesium (Mg) ions, which have an important role in the structure and function of the human body, in Calcium (Ca) ions from Hydroxyapatite. MgHA crystals are synthesized by mixing a solution of diammonium hydrogen phosphate and magnesium hydroxide into a calcium hydroxide solution which is then irradiated with microwaves, with variations in the concentration of Mg and irradiation time. From the XRD results show that along with the increase in Mg concentration and irradiation time the lattice parameter values a and c are reduced by 0.03 in lattice a and 0.01 in lattice c. The increase in irradiation time is proportional to the increase in crystal size (L) and crystallinity index (CI). At t = 35 it is found L = 19.08 nm and CI = 0.14. The increase in Mg concentration is proportional to the increase in crystal size and crystallinity index, the increase in Mg concentration above 0.6 M shows the presence of saturation in the binding process of Mg in the apatite structure. The sintering process at 900ºC increases the crystal size value from 19.08 nm to 52.09 nm and the crystallinity index from 0.14 to 2.97. Morphology of MgHA produces rod-shaped particles with agglomeration caused by a large amount of Mg content in apatite.

Functional element coatings on Ti-alloys for biomaterials by plasma electrolytic oxidation

In this study, functional element coatings on Ti-alloys for biomaterials by plasma electrolytic oxidation (PEO) were studied using different experimental techniques. Si- and Mg-doped hydroxyapatite films were formed on the Ti–6Al–4V alloy via anodization at an applied DC voltage of 280 V for 3 min. The chemical composition of the surface layers was examined using energy-dispersive X-ray spectroscopy mapping and line-profile analysis. The morphology of the surface was observed using field-emission scanning electron microscopy. The phase composition was determined using X-ray diffraction. The size of the micro-pore formed on the Ti–6Al–4V alloy decreased, and the area occupied by the micro-pores decreased with increasing Mg concentration. With the increase in Mg concentration, the number of small micro-pores on the PEO films formed on Ti–6Al–4V alloys increased, whereas the number of large micro-pores decreased. The number of circular particles formed in the pores and on the exterior surface increased with increasing Mg concentration. The thickness of the PEO film was approximately 1.94–2.03 μm and the coating elements Ca, P, Si, and Mg were uniformly distributed throughout the PEO film. The anatase and hydroxyapatite(HA) peaks shifted slightly from the original anatase and pure HA peaks as the Mg concentration increased.

Enhanced efficiency of quantum dot light-emitting diode by sol-gel derived Zn1-xMgxO electron transport layer

Abstract In this study, sol-gel derived Zn1-xMgxO (ZMO) is proposed as an electron transport layer (ETL) for solution-processed quantum-dot light-emitting diodes (QLEDs). It is demonstrated that the increase of Mg content in Zn1-xMgxO films from 0% to 20% causes a dramatic suppression of electron current, which is attributed to the lifting of conduction band minimum and reduction of electron mobility. As a result of Mg-doping, the charge carrier balance might be achieved in the QLED with the Zn0.85Mg0.15O layer resulting in maximum external quantum efficiency of 5.74% and current efficiency of 18 cd A−1, which are over 3-fold higher than in the case of the device with ZnO layer. Improved device performance is further explained by reduced exciton quenching at QDs/ZMO interface, which is confirmed by time-resolved PL experiments. Obtained results indicate that sol-gel derived ZMO is a promising candidate for ETL in quantum-dot based optoelectronic devices.

MgxZn1−xO Prepared by the Sol–Gel Method and Its Application for Ultraviolet Photodetectors

MgxZn1−xO (x = 0.05, 0.10, 0.15, and 0.20) films prepared on quartz substrates by the sol–gel method were characterized and studied. According to scanning electron microscopy and x-ray diffraction data, the MgxZn1−xO films exhibited a particle-stacking morphology and a hexagonal wurtzite crystal structure. An increase in Mg content led to an obvious increase in particle size. However, a weakening of the hexagonal wurtzite structure was observed and indicated the transition of the MgxZn1−xO crystal structure, which was also confirmed by the Raman spectra results. An increase in bandgap energy from 3.38 eV to 3.55 eV with increased Mg content was determined from the transmittance spectra. Ultraviolet photodetectors based on MgxZn1−xO with interdigital electrodes were then fabricated. Dark current as low as 10 pA (corresponding to 5 nA/cm2) under bias of 10 V was achieved. A blueshift of the peak wavelength and cutoff wavelength was observed with increasing Mg content. Noise equivalent power as low as 2 × 10−15 W was achieved, detectivity was found to be about 1.2 × 1011 cm Hz1/2/W, and quantum efficiency was nearly 100%, which was related to the photoconductive gain.

