Characterization Of Al2O3 Research Articles

Aluminum oxide, cobalt aluminum oxide, and aluminum-doped zinc oxide nanoparticles as an effective antimicrobial agent against pathogens

Since the clock of antimicrobial resistance was set, modern medicine has shed light on a new cornerstone in technology to overcome the worldwide dread of the post-antimicrobial era. Research organizations are exploring the use of nanotechnology to modify metallic crystals from macro to nanoscale size, demonstrating significant interest in the field of antimicrobials. Herein, the antimicrobial activities of aluminum oxide (Al2O3), cobalt aluminum oxide (CoAl2O4), and aluminum doped zinc oxide (Zn0.9Al0.1O) nanoparticles were examined against some nosocomial pathogens. The study confirmed the formation and characterization of Al2O3, CoAl2O4, and Zn0.9Al0.1O nanoparticles using various techniques, revealing the generation of pure nanoscale nanoparticles. With inhibition zones ranging from 9 to 14 mm and minimum inhibitory concentrations varying from 4 mg/mL to 16 mg/mL, the produced nanoparticles showed strong antibacterial activity against Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, and Staphylococcus aureus. Meanwhile, the bactericidal concentrations ranged from 8 mg/mL to 40 mg/mL. In culture, Zn0.9Al0.1O NPs demonstrated a unique ability to inhibit the development of nosocomial infections with high bactericidal activity (8 mg/mL). Transmission electron microscope images revealed changes in cell shape, bacterial cell wall morphology, cytoplasmic membrane, and protoplasm due to the introduction of tested nanoparticles. These results pave the way for the use of these easily bacterial wall-piercing nanoparticles in combination with potent antibiotics to overcome the majority of bacterial strains' resistance.

Characterization of Al2O3, TiO2, hybrid Al2O3-TiO2 and graphene oxide nanofluids and their performance evaluations in photovoltaic thermal system

Characterization of Al2O3, TiO2, hybrid Al2O3-TiO2 and graphene oxide nanofluids and their performance evaluations in photovoltaic thermal system

Characterization of Al2O3 in Fe3Al-30 vol.% Al2O3 nanocomposite powder synthesized by mechanochemical process

During the last decade, mechanochemical synthesis, which can provide the nanostructured constituents, has been considered as an alternative technique to the conventional thermite reactions to produce the metallic-ceramic composite. Detection of the reinforcement in such nanocomposite powders has been provided challenges as a result of low volume fraction and high induced lattice strain. In this work, the mechanochemical reaction of a non-stoichiometry Fe2O3-Al system (Fe2O3+Al+Fe powder mixture) was performed to produce the Fe3Al-30 vol.% Al2O3 nanocomposite. The progress of the reaction was followed by X-ray diffractometry (XRD) and transmission electron microscopy (TEM). XRD analysis of mechanochemically synthesized Fe3Al-30 vol.% Al2O3 nanocomposite showed no evidence of the produced Al2O3 phase, whereas TEM analysis revealed the crystalline Al2O3 phase. The X-ray absorption by component higher mass absorption coefficient (Fe3Al matrix) in highly strained nanocomposite leads to a decrease in the diffraction intensity of components with lower mass absorption coefficient and with low volume fraction (Al2O3). High-temperature heat treatment lead to crystallite growth as well as lattice strain reducing, which resulted in the capability of detection of Al2O3 by XRD analysis.

Microwave assisted synthesis and characterization of Al2O3

Microwave radiations produce heat on any materials that contains mobile electric charges by acting as high frequency electric field. Alumina Nanoparticles are the future of aluminium used platforms. Effectiveness, compact size, better conductivity and many more facilities can be attained by alumina nanoparticles. In this work, a facile, cost effective microwave method to prepare Aluminium Oxide Nanoparticles is used for synthesis with variations. Two types of aluminium precursor were used. Various parameters were changed to study the size and shape of the resultant particles. FT-IR was taken to confirm the presence of the compounds. The prepared nano particles was characterized by XRD the shape and size of the sample was analyzed by Scanning Electron Microscopy. Precursors and Microwave power were the key factors of the size of nanoparticles. This work will continue in electrochemistry oriented applications.

