Preparation Of Mg Research Articles

Electrochemical Formation of Mg–Li–Yb Alloys at Solid Magnesium Electrode from LiCl–KCl–YbCl3 Melts at Low Temperature

Abstract This work presents a novel study on electrochemical preparation of Mg–Li–Yb alloys at a magnesium electrode in LiCl–KCl–YbCl3 melts at 743 K. Cyclic voltammograms showed that the reduction of ytterbium(III) ions is a stepwise reaction. The codeposition of Yb and Li takes place at magnesium electrode when the current intensity exceeds 60 mA in LiCl–KCl melts containing 2 wt % YbCl3. α, α + β, and β phases. Mg–Li–Yb alloys with different lithium contents were obtained by potentiostatic electrolysis at a magnesium electrode from LiCl–KCl melts with different concentrations YbCl3.

Preparation of Mg–Al Layered Double Hydroxide Intercalated with 2,7-Naphthalene Disulfonate and Its Selective Uptake of Aromatic Compounds from Aqueous Solutions

Abstract Mg–Al layered double hydroxide intercalated with 2,7-naphthalene disulfonate ion (2,7-NDS·Mg–Al LDH) was prepared by coprecipitation and was found to selectively take up aromatic compounds from aqueous solutions. The amount of material absorbed by 2,7-NDS·Mg–Al LDH depends on the electron-donating or -withdrawing properties of the functional groups on the molecules to be absorbed. The absorption mechanism is dependent on π–π stacking interactions between the aromatic ring of the molecules to be absorbed and the naphthalene moiety of 2,7-NDS2−.

Preparation of Mg–Al layered double hydroxides intercalated with alkyl sulfates and investigation of their capacity to take up N, N-dimethylaniline from aqueous solutions

This study examined the effect of the interlayer spacing of a Mg–Al layered double hydroxide (Mg–Al LDH) on the ability of the Mg–Al LDH to take up a nonionic organic material. Mg–Al LDHs, intercalated with 1-propanesulfonate (PS −), 1-hexanesulfonate (HS −), and 1-dodecanesulfonate (DS −), were prepared by coprecipitation, yielding PS·Mg–Al LDH, HS·Mg–Al LDH, and DS·Mg–Al LDH, respectively. The increase in the alkyl chain lengths of the Mg–Al LDHs (PS − < HS − < DS −) resulted in the perpendicular orientation of the organic acid anions in the interlayer of Mg–Al LDH, which in turn resulted in more organic acid anions being accommodated in the interlayer space. An organic acid anion with a large molecular length was more easily intercalated in the interlayer of Mg–Al LDH than one with a small molecular length. This was attributed to the hydrophobic interaction between the alkyl chains, affecting the intercalation of the organic acid anions. The uptake of N, N-dimethylaniline (DMA) by Mg–Al LDHs increased in the order PS·Mg–Al LDH < HS·Mg–Al LDH < DS·Mg–Al LDH. The uptake was attributed to the hydrophobic interactions between DMA and the intercalated PS −, HS −, and DS −. Thus, Mg–Al LDH, which has a lot of large interlayer spacings when intercalated with organic acid anions, can take up a large number of DMA molecules from an aqueous solution.

Characterization and preparation of Mg–Al–Zn alloys with minor Sc

Mg–9Al–1Zn alloys with 0.3% Sc content (mass fraction) were prepared by ingot metallurgy. The effects of scandium addition on the microstructure and mechanical properties of the alloys have been investigated using optical microscope, scanning electron microscopy and tensile testing. It has been shown that the microstructure is mainly composed of α-Mg matrix, β-Mg 17Al 12 phase and Mg 5Al 4Sc intermetallic compound when 0.3% Sc was added. The scandium addition improves the morphology and distribution of Mg 17Al 12 phase, which substantially improves the mechanical properties of the alloy at both room temperature and high temperature.