Probing Heterogeneity in Bovine Enamel Composition through Nanoscale Chemical Imaging using Atom Probe Tomography

ObjectiveThe aim of this study was to determine the heterogeneity in chemical composition of bovine enamel using atom probe tomography, and thereby evaluate the suitability of bovine enamel as a substitute for human enamel in in vitro dental research. DesignEnamel samples from extracted bovine incisor teeth were first sectioned using a diamond saw and then milled into needle-like samples (<100 nm diameter) by focused ion beam (FIB) coupled with a scanning electron microscope (SEM). These samples were analyzed in the atom probe to acquire three-dimensional (3D) images and quantify the atomic chemistry and distribution in bovine enamel. ResultsFor the first time, the atomic-level composition and clustering of major constituents and impurities within bovine enamel were determined and imaged. We discovered that the chemical composition of bovine enamel is spatially inhomogeneous at the atomic scale. The average bulk Ca/P ratio, ∼1.4, was in agreement with previously reported literature values from alternative conventional methods. When assessed locally at the atomic scale, the Ca/P ratio varied between 1.1 and 2.03. We also discovered that the Mg impurities were significantly segregated throughout the enamel, and such clustering influenced the variation of Ca/P ratios. The increase in Mg concentrations, near the Mg clusters, correlated with increased Ca and decreased P concentrations. ConclusionThe presented findings of variability in local composition should be taken into account when interpreting dental research results from bovine enamel.

Effects of Cu and Mg on thixoformability and mechanical properties of aluminium alloy 2014

Abstract Thixoforming is a processing method that deforms metal in a semisolid state. The advantages of this process include the production of parts with good surface finish, fine microstructures and superior mechanical properties. However, the process mostly produces parts from aluminium cast grades, thereby not fully utilising the true potential of this method. Hence, thermodynamic modelling can be used to formulate alloy compositions that favour this processing method. Here, the effects of reducing copper content and increasing silicon and magnesium contents on the thixoformability of aluminium alloy 2014 were presented. The work consists of both the modelling and experimental validation. Results showed that by increasing Si and decreasing Cu content in the alloy, the solidification interval temperature was decreased and the temperature working window between the stipulated liquid fractions was widened, two of the characteristics favouring the process. A high solid-solution temperature employed resulted in the dissolution of unfavourable Mg2Si compound. An increase in Mg content used also resulted in the formation of the compact π-Al8FeMg3Si6 phase and the decrease in the amount of the sharp and plate-like structure of the β-Al5FeSi phase, improving the strength of the modified alloy. Subsequent T6 heat treatment successfully further increased the strength of the modified alloy.

Effect of Mg on the Evolution of Inclusions and Formation of Acicular Ferrite in La–Ti‐Treated Steels

The size distribution and compositions of inclusions and microstructures in steels with different Mg contents are systematically investigated. The results show that Mg treatment modified and refined the inclusions. With Mg addition, the dominant inclusions in the samples evolve from LaAlO3 with MnS to a Mg‐enriched core enwrapped by a La‐enriched shell with MnS. While the Mg content increases from 11 to 66 ppm, the core changes from MgO·Al2O3 to MgO, and the shell develops from LaAlO3 to La2O2S. With the increase in Mg content from 0 to 44 ppm, the number density of effective inclusions is improved, and the proportion of acicular ferrite (AF) increases from 15% to 39%. However, the AF fraction decreases to 16% due to the relatively low amount of effective inclusions in the sample Mg3 with 66 ppm Mg.

Mechanism of Improving Heat-Affected Zone Toughness of Steel Plate with Mg Deoxidation after High-Heat-Input Welding

In the present study, the mechanism of improving HAZ toughness of steel plate with Mg deoxidation after the simulated welding with the heat input of 400 kJ/cm was investigated through in situ observation, characterization with SEM-EDS and TEM-EDS, and thermodynamic calculation. It was found that intragranular acicular ferrite (IAF) and polygonal ferrite (PF) contributed to the improvements of HAZ toughness in steels with Mg deoxidation. With the increase of Mg content in steel, the oxide in micron size inclusion was firstly changed to MgO-Ti2O3, then to MgO with the further increase of Mg content in steel. The formation of nanoscale TiN particles was promoted more obviously with the higher Mg content in the steel. The growth rates of austenite grains at the high-temperature stage (1400~1250 °C) during the HAZ thermal cycle of steels with conventional Al deoxidation and Mg deoxidation containing 0.0027 and 0.0099 wt% Mg were 10.55, 0.89, 0.01 μm/s, respectively. It was indicated that nanoscale TiN particles formed in steel with Mg deoxidation were effective to inhibit the growth of austenite grain. The excellent HAZ toughness of steel plates after welding with a heat input of 400 kJ/cm could be obtained by control of the Mg content in steel to selectively promote the formation of IAF or retard the growth of austenite grain.

