Abdulrahman Mallah | Qassim University (original) (raw)
Papers by Abdulrahman Mallah
Journal of electronic materials, Jul 1, 2024
Journal of electronic materials, Jul 2, 2024
Journal of science. Advanced materials and devices/Journal of science. Advanced materials and devices (Print), May 1, 2024
Journal of materials science. Materials in electronics, Apr 1, 2024
Crystals, May 30, 2023
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
Applied Physics A, Dec 16, 2016
In this work, we present the effect of Mg substitution on the structural and impedance spectrosco... more In this work, we present the effect of Mg substitution on the structural and impedance spectroscopic characteristics of Co 1-x Mg x Fe 2 O 4 (x = 0.0, 0.3, 0.6, 0.9 and 1.0) samples, prepared by sol-gel auto-combustion method. As-burnt and fluffy powder samples were grinded and subsequently calcined at 600 ºC for 6 h to change single phase cubic spinel structure, as confirmed by X-ray diffraction. The data obtained from diffraction was also utilized to perform Rietveld's refinement which provided detailed information on the structural changes occurred during the substitution. Frequency and temperature dependent electrical, and impedance studies were performed using an impedance analyzer in a wide frequency and temperature range. The behavior of characteristic dielectric parameters has been investigated using Maxwell-Wagner's model and Koop's theory. The impedance plot was used to define electro-active regions of the prepared samples, useful in modelling an equivalent circuit for each region. Frequency dependent Nyquist plot revealed the effect of grain, grain boundaries and electrode effect. Samples exhibited distinct grain and grain boundary contributions to the conductivity. Temperature dependent electrical characterization revealed that samples had negative temperature coefficient of resistance. The binding energies at different temperatures have also been estimated.
Journal of Inorganic and Organometallic Polymers and Materials, Sep 7, 2022
In this study, cupric oxide (CuO) nanoparticles were synthesized via sonochemical method. The sam... more In this study, cupric oxide (CuO) nanoparticles were synthesized via sonochemical method. The samples were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscope, and transmission electron microscopy. The spherical CuO nanoparticles were dispersed in sodium hexametaphosphate under sonication (25 kHz) to analyze the particle size distribution and UV absorption spectra. Using these absorption spectra, we further examined the CuO nanoparticle to explore the possibility of using them as a material for applications such as solar cell and textile production.
Crystals, Jan 10, 2023
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
Journal of Superconductivity and Novel Magnetism, Jan 10, 2020
Ni0.4Cd0.3Zn0.3Fe2O4 ferrites have been prepared through the use of sol-gel method at 900 °C and ... more Ni0.4Cd0.3Zn0.3Fe2O4 ferrites have been prepared through the use of sol-gel method at 900 °C and 1100 °C. Rietveld refinements of XRD patterns indicate that the prepared samples crystallize in the cubic spinel structure. Lattice constant and grain size are found to increase with sintering temperature. Magnetic measurements show that the maximum magnetization (Ms) rises; whereas both coercivity (Hc) and remanence (Mr) decrease when increasing the sintering temperature. Frequency and temperature dependence of electrical conductivity, electrical modulus and electrical impedance have been studied using impedance spectroscopy technique. As the sintering temperature increases, the conductivity of the samples increases. The variation of imaginary part of modulus (M'') displays the presence of an electrical relaxation phenomenon and non-Debye nature. Nyquist representations have been analyzed using an electrical equivalent circuit. The obtained results reveal that the conduction mechanism of the samples is achieved basically of the grain boundary contribution.
