Oxide Nanopowders Research Articles

Electrophoretic Deposition of One- and Two-Layer Compacts of Holmium and Yttrium Oxide Nanopowders for Magneto-Optical Ceramics Fabrication

In this work, the possibility of fabricating composite magneto-optical ceramics by electrophoretic deposition (EPD) of nanopowders and high-temperature vacuum sintering of the compacts was investigated. Holmium oxide was chosen as a magneto-optical material for the study because of its transparency in the mid-IR range. Nanopowders of magneto-optical (Ho0.95La0.05)2O3 (HoLa) material were made by self-propagating high-temperature synthesis. Nanopowders of (Y0.9La0.1)2O3 (YLa) were made by laser synthesis for an inactive matrix. The process of formation of one- and two-layer compacts by EPD of the nanopowders from alcohol suspensions was studied in detail. Acetylacetone was shown to be a good dispersant to obtain alcohol suspensions of the nanopowders, characterized by high zeta potential values (+29–+80 mV), and to carry out a stable EPD process. One-layer compacts were made from the HoLa and YLa nanopowders with a density of 30–43%. It was found out that the introduction of polyvinyl butyral (PVB) into the suspension leads to a decrease in the mass and thickness of the green bodies deposited, but does not significantly affect their density. The possibility of making two-layer (YLa/HoLa) compacts with a thickness of up to 2.6 mm and a density of up to 46% was demonstrated. Sintering such compacts in a vacuum at a temperature of 1750 °C for 10 h leads to the formation of ceramics with a homogeneous boundary between the YLa/HoLa layers and a thickness of the interdiffused ion layer of about 30 μm.

High-density polyethylene with ZnO and TiO2 nanoparticle filler: Computational and experimental studies of radiation-protective characteristics of polymers

BackgroundRadiation protection seeks to prevent the negative consequences of ionizing radiation by reducing unneeded radiation exposure. PurposeA widely established principle for working to assure radiation safety, the goal of this study is to optimize radiation protection. MethodsIn this study, high density polyethylene C2H4 (HDPE) was created utilizing additions of zinc oxide and titanium dioxide nanopowder in accordance with the HDPE(ZnO)x and HDPE(TiO2)x formulas, where x = 0, 2, 4, 6, 8, 10,12, and 15 mol%, respectively. The created samples were exposed to radiation from four typical point sources: 214 Am (59.5 keV), 133 Ba (303 and 356 keV), 137 Cs (661.7 keV), and 60 Co (1173 and 1332.5 keV). A sodium iodide (NaI (TI)) scintillation detector (2" × 2″) was used to measure the energy intensity. Experimental measurements and a calculation utilizing the WinXCOM database were used to determine the mass attenuation coefficient (μ/p) values for the prepared samples. ResultsThe findings of the experiment and the hypothesis were found to be highly similar. The sample with a combination of 15% ZnO and HDPE demonstrates superior efficacy in shielding against gamma radiation. The energy level of 1.332 MeV is associated with a 15% rise in the fraction of zinc oxide nanoparticles, which in turn leads to a 20% increase in the mass attenuation coefficient. Finally, it should be noted that the half value layer saw a decrease of 34% when the concentration of zinc oxide nanoparticles was increased by 15% at an energy level of 1.332 MeV. ConclusionIt can be deduced that the mass attenuation coefficient increased by 20% at 1.332 MeV with a 15% increase in the proportion of zinc oxide nanoparticles.

Effect of Tantalum Oxide Nanopowder on Heat Cure Acrylic Resin Impact Strength and Surface Hardness

Background: In elderly patients, fracture of the denture is one of the most common problems. Therefore, in this research, a chemical tantalum oxide was added to test its effect on the extent of increasing the strength of the denture and its ability to withstand fracture.
 Objective: To assess how Tantalum oxide affected heat – cured acrylic s impact strength and hardness.
 Patients and Methods: The Intention was to create a total of (60) specimens. Twenty samples were made without additives (control), and 40 had made with tantalum oxide at two different amounts ( 1%, 1.5%).
 Results: The impact strength tests showed highly significant difference among studied groups . The hardness test also showed really significant difference between the two groups, the controls and the experiments. when tantalum oxide had added the impact strength and hardness had increase in all concentration.
 Conclusion: Denture fracture in elderly patients is the main problem, while when adding this substance, a decrease in the fracture rate was observed when compared with dentures without adding this substance.
 