Effects of Mg content on keyhole behaviour during deep penetration laser welding of Al-Mg alloys

This paper concerns the effects of Mg content on keyhole behaviours during the laser welding process of 5754, 5083 and 5A06 Al-Mg alloys. The features of the vapour plume and keyhole area are extracted from high-speed images with image processing methods. The increase of Mg content leads to the increase of hydrodynamic pressure caused by metal evaporation and decrease of surface tension acting on the keyhole wall. The strong metal evaporation and decrease of surface tension help the formation of keyhole, which both result in a large size of keyhole with deep penetration and low frequency of keyhole collapse. However, the impact of metal vapour could be enhanced by the increase of evaporation and the decrease of both surface tension and viscosity, which leads to the frequent generation of swelling at the rear weldpool and poor formation of the weld bead.

Synthesis and characterization of magnesium oxide nanoparticle-containing biochar composites for efficient phosphorus removal from aqueous solution

The effective removal and recovery of phosphorus from aquatic environments are highly important for successful eutrophication control and phosphorus recycling. Herein, we prepared biochar containing MgO nanoparticles (MgO-biochar) by fast pyrolysis of MgCl2-impregnated corn stalks, probed its phosphate adsorption performance. Through the fast pyrolysis, the MgCl2 promoted the formation of micropores and mesoporous, and decomposed into MgO nanoparticles with the size smaller than 100 nm. The adsorption experiments showed that the adsorption property increased with the increase of Mg content, and had a strong correlation with the external surface area. And the phosphate adsorption was well described by the Langmuir-Freundlich model (maximum adsorption capacity was determined as 60.95 mg P/g). Kinetic analysis and characterization analysis of MgO-biochar for different adsorption time indicated that phosphate adsorption onto MgO-biochar was mainly controlled by rapid binding to the external surface (about 75% of the equilibrium adsorption amount), and the uptake rate was limited by the slow diffusion of phosphate into the biochar interior (about 25% of the equilibrium adsorption amount). The results suggested that the synthesized MgO-biochar with enough MgO active site dispersed on a higher external surface can be used as a potential adsorbent for phosphate removal and recovery from aqueous solution.

Optical properties tuning by sodium and magnesium co-doping in ZnO thin films for optoelectronic applications

Sodium (Na) and magnesium (Mg) co-doped ZnO thin films (Na: Mg: ZnO) for a fixed 8 mol% Na concentration along with varied 1, 2 and 3 mol% Mg concentrations have been deposited on conducting fluorine-doped tin oxide (FTO) coated glass substrates using the sol-gel spin coating method. The synthesized films were annealed at 500 °C for 1 h. The structural and optical properties of annealed thin films were studied using an x-ray diffractometer and UV–visible spectrometer, respectively. Structural degradation followed by a linear red shift of the optical band gap was observed due to an increase in Mg concentration. Reflectance was decreased for higher Mg concentrations making the thin films suitable for solar cell window material. The refractive index was improved for higher Mg concentrations. Refractive index variation with Mg co-dopant concentration makes these films a suitable candidate for integrated optics. Urbach tail width increased upon increasing Mg concentrations which indicate overall increment of disorder at higher Mg concentrations.

Effect of Mg Content on Microstructure and Properties of Al-Mg Alloy Produced by the Wire Arc Additive Manufacturing Method.

In this study, an Al–Mg alloy was fabricated by wire arc additive manufacture (WAAM), and the effect of Mg content on the microstructure and properties of Al–Mg alloy deposits was investigated. The effects on the deposition surface oxidation, geometry, burn out rate of Mg, pores, microstructure, mechanical properties and fracture mechanisms were investigated. The results show that, when the Mg content increased, the surface oxidation degree increased; a “wave”-shaped deposition layer occurred when the Mg content reached 8%. When the Mg content was more than 6%, the burning loss rate of the Mg element increased significantly. With the increase of Mg content, the number of pores first decreased and then increased, and the size first decreased and then increased. When the Mg content reached 7% or above, obvious crystallization hot cracks appeared in the deposit bodies. When the Mg content increased, the precipitated phase (FeMn)Al6 and β(Mg2Al3) increased, and the grain size increased. When the Mg content was 6%, the comprehensive mechanical properties were best. The horizontal tensile strength, yield strength and elongation were 310 MPa, 225 MPa and 17%, respectively. The vertical tensile strength, yield strength and elongation were 300 MPa, 215 MPa and 15%, respectively. The fracture morphology was a ductile fracture.