Study on the preparation of Mg–Li–Zn alloys by electrochemical codeposition from LiCl–KCl–MgCl 2–ZnCl 2 melts

Electrochemical codeposition of Mg, Li, and Zn on a molybdenum electrode in LiCl–KCl–MgCl 2–ZnCl 2 melts at 943 K to form Mg–Li–Zn alloys was investigated. Cyclic voltammograms (CVs) showed that the potential of Li metal deposition, after the addition of MgCl 2 and ZnCl 2, is more positive than the one of Li metal deposition before the addition. Chronopotentiometry measurements indicated that the codeposition of Mg, Li, and Zn occurs at current densities lower than −0.78 A cm −2 in LiCl–KCl–MgCl 2 (8 wt.%) melts containing 1 wt.% ZnCl 2. Chronoamperograms demonstrated that the onset potential for the codeposition of Mg, Li, and Zn is −2.000 V, and the codeposition of Mg, Li, and Zn is formed when the applied potentials are more negative than −2.000 V. X-ray diffraction (XRD) indicated that Mg–Li–Zn alloys with different phases were prepared via galvanostatic electrolysis. The microstructure of typical α + β phase of Mg–Li–Zn alloy was characterized by optical microscope (OM) and scanning electron microscopy (SEM). The analysis of energy dispersive spectrometry (EDS) showed that the elements of Mg and Zn distribute homogeneously in the Mg–Li–Zn alloy. The results of inductively coupled plasma analysis showed that the chemical compositions of Mg–Li–Zn alloys are consistent with the phase structures of the XRD patterns, and that the lithium and zincum contents of Mg–Li–Zn alloys depend on the concentrations of MgCl 2 and ZnCl 2.

Preparation of Mg and Al co-doped ZnO thin films with tunable band gap

Al （Al2O3，2wt%） doped ZnO thin films （ZAO） with tunable band gap，alloyed with different Mg contents （1wt%，3wt% and 5wt%），were prepared by radio frequency magnetron sputtering on glass substrates and annealed at 500℃ in air. The optical and electrical properties of the films were measured by X-ray diffractometer，four-point probe method，Hall-effect configuration，and UV-VIS spectrophotometer. The results show that the Mg co-doped ZAO thin films have a wurtzite structure with （002） preferred orientation. Compared with ZAO film，the optical transmission of Mg co-doped ZAO thin films in the ultraviolet region increases and the average optical transmissions in the visible region is greater than 85%，except the 5wt% Mg doped films. The band gaps of ZAO and Mg co-doped ZAO thin films can be modulated from 344 eV to 351 eV by increasing the Mg content from 1wt% to 5wt%. For 1wt%，3wt% and 5wt% Mg doping，the Mg co-doped ZAO thin films have the resistivity of 12×10-3，37×10-3 and 85×10-3 Ω·cm，respectively. Stokes shifts of 20，14 and 50 meV were observed for doping of 1wt%，3wt%，and 5wt% Mg contents. We find that a large Mg doping content will degrade the crystal quality of Mg co-doped ZAO thin films，decrease the optical transmissions in the visible region and decrease the carrier mobility in the films. Therefore，the resistivity of Mg co-doped ZAO thin films increases with the Mg doping content.

Preparation of Mg,Al-Hydrotalcite/PE-EVA Flame-Retardant Nanocomposite

The Mg,Al-hydrotalcite/PE-EVA flame-retardant nanocomposites were prepared by the co-mixing method at atmospheric pressure successfully. Moreover, the preparation of Mg,Alhydrotalcite/ PE-EVA nanocomposites was investigated according to the mechanical and flame-retardant tests of the samples. And the results show that the Mg,Al-hydrotalcite nanocrystalline is a highperformance inorganic flame-retardant agent.

Preparation of Mg and Ti Co-Doped NiO-Based Ceramic and its High Dielectric Properties

We present Mg and Ti co-doped NiO-based polycrystalline ceramic with high-permittivity dielectric properties. Analysis of the ceramic’s microstructure and composition proves that obvious grain boundaries NiTiO3 are formed. The measurements of frequency and temperature dependence of impedance and dielectric permittivity indicate that the grain and grain boundaries have remarkable influence on the dielectric properties due to the various activation energies.

