MgO Phase Research Articles

Comparison of the properties and catalytic activity of commercially and laboratory prepared Mg/Al mixed oxides in aldol condensation of cyclohexanone with furfural

In recent years, for deeper understanding of the behavior of various heterogeneous catalysts, aldol condensation of acetone and furfural has been researched in detail. In this article, the carbonyl reactants are represented by cyclohexanone and furfural as the platform chemicals for synthesis the fundamental building blocks for future biorefineries. Our main goal was to explore the structural and acid–base properties and to compare them with catalytic characteristics of Mg/Al mixed oxides in aldol condensation of cyclohexanone with furfural. The aforesaid basic heterogeneous catalysts were obtained by the calcination of commercially and laboratory prepared hydrotalcites with different molar ratios (1:1–5:1). Their physicochemical properties were determined based on several analytical methods: XRD, ICP-OES, SEM, N2 physisorption, TGA, TGA-MS, DRIFT, TPD-CO2 and TPD-NH3. Through XRD, it was found that as-synthesized laboratory hydrotalcites had the pure crystalline hydrotalcite structure while commercial ones contained also the brucite and MgO phases. By using TPD-CO2 and TPD-NH3, the measured values, especially the total amount of basic sites, provided the best correlation with the catalytic activity of investigated catalysts. Comparable conversions of furfural (ca. 87%) were achieved on laboratory and commercial mixed oxides with the Mg/Al molar ratio 1:1 and 3:1, respectively. They had no obvious difference in selectivity to FCH (about 20%) whereas the commercial samples showed higher selectivity to F2CH (26% at max conversion) than the laboratory ones (17%).

Preparation and corrosion resistance of superhydrophobic coatings on AZ31 magnesium alloy

Abstract In order to improve the corrosion resistance of the Mg alloys, the superhydrophobic coatings on AZ31 Mg alloy were prepared by a two-step process of micro-arc oxidation treatment and superhydrophobic treatment in stearic acid ethanol solution. The effects of voltages, frequencies and treatment time on the contact angle of the superhydrophobic treated sample were investigated. The results showed that with increasing the voltage, frequency and treatment time, all of the contact angles of the superhydrophobic treated sample increased first, and then decreased, reaching the maximum values at 350 V, 1000 Hz and 5 min, respectively. The optimal superhydrophobic coating was mainly composed of MgO and Mg2SiO4 phases, with the pore diameter of ∼900 nm, the thickness of ∼6.86 μm and the contact angle of 156.96°. The corrosion current density of the superhydrophobic AZ31 sample decreased by three orders of magnitude, and the amount of hydrogen evolution decreased by 94.77% compared with that of the AZ31 substrate sample.

Effect of malonic acid and of different doping methods on the superconducting properties of MgB2 superconductors

In this paper, malonic acid was tested as a new carbon source and its effects on the structural and superconducting properties of bulk MgB2 have been systematically investigated. The detailed pyrolysis process of malonic acid was analyzed to understand the possible doping mechanism of malonic acid added MgB2 samples. The weight fraction of MgO phase and the actual carbon substitution level in bulk MgB2 increased with a higher amount of malonic acid addition, which was proven to be mainly caused by the reaction of Mg and CO2 gas. A moderate amount of malonic acid addition resulted in grain refinement and enhanced flux pinning. Bulk MgB2 with 10 wt% malonic acid addition showed much higher Jc values in the entire magnetic field range. Three different doping methods with the same amount of malonic acid addition were compared. MgB2 samples using malonic acid and ethanol processed boron showed the highest Jc value, which was 7.2 times larger than that of the pure MgB2 at 20 K and 5 T.

Insights into the structural requirements for oxidative dehydrogenation of propane on crystalline Mg-V-O catalysts