Effect of Tantalum Oxide Nanopowder on Heat Cure Acrylic Resin Impact Strength and Surface Hardness

Background: In elderly patients, fracture of the denture is one of the most common problems. Therefore, in this research, a chemical tantalum oxide was added to test its effect on the extent of increasing the strength of the denture and its ability to withstand fracture. Objective: To assess how Tantalum oxide affected heat – cured acrylic s impact strength and hardness. Patients and Methods: The Intention was to create a total of (60) specimens. Twenty samples were made without additives (control), and 40 had made with tantalum oxide at two different amounts ( 1%, 1.5%). Results: The impact strength tests showed highly significant difference among studied groups . The hardness test also showed really significant difference between the two groups, the controls and the experiments. when tantalum oxide had added the impact strength and hardness had increase in all concentration. Conclusion: Denture fracture in elderly patients is the main problem, while when adding this substance, a decrease in the fracture rate was observed when compared with dentures without adding this substance. Keywords: acrylic resin , polymethylmethacrylate , and tantalum oxide

Effect of Tantalum Oxide Nanpowder on Heat Cure Acrylic Resin Thermal Conductivity and Surface Roughness

The main problem with heat cure acrylic is their poor thermal conductivity and their roughness. This study aims at evaluating the effect of tantalum oxide nanopowder on the thermal conductivity and surface roughness of heat cure acrylic resin. Material and Method: The Intention was to create a total of (60) specimens. Twenty samples were made without additives (control), and 40 had been made with tantalum oxide at two different amounts (1 %, 1.5%). Results: the thermal conductivity tests showed non-significant difference among studied groups. The surface roughness tests showed highly significant difference among studied groups. when tantalum oxide had added to heat cure acrylic at two different amounts (1%, 1.5%). Conclusion: adding tantalum oxide increases the thermal conductivity and decreases the surface roughness of the two experimental groups.

Facile synthesis of high-entropy (Co0.2Cr0.2Fe0.2Mn0.2Ni0.2)3O4 nanopowders and their electrochemical properties as supercapacitor electrode

High-entropy oxide (HEO) nanopowders are expected to have unique electrochemical energy storage properties due to their unique structural characteristic and tailorable chemical composition. However, HEO nanopowders are difficult to be prepared because of severe grain coarsening and particle agglomeration in high temperature calcination. In this study, a polyacrylamide gel method was presented to prepare high-entropy (Co0.2Cr0.2Fe0.2Mn0.2Ni0.2)3O4 nanopowders. The mole ratio of acrylamide/metal cations (A/M) had a significant influence on the average particle size of HEO nanopowder, which was decreased with the increase of A/M mole ratio. Electrochemical tests demonstrated that as-prepared HEO nanopowders had a specific capacitance of 384 F/g at a current density of 1 A/g, which was remained 57 % as the current density was increased to 20 A/g. Furthermore, a relatively high capacitance retention of 60 % was obtained after 2000 charge-discharge cycles at 5 A/g. In addition, a HEO//activated carbon asymmetric supercapacitor was assembled, which achieved an energy density of 24 Wh/kg at a power density of 746 W/kg. This study presents a simple and cost-effective method to prepare HEO electrode material for supercapacitors.

Studying an Iron Oxide Nanopowder as a Bioactive Material

Studying an Iron Oxide Nanopowder as a Bioactive Material

Effect of ZnO Nanoparticles on the Kinetics and Photo-degradation of Certain Textile Effluent Dyes

Untreated effluents especially in discharges from textiles and fabric industries, usually contain dyes. Synthetic dyes have adverse effects on all forms of life when discharged directly into the environment. This paper investigates the photo-degradation of a mixture of direct orange 39, chlorantine fast red 5B, Viscose Black B and direct sky blue K, all present in a real textile effluent based on the influence of ZnO photocatalyst dose and irradiation time at a specific UV power source. The photo-degradation experiments were conducted in a batch stirred photoreactor equipped with UV lamp of rated at 30 W, a magnetic stirring system and a thermometer. The photocatalyst used was zinc oxide nanopowder (ZnO) The results showed that changes in these parameters influenced the efficiency of the photo-degradation. The kinetic studies showed that the dyes degradation followed the Langmuir-Hinshelwood model that has been modified to accommodate reactions occurring at the solid-liquid interphase. At the catalyst dose of 0.5 g/l, the apparent first order rate constant, was 0.00411 ; but at 2.5 g/l, this reduced to . The best degradation was at the catalyst dose of 2.0 g/l with rate constant of .

