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In this study, Bi1-xSmxFe1-yCryO3 (x = 0.0, 0.05, 0.1, y = 0.0, 0.01, 0.02, 0.03) nanostructures were prepared by hydrothermal method at 220 °C using the KOH concentration of 4 M during 6 h. X-ray diffraction analysis showed that the samples have a distorted rhombohedral perovskite structure with the symmetry of an R3c space group. The FT-IR spectrums of BiFeO3 and Bi1-xSmxFe1-yCryO3 are confirmed by the metal-oxide absorption bands that appeared at 400 cm−1–600 cm−1, which are the characteristic bands of FeO6 octahedral groups in the perovskite structure. FESEM images showed that the particle size has been decreased by doping the elements Sm and Cr. The magnetic properties of Bi1-xSmxFe1-yCryO3 have been improved compared to the undoped BiFeO3. The results of the magnetic properties showed that a maximum magnetization at 15 k Oe of BiFeO3 (0.148 emu/g) to Bi0.9Sm0.1Fe0.97Cr0.03O3 (1.895 emu/g) has been increased. The optical properties showed that the optical bandgap energy of samples with co-doping of Sm and Cr has been reduced from 2.8 to 2.1 eV. The results of PL analysis showed that the electron–hole recombination with an increase of the doping of Sm and Cr contents has been decreased which result in an effect on the photocatalytic performance. The Congo red (CR) degradation efficiency under visible light irradiation with increased co-doped Sm and Cr consents has been increased and the Congo red degradation rate followed the first-order Langmuir–Hinshelwood kinetics model. [ABSTRACT FROM AUTHOR]

This research studied the effect of two‐stage over aging treatment on corrosion behavior of the weld metals in the 17‐4 precipitation hardening stainless steel. Gas tungsten arc welding was performed under solution annealed condition. After the welding, weld metal was subjected to double over aging treatments. Hydrogen induced cracking and stress corrosion cracking standard tests were carried out on weld metals before and after ageing treatment. Charpy impact test and microhardness test were conducted to evaluate the mechanical properties of weld metals. Microstructural examinations of the welding zones were performed by the optical microscope and field emission scanning electron microscope. The results showed that the as‐weld lath and coarse martensite were transferred to severely tempered martensite after over aging treatment with the formation of reversed austenite. In the latter case, the reversed austenite was about 30 % compared to 7 % before over aging treatment. The over aged weld metals were significantly more resistant to hydrogen induced cracking, and exhibited a longer time‐to‐failure in stress corrosion cracking test. The weld metal in the as‐weld condition in hydrogen induced cracking test showed severe cracking and failed rapidly in the stress corrosion cracking test. [ABSTRACT FROM AUTHOR]

In this paper, spinel-strontium ferrite nanoparticles (SrFe2O4) were prepared by the sol-gel method. Structural, dielectric, and optical properties were characterized by the X-ray diffraction (XRD), LCR, UV-visible spectrophotometry, and photoluminescence spectroscopy (PL). The X-ray diffraction pattern shows that the single-phase cubic spinel structure for a sample at temperature of 700 °C has been formed. Also, studies of the field-scattering scanning electron microscope show that morphology synthesized samples are homogeneous, but since the samples have a magnetic property, thus the samples are aggregated. The dielectric parameters such as the dielectric constant (έ), dielectric loss (ἕ), and the ac electrical conductivity (σac) of the samples were investigated by using LCR-meter at room temperature in the frequency range of 20 Hz to 10 MHz. The results of the dielectric parameters show that by decreasing the frequency, the dielectric constant and the dielectric loss are increased, while the ac electrical conductivity increases in which these changes are justified by the Maxwell-Wegener model. The results of ultraviolet-light spectroscopy show that, by increasing temperature, the energy gap of SrFe2O4 nanoparticles decreases. Also, the results of photoluminescence spectroscopy of SrFe2O4 nanoparticles show that there is an emission peak in the ultraviolet region that is due to the recombination of free excitements arising from an exciton-exciton process which is known as the near band edge (NBE). [ABSTRACT FROM AUTHOR]