Microstructure characterization of Al2O3–Mullite–AlN multiphase ceramic film on Cr/WCu substrate

Microstructure characterization of Al2O3–Mullite–AlN multiphase ceramic film on Cr/WCu substrate

Synthesis and characterization of Al2O3 and CuO nanoparticles into nanofluids for solar panel applications

Nanofluids are the new class of fluids with the suspension of nanomaterials which have the average particle size below 100 nm. The nanometer-sized materials are nanoparticles, nanofibers, nanotubes, nanowires, nanorods, nanosheet or droplets. In this research work, oxide ceramics of CuO and Al2O3 are synthesized successfully by two-step combustion route while using glycine as an organic fuel followed by heat treatment. The obtained nanoparticles are characterized by powder X-ray diffractometer. It confirms the formation of CuO and Al2O3 with the phase pure of monoclinic and rhombohedral respectively. Morphological studies carried out by Scanning electron microscopy which shows spherical shape nanoparticles of CuO and leaf-shaped Al2O3 in particles with submicron range. The importance in the choice of coolant materials with base fluids for solar panel applications is briefly discussed by plotting I-V and P-V spectrum. As a result, the cooling efficiency of both CuO and Al2O3 are found as 18.2%, which is higher than the conventional one. The obtained efficiency value has been also compared with the reported data. This shows that CuO and Al2O3 will be a promising candidate with a base fluid of water for solar panel applications.

Synthesis and Characterization of Nanocoatings Thin films by Atomic Layer Deposition for Medical Applications

In this work, synthesis and characterization of Al2O3, TiO2and Al2O3 / TiO2hyper thin films, with 25 nm and 50 nm,have been investigated by using Atomic layer deposition method (ALD) at high vacuum (0.27 Torr) onto the cobalt chromium alloy (ASTM F75) and si-wafer (100) substrates. The characterizationshave been investigated using transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDX), optical profilometer and ellipsometry spectroscopy. Morphological characterization and thickness evaluation has been obtained by optical profiler and ellipsometry spectroscopy respectively. SEM has been used to find the presence of thin film defects and the particle shape/size of the thin films. EDX has been used to obtain the element analysis of the thin films. The results have shown good quality thin films, homogeneity, without defects or micro-crack and good thin films properties. Small crystalline regions have been found in the TiO2thin film by selected area diffraction pattern(SADP) image. Al2O3ALD film exhibited lower surface roughness values and good thin film thickness control compared with TiO2and Al2O3 / TiO2.

Synthesis and characterization of Al2O3 - ZrO2-based eutectic ceramic powder material dispersion-hardened with ZrB2 and WB particles prepared by SHS

Method of self-propagating high-temperature synthesis (SHS) was used to obtain ceramic powder material based on Al2O3-ZrO2-WB/ZrB2 system with size of particles ranging from 10 to 200 µm. The routes of chemical reactions taking place in the process of synthesis depending on the source mixture composition have been determined. It was shown that the formation of zirconium boride strengthening phase depends on the content of source components В and W and combustion temperature of mixture. The analysis of microstructure has shown that powder particles feature complex composite structure consisting of oxide eutectics of Al2O3-ZrO2, individual phases of aluminum oxide and zirconium oxide as well as particles of WB and/or ZrB2. The technological properties of produced powders have been investigated.

Characterization of Al2O3 in High-Strength Mo Alloy Sheets by High-Resolution Transmission Electron Microscopy.

A novel type of alumina (Al2O3)-doped molybdenum (Mo) alloy sheet was prepared by a hydrothermal method and a subsequent powder metallurgy process. Then the characterization of α-Al2O3 was investigated using high-resolution transmission electron microscopy as the research focus. The tensile strength of the Al2O3-doped Mo sheet is 43-85% higher than that of the pure Mo sheet, a very obvious reinforcement effect. The sub-micron and nanometer-scale Al2O3 particles can increase the recrystallization temperature by hindering grain boundary migration and improve the tensile strength by effectively blocking the motion of the dislocations. The Al2O3 particles have a good bond with the Mo matrix and there exists an amorphous transition layer at the interface between Al2O3 particles and the Mo matrix in the as-rolled sheet. The sub-structure of α-Al2O3 is characterized by a number of nanograins in the $\left[ {2\bar{2}1} \right]$ direction. Lastly, a new computer-based method for indexing diffraction patterns of the hexagonal system is introduced, with 16 types of diffraction patterns of α-Al2O3 indexed.