In situ preparation of Mg(OH)2/polystyrene nanocomposite via soapless emulsion polymerization

Magnesium hydroxide nanoneedles modified by oleic acid [OA–Mg(OH)2] were synthesized via alkaline injection into magnesium chloride solution in the presence of oleic acid (OA). The magnesium hydroxide/polystyrene nanocomposite [Mg(OH)2/PS] was then prepared by soapless emulsion polymerization technique in an aqueous suspension. The Fourier transform infrared (FT–IR) analysis shows that the polystyrene was covalently grafted onto the surfaces of the Mg(OH)2nanoneedles [OA–Mg(OH)2]. The dispersion of Mg(OH)2nanoneedles in polystyrene is uniform as observed by transmission electron microscope (TEM). The grafting percentage was determined by means of elemental analysis (EA). The thermal behavior determined by the differential scanning calorimetry (DSC) indicated that Mg(OH)2/PS had a higher glass transition temperature than PS matrix, and it can be concluded that Mg(OH)2 could retard the degradation of PS based on the data of thermal gravimetric analysis (TGA) and differential thermoanalysis (DTA).

Preparation of Mg–23.5Ni–10(Cu or La) hydrogen-storage alloys by melt spinning and crystallization heat treatment

Mg–23.5 wt%Ni–10 wt%Cu and Mg–23.5 wt%Ni–10 wt%La alloys were prepared by melt spinning and crystallization heat-treatment. The Mg–23.5Ni–10Cu alloy (5.18 wt%) after planetary ball milling has a higher hydrogen-storage capacity than the Mg–23.5Ni–10La alloy (4.98 wt%) at 573 K. The activated Mg–23.5Ni–10Cu alloy has a slightly lower hydriding rate in the beginning, but a higher hydriding rate after about 5 min than the activated Mg–23.5Ni–10La alloy at 573 K. The activated Mg–23.5Ni–10Cu alloy has a much higher dehydriding rate and a larger quantity of the decomposed hydrogen than the activated Mg–23.5Ni–10La alloy at 573 K.

The Preparation of Mg, Cd and Zn Samples for Crystal Orientation Mapping with BKD in an SEM

Abstract Backscatter Kikuchi Diffraction (BKD) from crystalline solids has been known since 1928. But only during the last decade, when sufficiently sensitive cameras, fast PCs and high-performance SEMs have been available, has this technique been developed into an invaluable tool for materials' science and geology. BKD is also known as “Backscatter Electron Diffraction” (EBSD) if referred to the commercial trademarked systems OXFORD/HKL “Channel” or EDAX-TSL “OIM”. Crystal Orientation Measurement/ Mapping (COM), without user intervention, is performed in an SEM by digitally scanning the beam spot across the specimen, acquiring and transferring one Backscatter Kikuchi Pattern (BKP) after another into the computer, indexing it, and calculating the crystal orientation of the grain under the beam spot. The sample is typically tilted by 70° towards a phosphor screen for pattern collection. Spatial resolution is in the range of &amp;lt;0.05 μm and accuracy is better than 0.5°.

Preparation of Mg–Li alloys by electrolysis in molten salt at low temperature

A new technology for preparation of low cost Mg–Li alloys was studied. The alloys were prepared by electrolysis in molten LiCl–KCl (weight ratio is 1:1) electrolyte with Mg rod severing as the consumed cathode. Main factors that affect current efficiency were investigated, and optimal electrolysis parameters were obtained. Mg–Li alloys with low lithium content (about 25%) were prepared by the unique method of a higher post-thermal treatment temperature after electrolysis at low temperature. The results showed that the electrolysis can be carried out at low temperature, which resulted in reducing preparation cost due to energy saving. The new technology for the preparation of Mg–Li alloy by electrolysis in molten salt was proved to be feasible.

An electrochemical method for the preparation of Mg–Li alloys at low temperature molten salt system

Mg–Li alloys have been prepared by electrolysis in a molten salt electrolyte of 50% LiCl–50% KCl (mass%) at low temperature of 420–510 °C. The effects of electrolytic temperature and cathodic current density on alloy formation rate and current efficiency were studied. For the deposition of metallic lithium on the cathode consisting of solid Mg and liquid Mg–Li, both electrolytic temperature and cathodic current density have no obvious influence on current efficiency; while for the deposition of metallic lithium on the solid magnesium cathode, both electrolytic temperature and cathodic current density greatly affect alloy formation rate and current efficiency. The optimum electrolysis condition is—molten salt mixture, LiCl:KCl = 1:1 (mass%), electrolytic temperature: 480 °C, cathode current density: 1.13 A cm −2. Mg–Li alloys with low lithium content (about 25 wt% Li) were prepared via electrolysis at low temperature following by thermal treatment at higher temperature.