We study the magnetoresistance (MR) and spin transport in a graphene-based ferromagnetic/ferromagnetic barrier/s-wave superconductor (FFBS) junction for two regimes including retro-Andreev reflection (AR) (EF = 100Δ0) and retroreflection crossing over to specular Andreev reflection (EF = Δ0). We observed that the variation of exchange energy in the ferromagnetic region h1 has a stronger effect on the amplitude of the MR oscillations rather than length, exchange energy, and effective gate potential in the FB region in both regimes. In the EF = 100Δ0 regime, the higher values of exchange energy h1 approach EF, which decrease the amplitude of the MR oscillations with respect to FB length. By increasing the exchange energy up to h1 > EF, a phase shift occurs for the peaks of the MR curves and the amplitude of the MR oscillations reaches its maximum value at the exchange energy hc = 2EF + U0. Furthermore, in the EF = Δ0 regime, at the exchange energy h1 = eV, the amplitude of the MR oscillations approaches its maximum value. At this value of energy of carriers eV + h1 - EF (Dirac point), the sign of the energy will be reversed and a transition from the retroreflection to the specular Andreev reflection occurs. Thus, in this regime (EF = Δ0), by observing the maximum of the MR at specified values of eV and h1, we can measure the Fermi energy of the graphene. While in the EF = 100Δ0 regime, the MR versus bias energy can be tuned from the positive to negative values by varying h1, but in the EF = Δ0 regime, the MR shows only the positive values. In addition, we have investigated the spin conductance in both regimes. [ABSTRACT FROM AUTHOR]

In the present investigation, structural, morphological and magnetic properties of SrFe2O4 ferrite nanoparticles prepared by a sol–gel method were studied. The techniques used in this investigation were thermogravimetric analysis/differential thermal analysis (TGA/DTA), X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDX), field emission scanning electron microscopy (FESEM), Fourier transform infrared spectrometry (FT-IR), vibrating sample magnetometry (VSM) and Curie temperature analysis. The average crystallite sizes of the SrFe2O4 were calculated using the Scherrer formula and found in the range of 11–22 nm, and this can be attributed to the grain growth of the particles. The lattice parameter of SrFe2O4 nanoparticles decreased from 6.64 to 6.51 nm as the sintering temperature was raised from 600 to 900 °C. FT-IR analysis confirmed that bands in the range 430–590 cm− 1 are due to the stretching vibration of oxygen atom and metal ions (M–O) that is Fe–O confirming the formation of spinel ferrite. Surface morphology of the samples has been studied using FESEM. The elemental composition along with their relative ratios was given by EDX and was found to be in agreement with their initial calculated values. The saturation magnetization, magnetic coercivity and remanence increase with an increasing sintering temperature from 600 to 900 °C. The present study reports the Curie temperature with an amount of 551 °C of the synthesized strontium nanoferrites using the Faraday technique. [ABSTRACT FROM AUTHOR]

We report the low-temperature preparation of WS2 nanosheets by chemical vapor deposition (CVD) method for photoelectrochemical (PEC) water splitting application. The WS2 nanosheets were synthesized onto the FTO, ITO, SiO2, and glass substrates at a relatively low temperature of 500 °C under pressure of 10−2 Torr. Compared to temperatures of conventional WS2 synthesis via CVD method, the deposition was performed at a sufficiently low temperature, which has not been reported for the layer deposition yet. The samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and ultraviolet–visible (UV–visible) spectroscopy. The results show that WS2 nanosheets were grown almost vertically and alike a single crystal. Based on the SEM images, the WS2 nanosheets grew homogenously on the FTO substrate and covered the entire surface of the substrate. Linear sweep voltammetry (LSV), applied bias photon to current efficiency (ABPE), photocurrent response, and electrochemical impedance spectroscopy (EIS) of the fabricated nanosheets were measured for the photoelectrochemical response. Because of no transferring to damage layer, the results showed that WS2 nanosheets on FTO substrate had good photoelectrochemical activity. The measured photocurrent of 32 µAcm−2 and ABPE efficiency of 0.84% at a 0.75 V bias (versus RHE) was considerably high compared to the other results reported for WS2 nanosheets. [ABSTRACT FROM AUTHOR]