Materials
In this study, we used a novel composite material based on magnesium phosphate cement (MPC) to ex... more In this study, we used a novel composite material based on magnesium phosphate cement (MPC) to explore the retention of fluoride from used water. Dead-burned magnesium oxide (MgO), ammonium dihydrogen phosphate (NH4H2PO4), and a few retarders were used to create this particular substance. Several studies have corroborated the performance of using aluminum in the capture of fluoride. From this perspective, we attempted to reinforce our matrix with different quantities of aluminum, which increased the resistance of the composite in water. The optimal conditions that were obtained were evaluated and scrutinized using a range of techniques, including scanning electron microscopy (SEM), X-ray diffraction (XRD), thermogravimetric analysis (TGA), Fourier transforms infrared spectroscopy (FTIR), and Brunauer–Emmett–Teller (BET). The adsorbents demonstrated a powerful ability to remove fluoride from contaminated water and the defluoridation capacity was evaluated at 4.84 mg/g. Equilibrium mo...
Journal of Materials Science: Materials in Electronics, 2022
In this work, the microstructural, optical, magnetic, magnetocaloric, and critical behaviors for ... more In this work, the microstructural, optical, magnetic, magnetocaloric, and critical behaviors for the Ni0.5Fe0.5Cr2O4 (abbreviated as NFCO) chromite spinel synthesized by sol–gel route were investigated. Rietveld refinement of the X-ray diagram shows that the compound was well crystallized in the cubic spinel structure (Fd3¯m\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$Fd\overline{3}m$$\end{document} space group). The surface morphology of the sample was also examined by SEM analysis. The characteristic vibrational modes for the prepared sample were evaluated from the FTIR spectrum at room temperature. The behavior of the optical absorbance revealed that NFCO sample exhibits remarkable absorption of visible light with significantly lower band gap energy (Egd = 1.74 eV). By comparing our results to those reported for the NiFe2O4 spinel, we show a drastic increase in coercivity, indicating the ability of Fe2+-substitution in improving the magnetic properties of nickel chromites for magnetic applications such as permanent magnets, permanent data storage tapes, and high-density magnetic recording. The magnetic transition from the ferrimagnetic (FiM) state to the paramagnetic (PM) state was observed from the M(T) curve at the Curie temperature (TC = 90 K). The critical exponents were studied using the magnetic isotherms. The modified Arrott plots (MAP) and the critical isotherm show that both γ and δ exponents belong to an unconventional model; however, the β exponent shows small deviation from the mean-field model.
Research Square (Research Square), Feb 24, 2021
Polycrystalline Mg0.5Co0.5Fe1.6Al0.4O4 ferrite was prepared with sol-gel method. This sample was ... more Polycrystalline Mg0.5Co0.5Fe1.6Al0.4O4 ferrite was prepared with sol-gel method. This sample was characterized by powder X-ray diffraction (XRD), Scanning electron microscopy, and impedance spectroscopy. X-ray diffraction analysis combined with the Rietveld refinement confirmed that the sample crystallizes in a single-phase cubic spinel structure with (SG: 3 ̅). Electrical conductivity obeying the Jonscher power law indicates that the prepared material exhibits semiconductor behavior, and the conduction process follows the "non-overlapping small polaron tunnelling" model between neighbors' sites. The behavior of dielectric constants such as permittivity and loss coefficient has been interpreted based on the Maxwell-Wagner's theory of interfacial polarization. The curves of imaginary parts of impedance (Z'') and modulus (M'') show a dielectric-relaxation phenomenon in the sample with activation energy near to that determined from the dc conductivity study. Nyquist plots (Z″ vs. Z') show a monotonic decrease in both grain resistance (Rg) and grain boundary resistance (Rgb) with increasing temperature such as Rgb>>Rg. This result confirms that the transport mechanism for Mg0.5Co0.5Fe1.6Al0.4O4 compound is governed by the grain boundaries effect.