Vermiwash-mediated synthesis of molybdenum doped TiO2 nanoparticles: Evaluation of photocatalytic and biomedical properties

Combined effects of molybdenum (Mo) doping and enzyme incorporation on the photocatalytic and certain biomedical activities (antibacterial, antioxidant and antidiabetic) of titanium oxide nanopowder were studied. A soft-chemical eco-friendly approach was adopted to prepare enzyme powered Mo doped TiO2 nanoparticles (MTV). The photocatalytic dye degradation study against MB dye showed that the Mo addition increases the degradation efficiency from 73 to 86%. The enzyme incorporation into the system through the addition of vermiwash improves the efficiency further to 97%. The doping of Mo and addition of enzymes effectively controlled the growth of the tested bacteria Proteus vulgaris, Bacillus subtilis, and Pseudomonas aeruginosa. The minimum inhibitory concentration (MIC) of bare TiO2 against the bacteria viz. P. vulgaris, B. subtilis and P. aeruginosa are 125, 125 and 250 µg/mL, respectively, whereas the MIC of vermiwash activated Mo doped TiO2 are as low as 15.62 µg/mL, 07.81 µg/mL and 15.62 µg/mL, respectively. The antioxidant capacity of the sample MTV expressed potential free radical scavenging effect by 2,2-diphenyl-1-picrylhydrazyl (DPPH) with an inhibition of 89.77% and 2,2′-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) with an inhibition of 87.02% compared to the standard ascorbic acid. In addition, the MTV nanopowders exhibited significant anti-diabetic effect (89.29%) by inhibiting the α-glucosidase enzyme. The mechanism involved in the enhancement of efficiency of the synthesized material is elaborated in this article. The XRD, SEM, FT-IR, Raman, XPS and BET results support the discussions on the property enhancement of the prepared material.

Numerical deconvolution approaches for dielectric characteristics of complex composite materials based on liquid crystals and oxide nanopowders

Dielectric spectroscopy is a well-known method to characterize different liquid or solid (nano) materials such as liquid crystals, polymers, composites, ceramics etc. More the material structure is complex, more the molecular dynamics are put in evidence with difficulty. In many such cases, the analysis of the spectra with the classic Havriliak-Negami (H–N) functions is hard to apply or even fails. Therefore, we propose a simple numerical approach (with two different procedures) for the deconvolution of complex spectra in dielectric spectroscopy (DS). The final goal is to obtain the frequency of maximum loss (fmax) depending on the temperatures, Arrhenius diagram, and the activation energy/energies. The developed procedures have as their starting point the “logarithmic derivative of the permittivity”. To our knowledge, these procedures have not yet been presented in the literature. The proposed first numerical processing allows a better separation of the different relaxation processes, a decrease in the contribution of the electrical conductivity and a better localization of the frequencies where the dielectric loss has maximum values. The second of the procedures is applied in certain particular situations, and the other procedure is more general. Where the former can be applied, it is equivalent to using the classical H–N functions in terms of obtaining the fmax, but it is simpler to apply. The first procedure uses an “artificial” and simpler H–N function, in which the fewer fitting parameters have no physical meaning, but allow a good localization of the frequency of maximum dielectric loss. The proposed procedure was applied on experimental data of dielectric spectroscopy obtained on pristine materials (nematic mixture E7 and ZnO) and composites E7-ZnO, obtained by a “green technology”. The complicated spectra of the dielectric permittivity presented by these samples represent the suitable test to highlight the advantages but also the limitations of our approach. Comparing the values of the activation energy obtained for the two procedures is the criterion for verifying their correctness. The volume of processed experimental data is large, for this reason we present only the results obtained based on numerical approaches. The differences between the results obtained with the two procedures are small. The procedures can be considered as alternatives to the application of fitting with H–N functions. One procedure replaces H–N by eliminating the use of functions with complex variables and the method of least squares and has the advantage that it can apply non-specialized software like Origin. The other allows a better analysis of spectra being an improved-modified H–N approach. Proposed procedures are sufficiently effective to be used in the dielectric spectroscopy data analysis of a wide variety of liquid crystals, composites, ceramics, nanomaterials, etc.

