Papers by Keyword: MgO

Abstract: This study discusses the development of enhanced insulating materials for High Voltage Direct Current (HVDC) cable insulations by reinforcing Low-Density Polyethylene (LDPE) with nanomagnesia (MgO) particles. The main emphasis of this work is to investigate the DC breakdown voltage performance of LDPE/MgO nanocomposites as a function of filler content. Increase in DC breakdown strength is very important for long-term reliability and safety of HVDC cable insulation. Besides electrical performance, tensile strength and morphological study were made as complementary studies to check the mechanical stability and quality of particle dispersion. The nanocomposites were fabricated using the melt-blending method, where 40 grams of LDPE was mixed with 1.25 wt.%, 2.5 wt.% and 5wt.% of nanomagnesia at 170 [°C] and 50 rpm (rotation per minute) using a Haake internal mixer. The resulting materials were hot-pressed into 1 mm thin films at 160 [°C] and 50 bar pressure. DC breakdown voltage tests were conducted on the samples to determine their breakdown voltage. Tensile testing was conducted for the mechanical property evaluation where the LDPE and 2.5 wt% MgO composite show slightly lower strain, indicating decreased ductility. Overall, the incorporation of MgO enhances stiffness but reduces flexibility and strain-hardening capacity, resulting in a stronger yet less ductile material. Scanning Electron Microscopy (SEM) was undertaken to complement the results, which included the dispersion quality of MgO particles and the filler interfacial bonding. Results indicated that nanomagnesia incorporation improved the DC breakdown voltage of LDPE, with the optimum value at 2.5 wt.% of MgO. At this loading, the material showed the strongest dielectric strength while retaining reasonable tensile properties. Thus, this study has proven that LDPE reinforced with 2.5 wt.% of nanomagnesia is a viable and efficient insulation material for HVDC cable applications at average of 40.1 [kV] compared to pure LDPE at 32.41 [kV].

Abstract: Transparent resistive random-access memory (T-RRAM) is a key technology for next-generation optoelectronic devices. MgO, with its high transparency and stability, is a promising switching layer, but its performance is strongly influenced by oxygen vacancies. This study explores the effect of oxygen flow modulation during deposition on MgO-based T-RRAM. X-ray photoelectron spectroscopy (XPS) confirms that optimizing oxygen flow reduces excess vacancies while maintaining necessary defect sites for stable switching. Electrical measurements indicate that an oxygen flow of 20 sccm results in an ON/OFF ratio exceeding 10³, along with enhanced retention characteristics. These findings demonstrate that oxygen flow control is an effective method for enhancing MgO-based T-RRAM, paving the way for its integration into transparent electronic systems.

Abstract: Magnesium Oxide (MgO) thin films were deposited on SiO₂/Si substrate by electron beam evaporation. The properties of MgO thin film with and without oxygen partial pressure have been investigated by X-ray photoelectron spectroscopy (XPS), Reflection Electron Energy Loss Spectroscopy (REELS), and Ultra-Violet Photoemission Spectroscopy (UPS). The XPS was used to investigate the chemical state of the film. REELS spectra revealed that MgO thin films deposited under oxygen partial pressure had band gaps of 6.07 eV. Meanwhile, the band gap for MgO thin films grown without oxygen partial pressure was 7.17 eV. The UPS results showed that the work functions of MgO thin film with and without oxygen partial pressure are 4.75 and 4.84 eV, respectively. In the MgO thin film with oxygen partial pressure, the intensity for the valence band peak at 12.16 eV decreased, but the work function remained relatively the same. Our results demonstrated that the oxygen partial pressure played a crucial role in improving the electronic properties of MgO thin films.

Abstract: Dolomite is widely used in the construction, glass ceramics, iron and steel, pharmaceutical industries, as a source of CaO and MgO and as thermal energy storage material. Thermal decomposition analysis of natural dolomite of the so-called Jeddih limestone has been carried out. A thermogravimetry analysis (TGA) in the air evaluates the thermal decomposition of dolomite. The natural dolomite has been analyzed by x-ray flourescence (XRF) and x-ray diffraction (XRD) to test crystal structure and decomposition phase, fourier transform infra-red (FTIR) was utilized to identify the presence of functional groups. The particle morphology was observed by scanning electron microscopy. TGA curve shows that the thermal decomposition of dolomite occurs in two stages. The first stage is in temperature range of 600 - 779°C and the second one is at the temperature 779°C. The results are in line with the XRD and FTIR measurements. Which shows that calcite begins to grow at a temperature of 600°C and MgO phase is observed at 700 - 900°C. Moreover, CaO phase starts to be found at 800°C.

Abstract: A theoretical charge transport rate approach has taken to study the charge transfer properties in non-homogeneous N3-MgO systems. It develops at the fully quantum transition theory by means of transition energy, potential, driving energy and coupling constant. It is obtained that transition energy is determined by the donor acceptor scenario, dependent on the radii of N3 and MgO, dielectric constant and refractive index of solvents. The transition energy of charge carriers increased with increased dielectric constant and decreased refractive index of solvents. Transition energy of N3-MgO system reach to top with methanol (0.582 ev) and has minimum with Chlorobenzene (0.104eV). Dependences of the driving energy versus chemical potential of N3 dye and conduction band of semiconductor with potential barrier, the charge transfer rate are increased with decreased driving force of system. It is established that increased coupling constant factor reduces to increased charge transfer rate.

