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Papers by reza gordani

Evaluating the Ge: C ratio on the bonding structure, hardness, and residual stress of Ge1-x-Cx coatings fabricated by the PE-CVD method

Vacuum

Synthesis, microstructure, magnetic and electromagnetic behavior of graphene oxide/hexagonal barium ferrite aerogel nanocomposites within the frequency range of 1–18 GHz

Arabian Journal of Chemistry

Lightweight cellulose/MWCNT/SrFe12O19 aerogel composites: microstructure, density, mechanical properties, and electromagnetic behavior

Cellulose

Korean Journal of Materials Research

This research examines the effect of adding aluminum on the structural, phasic, and magnetic prop... more This research examines the effect of adding aluminum on the structural, phasic, and magnetic properties of CoCrFe NiMnAl x high-entropy alloys. To this aim, the arc-melt process was used under an argon atmosphere for preparing cast samples. The phasic, structural, and magnetic properties of the samples were characterized by x-ray diffraction (XRD), scanning electron microscopy (SEM), and vibrational magnetometry (VSM) analyses. Based on the results, the addition of aluminum to the compound caused changes in the crystalline structure, from FCC solid solution in the CoCrFeNiMn sample to CoCrFeNiMnAl BBC solid solution. It was associated with changes in the magnetic property of CoCrFeNiMnAl x high-entropy alloys, from paramagnetic to ferromagnetic. The maximum saturation magnetization for the CoCrFeNiMnAl casting sample was estimated to be around 79 emu/g. Despite the phase stability of the FCC solid solution with temperature, the solid solution phase formed in the CrCrFeNiMnAl high-entropy compound was not stable, and changed into FCC solid solution with temperature elevation, causing a reduction in saturation magnetization to about 7 emu/g.

Investigation of nanosized alumina‐binder feedstock rheology for ceramics injection molding (CIM) and survey spark plasma sintering of output green body to obtain transparent alumina

International Journal of Applied Ceramic Technology

An assessment of electromagnetic properties of substituted hexaferrite/SWCNTs nanocomposite

Journal of Magnetism and Magnetic Materials, 2021

Abstract SrZn2-x(MnCa)x/2Fe16O27(x = 0–0.6) nanoparticles synthesized by Co-precipitation method ... more Abstract SrZn2-x(MnCa)x/2Fe16O27(x = 0–0.6) nanoparticles synthesized by Co-precipitation method and single walled carbon nanotube (SWCNTs) were used to prepared microwave absorption nanocomposite. X-ray diffractometry (XRD), scanning electron microscopy (SEM), Fourier-transform infrared (FT-IR) spectroscopy, vibrating sample magnetometry (VSM), and vector network analyzer (VNA) were utilized to characteriziation of samples. The results showed that the particle size of Zn2W hexaferrite varies in the range of 55–75 nm with a good hexagonal shape. Structural changes due to the addition of divalent cations change the magnetization (M) and coercivity (Hc) of samples. The highest magnetization and coercivity are obtained in the sample containing x = 0.4 (M = 70 emu/g) and the nanocomposite sample (Hc = 605 Oe), respectively. Based on reflectivity measurement, the nanocomposite sample contains nanoparticles of hexaferrite with x = 0.4 and SWCNTs showed a maximum reflection loss of −42 dB at the frequency of 10.2 GHz. This sample also covers the entire x bandwidth (4 GHz) less than −10 dB and 1.5 GHz less than −20 dB.

Microstructure, phase, magnetic properties, and electromagnetic wave absorption of graphene oxide – Ni0.7Zn0.3Fe2O4 – Al2O3 aerogel

Ceramics International, 2021

Journal of Superconductivity and Novel Magnetism, 2020

High entropy alloys (HEA) based on CoNi systems contain of Mn, Cr, and Al elements were prepared ... more High entropy alloys (HEA) based on CoNi systems contain of Mn, Cr, and Al elements were prepared through mechanical alloying and subsequent annealing method. The structural and magnetic properties of CoNi alloy system were discussed based on the results of X-ray diffraction (XRD), scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and vibrating sample magnetometer (VSM) analysis methods. There were different chemical compounds formed in CoNi-Mn-Cr samples, while a simple solid solution phase with FCC or BCC structural evolved in CoNiMnCrAl high entropy alloy after mechanical milling and subsequent annealing process at 750 and 900°C. This sample exhibited excellent soft magnetic properties with the saturation magnetization and coercivity of about 31 emu/g and 39 Oe, respectively, after annealing at 750°C. Annealing at 900°C could improve soft magnetic properties of CoNiMnCrAl high entropy alloy in the range of 58 emu/g for saturation of magnetization and 18 Oe for coercivity due to the formation of a single solid solution phase with BCC structure.

