Properties Of Nanopowders Research Articles

Investigation on crystallographic alignment of Sm-Co alloy nanoparticles by external magnetic field

In order to improve the magnetic properties of Sm-Co nanopowder prepared using the low oxygen-induction thermal plasma (LO-ITP) process, the effect of heat treatment on the phase transformation and magnetic properties of Sm-Co nanopowder was investigated. Sm-Co nanopowder was annealed at 873, 973, 1073, and 1173 K. The X-ray diffraction results indicate that uniform Sm-Co nanopowder with a dominant SmCo5 phase can be prepared at annealing temperatures higher than 1073 K. The coercivity of the Sm-Co nanopowder annealed at 1173 K was measured to be 1.5 MA/m. The Sm-Co nanoparticles can be sufficiently oriented using an external magnetic field. Although perfect crystal orientation could not be achieved in the annealed nanopowder owing to necking, short-duration heat treatment promoted the formation of the hard magnetic phase and suppressed necking. The results of this study demonstrate the importance of the rapid heat treatment effect during particle formation in the ITP process for preparing dispersible Sm-Co nanoparticles with high coercivity and improved anisotropic magnetic behavior.

The evaluation of the electrochemical properties of Co3O4 nanopowders synthesized by autocombustion and sol–gel methods

The evaluation of the electrochemical properties of Co3O4 nanopowders synthesized by autocombustion and sol–gel methods

Magnetic properties of nanopowder h-BN doped with Fe and Fe3O4 nanoclusters

Magnetic properties of nanopowder h-BN doped with Fe and Fe3O4 nanoclusters

The effect of Ho-doping on the synthesis, structure and magnetic characteristics of ZnFe2O4-based nanopowders

The successful production of nanopowders consisting of Ho-doped zinc ferrite (ZnFe2-xHoxO4, with x values ranging from 0 to 0.08) has been accomplished using the glycine-nitrate combustion (GNC) method, followed by calcination in air. Various analytical techniques, such as EDXS, DTA-TG, SEM, PXRD, Raman spectroscopy, and vibrating sample magnetometry (VSM), were employed to examine the resulting samples. The outcomes of our investigation indicated that an excess of fuel during the GNC process yields X-ray amorphous foamy products, which subsequently crystallize after being held at a temperature of 550 °C for a duration of 4 h. PXRD data analysis showed that the obtained samples consist of single-phase Ho-doped zinc ferrite with a spinel structure. The incorporation of holmium into the ferrite spinel structure was established to occur when the calcination temperature is elevated to 700 °C. Rietveld refinement revealed that the degree of inversion varies from 0.078 to 0.309 as the level of Ho-doping increases from x = 0 to x = 0.08. Furthermore, the incorporation of Ho leads to a more than twofold reduction in the crystallite size of ZnFe2-xHoxO4, decreasing from 61.7 to 27.3 nm. The magnetic properties of the nanopowders are shown to be systematically altered by changes in the degree of inversion and the crystallite size of zinc ferrite, which are interrelated with the holmium content. For instance, the saturation magnetization (Ms) increases by 20% and attains a value of 54.9 kOe at x = 0.08. This finding suggests that the magnetic behavior of ZnFe2–xHoxO4 nanoparticles can be deliberately adjusted, making them a promising candidate for functional materials in the field of magnetic hyperthermia. In summary, this research provides valuable insights into the synthesis, structure, and magnetic properties of Ho-doped zinc ferrite nanopowders, underscoring their potential applications in the realm of magnetic hyperthermia.

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.

Precipitation Synthesis of CeO2 Nanopowder Pigment

Nanopowder pigments of CeO2 and CeO2:Fe were synthesized by precipitation method at a moderate calcination temperature of 500oC. The pigments exhibited pale yellow for CeO2 nanopowder and brick red for CeO2:Fe nanopowder. Both pigments possessed mesoporous and cubic fluorite structures of CeO2. The incorporation of Fe into CeO2 reduced crystallite size and increased surface area. Moreover, it widens bandgap energy and significantly improved the absorption property of CeO2 nanopowder.