Effect of calcination temperature on NiO for hydrogen gas sensor performance

In this work, we have synthesized the nickel oxide (NiO) nanopowders via twofold facile solvothermal synthesis. Later, the products are calcined at 300 °C, 400 °C, and 500 °C in an air atmosphere to form NiO nanopowders, which are deposited onto the SiO2/Si substrate via the spin coating technique. The morphological studies depict the high porosity at 400 °C calcinated NiO thin film than other conditions. Further, the Brunauer-Emmett-Teller (BET) surface analysis reveals that at 400 °C calcinated NiO sample exhibits a higher surface area of 52.3 m2g-1 due to the existence of porous grain-like surface morphology. To examine the gas sensing performance, Ag/NiO/Ag hydrogen gas sensor device is fabricated by depositing planar-type silver (Ag) electrodes onto the NiO thin film via thermal evaporation technique. The gas sensing behaviour of the fabricated gas sensor test-devices has been examined at various operating temperatures (100 °C–300 °C) and concentrations (100 ppm–300 ppm). The hydrogen gas sensor test-device fabricated using NiO nanopowder calcined at 400 °C shows good crystalline nature, a highly porous surface with efficient oxygen vacancies, and narrowed bandgap, which results in the maximum responsivity of 97.2% at the operating temperature of 250 °C with response and recovery time of 56 s and 21 s, respectively. Therefore, the Ag/NiO/Ag gas sensor test-device can be a potential route toward the development of hydrogen gas sensor devices.

Photoluminescence enhancement of ZrO2:Dy3+ Nanocrystals adding Li+ ions with controlled N2 atmosphere synthetized by coprecipitation method

A series of Dy3+ (0–1 mol%) and Li+ (0.05–1.5 mol%) co-doped zirconium oxide (ZrO2) nanopowders are prepared via coprecipitation, followed by a hydrothermal treatment in nitrogen atmosphere. It was found an optimal concentration of Dy-doped ZrO2 (0.5 mol %) with high emission, showing peaks at 490 nm (blue) and 577 nm (yellow) corresponding to 4F9/2 → 6H15/2, and 4F9/2 → 6H13/2 transitions, respectively with excitation at 350 nm wavelength. Furthermore, the samples of ZrO2:Dy3+ annealing with a controlled N2 showed an increase of 73 and 83% in blue and yellow bands due to decrease of hydroxyl groups (–OH), according to infrared (IR) spectroscopy, which helps to reduce the non-radiative relaxation process. In addition, incorporation Li+ ions up to 0.25 mol% into ZrO2:Dy3+ nanopowders exhibited a further enhancement emission intensity of both bands, owing to this monovalent cation act as coactivator and charge compensator. On the other hand, the color coordinates (x, y) and correlated color temperature (CCT) results suggests that the synthesized nanophosphor can be used as a yellow-orange component for the fabrication of near UV-based w-LEDs.

Tungsten oxide nanopowders: pulse alternating current electrosynthesis, structure optimization and performance in a flow photocatalytic fuel cell

Tungsten oxide nanopowders: pulse alternating current electrosynthesis, structure optimization and performance in a flow photocatalytic fuel cell

Crystallization of Magnetic Iron Oxide Nanoparticles during Chemical Synthesis from Iron Salt Solutions with Exposure to Ultrasound

Iron oxide nanopowders are synthesized via chemical precipitation. It is shown that synthesis produces an iron oxide phase with a magnetite structure (either a magnetite–maghemite solid solution or a mixture of this solid solution and goethite). The sizes of the CSR and particles for the main phase are ~10–20 nm. The synthesized iron oxide powders have developed surfaces, specific surface area SBET ≈ 92 and 117 m2/g, and identical fairly large specific pore volumes (VP/P0→0.99/0→0.99 = 0.35 cm3/g). It is shown that additional in situ ultrasonic treatment of the magnetic iron oxide nanoparticles in the mother liquor results in abrupt oxidation of iron(II) ions and creates a nonmagnetic impurity phase of goethite.

Synthesis of zinc oxide photocatalysts from zinc-dust waste for organic dye degradation

Zinc-dust waste from a hot-dip galvanizing plant in the metal plating industry was successfully used as the starting material to synthesize zinc oxide (ZnO) nanopowder via a hydrothermal method. Effects of acid types in zinc-dust dissolving process and concentration of NaOH for precipitation on physical characteristics and photocatalytic activity of the synthesized ZnO were investigated. Elemental composition, phase and crystallite size, morphology with chemical composition, and specific surface area of the ZnO nanostructures were characterized by X-ray fluorescence spectroscopy (XRF), X-ray diffraction (XRD), scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDS), and gas adsorption-desorption analysis, respectively. The photocatalytic performance of the prepared ZnO was evaluated by photodegradation of rhodamine B (RhB) under UV light irradiation. The ZnO nanostructures synthesized by dissolving zinc-dust with nitric acid, then precipitating with a solution of 6 M NaOH, and hydrothermal treatment at 170℃ for 8 h exhibited the highest dye degradation efficiency. It is up to 89.7% after UV irradiation for 240 min, which is comparable to the degradation efficiency of a commercial ZnO nanoparticles (92.7%). This work offers materials and synthesis method for alternative photocatalysts prepared from industrial waste that possess high photocatalytic activity for organic dye degradation.