Journal of Sulfur Chemistry, 2018

The present study investigates the diffusion mechanism, morphology and structural characteristics... more The present study investigates the diffusion mechanism, morphology and structural characteristics of crystalline zinc sulfide (ZnS) during the reactive diffusion process. The samples with nominal composition of Zn 50 S 50 were prepared via capsulation of high purity of zinc and sulfur followed by the annealing process at various reaction temperatures. The prepared samples were characterized using X-ray diffraction, differential scanning calorimetry and scanning electron microscopy. The structural measurements confirm the formation of zinc sulfide with wurtzite structure during the annealing process at 550°C. The wurtzite allotrope of ZnS is not stable at a high annealing temperature and is transformed to cubic zinc-blende structure. During the annealing process, a continuous layer of ZnS compound forms at the Zn/S interface. Both Zn and S diffuse into the formed ZnS layer and the growth of that occurs mainly toward the Zn side. Under this condition, Kirkendall voids form and accumulate near the ZnS/S interface.

Journal of Magnetism and Magnetic Materials, 2019

Co 2 W-type hexaferrite nanoparticles with composition of SrCo 2−x (MnZnCa) x/3 Fe 16 O 27 (x = 0... more Co 2 W-type hexaferrite nanoparticles with composition of SrCo 2−x (MnZnCa) x/3 Fe 16 O 27 (x = 0-0.5) were synthesized by a co-precipitation method. The synthesized nanoparticles were decorated on the outer surface of multi-walled carbon nanotubes by chemical method. X-ray diffractometry, scanning electron microscopy, vibrating sample magnetometry, magnetic susceptometer and vector network analyzer were utilized to characterize the structural, magnetic, and reflection loss properties of the nanocomposites. The structural results showed a perfect diffusion of Mn, Zn and Ca ions into the crystal structure of Co 2 W hexaferrite without forming any secondary phases. The SEM images provide clear information about the size of nanoparticles (50-85 nm) through these samples. The hysteresis loops showed hard magnetic property with enhanced coercivity which reflects that the synthesized particles have almost high magnetic anisotropic field, well suitable for absorbing materials. The coercivity (H c) increased from 1450 Oe at x = 0.0, to 1650 Oe at x = 0.3, and then decreases to 1320 Oe at x = 0.5. High reduction in the coercivity was detected consistent with the large particle sizes for these samples. Ferrite nanoparticles were decorated on the surface of carbon nanotubes in almost constant distance. The interacting mode was confirmed between magnetic nanoparticles by means of plotting real and imaginary parts of magnetic susceptibility versus temperature at various frequencies. Based on reflectivity measurement, the sample with x = 0.3 showed a maximum reflection loss of −37 dB at the frequency of 9.4 GHz. This sample revealed the best performance with low reflectivity and high absorption broadband (4 GHz) at X-band frequency range.

Journal of Magnetism and Magnetic Materials, 2018

In this study, the effect of substitution of Co with Fe on structural and magnetic characteristic... more In this study, the effect of substitution of Co with Fe on structural and magnetic characteristics of nanocrystalline Fe-Co-Cr alloys has been investigated. In this regard, different combinations of Fe, Co and Cr elements with nominal composition of Fe 72-x Co x Cr 28 (10<X<22) were mechanically milled and subsequently annealed in the range of 560-640 o C. The samples were characterized using X-ray diffraction, scanning electron microscopy and vibrating sample magnetometer. Based on results, during milling process Cr and Co elements have been dissolved in Fe matrix and Fe-Cr-Co solid solution (with combination of α 1 and α 2 spinodal phases) has been formed. The coercivity and saturation of magnetization of formed alloys were in the range of 110-187 Oe and 150-175 emu/g, respectively. The coercivity of Fe 72-x Co x Cr 28 (10<X<22) alloys showed an anomalous behavior at 18 at.% of Co as a result of optimal interaction between α 1 and α 2 phases in this composition. The formed Fe-Co-Cr αphase solid solutions were not stable and transformed to σ and γ phases during annealing process at temperatures higher than 600 o C. The formation of non-magnetic σ and γ phases had destructive effect on magnetic properties of prepared samples with different composition.