Indian Journal of Physics
Crystals
The sol-gel process was used to produce ferrite Ni0.3Zn0.7Cr2−xFexO4 compounds with x = 0, 0.4, a... more The sol-gel process was used to produce ferrite Ni0.3Zn0.7Cr2−xFexO4 compounds with x = 0, 0.4, and 1.6, which were then subsequently calcined at several temperatures up to 1448 K for 48 h in an air atmosphere. X-ray diffraction (XRD), scanning electron microscopy (SEM), vibrating sample magnetometer (VSM), and 57Fe Mössbauer spectrometry were used to examine the structure and magnetic characteristics of the produced nanoparticles. A single-phase pure Ni0.3Zn0.7Cr2−xFexO4 nanoparticle had formed. The cubic Fd3¯m spinel structure contained indexes for all diffraction peaks. The crystallite size is a perfect fit for a value of 165 ± 8 nm. Based on the Rietveld analysis and the VSM measurements, the low magnetization Ms of Ni0.3Zn0.7Cr2−xFexO4 samples was explained by the absence of ferromagnetic Ni2+ ions and the occupancy of Zn2+ ions with no magnetic moments in all tetrahedral locations. Moreover, because of the weak interactions between Fe3+ ions in the octahedral locations, the ma...
Journal of Molecular Structure
Crystals
The structural, mechanical, electronic, and optical characteristics of Alkali chalcogenide and ox... more The structural, mechanical, electronic, and optical characteristics of Alkali chalcogenide and oxychalcogenides, i.e., A2O2B2Se3 (A = Sr, Ba; B = Bi, Sb), were investigated using density functional theory (DFT). After full relaxation, the obtained structural parameters are in good agreement with the experimental parameters. Furthermore, the calculated elastic stiffness Cij shows that all of the studied compounds followed the mechanical stability criteria. Ductility for these compounds was analyzed by calculating Pugh’s ratio; we classified the Sr2O2Bi2Se3, Sr2O2Sb2Se3, and Ba2O2Bi2Se3 as ductile, and the Ba2O2Sb2Se3 as brittle. The Debye temperature and acoustic velocity were estimated. In addition, electronic and chemical bonding properties were studied from the analysis of the band structure and density of state. The main features of the valence and conduction bands were analyzed from the partial density of states. Electronic band structures are mainly contributed to by Se-4p and ...
Journal of electronic materials, Jul 1, 2024
Journal of electronic materials, Jul 2, 2024
Journal of science. Advanced materials and devices/Journal of science. Advanced materials and devices (Print), May 1, 2024
Journal of materials science. Materials in electronics, Apr 1, 2024
Crystals, May 30, 2023
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
Applied Physics A, Dec 16, 2016
In this work, we present the effect of Mg substitution on the structural and impedance spectrosco... more In this work, we present the effect of Mg substitution on the structural and impedance spectroscopic characteristics of Co 1-x Mg x Fe 2 O 4 (x = 0.0, 0.3, 0.6, 0.9 and 1.0) samples, prepared by sol-gel auto-combustion method. As-burnt and fluffy powder samples were grinded and subsequently calcined at 600 ºC for 6 h to change single phase cubic spinel structure, as confirmed by X-ray diffraction. The data obtained from diffraction was also utilized to perform Rietveld's refinement which provided detailed information on the structural changes occurred during the substitution. Frequency and temperature dependent electrical, and impedance studies were performed using an impedance analyzer in a wide frequency and temperature range. The behavior of characteristic dielectric parameters has been investigated using Maxwell-Wagner's model and Koop's theory. The impedance plot was used to define electro-active regions of the prepared samples, useful in modelling an equivalent circuit for each region. Frequency dependent Nyquist plot revealed the effect of grain, grain boundaries and electrode effect. Samples exhibited distinct grain and grain boundary contributions to the conductivity. Temperature dependent electrical characterization revealed that samples had negative temperature coefficient of resistance. The binding energies at different temperatures have also been estimated.