Effect of Mg addition on microstructure and mechanical properties of Al-Si-Cu-Fe alloy with squeeze casting

In this work, the Al-10Si-2.5Cu-0.8Fe alloy was used as the base alloy to squeeze casting with different content Mg-10Al master alloy addition. The effects of microstructure and mechanical properties were investigated by XRD, OM, SEM, and tensile test analysis. The results show that with the increase of Mg addition, the morphology of eutectic Si in the alloy changes from strip to fiber and the size is obviously reduced. Al8Mg3FeSi6 phase in the microstructure gradually grows, and the splitting effect on the matrix structure is increased. The tensile strength and elongation of the alloy increased first and then decreased with the increase of Mg content. When the Mg content is 1.38%, the tensile strength of the alloy reached a maximum of 289 MPa and the elongation is 2.24%. The hardness of the alloy gradually increases. When the Mg content is 2.51%, the hardness reaches 121.8 HV. The cleavage surface in the fracture becomes fine with the increase of Mg content, the number of dimples increases, and the fracture mode transitions from quasi-cleavage fracture to brittle fracture.

Effect of Mg doping concentration of electron blocking layer on the performance of GaN-based laser diodes

Performance of InGaN-based laser diodes (LDs) with different Mg concentrations of electron blocking layer (EBL) is investigated by simulation and experimental methods. It is found from the simulation results that the threshold current decreases and slope efficiency increases, when the Mg concentration of EBL increases from 2 × 1018 to 6 × 1019 cm−3; it is attributed to the suppression of the leakage of electrons and the enhancement of the injection of holes due to the variation of potential barrier for them as the increase of Mg concentration of EBL. These simulation results agree well with the experimental ones, when the Mg concentration of EBL is lower than 7.5 × 1018 cm−3. However, it deteriorates when the Mg concentration increases to 1.2 × 1019 cm−3. It may be due to the increase of the absorption loss of LDs.

Structural, mechanical and optoelectronic features of cubic MgxCd1−xS, MgxCd1−xSe and MgxCd1−xTe semiconductor ternary alloys: Theoretical investigations using density functional FP-LAPW approach

Structural, mechanical and optoelectronic features of cubic MgxCd1−xS, MgxCd1−xSe and MgxCd1−xTe are calculated using density functional FP-LAPW approach. Exchange-correlation potentials are calculated for structural and mechanical properties with WC-GGA and optoelectronic properties with mBJ, EV-GGA and PBE-GGA schemes. Each ternary specimen exhibits thermodynamic stability. In each system, nonlinear decrease in each of the a0, B0, C11, C12 and C44 with increase in Mg-concentration x is observed. Each specimen exhibits elastic anisotropy, ductility and dominancy of ionic bonding. Each binary and ternary specimen is a direct (Γ-Γ) band gap (Eg) semiconductor. In each system, calculated Eg increases nonlinearly with increase in x. Optical excitations from chalcogen-p to Cd-6s, 5p and Mg-4s, 4p contribute intense peaks in each ε2(ω) spectra. Nature of variation of zero-frequency limit in each of the ε1(ω), n(ω) and R(ω) spectra and critical point in each of the ε2(ω), k(ω), σ(ω) and α(ω) spectra with x is opposite and similar, respectively, to the nature of variation of Eg with x.

Band gap tuning, n-type to p-type transition and ferrimagnetic properties of Mg doped α-Fe2O3 nanostructured thin films

Fe2O3 thin films have a wide range of applications in gas sensing, biosensing, optoelectronics, spintronics, etc. In this paper, pure and Mg doped Fe2O3 thin films are prepared onto glass substrates by a simple chemical spray pyrolysis technique. Cubic and rectangular cuboid shaped nanocrystals are observed in the FESEM images of the films up to 6 at% Mg concentration. XRD patterns of Mg doped Fe2O3 thin films match with the corundum structure showing the predominance of (104) orientation. Crystallite size increases from 29 to 87 nm with the increase of Mg concentration in the films. Raman spectroscopy indicates that Mg doped Fe2O3 thin films consist of only pure hematite or α-Fe2O3 phases. Chemical composition of the films are confirmed by energy dispersive X-ray analysis. Optical transmittance and band gap rise with the uplift of Mg concentrations. The maximum transmittance is found to be 83% for 10 at% Mg doped Fe2O3 thin film. In the photoluminescence spectroscopy, green emission is dominant up to 6 at% Mg doping and dominance of blue emission is observed in the 8 and 10 at% Mg doped Fe2O3 thin films. The n-type electrical conductivity of Fe2O3 changed into p-type for 6, 8 and 10 at% Mg doping. Electrical resistivity is found in the order of 105 Ω-cm which rises with Mg concentration. Pure Fe2O3 thin film shows ferromagnetic nature, whereas Mg doped Fe2O3 thin films show ferrimagnetic nature at room temperature. Mg doped Fe2O3 thin films may be suitable for sensing purposes and high power devices.