Journal of Magnetism and Magnetic Materials, 2017

Ferromagnetic Heusler alloys of Co 2 MnSi were synthesized by mechanical alloying method at low t... more Ferromagnetic Heusler alloys of Co 2 MnSi were synthesized by mechanical alloying method at low temperature. The effect of milling time and annealing process on structural and magnetic properties of ferromagnetic alloy samples were studied by X-ray diffraction, scanning electron microscopy and vibration sample magnetometer methods, respectively. Structural characteristics such as crystallite size, phase percentage, and lattice parameter determined using the Rietveld method. The values of these parameters were obtained 362.9 nm, 5.699 Å and 98.7%, respectively for annealed sample. Magnetization studies show that the Co2MnSi phase is formed at 15 h of milling and is optimized after 20 h of milling. VSM results showed that saturation magnetization (M s) of milled samples reduces from 112 to 75 (emu/g) with increasing milling time and then increased gradually to 95 emu/g. The effect of post-annealing on the structural and magnetic properties of milled samples was also investigated. The saturation magnetization of annealed sample (120 emu/g) is higher than the optimum milled sample (95 emu/g) due to increasing preferential ordered L2 1 structure.

Journal of Advanced Materials In Engineering, 2016

Nanoparticles of Mg-Co-Ti substituted strontium hexaferrite with nominal composition of SrFe 12-2... more Nanoparticles of Mg-Co-Ti substituted strontium hexaferrite with nominal composition of SrFe 12-2x (Mg,Co) 0.5x Ti x O 19 (x=0-2.5) were synthesized by a co-precipitation method. The structural, magnetic and electromagnetic properties of samples were studied as a function of x by thermal gravimetric (TG), X-ray diffraction (XRD), transmission electron microscopy (TEM), vibrating sample magnetometer (VSM) and vector network analysis. It was found that the synthesis temperature increases with an increase in Mg-Co-Ti substitution and hence the particle size decreases. The XRD results showed that whole samples had good crystallinity and with an increase incations, the impurity phase of Fe 2 O 3 appears. The results of hysteresis loops indicated that the saturation of magnetization of ferrite decreases from 40 emu/g to 19 emu/g with an increase in x. The Mössbauer spectroscopy showed that the cations are substituted in the 12k site of magnetoplumbite structure. Vector network measurements showed that the doped samples had much more effective reflection loss values than those of undoped ferrites. As a result, Mg-Co-Ti doped Sr-hexaferrites with x=2 can be proposed as suitable absorbers for applications in microwave technology with a good deal of consistency.

Microstructure, magnetic and microwave absorptive behavior of doped W-type hexaferrite nanoparticles prepared by co-precipitation method

Materials Research Bulletin, 2016

Abstract Substituted W-type hexaferrite nanoparticles of SrZn 2− x Co x /2 Ni x /2 Fe 16 O 27 wer... more Abstract Substituted W-type hexaferrite nanoparticles of SrZn 2− x Co x /2 Ni x /2 Fe 16 O 27 were synthesized by a chemical co-precipitation method. The X-ray diffraction results confirmed that W-type ferrite was identified as the main phase in whole samples in the range of x = 0–0.4. According to magnetic hysteresis loops, with increasing of substituted cations, saturation of magnetization increased and coercivity decreased due to crystalline site occupation of Zn with Ni and Co cations. The microwave reflection loss analysis results in the K u band (12–18 GHz) show that the highest value of reflection loss of samples was −29.11 dB at frequency of 14.57 GHz with an absorption bandwidth of more than 6 GHz by choosing reflection loss value of −10 dB as a reference. The results indicate that, the sample with appropriate amount of substituted cations hold great promise for microwave device applications.

Y-Type Strontium Hexaferrite: the Role of Al Substitution, Structural, and Magnetic Consequence

Journal of Superconductivity and Novel Magnetism, 2015

In this study, Y-type Sr-hexaferrite nanoparticles with nominal chemical composition of Sr2Co2Fe1... more In this study, Y-type Sr-hexaferrite nanoparticles with nominal chemical composition of Sr2Co2Fe12−y/2Aly/2O22 (y = 0, 0.5, 1.0, 1.5, 2.0, 2.5, 3.0) were synthesized by a co-precipitation method. Crystal structure, morphology, and magnetic consequence of nanoparticles were characterized by employing X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), energy dispersive analysis of X-ray spectroscopy (EDS), Fourier transform infrared spectroscopy (FTIR), and vibrating sample magnetometer (VSM), respectively. XRD spectra revealed that the high-purity hexagonal Sr2Co2Fe12−y/2Aly/2O22 single phase was formed at synthesis temperature of 900 °C or 1 h. It was also found that the crystallite size of nanoparticles was increased from 32.8 to 37.6 nm by an increase in the substitution content. FE-SEM results showed that the particle size increased with an increase in aluminum ion substitution, and the morphology of particles was gradually turned from irregular platelet to pyramidal shapes. The FTIR analysis was employed to approve different bond modes which were structured. The VSM analysis showed that, with an increase in amount of substitution, the coercivity decreases from 456 to 98 Oe.