Preparation of Mg&amp;ndash;Li&amp;ndash;Al&amp;ndash;Zn Master Alloy in Air by Electrolytic Diffusing Method

Electrolytic diffusing method was conducted at 500°C to prepare Mg–Li–Al–Zn master alloy in air. It was also explored for the melting and casting of Mg–Li alloy in air, as the Mg–Li–Al–Zn master alloy used as raw material. A mixture of 45 mass% lithium chloride (LiCl) and 55 mass% potassium chloride (KCl) was employed as the electrolyte. Mg–9 mass%Al–1 mass% Zn (AZ91) alloy was used as cathode material while graphite selected as anode. Experimental results showed that the electrolysis current linearly depended on the applied working voltage. Deposition of lithium occurred on the cathode surface. After the electrolysis experiments, Mg–12 mass% Li–9 mass% Al–1 mass% Zn alloy sheet can be obtained. At working voltage of 4.2 V and one hour electrolysis, the hexagonal-closed-pack AZ91D sheet (1.5-mm thickness) was fully converted to body-centered-cubic Mg–Li–Al–Zn alloy. The formation of Mg–Li phase during electrolysis was studied by inductively coupled plasma-atomic emission spectrometer (ICP), X-ray diffraction, and optical microscopy. It is diffusion rather than deposition rate (electrolysis current) that controlled the depth of Mg–Li phase formed in the cathode sample. The Mg–Li–Al–Zn alloy used as master alloys could be melted and casted in air without ignition. However, the content of lithium in the as-cast block was reduced to 3.77 mass%, properly due to oxidation of lithium metal during melting.

Novel and effective surface enrichment of active species in Ni-loaded catalyst prepared from Mg–Al hydrotalcite-type anionic clay

Egg shell-type Ni loaded catalysts have been prepared by adopting the “memory effect” of Mg–Al hydrotalcite and have been successfully used in the steam reforming of CH 4. Mg–Al(3/1) mixed oxide particles were first prepared as the catalyst support by the thermal decomposition of Mg–Al hydrotalcite. When the particles were dipped in aqueous solution of Ni(II) nitrate, Mg–Al hydrotalcite was reconstituted in the surface layer of the particles, and simultaneously Ni(II) substituted for the Mg(II) sites, leading to the formation of egg shell-type Ni-loading. The conditions of both preparation of Mg–Al(3/1) mixed oxide and dipping in Ni(II) nitrate solution were varied, and their influences on egg shell-type Ni-loading and on the catalytic activity were studied. The shape of egg shell-type Ni-loading was significantly affected by the rate of heating, the final calcination temperature of Mg–Al(3/1) mixed oxide, the pH of Ni(II) nitrate aqueous solution, and the dipping time of the mixed oxide in the aqueous solution. The smaller heating rate, the lower temperature calcination, and a dipping in the aqueous solution at the lower pH were preferable for the Ni-loading in egg shell-type. Under the mild heating conditions, periclase-like MgO structure was formed, on which the reconstitution of Mg–Al hydrotalcite was preferentially provoked in the surface layer of the particle by “memory effect” during the dipping at the lower pH. It is concluded that the activity of egg shell-type Ni-loaded catalyst was enhanced by the surface enrichment of well-dispersed Ni metal particles.

A Non-Hydrolytic Sol-Gel Approach for the Preparation of MgxAl2(1-x)Ti(1+x)O5Powders

The study of non-hydrolytic reactions for the synthesis of MgxAl2(1−x)Ti(1+x)O5 solid solution with x = 0.6 is reported. The reagents chosen were Al(OsBu)3, Ti(OiPr)4, TiCl4 and Mg(NO3)2·6H2O in toluene. The reactions were followed using 13C Nuclear Magnetic Resonance (NMR) spectroscopy. Sol-gel synthesized powders were calcined in air at 300, 500, 1000, and 1200°C for 1 h. The powders were analysed by X-Ray Diffraction (XRD) demonstrating the formation of a Mg0.6Al0.8Ti1.6O5 phase in samples treated at the higher calcination temperature.