Abstract: In this study, the microstructure, hardness, and dry sliding wear behavior of the hardfaced layers made by a cored wire Fe-B-C-Ti alloy were investigated. St37 steel was used as the substrate and the deposition of the hardfaced layers was conducted by the flux cored are welding(FCAW) process Under single-, two-, and three-pass conditions. Dry sliding wear tests were performed by a pin-on-disk apparatus, based on. ASTM-G99. at room temperature 25°i') at the normal applied loads of 50. 100. and 150 N with a constant speed of 0.08 m's for a sliding distance of 1000 m. The micurstructral and phase analyses were carried out by field emission scanning electron microscopy (FE-SEM) and X-ray diffraction (XRD), respectively. The results showed that the hardfaced layer produced by the single-pass process contains TiC rectangular phase distributed within a matrix containing ferrite and the eutectic of (a-FeB). But the hardfaced layers produced by the two- and three-pass process contain TiB, hexagonal phase in addition to TIC. winch prevents the formation of detrimental FeB phase around Fe2β and reduces the number of micro-cracks Moreover, the sample hardfaced by the three-pass process had the best wear resistance due to the greater hardness resulted from the higher amounts of TiC and TiB' phases. In addition increasing the number of passes has led to the reduction of wear rate at all the three applied loads At the applied load of 100 N. the wear mechanism for the all three hardfaced samples was an oxidation wear However, at the applied load of 150 N. the wear mechanism was a combination of oxidation and delamination. [ABSTRACT FROM AUTHOR]

Y3Ba5Cu8O18 superconductors were prepared through a standard solid-state reaction and the structural properties of the samples were studied through XRD and the Rietveld refinement method. The effect of silver nanoparticles doping on the Y3Ba5Cu8O18 superconductors was studied as well. It is known that the size of nanoparticles is increased during aging. Therefore, two batches of samples with 1 and 2 wt% of Ag nanoparticles and the size range of 30, 200, 500, 700, 800, and 1000 nm were prepared. After preparing the samples and observing the Meissner effect, the crystallography, critical current density, critical temperature, magnetic susceptibility, SEM, and EDX experiments of the samples were carried out. The results of the critical current density measurements showed that the sample with 2 wt% Ag nanoparticles and the size of 700 nm has the maximum current density. In both batches of samples, increasing the nanoparticle size to 700 nm led to an increase in the critical current density. The crystallography studies showed that silver nanoparticles do not insert into the superconductor’s frame. Actually, they are placed in the samples as a distinct phase. [ABSTRACT FROM AUTHOR]

The present study tries to investigate Wiedemann-Franz law near and far from the critical temperatures, given the tunneling between the grains in Cooper pair fluctuation propagator and impurity vertex. By means of Dyson’s equation, the Cooper pair fluctuation propagator, L(qkΩμ) and the Cooperon (impurity vertex), λ(q, k, ε1, ε2), are initially calculated in the presence of tunneling between the grains. Then, the three distinct contributions of density of states, Maki-Thompson, and Aslamazov-Larkin, are calculated in the frameworks of the Green’s functions formalism and the Kubo formula technique. The evaluation is conducted under the limited tunneling conductance between the grains. Findings show that although the tunneling is efficient near the critical temperature, it is not effective when it is far from the critical temperature Compared to that in high temperatures, moreover, the deviation from the Wiedemann-Franz law is much more evident in low temperatures. [ABSTRACT FROM AUTHOR]