Abstract: The effect of doping small amounts of Magnesium Oxide ranging between 0 to 1 vol% on Zirconia Toughened Alumina (ZTA) composites which is one of main biomaterial used for production of total hip arthroplasty were investigated. The samples were produced via conventional two-stage sintering with T₁ varies between 1450°C and 1550°C with heating rate of 20°C/min. The samples were then rapid cooled to T₂ set at 1400°C with holding time of 12 hours. The microstructural and mechanical properties of the two-stage sintered ZTA are then investigated to determine the feasibility of MgO addition. Combination of two-stage sintering at T₁ above 1500 and also small amount of MgO up to 0.5 vol% were shown to have positive effect on ZTA which exhibited improvement on its grain size, mechanical properties such as Vickers hardness, Young’s modulus and fracture toughness compared to undoped ZTA composites. The sample with 0.5 vol% MgO addition sintered at T₁ of 1500°C and T₂ 1400°C was able to achieve Vickers hardness of 19.6 GPa, Young’s modulus of 408 GPa and fracture toughness of 6.8 MPam^1/2 without significant grain growth compared to undoped ZTA composites.

Abstract: The phase composition and microstructure of ZrO₂ metering nozzle matrix doped with different content stabilizer were researched by XRD, SEM and EDS. Result showed that the content of cubic phase increased accompanied with monoclinic phase decreased after sintering, different content of stabilizer made phase transition not the same; After sintering in the solid solution formed by MgO and ZrO₂, with closer location to the MgO particles, substitution degree was more obvious, but the diffusion and solid solution state of the stabilizer were far from uniform.

Abstract: This paper investigated the performance of ZTA cutting tool with the addition of different particle size of MgO additive. Therefore, the objective of this research is to compare the effects of machining parameters on tool wears of ZTA cutting tools added with micro and nanoparticle of MgO. The experiments were conducted using BridgePort-Romi Powerpath CNC machine using a tool holder Sandvik Coromant (CoroTurn CCLNR 164D-4) to hold the cutting tools properly. The parameters are set up as cutting speeds used between range 354 to 472 m/min, feed rate from 0.1 to 0.5 mm/rev with a constant depth of cut of 0.2 mm. Three types of wear were analyzed which are flank wear, crater wear and tool chipping. Flank wear and crater wear images captured using measuring microscope (NIKON MM-400/L) and the crater wear areas are analyzed using MatLab programming software. Tool chipping is observed via SEM (JEOL JSM-5600). The experimental result shows that flank wear and crater wear increase when cutting speed and feed rate increase. ZMN cutting tool shows lower value of flank wear at 0.143 mm and 3.741 mm² for crater wear than ZMM, 0.321 mm and 3.808 mm² respectively. On the contrary, cutting speed did not affect the tool chipping severely as feed rate. Moreover, ZMN also shows that the tool breakage occurred severely than ZMM due to the high load on the tool nose.

Abstract: Preparation of MgO and Mg_0.95Zn_0.05O nanomaterials using self-propagating combustion method are done to investigate the effect of doping on the band gap energy. The synthesis condition has been optimized to obtain pure MgO and Mg_0.95Zn_0.05O materials which confirmed by XRD. FESEM results shows agglomeration of crystallite with average crystallite size of samples between 30 nm to 125 nm. The band gap obtained from the measurement of UV-Vis NIR spectrophotometer for MgO nanostructure is 6.36 eV which is lower than bulk MgO of 7.8 eV. The presence of Zn in Mg_0.95Zn_0.05O sample causes the narrowing of band gap to 5.33 eV.

Abstract: Carbon capture and storage (CCS) is one of the method in reducing carbon dioxide (CO₂) emissions into the atmosphere. CO₂ capturing using calcium oxide (CaO) solid sorbents has been considered as an advanced concept for CO₂ capture and recovery. However, the adsorption capacity of CaO decreases during repeated adsorption/desorption cycles. The stability of Ca-based sorbents during cyclic runs can be achieved via the incorporation of inert support materials. Among the available inert materials, MgO is most promising for CO₂ due to high stability and a high Tammann temperature. Most of Ca- based MgO hybrid adsorbent synthesis methods sorbent come with its own limitations which are longer synthesis duration and complex or multistep methods. In this research, Ca-based MgO hybrid adsorbent was prepared via two-step method. Calcium acetate and magnesium nitrate as precursor had dissolved in water, follow by addition of ethanol. The mixture then became gelated and proceeded for calcination at 550°C and 650°C. The prepared sorbent was characterized by Scanning Electron Microscope (SEM), X-Ray Diffraction (XRD) and fourier transfer infrared spectroscopy (FTIR). The XRD analysis of the Ca-based MgO hybrid adsorbent showed the existence of MgO,CaO and CaCO₃. FTIR analysis showed presence of Ca─O bond and Mg═O bond. The morphology of the hybrid adsorbent was found to be spherical to granular shape and agglomerated. The Ca- based MgO hybrid adsorbent structural and morphological shows great potential for CO₂ capturing capacity over multiple carbonation cycles for CO₂ capturing application.