Journal of Magnetism and Magnetic Materials, 2015

In this study, the electromagnetic properties of a novel nanocomposite material made of substitut... more In this study, the electromagnetic properties of a novel nanocomposite material made of substituted Sr-hexaferrite nanoparticles and different percentage of single walled carbon nanotube have been studied. The structural, magnetic and electromagnetic properties of samples were studied as a function of volume percentage of SWCNTs by X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, vibrating sample magnetometer and vector network analysis. Well suitable crystallinity of hexaferrite nanoparticles was confirmed by XRD patterns. TEM and FESEM micrographs were shown the good homogenity and high level of dispersivity of SWCNTs and Sr-hexaferrite nanoparticles in nanocomposite samples. The VSM results shown that with increasing in amount of CNTs (0-6 vol%), the saturation of magnetization decreased up to 11 emu/g for nanocomposite sample contains of 6%vol of SWCNTs. The vector network analysis results show that the maximum value of reflection loss was −36.4 dB at the frequency of 11 GHz with an absorption bandwidth of more than 4 GHz (<-20 dB). The results indicate that, this nanocomposite material with appropriate amount of SWCNTs hold great promise for microwave device applications.

Journal of Superconductivity and Novel Magnetism, 2014

In this study, the effects of substitution of divalent ions such as Mn, Ni, and Cu on the structu... more In this study, the effects of substitution of divalent ions such as Mn, Ni, and Cu on the structural and magnetic properties of Z-type barium hexaferrite with a composition of Ba 3 Co 2−x Mn x Ni x Cu x Fe 24 O 41 (x = 0-0.5) were investigated. X-ray diffraction (XRD), Fourier transformed infrared spectroscopy (FTIR), field emission scanning electron microscopy (FE-SEM), and a vibrating sample magnetometer (VSM) analysis were carried out to investigate the structural and magnetic properties of samples. The XRD results showed that the Z-type ferrite phase was formed successfully in all samples, and the average crystallite size of the pure sample was also larger than those of substituted samples. FE-SEM micrographs showed that the average particle size was decreased with increasing x. The FTIR spectra also indicated that there are two bands characterizing ferrites in the range of 431-589 cm −1. They were identified as the metal-oxygen stretching vibrations of Ba-Z hexaferrite. The VSM results showed that with an increase in the amount of dopant from x = 0 to x = 0.2, the saturation magnetization and coercivity were increased from 50 emu/g and 186 Oe to 58 emu/g and 1255 Oe, respectively.

Modified Synthesis Temperature of Ba₃Co_1.7Ni_0.1Cu_0.1 Mn_0.1Fe₂₄O₄₁Z-Type Ferrite Nanoparticles Prepared by Co-Precipitation Method

Advanced Materials Research, 2013

In this study, the low temperature synthesis of barium-Z type hexaferrite nanoparticles was consi... more In this study, the low temperature synthesis of barium-Z type hexaferrite nanoparticles was considered. In this manner, the Z-type hexaferrite with the chemical composition of Ba3 Co1.7 Ni0.1 Cu0.1 Mn0.1 Fe24 O41 was synthesized at different temperatures of 900, 1000 and 1100 0C for 3hr. An X-Ray diffraction, field emission scanning electron microscopy (FE-SEM) and a vibrating sample magnetometer (VSM) analysis were carried out to investigate structural and magnetic properties of samples. XRD results showed that the Z-type ferrite phase was formed in all samples. However, At the low temperature synthesis (T=900 0C), the Ba2Me2Fe12O22 and BaFe2O4 phases were also detected. FE-SEM micrographs showed that with increasing the synthesis temperature, the particle size was increased. It was found that the saturation of magnetization was slightly increased from 54 to 55. 5emugr with an increase in synthesis temperature from 900 to 11000C, while the coercivity increased initially from 670 Oe...

Recent Trends in Processing and Degradation of Aluminium Alloys, 2011

Optics and Lasers in Engineering, 2008

Laser surface alloying of an electroless plating NiP coatings on an Al-356 aluminium alloy was ca... more Laser surface alloying of an electroless plating NiP coatings on an Al-356 aluminium alloy was carried out using a 1-kW pulsed Nd:YAG laser. The microstructure, chemical composition and phase identification of the alloyed layer were determined using scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX) and X-ray diffractometry (XRD), respectively. It was shown that laser surface treatment produced a relatively smooth, crack-free and hard surface layer. The hardness of the surface significantly increased due to the formation of the uniformly distributed fine Ni-Al intermetallic phases. The corrosion behaviour of the surface alloyed specimens in 3.5% NaCl solution at 23 1C was also determined by electrochemical techniques. The laser-alloyed surface showed an improved corrosion and pitting potential compared to the substrate as well as the plated NiP coating.