Synthesis and investigation of the physicochemical properties of polymorphic 3C–SiC

Silicon carbide (SiC) nanopowders were synthesized under Ar atmosphere via the carbonization reaction method using silicon powders and expanded graphite as initial materials, and ferric nitrate as catalyst precursor. The effects of heat treatment temperature and the C/Si molar ratio on SiC products were studied. The microstructure, phase composition and chemical state of the products were analyzed by XRD, SEM, XPS, TEM and Raman. The photoluminescence (PL) properties of SiC nanopowders were tested. The results showed that the content of the 3C–SiC product is higher after heat treatment at 1400 °C for 3 h with a molar ratio of C/Si of 1:1. 3C–SiC exists in the form of particles and wires. The formation process of 3C–SiC can be explained by a two-step method, nucleation under catalysis and growth under Vapor-Solid (VS) mechanism. Two ultraviolet light emission peaks are observed at about 318 and 380 nm. The main PL spectra of 3C–SiC nanopowders exhibit larger blueshifts. The blueshift is attributed to the stacking fault, oxygen defects, morphology and quantum confinement effect. It has potential application prospects in ultraviolet detectors, optoelectronic devices and light emitters.

The Synthesis Regimes Effect on Powders and Ceramics of MgAl<sub>2</sub>O<sub>4</sub> Doped with Cr<sup>3+</sup>

This work presents the investigation of nanopowders from magnesium aluminum spinel doped with Cr3+. Different synthesis conditions were used to determine the influence on lattice parameter. The following synthesis parameters varied: time of calcination, cold pressing and alternative precursor of Cr3+. The nanopowders properties were measured by XRD, optical transmission and EDX spectroscopy. The determined average size of synthesized nanoparticles is around 70 nm. Ceramic samples are given by hot pressing and studied by transmission spectroscopy and luminescent spectroscopy. The excitation and emission spectra demonstrates 2E - 4A2 (687 nm), 4A2 - 4T1 (400 nm) and 4A2 - 4T2 (532 nm) transitions.

A comparative study on the influence of heating modes on the properties of cobalt and nickel nanopowders produced by the chemical-metallurgy method

The effect of heating modes on the properties of Co and Ni nanopowders obtained by the chemical-metallurgy method was compared. It was shown that all established heating modes (isothermal, non-isothermal and mixed) ensure the production of Co and Ni nanopowders with an average size of less than 100 nm, while the mixed regime makes it possible to obtain reduction products with the best characteristics in terms of dispersion and morphology.

Characterization of CuO doped CdO nanomaterials synthesized by sol gel spin coating and hydrothermal method

CuO-CdO nanomaterials were synthesized by sol gel spin coating and hydrothermal methods. Undoped CdO and 0.2%, 0.5%, 1%, and 2% CuO doped CdO were produced as thin films and nanopowders. The structural, optical, and electrical properties of the thin films and nanopowders produced were investigated. It was determined by X-ray diffraction (XRD) analysis that thin films and nanopowders were polycrystalline and face-centered cubic structures. From Atomic Force Microscope (AFM) images, it was observed that the structure of the thin films was homogeneous and dense rod-shaped structures, and the nanopowders were urchin-like structures consisting of spherical nanoparticles from the Field Emission Scanning Electron Microscopy (FESEM) images. It was determined that nanopowder and thin films have direct band transition from Ultraviolet–visible spectroscopy (UV–Vis) analysis. From all the results obtained, it was concluded that structural, optical, and electrical properties of thin films and nanopowders vary depending on the doping rate and method differences.

Effect of the TiO2 Colloidal Size Distribution on the Degradation of Methylene Blue.