MgV2O6, α-Mg2V2O7 and Mg3V2O8 model catalysts with high phase purity were prepared and studied in the oxidative dehydrogenation (ODH) of propane to determine the active and selective Mg-V-O crystalline structures required for the propane ODH reaction. Initial activities and selectivities, and rate constants for the propane ODH (k1), propane combustion (k2) and propylene combustion (k3) reactions were rigorously measured within the kinetically controlled regime. MgV2O6 exhibited the highest propane turnover rates, but it was not a selective phase for the formation of propylene, due to the favorable propylene combustion on its surface reflected by the high k3/k1 ratio. α-Mg2V2O7 exhibited both superior propane ODH rates and propylene selectivity relative to Mg3V2O8, indicating that α-Mg2V2O7 consisting of dimeric V2O7 units is intrinsically more active and selective than Mg3V2O8 containing isolated VO4 tetrahedra in the ODH of propane, consistent with the smallest k2/k1 and k3/k1 ratios measured for α-Mg2V2O7 among the three pure Mg vanadates. Moreover, a detailed comparison between the crystalline Mg-V-O catalysts and their physical mixtures in terms of the intrinsic activities and selectivities demonstrated no synergetic effects between either α-Mg2V2O7 and Mg3V2O8 or Mg3V2O8and MgO phases in the ODH of propane. This study provides directions for optimization of compositions and design of new structures based on the well-studied Mg-V-O catalysts towards the efficient synthesis of propylene from the ODH of propane.

Synthesis and characterization of pure and cobalt doped magnesium oxide nanoparticles: Insight from experimental and theoretical investigation

Undoped and cobalt doped MgO nanoparticles (Mg1-xCoxO, x = 0, 0.03, 0.06 and 0.12) were prepared by co-precipitation method. The synthesized samples were characterized by using X-ray diffraction (XRD), differential thermal analysis (DTA) and Ultraviolet–Visible (UV–Vis) spectroscopy. The UV–Visible absorption spectra showed a redshift with the increase in cobalt doping content in MgO host lattice while corresponding bandgap energy of cobalt doped MgO-NPs was decreased with the increase of doping concentration. The XRD patterns revealed the formation of rock salt MgO phase nanostructures. The Rietveld analysis revealed the formation of impurity phase (Co3O4), which was remarkably appear at higher doping concentration (x = 0.12). Rietveld refinement was utilized to investigate the individual influences of coherent domain sizes and lattice strain on the peak broadening of the pure and cobalt doped MgO-NPs. The coherent domain size increased from 7.44 nm to 8.11 nm with increasing Co doping amount up to x = 0.06. The strain decreased with increasing in cobalt content. The decreasing trend in lattice constant "a" was observed with increasing doping concentration which confirms the incorporation of Co ions into the MgO host lattice. Furthermore, the linear and planar defects were also considered. First-principles calculations based on DFT were employed to determine elastic constants for the pure and doped MgO. These values were then used in combination with X-ray diffraction data to measure stacking fault energies as a function of doping concentration. The results showed that the stacking fault energy decreased as the doping concentration increase. The formation enthalpy and bonding properties of the studied compounds were also inspected. Further, the magnetic features of Co monodoping and (Co, Mg or O vacancy) co-doping in MgO host lattice were studied. The results reveal that the studied compounds may have potential applications in spintronics and magnetic data storage.

Improved energy storage properties of 0.55Bi0.5Na0.5TiO3-0.45Ba0.85Ca0.15Ti0.85Zr0.1Sn0.05O3 ceramics by microwave sintering

0.55BNT-0.45BCTZS-x wt% MgO ceramics were sintered by microwave sintering method. XRD data shows that the reaction between MgO and the matrix phase was suppressed and the secondary phase of MgO was observed in MgO doped samples. SEM and EDS mapping results prove that all samples exhibit a dense microstructure and MgO mainly aggregates at grain boundaries. Dielectric properties indicate that the relaxor behavior can be enhanced by MgO addittives, while x = 3–7 samples show a diffuse phase transition characteristic. The maximum polarization of the samples prepared by microwave sintering is higher than that of the samples prepared by traditional sintering. A high energy storage density of 2.09 J/cm3 and the breakdown strength of 18.97 kV/mm were obtained in the x = 5 sample, of which the energy efficiency was 79.51%.

Antiferroelectric-like properties in MgO-modified 0.775Na0.5Bi0.5TiO3-0.225BaSnO3 ceramics for high power energy storage

Antiferroelectric-like 0.775NBT-0.225BSN-x wt%MgO ceramics have been prepared by solid state methods. The second phase of MgO was found in grain boundary surroundings with fine grains, which has been confirmed by EDS mapping and XRD results. Frequency dispersion of x = 0 sample was replaced by diffuse phase transition of MgO-doped samples. Antiferroelectric-like properties were firstly observed in MgO modified ceramics. The evolution of antiferroelectric-like /ferroelectric transitions was demonstrated by I-E curves. With increasing MgO concentration, the BDS and EF-EB gradually increase. The leakage current can be reduced by suitable amount of MgO addition. When the doping content is 5 wt.%, the maximum discharge energy density of 2.13 J/cm3 at an electric field of 215 kV/cm was achieved. Detailed analysis can be found in the study.

