Papers by Keyword: MgO

Abstract: Recently, several synthesis methods have been reported for producing magnesium oxide (MgO) nanostructures such as sol-gel, combustion, thermal evaporation, chemical precipitation, etc. This work describes a simple method to synthesize MgO nanostructures via a conventional solid-state reaction method using magnesium acetate tetrahydrate as a starting material. Magnesium acetate tetrahydrate was directly annealed at a temperature of 600 °C and 800 °C for 24 h. The X-Ray Diffraction (XRD) revealed that the annealed samples were pure while Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM) showed different morphologies of MgO. From the results, it is found that TEM may reveal information that cannot be observed in the SEM micrographs.

Abstract: Poly(vinylidene flouride)/nano-magnesium oxide (PVDF/MgO) nanocomposites with MgO loading percentage of (7% wt. %) were annealed with various annealing temperatures ranging from 70°C to 170°C with rapid removal from the oven. From dielectric constant, the samples annealed at temperature of 70°C showed an improvement in the dielectric constant from 21 to 23 at frequency 10³ Hz for UN and AN70 respectively. However, as the temperatures were increased, the dielectric constant of PVDF/MgO (7%) was found to decrease. XRD showed the presence of β-phase for PVDF/MgO(7%) sample annealed at 70°C in comparison to unannealed sample, hence PVDF/MgO(7%) film is suitable to be used for low frequency capacitor application.

Abstract: We report an antibacterial and wash durability behaviour of MgO and NiO nanoparticles treated cotton fabric using sodium alginate as cross linker. The metal oxide nanoparticles treated cotton fabric using sodium alginate as a crosslinker was characterized employing SEM-EDX and their antibacterial activity was analyzed. The enhanced zone of inhibition and wash durability behaviour was observed for NiO nanoparticles treated fabric. However, MgO nanoparticles showed less significant antibacterial and wash durabilty activities when compared to NiO nanoparticles treated cotton fabrics.

Abstract: Poly (vinylideneflouride)/nanomagnesium oxide (PVDF/MgO) nanocomposites with MgO loading percentage of 7% were annealed with various annealing temperatures ranging from 70oC to 170oC. The PVDF/MgO(7%) thin films were fabricated using spin coating technique with MIM structure. The dielectric constant of PVDF/MgO(7%) was studied over a wide range of annealing temperatures with rapid removal from the oven once the annealing was utilized. The nanocomposites thin films annealed at temperature of 70oC (AN70) shows an improvement in the dielectric constant of 23 at 10³ Hz compared to unannealed sample (UN), which was 21 at the same frequency. However, as the annealing temperatures were increased from 90oC (AN90) to 170o C (AN170), the dielectric constant of PVDF/MgO(7%) were found to decrease from 16 to 7 respectively, which were lower than the UN thin films. AN70 also produced low value of tangent loss at low frequency˼˰˸̱̈́̾˰δ˹˰̴̷̹̹̳̱̹̾̈́̾˰̸̱̈́̈́˼˰̵̷̱̱̼̹̾̾̾˰̱̈́˰temperatures 70oC is favourable temperature used to improve the dielectric constant of PVDF/MgO(7%).

Abstract: Effect of ZrO₂ on sintering properties of MgO prepared from natural brine from Qarhan Salt Lake, crystalline bischofite and MgCl₂·6H₂O(AR) was studied. The results showed that ZrO₂ of addition exceeded 1 wt% had promotive effect on sintering of magnesia prepared from MgCl₂·6H₂O(AR). While 1.5 wt% ZrO₂ was added, the bulk density of sample was 3.37 g/cm³, and relative density was 94.1%. With 1 wt% ZrO₂, the bulk densities of magnesia prepared from crystalline bischofite and brine were 3.10 and 3.27 g/cm³, and the relative densities increased by 10.0% and 19.6%, respectively. The main reasons for promoting MgO sintering with ZrO₂ were that monoclinic phase ZrO₂ converted to cubic phase Zr₂O and excess ZrO₂ reacted with MgO to generate Mg_0.13Zr_0.87O_1.87, which activated lattice and promoted the diffusion of ions during sintering process. In addition, liquid phase sintering was also one of the main reasons for promoting the sintering of brine magnesia.

