Effect of ‘Zn’ substitution on structural,morphological, magnetic and optical properties of Co–Zn ferrite nanoparticles for ferrofluid application

Journal of Materials Science: Materials in Electronics - The Co1?xZnxFe2O4 (Co–Zn) ferrite nanoparticles with x varying from 0.0 to 0.4 have been manufactured by facile chemical...     

Effect of alloy composition on structural, optical and morphological properties and electrical characteristics of GaxIn1−xP/GaAs structure

The structural, optical and morphological properties of Ga-rich Ga_xIn_1?xP layers with various gallium compositions grown on epi-ready semi-insulating (100)-oriented GaAs substrates by using Molecular Beam Epitaxy technique are presented in this study. The Ga_xIn_1?xP/GaAs structures (S1, S2 and S3) have been evaluated by means of high resolution X-ray diffraction, photoluminescence (PL) and atomic force microscopy measurements at room temperature. Experimental forward and reverse bias current–voltage (I–V) characteristics of structure S3 was investigated at room temperature due to its better characteristics when compared to the other two samples. The main electrical parameters such as ideality factor (n), barrier height (Φ _b ) and series resistance (R _s ) were extracted from forward bias I–V characteristics and Cheung’s function. In addition, Hall measurements were carried out as a function of temperature (30–300 K) and at a magnetic field of 0.4 T were presented for structure S3.     

Effect of γ-radiation on optical properties of Eu2+ ions in the KCl: Eu2+ system

Emission spectra and luminescence time decay of Eu²⁺ ions in KCl crystals annealed at 873 K and quenched to room temperature before irradiation were measured at 80 K after -irradiation which was performed at 295 and 200 K. The results are consistent with radiation-induced aggregation of the original isolated europium dipoles.     

Influences of La3+ ion substitution on dielectric,susceptibility and permeability properties of Mg–Zn ferrite nanoparticles

Journal of Materials Science: Materials in Electronics - Nanoparticles of lanthanum-substituted magnesium zinc ferrites with general formula Mg0.6Zn0.4La2yFe2?2yO4 (where y?=?0.0,...     

Influence of annealing on structural, morphological and optical properties of Cd x Zn1?x O nanopowder prepared by Co-precipitation method

Structural and optical properties of Cd _x Zn_1?x O (x = 0.0, 0.025, 0.050, 0.075, 0.1) nanopowder, synthesized by co-precipitation method have been investigated. The effect of annealing on the structural and morphological properties was studied using X-ray diffraction. The samples with x = 0.0 up to 0.075 exhibit wurtzite hexagonal phase, whereas, the sample with x = 0.1 shows two phases: wurtzite hexagonal ZnO and cubic CdO phase. This behavior is explained on the basis of solubility of CdO in ZnO. Energy Dispersive X-ray analysis (EDX) results revealed the existence of Cd, Zn, and O elements in the nanopowder. Transmission Electron Microscopy (TEM) images confirm that the particle size of the prepared samples is in nano range. The optical band gap values obtained from the absorption spectra show that absorption depends on Cd composition. By doping of ZnO with CdO, a red shift in the absorption edge was observed.     

Effect of amount and atomic ratio of dual modifiers Ca and Mg on phase formation and mechanical properties of Ca,Mg-α-Sialons

Multi-cation -Sialons ceramics containing calcium and magnesium for the compositions ((Ca,Mg)_xSi_{12 – 3x}Al_3xO_xN_{16 – x}), where x equals 0.6 and 1.0 with the different atomic ratios of Ca to Mg, were fabricated by hot-pressing. An exploration for Ca,Mg--Sialon involving phase compositions, cell dimensions, microstructure and mechanical properties were carried out in the present work.     