TiO2 is the most commonly used photocatalyst in water treatment. The particle size of TiO2 is an important factor that significantly influences its activity during photocatalytic degradation. In the presence of liquid, the properties of nanopowders composed of exactly the same product clearly differ according to their aggregation size. In this study, TiO2 nanoparticles with a controlled size were fabricated by focused ultrasound dispersion. The high energy generated by this system was used to control the size of TiO2 particles in the suspension. The constant high energy released by cavitation enabled the dispersion of the particles without a surfactant. The activities of the prepared TiO2 photocatalysts for methylene blue (MB) degradation were then compared. The dye degradation effect of the photocatalyst was as high as 61.7% after 10 min when the size of the powder was controlled in the solution, but it was only as high as 41.0% when the aggregation size was not controlled. Furthermore, when the TiO2 concentration exceeded a certain level, the photocatalytic activity of TiO2 decreased. Controlling the size of the aggregated photocatalyst particles is, therefore, essential in water-treatment technologies utilizing TiO2 photocatalytic properties, and adjusting the TiO2 concentration is an important economic factor in this photocatalytic technology. This study contributes to the development of processes for degrading dyes, such as MB, released from wastewater into aquatic environments.

Facilitating enhanced microwave absorption properties of barium hexaferrite/polyaniline composites based on tunable interfacial polarization by rare earth doping

Barium hexaferrite (BaM)/polyaniline (PANI) is a typical microwave absorbing composite that effectively integrates magnetic and electric losses. To enhance its microwave absorption properties, a facile method based on rare earth element doping was explored; the effects of rare earth elements on the microstructures and properties of both BaM nanopowders and the subsequent BaM/PANI composites were investigated. The use of rare earth elements, including La, Nd, and Ce, in the BaM particles alleviated the constraints of the electric polarization in PANI near the surfaces of the BaM particles; this resulted in more electric polarization at the interfaces of the Re-BaM and PANI phases. This provided a versatile way to enhance the absorption efficiency, expand the absorption frequency range, and reduce the thickness. The La-BaM/PANI composite demonstrated a maximum reflection loss of approximately − 63.6 dB at 7.76 GHz with an optimum thickness of 3.28 mm. The effective absorption range of the Nd-BaM/PANI composite was 4.72 GHz. Ce-BaM/PANI composites released a relatively broad effective frequency range of approximately 3.88 GHz and a small thickness of 1.58 mm.

Exploration of physical and optical properties of ZnO nanopowders filled with polydimethylsiloxane (PDMS) for radiation shielding applications. Simulation and theoretical study

Today, with the development of technology, different kinds of materials are being tested to increase the quality, efficiency and reliability of the materials used in the fields of space and aviation, computers, energy and health. In this direction, materials scientists and researchers from different disciplines make multidimensional analyzes and reveal the use of basic building materials in the technological field through both prototypes and simulation methods. In this way, it will be possible to use materials that can give better results than the materials currently used. In this study, polydimethylsiloxane C2H6OSi (PDMS) was prepared using zinc oxide nano powder additions according to the PDMS(ZnO) x formula, where (x=0, 2.5, 5, 7.5, 10, 15 mol %). UV–VIS spectroscopy was performed on the examined PDMS-PDMS(ZnO)15 samples to estimate their optical properties. Transmission spectra demonstrate that the λcutoff wavelength and color of the PDMS-PDMS(ZnO)15 polymer samples both changed to a longer wavelength when ZnO concentration increased (stronger White). Additionally, FTIR analysis of samples were performed. Due to the physical blending of the nanoparticles with the polymeric matrix, the FTIR Spectra of the PDMS with ZnO nanoparticle samples demonstrate that no new peaks were discovered. The mass attenuation coefficient μm of the prepared samples was calculated using the MCNP N-Particle Monte Carlo code and WinXCOM. It was discovered that the theoretical and simulation results were quite close. The addition of ZnO nanoparticles to the PDMS (ZnO) samples increased μm values. The PDMS(ZnO)15 polymer sample showed the lowest HVL, MFP, and TVL values of all the polymer samples due to its high ZnO content. It was included that the PDMS(ZnO)15 is an effective promising material that could be used against gamma-radiation.