Abstract: To improve the agglomerate phenomena of polarity nanosized MgO-filler in non-polar low density polyethylene (LDPE) matrix, in the composite (MgO/LDPE) master batch preparation process, adding a certain amount of ethylene-vinyl acetate copolymer (EVA), in order to improve the compatibility of nanoparticles and matrix materials. The dispersion states of MgO in the MgO/LDPE and EVA/MgO/LDPE composite material was evaluated by using scanning electron microscope (SEM), results shown that compared with MgO/LDPE nanocomposite, the dispersion of EVA modified MgO/LDPE is better and the agglomerate phenomena is not seen. DC breakdown tests shown that EVA modified MgO/LDPE compared with other several kinds of materials (LDPE; EVA/LDPE; MgO/LDPE and EVA/MgO/LDPE); the DC breakdown strength has improved significantly.

Abstract: Al2O3-MgO, Al2O3-Y2O3 and Al2O3-MgO-Y2O3 composite ceramics were fabricated respectively by hot-press sintering technique. With the analysis of the mechanical properties and microstructure, it was found that single additive MgO could be more favorable to the grains’ refinement and densification than Y2O3; the composite additive including both MgO and Y2O3 was better than single additive MgO or Y2O3, because their interactions could improve the mechanical properties of the Al2O3 ceramics; The sintering temperature could be reduced by adding the suitable amount of composite additives.

Abstract: The thermal properties of MgO were simulated by molecular dynamics (MD) method. In this present, we have investigated thermophysical properties of MgO at the temperature range from 300 to 2000 K. The MD could be indicated lattice parameter, bulk modulus, linear thermal expansion coefficient (α_lin), heat capacity at constant volume, heat capacity at constant pressure, pair correlation of ions and thermal conductivity by partial ionic model (PIM). The Busing-Ida with potential parameters was employed for interatomic potential function. The results showed the lattice parameters, the α_lin and the heat capacities of MgO increases with increasing temperature,whereas the bulk modulus and the thermal conductivity decreases with increasing temperature are agreement with literature data.

Abstract: Effect of LiCl·H₂O on sintering properties of MgO prepared from natural brine from Qarhan Salt Lake, crystalline bischofite and MgCl₂·6H₂O(AR) was studied. The results showed that LiCl·H₂O of addition exceeded 1 wt% had promoting effect on sintering of magnesia prepared from MgCl₂·6H₂O(AR). While 1.5 wt% LiCl·H₂O was added, the bulk density of magnesia was 3.40 g/cm³, and the relative density was 95.0%. With 0.5 wt% LiCl·H₂O, the bulk densities of magnesia prepared from crystalline bischofite and brine were 3.04 and 3.10 g/cm³, and the relative densities increased by 8.4% and 14.8%, respectively. The main mechanism for promoting MgO sintering with LiCl·H₂O was that Li₂O produced by hydrolysis solubilized in MgO to form solid solutions and oxygen vacancies which were favorable to sintering. The main reasons for promoting sintering of brine magnesia with LiCl·H₂O were solid solution and liquid phase sintering, while the main reason was solid solution for magnesia from crystalline bischofite and MgCl₂·6H₂O(AR).

Abstract: The adsorption of propylene oxide (PO) onto MgO, ZnO and Al₂O₃ was investigated by using in situ-IR measurements. Detailed mechanisms for PO adsorption onto these metal oxides are proposed. It was found that the PO epoxide ring exhibits two opening tendencies, depending on the acid-base properties of the metal oxide. PO adsorbed onto MgO is preferentially opened at the O-C (1) bond. The epoxide ring provides two ways to open, at the O-C (1) or the O-C(2) bond on Al₂O₃. PO adsorbed onto ZnO showed no chemical adsorption on its surface.