Effect of non-magnetic substitution on the structural and magnetic properties of spinel cobalt ferrite (CoFe2−xAlxO4) ceramics

One set of CoFe_2?xAl_xO₄ (x = 0.1, 0.2, 0.3 and 0.4) ceramics in single domain range and another set in multi domain range were prepared by sintering at 400 and 800 °C respectively. Rietveld refinement of XRD patterns revealed that samples are mixed spinel structure and crystallize to $ Fd\bar{3}m $ space group with cubic symmetry. The lattice constant and crystallite size decrease with the increase in Al³⁺ concentration. The Fourier transform infrared spectroscopy study confirms the spinel structure of the samples. Particle size distribution for all samples has been studied by field emission scanning electron microscopy. Moreover, thermogravimetric analysis was performed to determine the sintering temperature. The saturation magnetization has been analyzed by the “law of approach ” technique. Saturation magnetization, coercivity and magnetocrystalline anisotropy constant are found to decrease with the increase in Al³⁺ ion concentration which is due to the non-magnetic impurity in the magnetic matrix.     

Effect of γ-rays irradiation on the structure and magnetic properties of Mg–Cu–Zn ferrites

The effect of γ-irradiation on the structure and magnetic properties of ferrite samples with chemical formula Mg _x Cu_0.5−x Zn_0.5Fe₂O₄ (where x = 0.0, 0.2, and 0.4) prepared by conventional ceramic method has been studied. X-ray diffraction patterns (XRDPs) indicated the presence of a single spinel phase for all the investigated samples. The initial permeability and magnetization were measured, before and after irradiation on toroidal samples used as transformer cores. The initial permeability μ_i was measured as a function of temperature at constant frequency of 10 kHz and Curie temperatures (T _C) were determined. It was found that, due to irradiation, both of lattice parameter and porosity were increased. On the other hand, the values of magnetization and initial permeability were decreased as a result of irradiation. In addition, there was a decrease in the crystallite size, homogeneity, and the values of Curie temperature with significant decrease in the values of μ_i and T _C for the sample with x = 0.0. The results are discussed in the light of γ-rays interaction with ferrite lattice.     

Tunable structure,morphology of Zn1−xMgxO fine powder prepared by spray pyrolysis method and its luminescence properties

In this report, the role of Magnesium on the crystal structure, morphology, and its luminescence properties of Zn_1−xMg_xO particle were investigated. The Zn_1−xMg_xO particle was prepared by spray pyrolysis method. The obtained particle was analyzed using XRD, SEM-EDS, and photoluminescence spectroscopy correspondingly for crystal structure, morphology and elemental analysis, and photoluminescence properties due to the presence of magnesium dopant. The XRD results showed that the original structure of the particle is hexagonal wurtzite and change to cubical as the increase of Mg. The a- lattice parameter increased, and c- lattice parameter decreased with increasing the concentration of Mg in wurtzite crystal. The SEM results exhibited different morphology of the resulting particle. The morphology of the sample is dense with wrinkled shape and is changing to spherical as the result of Mg incorporation into the crystal. Photoluminescence study revealed that the addition of Mg affects the existence of new energy state beside native defect of ZnO in between valence and conduction band. The widening of bandgap on Zn_1−xMg_xO is due to the blue shift of excitonic peak in the excitation spectrum that usually called Burstein-Moss effect.     

Effect of Gd substitution on structural and magnetic properties of Zn–Cu–Cr ferrites prepared by novel rheological technique

Abstract

A novel rheological technique was developed to synthesise Gd substituted Zn–Cu–Cr ferrites, Zn_0·6Cu_0·4Cr_0·5Gd_xFe_1·5?xO₄ (x=0·00, 0·02, 0·04, 0·06, 0·08) powders. The effects of the Gd substitution on the structural and magnetic properties of the as prepared Zn–Cu–Cr ferrites were investigated. The microstructure, morphology and magnetic properties of the materials were characterised by X-ray diffraction, transmission electron microscopy and vibrating sample magnetometer. It was shown that the as prepared materials exhibited the single phase spinel structure. The lattice parameters increased while the crystallite sizes decreased with increasing Gd content. The magnetic properties of the as prepared materials were strongly affected by Gd content. The saturation magnetisation decreased, while coercivity increased with increasing Gd content.     

Effect of chemical substitution on the morphology and optical properties of Bi1−xCaxFeO3 films grown by pulsed-laser deposition

The morphological characteristics as well the optical properties of Ca-doped BiFeO₃ films grown by pulsed-laser deposition technique have been investigated. AFM images revealed that calcium has a radical effect on the surface features of BiFeO₃ films. By utilizing spectrophotometer, transmission behaviour of the films was investigated. Local IV characteristics of the films disclosed about three orders of magnitude enhancement concerning electrical conductivity through Ca doping. X-ray photoelectron spectroscopy results revealed that Ca can reduce the valence state of iron in the compound.     