Fundamental properties and phase stability of B1 and B2 phases of MgO over a wide range of pressures and temperatures: A first-principles study

Accurate determination of the phase diagram of MgO is proved to be a challenging task, mainly because of the very high B1–B2 transition pressures (Pt) and melting temperatures. Only very recently experimental observations of the B1–B2 and solid-liquid transitions of MgO have been achieved. In spite of the extensive experimental and theoretical studies, a satisfactory agreement about the phase diagram of MgO has not yet been reached. In this work, we will thoroughly investigate the various factors that may affect the calculated B1–B2 phase boundary, using first-principle techniques. The structural, vibrational and thermal properties of the B1 and B2 phases of MgO are also investigated. It has been found that Pt is quite sensitive to the set of pseudopotentials (PPs) used in the PP plane-wave approach, and volume (or pressure, P) range over which the Helmholtz free energy is directly calculated. An interplay between such a P range and the anharmonic effects is demonstrated, which allows (by a suitable choice of the P range) for a high reduction in these effects (i.e., highly extends the validity of the temperature range of the quasiharmonic approximation). The very recently proposed optimized norm-conserving Vanderbilt (ONCV) PPs are found to yield results in very good agreement with those obtained by the all-electron projected augmented wave calculations, contrary to other norm-conserving PPs. As for the exchange-correlation energy, the local density approximation is not only found to provide a good description of Pt of the above transition, but also its temperature dependence. The obtained results are discussed in comparison with the most recent theoretical results and experimental data. In particular, our results suggest that the estimated temperature of the B1–B2 transition directly observed by using the laser-driven ramp loading technique is highly exaggerated.

Synthesis, Corrosion and Bioactivity Evaluation of Gelatin/Silicon and Magnesium Co-Doped Fluorapatite Nanocomposite Coating Applied on AZ31 Mg Alloy

In this study, a nano-composite composed of gelatin as the matrix and Si-Mg-FA nano-particles as an additive was deposited on the AZ31 Mg alloy via dip coating method. In addition, a coating composed of MgO, MgSiO3 and Mg2SiO4 phases was applied on the AZ31 Mg alloy by anodizing process. It was found that the Nano-composite coating with a uniform distribution of nano-particles within the gelatin matrix with the thickness of about 9 µm was dense, crack-free and uniform whereas the surface of anodized layer was relatively coarse due to the presence of flaws and micro-cracks. The surface morphology, EDS analysis and FTIR results revealed the ability of nano-composite coated specimen to form the bone-like apatite. Due to the presence of aforementioned phases and special surface features, the anodized specimen possessed higher and lower corrosion resistance than uncoated and nano-composite coated specimens, respectively. The passive coating resistances (RCT) of nano-composite, anodized specimen and uncoated samples were 2164, 1449 and 1024 Ω cm2, respectively.

Flux Pinning and Superconducting Properties of MgB2-Diamond Nanocomposites

The present investigation focuses on a further performance improvement of disk-shaped bulk MgB2 superconductors by means of a nanoscopic diamond powder, using a single-step solid-state reaction process. MgB2 bulks were produced by in-situ solid state reaction in Ar gas using high purity commercial powders of Mg metal and amorphous B mixed in a fixed ratio of Mg:B = 1:2. Further, 0, 0.4, 0.8, and 1.2 wt% of nanoscopic diamond powder was added to improve flux pinning performance of the bulk MgB2 material. All samples were sintered at 775 °C for 3 hours in Ar atmosphere. X-ray diffraction confirmed that the sample consisted mainly of MgB2 phase and a small quantity of MgO phase. DC magnetization measurements showed a sharp superconducting transition with onset Tc at around 39.25 K and 37.42 K for the pure and 0.8 wt.% of nanoscopic diamond powder added samples, respectively. The highest self-field critical current density (Jc) around 300 kA/cm2 and 105 kA/cm2 were recorded at 20 K, in self-field and 1.5 T for the sample with 0.8 wt.% of nanoscopic diamond. The present results show that nanoscopic diamond powder is an effective pinning medium for bulk MgB2 and might thus be an alternative to further improve the superconducting performance of the bulk MgB2 material.