Fabrication and characterization of Al2O3 /Si composite nanodome structures for high efficiency crystalline Si thin film solar cells

We report on our fabrication and characterization of Al2O3/Si composite nanodome (CND) structures, which is composed of Si nanodome structures with a conformal cladding Al2O3 layer to evaluate its optical and electrical performance when it is applied to thin film solar cells. It has been observed that by application of Al2O3thin film coating using atomic layer deposition (ALD) to the Si nanodome structures, both optical and electrical performances are greatly improved. The reflectivity of less than 3% over the wavelength range of from 200 nm to 2000 nm at an incident angle from 0° to 45° is achieved when the Al2O3 film is 90 nm thick. The ultimate efficiency of around 27% is obtained on the CND textured 2 μm-thick Si solar cells, which is compared to the efficiency of around 25.75% and 15% for the 2 μm-thick Si nanodome surface-decorated and planar samples respectively. Electrical characterization was made by using CND-decorated MOS devices to measure device’s leakage current and capacitance dispersion. It is found the electrical performance is sensitive to the thickness of the Al2O3 film, and the performance is remarkably improved when the dielectric layer thickness is 90 nm thick. The leakage current, which is less than 4x10−9 A/cm2 over voltage range of from -3 V to 3 V, is reduced by several orders of magnitude. C-V measurements also shows as small as 0.3% of variation in the capacitance over the frequency range from 10 kHz to 500 kHz, which is a strong indication of surface states being fully passivated. TEM examination of CND-decorated samples also reveals the occurrence of SiOx layer formed between the interface of Si and the Al2O3 film, which is thin enough that ensures the presence of field-effect passivation, From our theoretical and experimental study, we believe Al2O3 coated CND structures is a truly viable approach to achieving higher device efficiency.

Mechanical and magnetic characterisation of Al2O3 reinforced Fe–Co alloy composites

Fe–Co based alloys were strengthened through Al2O3 homogenous dispersion within the matrix, using mechanical alloying method (MA). The structure and properties of alloys were investigated by X-ray diffraction (XRD), field emission scanning electron microscopy, Vickers hardness, tensile, compression and soft magnetic test. By Al2O3 nanoparticle reinforcing, the Fe–Co alloys have shown outstanding mechanical properties besides the high saturation magnetisation and high curie temperature, which can benefit their industrial application.

Development and Characterization of Al2O3 Dispersed Al/Mg/Cu/Ti Matrix Composite

The effect of dispersion with different weight fractions of Al 2 O 3 particles in metallic matrices (Al/Mg/Ti/Cu) fabricated by powder metallurgy was investigated. In the case of 15 wt% Al 2 O 3 reinforced composites, peak hardness was attained which subsequently decreased with increasing the content of Al 2 O 3 . A correlation between the microhardness and nanomechanical properties at submicron scale was examined for all the composites. Specific strength and specific modulus were measured in order to figure out the performance of the composites.

SU-E-T-106: Experimental Characterization of Al2O3:C Optically Stimulated Luminescence Detector (OSLD) Exposed to 6 MV X-Ray Beams