In this study, nanocrystalline Li-Zn ferrites with the chemical composition of LiZnFeO (where 0 ≤ x≤0.5) were synthesized by glycine-nitrate combustion process using glycine as a fuel, nitrate as an oxidizer, and microwave oven as a heat source. The as-synthesized powders were characterized using an X-ray diffraction technique. X-ray diffraction patterns show that nanocrystalline Li-Zn ferrite phase with a spinel structure has been formed successfully in all samples. Dielectric properties including dielectric constants, dielectric loss, AC conductivity, and complex dielectric impedance were measured in the frequency range 20 Hz-10 MHz using a LCR meter. Results show that dielectric constant, as well as dielectric loss, decreases with increasing frequency and then becomes roughly frequency independent at high frequencies. In contrast, AC conductivity follows an upward trend with frequency. Complex impedance spectroscopic studies show the presence of only one semicircle for all samples, suggesting the predominant effect of grain boundary property of the material. It is also found that substitution of Zn for Fe ions leads to a significant decrease in electrical conductivity due to decrease of ferrous and ferric ions available for the hopping process. Similarly, both dielectric constant and dielectric loss show reduction with the increase in Zn content as a result of the reduction of Fe/Fe ions. [ABSTRACT FROM AUTHOR]

SrFeNiO nanoparticles ( x = 0-1) were synthesized by a combustion sol-gel method. Their structure, dielectric and magnetic properties were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), an LCR metry, and vibrating sample magnetometry (VSM).The results reveal that all samples of Ni doped compounds (SrFeNiO) with x < 0.2 are single phase. It appears that the Fe ions are substituted by Ni ions on the crystallographic sites of the SrFeO structure; however, for x ≥ 0.2, the secondary Ni phase ferrite (NiFeO) appears, which reduces the saturation magnetization and coercivity. In addition, Ni doping reduces the dielectric constant, dielectric loss, and alternating current (ac) electrical conductivity of the samples. The variation in ac conductivity ( σ) with frequency shows that the electrical conductivity in these ferrites is mainly attributed to the electron hopping mechanism.Therefore; all the single-phase Ni doped samples are suitable for use in magnetic recording media and microwave devices. [ABSTRACT FROM AUTHOR]

In this work, a series of M-type strontium hexaferrite samples having nominal composition SrFeCoO (x = 0.0, 0.1 and 0.2) with different morphologies have been synthesized by sol-gel method The decomposition behavior and mechanism of phase formation of SrFeO were investigated using of thermogravimetric analysis (DTA/TGA). The crystal structure and morphology of samples were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. The XRD results showed that all of the samples have the major phase of SrFeO with M-type hexaferrite structure, and the Co-doped samples also have the minor phases of FeO and KFeO. It seems that the Fe ions are substituted by Co ions in the crystallography sites of the SrFeO structure. The average crystallites size is found in the range of 16-39 nm, which is small enough to obtain a suitable signal-to-noise ratio in high-density recording media. The morphology and average particles size of samples were determined by SEM. In the Fourier transform infrared spectrometry (FT-IR) spectra of all the samples, three peaks were observed. All of these peaks correspond to the metal-oxygen stretching in hexaferrites. [ABSTRACT FROM AUTHOR]

The growing trend in technological advances and Micro Electro Mechanical Systems (MEMS) has targeted for intelligent human lives. Accordingly, Ubiquitous Computing Approach was proposed by Mark Weiser. This paper proposes an ubiquitous surveying solution in Geometrics and surveying field. Ubiquitous Surveying provides cost-effective, smart and available surveying techniques while traditional surveying equipment are so expensive and have small availability specially in indoor and daily surveying jobs. In order to have a smart surveying instrument, different information technology methods and tools like Triangle method, Received Signal Strength Indicator (RSSI) method and laser sensor are used. These new ways in combine with surveying equations introduces a modern surveying equipment called Ubi-Total Station that also employed different sensors embedded in smartphone and mobile stand. RSSI-based localization and Triangle method technique are easy and well known methods to predict the position of an unknown node in indoor environments whereas additional measures are required for a sufficient accuracy. In this paper the main goal is to introduce the Ubiquitous Total Station as a development in smart and ubiquitous GIS. In order to public use of the surveying equipment, design and implementation of this instrument has been done. Conceptual model of Smartphone-based system is designed for this study and based on this model, an Android application as a first sample is developed. Finally the evaluations shows that absolute errors in X and Y calculation are 0.028 and 0.057 meter respectively. Also RMSE of 0.26 was calculated in RSSI method for distance measurement. The high price of traditional equipment and their requirement for professional surveyors has given way to intelligent surveying. In the suggested system, smartphones can be used as tools for positioning and coordinating geometric information of objects. [ABSTRACT FROM AUTHOR]