The hydrogen storage properties and catalytic mechanism of the CuFe2O4-doped MgH2 composite system

The influence of CuFe2O4 addition on the sorption performances of MgH2 prepared by ball milling was studied for the first time. The MgH2 + 10 wt% CuFe2O4 sample exhibited an enhancement in hydrogen storage performance compared to that of as-milled MgH2, with the onset decomposition temperature decreased from 340 °C to 250 °C. Dehydrogenation kinetic result revealed that CuFe2O4-added MgH2 released around 5.3 wt% H2 within 10 min at 320 °C, while the as-milled MgH2 released below 1.0 wt% H2 under the same condition. Furthermore, about 5.0 wt% H2 was absorbed at 250 °C in 30 min for the 10 wt% CuFe2O4-doped MgH2 sample. In contrast, the un-doped MgH2 only absorbed 4.0 wt% H2 at 250 °C in 30 min. From the Kissinger analysis, the apparent activation energy of as-milled MgH2 was 166.0 kJ/mol and this value decreased to 113.0 kJ/mol for 10 wt% CuFe2O4-added MgH2. The enhanced sorption performance of MgH2 in the presence of CuFe2O4 is believed to be due to the role of in situ formed Fe, Mg-Cu alloy, and MgO phases as an active species to catalyse the hydrogen storage properties of MgH2.

Structure of superconducting MgB2 thin films prepared by vacuum evaporation and ex-situ annealing in Ar and O2 atmospheres

Superconducting MgB2 thin films were fabricated on c-cut sapphire substrates by vacuum co-evaporation of magnesium and boron followed by an ex situ post-annealing. We show that annealing in oxygen atmosphere can significantly improve the superconducting properties of the MgB2 thin films compared to the typical annealing in argon atmosphere. In this work, influence of the ex-situ annealing atmosphere on the structure, texture and morphology of the superconducting MgB2 thin films has been studied by transmission electron microscopy, X-ray diffraction and pole figure measurements. Samples annealed at 800 °C in Ar, at 800 °C in O2 and at 500 °C in O2 have been compared. The annealing in O2 at 800 °C produces MgB2 thin films with the highest superconducting transition temperature and critical current density. We show that this is thanks to the thickest MgO layer at the surface produced in this case, which acts as a protecting barrier against out-diffusion of Mg during the annealing and leads to better stoichiometry and larger MgB2 grains compared to the samples annealed in Ar. Our method can be alternative to the customary ex-situ post annealing of Mg-B precursor in sealed vapor cell. In all samples, the MgB2 phase showed single axis texture with the (0 0 0 1) planes slightly inclined by 0° to 15° with respect to the Al2O3(0 0 0 1) substrate surface incurred with the initial precursor evaporation geometry. During the annealing, the excess Mg also reacts with the Al2O3 substrate and minor MgAl2O4 and MgO phases are produced at the substrate-layer interface.

Preparation of Mg2Si-based thermoelectric materials using waste silicon sludge as a source material

Sb-doped Mg2Si was prepared using waste silicon sludge via a liquid-solid phase reaction and pulse-current sintering. Two types of Si sludge were used as a silicon source. One is an unwashed Si sludge, and the other is Si sludge washed with a water-based agent. In the samples prepared from unwashed Si sludge, Mg2Si, Mg, and MgO phases existed. In the case of samples prepared from the washed Si sludge, the X-ray diffraction patterns showed almost a single phase, although a small MgO phase remained.The thermoelectric properties of Mg2Si prepared from the washed Si sludge were improved by control of weighed composition and carrier concentration. The obtained maximum figure of merit of this study was 0.66 in the samples prepared from the washed Si sludge, which is equivalent to materials prepared from reagent Si with identical carrier concentration.

Investigation of Corrosion Protection Performance of Multiphase PEO (Mg2SiO4, MgO, MgAl2O4) Coatings on Mg Alloy Formed in Aluminate-Silicate- based Mixture Electrolyte

Plasma electrolytic oxidation (PEO) coatings in the aluminate-silicate-based mixture electrolyte solution with different duty cycles were successfully applied on Mg alloy. The corrosion behavior of the samples was evaluated by water contact angle test, potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) and immersion tests. Hydrophobic PEO coating could be obtained by adjusting the duty cycle of the applied electric signal. This coating considerably diminished the Mg dissolution and could enhance the impedance values of Mg alloy in 3.5 wt % NaCl solution. However, the surface of other PEO coated samples showed more hydrophilic properties compared to that of the uncoated sample. Dense structure of the modified PEO multiphase (including Mg2SiO4, MgO and MgAl2O4 phases) coating and also its appropriate thickness provided an effective barrier to remarkably delay corrosive solution penetration into the PEO coating. This phenomenon led to major decrease in anodic current density of alloy in chloride solution.