Preparation of Mg 1− xFe xMoO 4 catalyst and its application to grow MWNTs with high efficiency

Iron/molybdenum/magnesium mixed oxide prepared by a sol–gel method shows its high efficiency for synthesis of MWNTs through catalytic decomposition of methane using chemical vapor deposition (CVD) method at 1000 °C. The weight production of the as-grown MWNTs can reach as high as 30 times of the catalyst in 30 min growth. Upon SEM and TEM observations, the product is found to be compacted bundles of MWNTs. Microstructure of the tubes was characterized by transmission electron microscopy (TEM) and Raman spectroscopy. Thermal gravimetric analysis (TGA) examination showed that the content of MWNT is high. Using this high-efficient catalyst, the cost of producing carbon nanotubes (CNTs) can be greatly reduced. In order to understand the formation of MWNTs bundles and the high efficiency of the catalyst, microstructural evolution of the catalyst at different growth stages to form MWNTs were systematically examined by TEM, and a plausible explanation is presented.

Preparation of Mg 2− xRE xNi (RE = La, Ce, Pr, Nd, Y) alloys and their electrochemical characteristics

A series of Mg 2− x Nd x Ni ( x=0.05, 0.1, 0.2, 0.3) and Mg 1.95RE 0.05Ni (RE=La, Ce, Pr, Nd, Y) ternary alloys were prepared by ball milling of mixed powder of Mg, Ni, RE and sintering under pure argon. XRD analysis shows that Mg 2− x Nd x Ni ( x=0.05, 0.1) and Mg 1.95RE 0.05Ni alloys are all single-phase with the same crystal structure as Mg 2Ni while three phases (including Mg 2Ni, NdNi and NdMgNi 4) were formed in Mg 1.8Nd 0.2Ni and Mg 1.7Nd 0.3Ni alloys. The lattice constants ( a, c, c/ a) of Mg 2Ni phase in these ternary alloys were calculated. Calculated values of a and c are strongly influenced by elemental substitution, while no different changes were observed in a/ c. The electrochemical characteristics of the alloys were evaluated by simulated battery test. It is found that the initial discharge capacity of Mg 2− x Nd x Ni alloy milled for 10 h was obviously improved with increasing Nd content. A good cycle life was also observed in the Mg 1.7Nd 0.3Ni alloy electrode. It is suggested that combined effects contribute to the enhancement in electrochemical characteristics, the presence of NdMgNi 4 being beneficial for the improvement in cycle life of Mg 2− x Nd x Ni ( x=0.2, 0.3), especially for the Mg 1.7Nd 0.3Ni alloy electrode. As to Mg 2− x RE x Ni alloys, the effectiveness in improving the discharge capacity increased in the following order: Pr>Nd>Ce>La>Y.

Preparation of Mg−Ti system alloy and FGM with density gradient by spark plasma sintering technique

A new kind of functionally graded materials (FGM) with density gradient has come to show great potentials as flier-plates for creating quasi-isotropic compression waves. In order to meet the demand of lower density in the front face for such flier-plate, Mg with a low density of 1.74 g/cm3 is selected to make a Mg−Ti FGM. Mg−Ti alloys with various weight ratios were sintered by spark plasma sintering (SPS) technique at relative low temperatures, and the processing of densification is mainly investigated. It is found that, up to 75wt% Ti, the Mg−Ti alloys can be fully densified at 560°C due to the conglutination of Mg and the formation of a small amount of Mg−Ti solid solution. Finally, the Mg−Ti FGM with a density gradient from 1.74 g/cm3 to 3.23 g/cm3 is successfully fabricated.

Preparation of Mg–Ni alloys through high pressure treatment

Studies involving the synthesis of diamonds with semiconductor properties require the use of Mg-based alloys. Alloys of the Mg–Ni system were obtained under high pressures of 1.0 GPa, high temperatures of up to 1577 K and 5 min processing. A microstructural examination of these alloys confirmed that an alloy with a basic MgNi 2 composition and another with a 0.23 at.% Mg+0.77 at.% Ni composition were obtained. The phases identified in the Mg–Ni alloys produced under high pressure confirmed the effectiveness of the interaction of the initial component, suggesting that the crystallization process occurred at high velocity.