Purposes: To characterize the response of Al2O3:C optically stimulated luminescencedetectors (OSLDs) to 6 MV x‐ray beams and to determine the optimal bleaching method that would allow the re‐use of the OSLDs. Methods: OSLDs were exposed to a 6 MV x‐ray linac beam in the dose range from 50 mGy–10 Gy. Readouts were performed with a commercial OSLD reader (microStarTM, Landauer Inc.). For 50 mGy and 100 mGy doses, OSLDs were readout using the reader's low‐dose mode, which provides higher stimulation power compared to the high‐dose mode. All other readouts were performed using the high‐dose mode. The OSLD response to dose, bleaching time and repeated readouts (depletion) were determined. Bleaching of the OSL signal was performed using a 250 W halogen lamp with two Methods: (a) direct exposure to light; and (b) exposure using a long‐pass optical filter to block wavelengths shorter than 495 nm. Results: The OSLD dose‐response was linear for the investigated dose range. After 100 readouts, the OSL signal was depleted by (24.5 ± 0.7) % and (3.16 ± 0.07) % with a depletion rate of (0.251 ± 0.002) and (0.023 ± 0.002) %/readout for low‐ and high‐dose modes, respectively. After a 5 min bleaching time, (85.1 ± 1.4) and (70.5 ± 2.0) % reductions in the OSL signal for all doses was attained using methods (a) and (b), respectively. After a 100 min bleaching time, (99.5 ± 0.2) % reduction was attained. Conclusions: We observed linearity of the OSLD's dose response for the investigated dose range. A 100 min bleaching time was sufficient to bleach 99.5 % of the OSL signal for both bleaching methods. The depletion rate using the low‐dose mode is 11 times higher than using the high‐dose mode. for the high‐dose mode of the reader, the depletion rate is independent on dose.

Applying Complementary Trap Characterization Technique to Crystalline $\gamma$-Phase-$\hbox{Al}_{2} \hbox{O}_{3}$ for Improved Understanding of Nonvolatile Memory Operation and Reliability

The operation and reliability of nonvolatile memory concepts based on charge storage in nitride layers, such as TANOS (TaN/Al2O3/Si3N4/ SiO2/Si), require detailed information on the energy and spatial distribution of the charge defects in both the nitride and the Al2O3 blocking dielectric. This paper focuses on the characterization of Al2O3. We have successfully applied complementary trap characterization techniques to crystalline γ-phase- Al2O3 in order to obtain a complete picture of the spatial and energetic distribution of the defect density. As a result, two defect types at energy levels 1.8 and 3.5 eV below the conduction band edge are found.

Characterisation of Al2O3 doped hexanoyl chitosan–LiCF3SO3–EC polymer electrolytes

The insolubility of chitosan in a wide range of organic solvents has limited the application of chitosan especially in electrochemical systems. In order to improve its solubility, acyl modification of chitosan was carried out in the present study. Films of hexanoyl chitosan-based polymer electrolyte were prepared by solution casting technique. The effect of filler on the transport properties of hexanoyl chitosan–LiCF3SO3–ethylene carbonate electrolytes has been investigated. The conductivity for fillerfree polymer electrolyte is 2·75 × 10–5 S cm–1. The addition of 6 wt-%Al2O3 increased the conductivity by one order of magnitude to 1·01 × 10–4 S cm–1. Within the temperature range investigated, the conductivity of the polymer electrolytes are thermally assisted and can be described by Arrhenius law. The conductivity variant has been justified via the Rice and Roth model in which the number of free ions per unit volume, mobility and diffusion coefficient of free ions were obtained.

Synthesis and characterization of Al2O3 and SiO2 films with fluoropolymer content using rf-plasma magnetron sputtering technique

Pure and molecularly mixed inorganic films for protection against atomic oxygen in lower earth orbit were prepared using radio-frequency (rf) plasma magnetron sputtering technique. Alumina (Al2O3) and silica (SiO2) films with average grain size in the range of 30–80nm and fully dense or dense columnar structure were synthesized under different conditions of pressure and power. Simultaneous oxide sputtering and plasma polymerization (PP) of hexafluoropropylene (HFP) led to the formation of molecularly mixed films with fluoropolymer content. The degree of plasma polymerization was strongly influenced by total chamber pressure and the argon to HFP molar ratio (nAr∕nM). An order of magnitude increase in pressure due to argon during codeposition changed the plasma-polymerization mechanism from radical-chain- to radical-radical-type processes. Subsequently, a shift from linear CH2 group based chain polymerization to highly disordered fluoropolymer content with branching and cross-linking was observed. Fourier transform infrared spectroscopy studies revealed chemical interaction between depositing SiO2 and PP-HFP through appearance of absorption bands characteristic of SiF stretching and expansion of SiO2 network. The relative amount and composition of plasma-polymerized fluoropolymer in such films can be controlled by changing argon to HFP flow ratio, total chamber pressure, and applied power. These films offer great potential for use as protective coatings in aerospace applications.