Methane dry reforming over Ni/Mg-Al-O: On the significant promotional effects of rare earth Ce and Nd metal oxides

In this study, with the purpose to obtain more efficient catalysts for methane dry reforming, an Mg-Al-O support having excess MgO and higher alkalinity than pure MgAl2O4 spinel support have been designed and used to prepare Ni/Mg-Al-O catalysts. XRD has demonstrated that this support consists of both MgO and MgAl2O4 spinel phases. As a result, Ni/Mg-Al-O displays better reaction performance than Ni/MgAl2O4 and Ni/Al2O3 catalysts. With the promotion by Ce and Nd oxides, the Ni dispersion and the surface active oxygen amount can be significantly improved, which results in more active and stable catalysts with also significantly improved coking resistance. It is revealed that the active metallic Ni surface area, surface alkalinity and active oxygen abundance are the major factors deciding the reaction performance of the Ni/Mg-Al-O catalysts. Because of the optimal concerted action of these factors, Ni-Ce/Mg-Al-O, the sample promoted by ceria, displays the best reaction performance among all the catalysts.

Porous Sb-Si-C Composite As a High-Performance Anode Material for Lithium Ion Batteries

Recently, with increasing use of mobile electronic devices and electric vehicles, demand for electrical energy storage devices is greatly rising. Among them, lithium ion batteries (LIBs) are one of the most attractive devices because of their reasonable cost and energy density. To meet the consumer demand for energy density, high-capacity electrode materials should be developed. Currently, carbonaceous materials such as graphite are widely used in anodes and however, its capacity is limited due to the use of intercalation chemistry (theoretical capacity of graphite: 372 mAh g–1). To increase the capacity of an anode, Li-alloy type materials have been intensively examined. For example, Si has the theoretical capacity of 3580 mAh g–1 for Li15Si4 phase, which is the final phase of electrochemical lithiation. However, the Li-alloying type materials have a problem of cycle performance. When Li ions are inserted and extracted during cycling, the active materials suffer from huge volume expansion and shrinkage (100~400 %). The volume changes cause the mechanical degradation of the active materials and the material can be separated from the current collectors. As a result, the cycle performance of the electrodes is deteriorated. To solve the problem, lots of researchers have tried to prepare composite materials by adopting diverse methods. For instance, composite materials including inactive phases were prepared to alleviate the volume change. In this study, we prepared Sb-Si-C composites as high-capacity anode materials. Antimony (Sb) is considered one of the candidates as Li-alloy type active material and it has the theoretical capacity of 660 mAh g–1 for the Li3Sb phase. To obtain high-capacity and stable cycling stability, porous Sb-Si-C composites were synthesized by high energy mechanical milling and etching process. First, antimony oxide (Sb2O3), magnesium silicide (Mg2Si), and a carbon source were ball-milled. During the milling process, Sb2O3 was reduced to Sb by Mg and the formed MgO phase was removed by a solution etching process. Finally, the porous Sb-Si-C composite was prepared, which was evaluated as LIB anode materials.

Bio-Corrosion Behavior of Ceramic Coatings Containing Hydroxyapatite on Mg-Zn-Ca Magnesium Alloy

Ceramic coatings containing hydroxyapatite (HA) were fabricated on a biodegradable Mg66Zn29Ca5 magnesium alloy through micro-arc oxidation by adding HA particles into the electrolytes. The phase composition and surface morphology of the coatings were characterized by X-ray diffraction and scanning electron microscopy analyses, respectively. Electrochemical experiments and immersion tests were performed in Hank’s solution at 37 °C to measure the corrosion resistance of the coatings. Blood compatibility was evaluated by in vitro blood platelet adhesion tests and static water contact angle measurement. The results show that the typical ceramic coatings with a porous structure were prepared on the magnesium alloy surface with the main phases of MgO and MgSiO3 and a small amount of Mg3(PO4)2 and HA. The optimal surface morphology appeared at HA concentration of 0.4 g/L. The electrochemical experiments and immersion tests reveal a significant improvement in the corrosion resistance of the ceramic coatings containing HA compared with the coatings without HA or bare Mg66Zn29Ca5 magnesium alloy. The static water contact angle of the HA-containing ceramic coatings is 18.7°, which is lower than that of the coatings without HA (40.1°). The in vitro blood platelet adhesion tests indicate that the HA-containing ceramic coatings possess improved blood compatibility compared with the coatings without HA. Utilizing HA-containing ceramic coatings may be an effective way to improve the surface biocompatibility and corrosion resistance of magnesium alloys.