In this paper, the CdO nanoparticles were synthesized by sol-gel method Then, the effects of CdO nanoparticles on the structure and weak-link behavior of the Bi-Pb-Sr-Ca-Cu-O system, which has a nominal starting composition of Bi Pb Sr Ca Cd Cu O (BPSCCC) ( x = 0.0, 0.01, 0.02, 0.03, 0.04, 0.1, 0.5, 1, and 2), were studied. The BPSCCC superconductor was made using a solid state reaction method. The structural analysis of BPSCCC was carried out using X-ray diffraction (XRD) measurements. The standard four-probe method was carried out to measure critical current density. The temperature dependence of ac magnetic susceptibility of samples was measured as a function of ac magnetic field amplitude by using a Lake Shore ac susceptometer. The results of XRD and ac magnetic susceptibility indicated that the Bi-2201 and Bi-2212 phases reduce the critical current density and critical temperature. In addition, the small amount of doping ( x = 0.01) was found to improve the superconducting properties of the Bi-Pb-Sr-Ca-Cu-O system. [ABSTRACT FROM AUTHOR]

In this paper, the propagation of acoustic waves in the phononic crystal of 3D with rhombohedral(I) lattice is studied theoretically. The crystal composite constituted of nickel spheres embedded in epoxy. The calculations of the band structure and density of states are performed with the plane wave expansion method in the irreducible part of Brillouin zone. In the present work, we have investigated the effect of lattice angle on the band structure and width of the band gap rhombohedral(I) lattice in the irreducible part of the first Brillouin zone and its planes separately. The results show that more than one complete band gape are formed in the four planes of the irreducible part. The most complete band gaps are formed in the (111) plane and the widest complete band gap in (443) with an angle greater than 80 $$^{\circ }$$ . So, if the sound passes through the (111) and (443) planes for the lattice angle close to 90 $$^{\circ }$$ , the crystal phononic displays the excellent insulation behavior. Moreover, in the other planes, the lattice angle does not affect on the width and the number of band gaps. Also, for the filling fraction 5 %, the widest complete band gap is formed. These results are consistent with the effect of symmetry on the band gap width, because the (111) plane has the most symmetry. [ABSTRACT FROM AUTHOR]

In this paper, the effect of Sb and Pb elements doping on the BiPbSbSrCaCuO (BPSSCCO) superconductor was studied. The BPSSCCO superconductor was synthesized by a solid state reaction method. The superconductivity properties such as the critical temperature, magnetic susceptibility, and room temperature resistivity have been investigated. In order to study the effect of Sb and Pb elements on the room temperature resistivity of the samples, the V-I curves were measured. The resistivity of the Sb doped samples at room temperature increases when the content of Sb is increased. It is also decreased by increasing the annealing time. The results showed that the optimum condition was x=0.35, y=0.05, with an annealing time of 270 h. [ABSTRACT FROM AUTHOR]

The flux pinning energy and magnetic properties of BiPbCdSrCaCuO (BPCSCCO) with x=0.0, 0.02, 0.04 and 0.06 were studied. A series of Bi-2223 superconductor samples with a nominal composition of BPCSCCO was synthesized and the effect of Cd substitution for Bi was investigated. As a result, Cd addition has been found to improve the superconducting properties of the Bi-Pb-Sr-Ca-Cu-O system. The effects of the annealing time and the amount of Cd doping on the structure, AC magnetic susceptibility, ρ- T curves and flux pinning energy were investigated. Also, for all samples the relation between the current and voltage in the mixed state was found to follow the model relationship V= α I. The maximum value of β is 22.30, which is obtained for the sample with an annealing time of 270 h and a Cd content of 0.04. [ABSTRACT FROM AUTHOR]