Analysis of entropy generation for Magnetohydrodynamics peristaltic motion of Carreau-Yasuda nanofluid through a curved channel with variable thermal conductivity and Joule heating

Present communication investigates the effects of entropy generation on the MHD peristaltic motion of Carreau–Yasuda nanofluid through a curved geometry with temperature-dependent thermal conductivity. Considered non-Newtonian model depicts the thermophysical properties of graphene nano-powder and Ethylene glycol. The assumed flow situation is modeled considering viscous dissipation, heat absorption/generation, Joule heating, thermophoresis effects, Brownian motion, and slip conditions using lubrication approximation. Numerical computations of resulting non-linear system of equations subject to the related boundary conditions are carried out using NDSolve. Physical behaviors of velocity profile, Bejan number, temperature profile, concentration profile, stresses at the wall, entropy production, mass, and heat transfer rates are computed and presented through graphs and tables. The results indicate that temperature rises and concentration of nanofluids reduces for larger values of thermal slip parameter. In the curved channel, the velocity of fluids decreases by enhancing the Hartman number. Entropy generation is reduced by increasing thermal conductivity parameter. Temperature distribution increases when the Eckert number is assigned higher values. Furthermore, the Hartman number and curvature parameter are observed to enhance the rates of mass and heat transfer at the wall. Additionally, the straight channel results can be obtained for the higher values of the curvature parameter.

Enhancing the structural, optical and electrical conductivity properties of ZnO nanopowders through Dy doping

• Doping ZnO nanopowders with different Dy percentages was successfully achieved with the co-precipitation method. • XRD analysis reveals a decrease in the lattice parameters and cell volume of the ZnO lattice due to stress relaxation induced by the formation of Dy 2 O 3 secondary on the surface of the nanoparticles. • Crystalline quality was improved on Dy doping. • The optical band gap was decreased on Dy doping where the disorder increased. • Electrical conductivity of ZnO was enhanced by increasing Dy doping concentration up to an optimum doping concentration of 4% and then lowered significantly. In this work, pure ZnO and Dy-doped ZnO nanopowdres (NPs) with varying doping concentration of Dy from 1 to 5 % were successfully synthesized by the co-precipitation method. The effect of Dy doping on the structure, morphology, optical and electrical conductivity of ZnO has been studied. XRD analysis shows that Dy-doped ZnO nanostructures exhibit primary wurtzite structure and a cubic Dy 2 O 3 secondary phase. The average crystallite sizes were found to be 20.14 nm for pure ZnO and in the range of 24–33 nm for Dy-doped NPs. Crystallite size of Dy-doped ZnO NPs increases with increasing Dy concentration from 1 % to 3 % and then decreases as Dy increases. The decrease in crystallite size was explained by the formation of Dy - O - Z n bonds on the surface of ZnO. Lattice parameters ( a and c ) and unit cell volume ( V ) decrease as Dy content is initially increased up to 2 % then increase for further increase in Dy content. The initial decrease in a , c and V is due to strain relaxation stresses resulting from the formation of Dy 2 O 3 secondary phase. FTIR spectra indicate the formation of the secondary phase and confirm the successful incorporation of Dy 3 + ions into Zn 2 + sites in ZnO structure. Optical band gap of pure and Dy-doped ZnO nanoparticles was evaluated from diffuse reflectance spectroscopy (DRS) spectra and found to be reduced in Dy-doped samples. Optical band gap decreases from 3.269 eV to 3.226 eV for the 1 % Dy-doped sample then increases on further increasing Dy concentration up to 4 % (3.252 eV) and slightly decrease again at 5 % (3.247 eV). PL emission spectra of Dy-doped samples, show the enhancement of the orange-red emission and the appearance of emission band at around 580 nm which may be assigned to the electrical dipole transition of Dy 3 + ions. The electrical conductivity was enhanced by increasing Dy concentration up to an optimum doping concentration of 4 %, then decreases significantly due to scattering of charge carriers caused by the excess of the secondary phase on the surface of ZnO nanoparticles.