Morphology,structural, optical,magnetic, and photocatalytic properties of Co1−xZnxFe2−yCeyO4 NPs

Journal of Materials Science: Materials in Electronics - In the current study, we looked into the effects of simultaneous trivalent Ce and divalent Zn doping on the optical, magnetic, and...     

Investigation of structural,luminescence, and anti-bacterial properties of novel Zn1−xEuxAl2−yO4Sry phosphor

Journal of Materials Science: Materials in Electronics - In this research work, we synthesized novel zinc aluminate (Zn1?xEuxAl2?yO4Sry) sky bluish phosphors at 500 °C via...     

Effect of Ce on microstructures and mechanical properties of rapidly solidified Mg–Zn alloy

Abstract

The rapidly solidified (RS) Mg–Zn based alloys with Ce addition were produced via atomising the alloy melt and subsequent splat quenching on the water cooled copper twin rollers in the form of flakes. The effects of Ce additions on the microstructures, phase compositions, thermal stability and isochronal age hardening behaviour of the RS Mg–Zn alloy were systematically investigated. The RS Mg–6Zn alloy is characterised by fine grains in the size of 6–10 μm and is composed of α-Mg, Mg₅₁Zn₂₀ and a small quantity of MgZn₂ and Mg₂Zn₃ phases. With the increment of Ce, the microstructures of the alloys are refined, and the volume fractions of dispersions are increased remarkably. The stable intermetallic compounds, i.e. the Mg_xZn_yCe_z ternary phases, are formed in the RS Mg–Zn–Ce alloys at the expense of the Mg₅₁Zn₂₀ phases, which leads to the enhanced thermal stability of the alloys, especially for the Mg–6Zn–5Ce alloy. In the alloy, the atomic percentage ratio of Zn/Ce in the Mg_xZn_yCe_z phase is close to two, and the maximum hardness is 91·5±7 HV after annealing at 200°C for 1 h. However, the age hardening behaviour of the alloys decreases with the increment of Ce, and the main reason is discussed.     

Dependence of structural, optical and electrical properties on substrate temperature for hexagonal MgxZn1−xO films

Single hexagonal-phase Mg_xZn_1?xO films were deposited on glass substrates by pulsed laser deposition from a ZnO target mixed with MgO. The effect of substrate temperature on the structural, electrical and optical properties was investigated by X-ray diffraction and the transmittance measurements. It was observed that Mg incorporation lead to a clear shift of the (002) peak position to lower angle with reference to pure ZnO films due to the residual stress change with deposition temperature. It was also found that Mg doping increased the resistivity by 2 orders of magnitude and the maximum resistivity was 0.072 Ω·cm at 550 °C with the carrier concentration of 1.1 × 10¹⁹ cm^?3. The visible transmittance of above 80 % was obtain in the alloy films, which optical band gap was observed to increase with the substrate temperature, attaining 3.85 eV at 600 °C. The possible mechanism was discussed.     

Effect of Al2O3 and Fe3Al on the phase formation and mechanical properties of β-sialon

The paper evaluated the mechanical properties of β-sialon composites prepared by hot-pressing sintering at 1600 °C in N₂ atmosphere using α-Si₃N₄, Al₂O₃, Y₂O₃ and Fe₃Al as raw materials. The influence of Al₂O₃ and Fe₃Al content on flexure strength, fracture toughness, hardness, and relative density was investigated. And phase formation and morphology of the composites were characterized by X-ray diffraction and electron microscopy. The experimental results indicate that the raw material Fe₃Al reacts with α-Si₃N₄ to form silicides at elevated temperature, and supplies more liquid phase to assist densification. Besides, the variation of flexure strength, fracture toughness and hardness is mainly consistent, and also in good agreement with the relative density measurements. The values all increase firstly, and then decrease when the Al₂O₃ content increases. Scanning electron microscopy illustrates that the metal particles act to inhibit the crack propagation.