Journal of Inorganic and Organometallic Polymers and Materials, Sep 7, 2022
In this study, cupric oxide (CuO) nanoparticles were synthesized via sonochemical method. The sam... more In this study, cupric oxide (CuO) nanoparticles were synthesized via sonochemical method. The samples were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscope, and transmission electron microscopy. The spherical CuO nanoparticles were dispersed in sodium hexametaphosphate under sonication (25 kHz) to analyze the particle size distribution and UV absorption spectra. Using these absorption spectra, we further examined the CuO nanoparticle to explore the possibility of using them as a material for applications such as solar cell and textile production.
Crystals, Jan 10, 2023
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
Journal of Superconductivity and Novel Magnetism, Jan 10, 2020
Ni0.4Cd0.3Zn0.3Fe2O4 ferrites have been prepared through the use of sol-gel method at 900 °C and ... more Ni0.4Cd0.3Zn0.3Fe2O4 ferrites have been prepared through the use of sol-gel method at 900 °C and 1100 °C. Rietveld refinements of XRD patterns indicate that the prepared samples crystallize in the cubic spinel structure. Lattice constant and grain size are found to increase with sintering temperature. Magnetic measurements show that the maximum magnetization (Ms) rises; whereas both coercivity (Hc) and remanence (Mr) decrease when increasing the sintering temperature. Frequency and temperature dependence of electrical conductivity, electrical modulus and electrical impedance have been studied using impedance spectroscopy technique. As the sintering temperature increases, the conductivity of the samples increases. The variation of imaginary part of modulus (M'') displays the presence of an electrical relaxation phenomenon and non-Debye nature. Nyquist representations have been analyzed using an electrical equivalent circuit. The obtained results reveal that the conduction mechanism of the samples is achieved basically of the grain boundary contribution.
Materials
In this study, we used a novel composite material based on magnesium phosphate cement (MPC) to ex... more In this study, we used a novel composite material based on magnesium phosphate cement (MPC) to explore the retention of fluoride from used water. Dead-burned magnesium oxide (MgO), ammonium dihydrogen phosphate (NH4H2PO4), and a few retarders were used to create this particular substance. Several studies have corroborated the performance of using aluminum in the capture of fluoride. From this perspective, we attempted to reinforce our matrix with different quantities of aluminum, which increased the resistance of the composite in water. The optimal conditions that were obtained were evaluated and scrutinized using a range of techniques, including scanning electron microscopy (SEM), X-ray diffraction (XRD), thermogravimetric analysis (TGA), Fourier transforms infrared spectroscopy (FTIR), and Brunauer–Emmett–Teller (BET). The adsorbents demonstrated a powerful ability to remove fluoride from contaminated water and the defluoridation capacity was evaluated at 4.84 mg/g. Equilibrium mo...
Journal of Materials Science: Materials in Electronics, 2022
In this work, the microstructural, optical, magnetic, magnetocaloric, and critical behaviors for ... more In this work, the microstructural, optical, magnetic, magnetocaloric, and critical behaviors for the Ni0.5Fe0.5Cr2O4 (abbreviated as NFCO) chromite spinel synthesized by sol–gel route were investigated. Rietveld refinement of the X-ray diagram shows that the compound was well crystallized in the cubic spinel structure (Fd3¯m\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$Fd\overline{3}m$$\end{document} space group). The surface morphology of the sample was also examined by SEM analysis. The characteristic vibrational modes for the prepared sample were evaluated from the FTIR spectrum at room temperature. The behavior of the optical absorbance revealed that NFCO sample exhibits remarkable absorption of visible light with significantly lower band gap energy (Egd = 1.74 eV). By comparing our results to those reported for the NiFe2O4 spinel, we show a drastic increase in coercivity, indicating the ability of Fe2+-substitution in improving the magnetic properties of nickel chromites for magnetic applications such as permanent magnets, permanent data storage tapes, and high-density magnetic recording. The magnetic transition from the ferrimagnetic (FiM) state to the paramagnetic (PM) state was observed from the M(T) curve at the Curie temperature (TC = 90 K). The critical exponents were studied using the magnetic isotherms. The modified Arrott plots (MAP) and the critical isotherm show that both γ and δ exponents belong to an unconventional model; however, the β exponent shows small deviation from the mean-field model.