Synthesis and characterization of Al2O3 and ZrO2–TiO2 nano-composite as a support for NOx storage–reduction catalyst

To improve the thermal stability of NOx storage–reduction catalysts, a novel support containing Al2O3, ZrO2, and TiO2 was synthesized by the coprecipitation method. The XRD and TEM results indicated that primary particles of γ-Al2O3 and a solid solution of ZrO2–TiO2 coexisted as secondary particles, that is, the synthesized support was a nano-composite of γ-Al2O3 and ZrO2–TiO2. The synthesized support had a characteristic single meso-pore, derived from the structure of the secondary particle. The basicity of the synthesized support was lower than that of the physically mixed oxide. After thermal treatment, aggregation of the ZrO2–TiO2 particles in the support was inhibited relative to that in the mixture of Al2O3 powder and ZrO2–TiO2 powder. This was attributed to the diffusion barrier (against ZrO2–TiO2) created by primary Al2O3 in the synthesized support. After a thermal aging test, the NOx storage–reduction catalyst containing the synthesized support had a larger NOx storage capacity than the catalyst containing the physically mixed oxide.

Mechanical Properties of Al<sub>2</sub>O<sub>3</sub>-TiO<sub>2</sub>-SiC Nanocomposites for the Femoral Head of Hip Joint Replacement

Microstructure and mechanical properties of Al2O3-TiO2-SiC nanocomposites were studied. To improve the mechanical and tribological properties of alumina, nano-sized TiO2 and SiC powders were dispersed. Spark Plasma Sintering (SPS) technique, at 1400°C, 50 MPa for 5 minutes, was applied for the densification of Al2O3-TiO2-SiC nanocomposites. Characterization of Al2O3- TiO2-SiC nanocomposites was carried out using Scanning Electron Microscopy (SEM), Transmission Electron Microscope (TEM), X-ray diffractometer and EDX. Fracture toughness and Vickers hardness were estimated by indentation technique. These experimental results on mechanical properties of Al2O3-TiO2-SiC nanocomposites indicated that they can be a potential material with high hardness and high fracture toughness to be used as femoral head in total hip joint replacement.

Characterization of Al2O3–ZrO2 Mixed Oxide Supported Mo Hydrotreating Catalyst

A series of molybdenum catalysts supported on Al2O3–ZrO2 mixed oxide containing 50% ZrO2 and 50% Al2O3 were prepared by incipient wetness technique and characterized by BET surface area, X-ray diffraction, temperature programmed reduction and oxygen chemisorption. The catalytic activities for hydrodesulphurization (HDS), hydrogenation (HYD), and hydrocracking (HYC) were determined using thiophene, cyclohexene, and cumene as model compounds, respectively. Results indicate that up to 8 wt% Mo loading, the catalyst is well dispersed and crystallite growth occurred beyond this loading. Also both oxygen uptake and catalytic activities increase with Mo loading up to 8 wt% and then decreases at higher loading. A linear correlation was obtained between oxygen uptake and all catalytic activities and the correlation coefficients obtained suggest that the order of catalytic activities for HDS, HYD, and HYC is: HDS > HYD > HYC. Furthermore, the catalytic activities of the mixed oxide supported catalyst for HDS, HYD, and HYC were higher than those supported on pure alumina and pure zirconia. The incorporation of 3% Co on 8% Mo catalyst was determined to result in enhanced activity for HDS, HYD, and HYC.

Characterization of Al2O3:Eu3+ Luminescent Coatings Prepared by Spray Pyrolysis Technique

Europium doped Al2O3 photoluminescent coatings have been prepared by an ultrasonic spray pyrolysis process, using a solution of 0.05M of AlCl3 · 6H2O as starting material and EuCl3 as doping. These films were deposited on Pyrex glass substrates at atmospheric pressure using purified air as a carrier gas. All films were amorphous in structure. The photoluminescence spectra were measured at room temperature as a function of substrate temperature and doping concentration. For an excitation wavelength of 395 nm, all the photoluminescent spectra show bands located at 587, 600, 612 and 648 nm, characteristics of the trivalent europium ion. We observed a concentration quenching of the photoluminescence at values of activator concentration above 10 at% in the starting solution.