Cracking of Heavy Oil in Supercritical Water in the Presence of Iron Oxide Nanopowder: Asphaltene Transformations and Process Kinetics

The products of catalytic cracking of heavy crude oil from the Ashalchinskoye oil field (the Almetyevsk district of the Republic of Tatarstan, Russia) were characterized. The effects of a Fe2O3 nanopowder catalyst and the presence of supercritical water (SCW) on the composition and structure of these cracking products were investigated. Cracking over 0.01 wt % Fe2O3 nanopowder in a SCW environment was found to enhance the yield of distillates by more than 34 wt % and to reduce the content of resinous asphaltene materials by a factor of 2.1 compared to the initial crude oil. It was further shown that Fe2O3-nanopowder-catalyzed cracking produces coke-like asphaltenes with a low H/C atomic ratio (no higher than 0.75). Reaction rate constants were evaluated for the thermal and catalytic cracking of the heavy oil from the Ashalchinskoye field.

Detection of dangerous metallic oxides nano-powders by a one-dimensional resonant phononic crystal sensor

Detection of dangerous metallic oxides nano-powders by a one-dimensional resonant phononic crystal sensor

Structural and optical analyses of hydrothermally synthesized ZrO2 nanopowder

In the present work, the hydrothermal method was used to synthesize mixed phase zirconium oxide (ZrO2) nanopowder. X-ray diffraction and scanning electron microscopy were employed for structural and morphological study, respectively. Fourier transform infrared spectroscopy confirms the presence of the Zirconium-Oxygen bond. To study the optical properties of ZrO2 nanopowder, Raman and Ultra-Violet visible spectroscopies were used at room temperature. The Tauc’s plot reveals that the average value of the optical bandgap is ∼ 3.4 eV. These studies of dual-phase ZrO2 nanopowder suggest that ZrO2 nanopowder can be a suitable candidate for many potential applications including optoelectronic devices and optical sensors.

Augmenting heat transfer performance in a heat exchanger with CeO2 nanofluids

ABSTRACT This work aims at determining the heat transfer enhancement as well as friction losses of CeO2 nanofluids (NFs) in a double pipe heat exchanger. Cerium Oxide nanopowder was characterised by Energy-Dispersive X-ray Spectroscopy (EDX), X-Ray Diffraction (XRD) and Scanning Electron Microscopy (SEM). Thermo-physical properties were measured at different temperatures and concentrations of the NF. Friction factor and Nusselt numbers were determined for various particles loading of 0.1%, 0.2% and 0.3%. Thermal conductivity enhanced by 7.92% to 12.9% than the based fluid. Experiments were performed for the range of Reynolds numbers of 2000 to 9000. Experimental results showed that for 0.3% concentration of NF, the maximum augmentation in the Nusselt number is 32.35% with a penalty of 1.18 times in terms of friction factor at a Reynolds number of 8720 in contrast to that of the carrier fluid.

Effect of pH of the precursor solution on the photocatalytic and biomedical applications of enzyme coupled ZnO and SnO2 nanomaterials: A comparative study

The focus of this study is to investigate the effects of pH of the precursor solution and the addition of vermiwash on the photocatalytic and certain biomedical applications of zinc oxide (ZnO) and tin oxide (SnO2) nanopowders prepared via co-precipitation method. The pH of the starting solution was varied as 8, 9 and 10 through the addition of suitable amount of sodium hydroxide (NaOH) and vermiwash. These vermiwash-derived enzymes activated ZnO and SnO2 nanopowders (prepared at different pH values) were applied for biomedical applications viz. antibacterial, antioxidant and antidiabetic activity for the first time. The prepared samples were also characterized using various analytical techniques viz. XRD, SEM, TEM, EDS, FTIR, XPS, BET, and UV-vis spectra. The results of these analytical studies are correlated with their photocatalytic degradation abilities and also biological applications. The photocatalytic activity of the nanoparticle were analyzed using a visible annular type photo reactor by degrading methylene Blue (MB) - a standard cationic dye - under UV-visible irradiation. A remarkable dye degradation efficiency of 98% and 94% were achieved for the best samples of vermiwash activated ZnO and SnO2 (prepared from starting solution with pH 9), respectively. The lower band gap values (2.97 and 3.1 eV) of these samples as calculated from Tauc's plots and their enhanced surface area as observed from the BET analysis play crucial roles in improving their photocatalytic efficiency. Remarkable antibacterial, antioxidant and antidiabetic activities were also recorded for the samples prepared at pH 9.