Research Square (Research Square), Feb 24, 2021
Polycrystalline Mg0.5Co0.5Fe1.6Al0.4O4 ferrite was prepared with sol-gel method. This sample was ... more Polycrystalline Mg0.5Co0.5Fe1.6Al0.4O4 ferrite was prepared with sol-gel method. This sample was characterized by powder X-ray diffraction (XRD), Scanning electron microscopy, and impedance spectroscopy. X-ray diffraction analysis combined with the Rietveld refinement confirmed that the sample crystallizes in a single-phase cubic spinel structure with (SG: 3 ̅). Electrical conductivity obeying the Jonscher power law indicates that the prepared material exhibits semiconductor behavior, and the conduction process follows the "non-overlapping small polaron tunnelling" model between neighbors' sites. The behavior of dielectric constants such as permittivity and loss coefficient has been interpreted based on the Maxwell-Wagner's theory of interfacial polarization. The curves of imaginary parts of impedance (Z'') and modulus (M'') show a dielectric-relaxation phenomenon in the sample with activation energy near to that determined from the dc conductivity study. Nyquist plots (Z″ vs. Z') show a monotonic decrease in both grain resistance (Rg) and grain boundary resistance (Rgb) with increasing temperature such as Rgb>>Rg. This result confirms that the transport mechanism for Mg0.5Co0.5Fe1.6Al0.4O4 compound is governed by the grain boundaries effect.
Indian Journal of Physics
Crystals
The sol-gel process was used to produce ferrite Ni0.3Zn0.7Cr2−xFexO4 compounds with x = 0, 0.4, a... more The sol-gel process was used to produce ferrite Ni0.3Zn0.7Cr2−xFexO4 compounds with x = 0, 0.4, and 1.6, which were then subsequently calcined at several temperatures up to 1448 K for 48 h in an air atmosphere. X-ray diffraction (XRD), scanning electron microscopy (SEM), vibrating sample magnetometer (VSM), and 57Fe Mössbauer spectrometry were used to examine the structure and magnetic characteristics of the produced nanoparticles. A single-phase pure Ni0.3Zn0.7Cr2−xFexO4 nanoparticle had formed. The cubic Fd3¯m spinel structure contained indexes for all diffraction peaks. The crystallite size is a perfect fit for a value of 165 ± 8 nm. Based on the Rietveld analysis and the VSM measurements, the low magnetization Ms of Ni0.3Zn0.7Cr2−xFexO4 samples was explained by the absence of ferromagnetic Ni2+ ions and the occupancy of Zn2+ ions with no magnetic moments in all tetrahedral locations. Moreover, because of the weak interactions between Fe3+ ions in the octahedral locations, the ma...
Journal of Molecular Structure
Crystals
The structural, mechanical, electronic, and optical characteristics of Alkali chalcogenide and ox... more The structural, mechanical, electronic, and optical characteristics of Alkali chalcogenide and oxychalcogenides, i.e., A2O2B2Se3 (A = Sr, Ba; B = Bi, Sb), were investigated using density functional theory (DFT). After full relaxation, the obtained structural parameters are in good agreement with the experimental parameters. Furthermore, the calculated elastic stiffness Cij shows that all of the studied compounds followed the mechanical stability criteria. Ductility for these compounds was analyzed by calculating Pugh’s ratio; we classified the Sr2O2Bi2Se3, Sr2O2Sb2Se3, and Ba2O2Bi2Se3 as ductile, and the Ba2O2Sb2Se3 as brittle. The Debye temperature and acoustic velocity were estimated. In addition, electronic and chemical bonding properties were studied from the analysis of the band structure and density of state. The main features of the valence and conduction bands were analyzed from the partial density of states. Electronic band structures are mainly contributed to by Se-4p and ...