Synthesis and Investigation of Physical and Chemical Properties of Nanopowders and Ceramics in the La2O3–SrO–Ni(Co,Fe)2O3 System

Synthesis and Investigation of Physical and Chemical Properties of Nanopowders and Ceramics in the La2O3–SrO–Ni(Co,Fe)2O3 System

Investigation of photoluminescent properties of MgO and Ga2O3 nanopowders for gas sensor applications

Investigation of photoluminescent properties of MgO and Ga2O3 nanopowders for gas sensor applications

Effect of Humidity on the Thermal Properties of Aluminum Nanopowders with Different Surface Coatings

To investigate the effect of surface coating materials on the humidity stability of aluminum (Al) nanopowders, three kinds of core–shell structure Al nanopowders with an Al2O3 passivation coating, carbon coating, and plasticizer dioctyl sebacate (DOS) coating were prepared through laser-induction complex heating method. After one year’s storage at 95% relative humidity, their thermal properties were tested through differential scanning calorimeter (DSC) and thermal gravimeter (TG) analysis. The results show that the thermal properties of Al2O3-passivated Al nanopowders are entirely lost under high humidity because the Al2O3 passivation coating is very sensitive to moisture. The thermal properties of carbon-coated Al nanopowders are not well-protected under a high humidity due to the uneven thickness and structural defects of carbon coatings. However, the thermal enthalpy of DOS-coated Al nanopowders remains at 3.56 KJ/g under high humidity, which indicates that an organic DOS coating with a hydrophobic nature has an excellent protective effect on the thermal properties of the Al nanopowders. Given the good forming performance of organic DOS coatings and other components of propellants, DOS-coated Al nanopowders are a kind of energetic material with potential application value.

DIFFERENTIAL METHOD OF QUALITY CONTROL OF PHYSICO-MECHANICAL CHARACTERISTICS OF KNITTED FABRIC FOR BATHING SUIT

The actuality of the introduction of textile materials with the content of nanopowders based on oxides of divalent and trivalent iron has been proven. The main directions of implementation of such materials into real practical results are shown. The algorithm for the synthesis of magnetic nanomaterials was developed. Adhesion properties of magnetic nanopowders to textile fibers are determined. It is shown that exposure for 5 – 7 days ensures almost absolute adhesive resistance and provides a combination of textile properties with magnetic nanopowders. Bacteriostatic properties of nanomagnetic textile materials were determined. For this purpose, the growth dynamics of mold fungi was determined. It is shown that the content of nanomagnetite significantly suppresses the growth of mold infections. The magnetic properties of textile materials are described, the possibilities of their introduction into elements of smart clothing, medical and protective materials are determined. Magnetic technologies in medicine, compression elements of clothing can be provided with the help of magnetic textile materials. The magnetic effects of such materials make it possible to create elements of clothing with a change in geometry. This determines the possibility of using such materials for smart clothes with new effects. The possibilities of creating magnetic nanomaterials with given structural characteristics have been proven. The addition of nanopowders reduces the size dispersion of structural elements, reduces their size, and increases density. This effect allows ensuring the specified transfer characteristics of textile materials, which provide the necessary parameters of heat transfer and mass transfer. The possibilities of using magnetic textile materials against electromagnetic radiation are shown. The structure of directions for the use of magnetic textile materials for medical and protective products, as well as for promising elements of smart clothing, has been developed.

Effect of Nb doping on the structural, optical, and photocatalytic properties of SrTiO3 nanopowder synthesized by sol-gel auto combustion technique

ABSTRACT Metal oxide photocatalyst is a promising wastewater treatment process due to its simplicity, high efficiency, and low cost, as well as being environmentally friendly and non-energy consuming. The perovskite structure material, SrTi1− x Nb x O3 (STNO) with x = 0, 0.01, 0.03, and 0.05, was successfully synthesized by the sol-gel auto-combustion method. Samples with a pure phase and cubic perovskite structure were obtained. The Rietveld refinement results showed that the lattice parameter and unit cell density increased as the Nb-doping level increased. The particle size of the STNO decreases with increasing Nb doping content. Photoluminescence was excited at 327 nm, producing violet, green, and blue emissions, while the Nb content asserts an insignificant effect on the bandgap (Eg ). The Nyquist plot and Mott-Schottky analysis were used to determine the photoelectrode performance of the STNO samples. The photocatalytic activity of STNO on the decolorization of methylene blue (MB) under UV irradiation increased with increasing Nb content and optimization at x = 0.05, corresponding to the results obtained from photoluminescence, Eg , Nyquist plot, and Mott-Schottky analyses.