Effect of sintering temperature on the microstructure and performance of a ceramic coating obtained by the slurry method

In this paper, SiO2, Cr2O3, Al2O3, and MgO were used as ceramic aggregates, and a small amount of Al powder was added. A ceramic coating was prepared on a Q235 steel substrate. The effect of the sintering temperature on the coating microstructure, phase structure and wear resistance was studied by Scanning Electron Microscope (SEM), X-ray Diffraction (XRD) and friction and wear testing. The results show that the tensile strength of the ceramic coating is increased after sintering, the structure becomes dense, and the size of coated micropores is increased to release the internal tensile stress. With the increase of the sintering temperature and tensile stress, the micropores begin to release the excess tensile stress in the form of crack initiation and expansion. The mineralization of MgO, Cr2O3, nMgO and mSiO2 phases can be achieved by sintering the coating at 200 °C; the oxygen in the atmosphere migrates along the micropores in the coating to react with Fe in the steel substrate, forming FeO, and the resulting FeO reacts with the SiO2 in the coating to form the Fe2SiO4 phase. The coating has the best wear resistance after being sintered at 400 °C, and the abrasion resistance of the sample is 6.7 times higher than that of the sample dried at room temperature.

Characterization of SiO2-encapsulated WSi2/W5Si3 nanoparticles synthesized by a mechanochemical route

This study reports on the mechanochemical synthesis (MCS) of SiO2-encapsulated WSi2/W5Si3 nanoparticles starting from tungsten oxide (WO3), silicon dioxide (SiO2) and magnesium (Mg) powder blends. MCS process, carried out in a high-energy ball mill, was evaluated in terms of various milling time and initial composition of WO3-SiO2-Mg powders. A subsequent purification step using aqueous HCl solution was conducted on the as-synthesized powders. Compositional, microstructural and thermal properties of the powders were characterized by using X-ray diffractometer (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM) and differential scanning calorimeter (DSC). Based on the adiabatic temperature values, SiO2-encapsulated WSi2/W5Si3 nanoparticles exhibit a high potential as a result of a mechanically induced self-sustaining reaction. The exothermic reaction took place after 20 min of milling, and WSi2, W5Si3, W, MgO, Mg2SiO4 and residual Mg phases were detected. The utilization of an optimized amount of excess Mg (3.5 mol) resulted in the elimination of unwanted Mg2SiO4 and W phases, leaving behind WSi2, W5Si3, Mg2Si, MgO and Mg. After removal of Mg-based by-products by leaching process, WSi2, W5Si3 and a very small amount of SiO2 phases were obtained. TEM analysis revealed that W silicide nanoparticles with an average size of 97 nm were encapsulated by SiO2 layers with an average thickness of 15 nm.

X-ray absorption spectroscopy investigation of relationship between Mg vacancy and magnetic properties of MgO powder

This paper reports on the ferromagnetism of MgO powder and degraded powder at room temperature. The starting material, Mg(OH)2, was analyzed by X-ray fluorescence (XRF) spectrometry and then calcined at 450 °C for 5 h to obtain fresh MgO powder. The calcined powder was separated into two batches (i) kept in vacuum sealed (MgO-F) and (ii) kept at ambient environment (30–32 °C at 45–55% relative humidity) for 2 days (MgO-D). The samples were characterized by X-ray diffraction (XRD), vibrating sample magnetometer (VSM) and X-ray absorption spectroscopy (XAS) including X-ray absorption near edge structure (XANES) and extended X-ray absorption fine structure (EXAFS). XRD and EXAFS confirmed that MgO phase in MgO-F. Both Mg(OH)2 and MgO compositions were found in MgO-D. The origin of ferromagnetism at room temperature of MgO-F and MgO-D is attributed to the Mg vacancies in the MgO structure that revealed and verified by XANES and EXAFS results.