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Nanocomposites of (Mg0.9Ni0.1O)x/(CoFe2O4)1-x, with 0 ≤ x ≤ 1 in weight fractions, were synthesized through the co-precipitation method followed by high-speed ball milling. The investigation of the structural, optical, and magnetic properties was conducted for the synthesized samples. X-ray diffraction (XRD) analysis confirmed the formation of CoFe2O4 and Mg0.9Ni0.1O distinct phases in the nanocomposites without any detectable impurities or minor phases. Transmission electron microscopy (TEM) and high-resolution TEM (HRTEM) revealed the presence of spherical particles in both the individual phases and their nanocomposites. Raman spectroscopy exhibited strong, well-defined modes for CoFe2O4, indicating its spinel phase formation, while Mg0.9Ni0.1O displayed two broad peaks (G and D bands). X-ray photoelectron spectroscopy (XPS) was utilized to analyze the elemental compositions and oxidation states (Co2+, Fe2+, Fe3+, Mg2+, Ni2+, and O2−). The magnetic measurements revealed the soft ferromagnetic behavior of pure cobalt ferrite and a combination of weak ferromagnetism and paramagnetic behavior at high magnetic fields for pure Mg0.9Ni0.1O. [ABSTRACT FROM AUTHOR]

(BaFe12O19)1 − x/(MgO)x nanocomposites, with weight fraction x = 0, 0.1, 0.2, 0.4, 0.8 and 1, have been synthesized by co-precipitation method followed by high-speed ball-milling techniques. Structural, optical, and magnetic properties have been studied. XRD analysis confirmed the formation of the two pure phases BaFe12O19 and MgO, with the formation of a MgFe2O4 as a minor phase in the nanocomposites. Transmission electron microscopy (TEM) followed by high resolution TEM and SAED were used to study the morphology, crystallinity and lattice spacing, respectively. TEM micrographs revealed the co-existence of spherical and nanorod-shaped particles for pure BaFe12O19, and cubic shape for MgO nanoparticles. Raman spectrum for BaFe12O18 showed strong and sharp modes, identifying the formation of barium hexaferrite phase. However, MgO showed two broad peaks attributed to G and D bands. The energy dispersive X-ray and scanning electron microscope were performed for elemental analysis and surface topography, respectively. The real elemental compositions matched well with the starting values. X-ray photoelectron spectroscopy was conducted for the investigation of the elemental compositions and the oxidation states of (Ba2+, Fe2+, Fe3+ Mg2+ and O2−). The magnetic properties like saturation magnetization, remanent magnetization, coercivity and squareness ratio have been determined using the M–H loops. These loops revealed the hard ferromagnetic behavior of pure barium hexaferrite and the mixture of ferromagnetism with diamagnetic behavior at high fields for pure MgO. The saturation and remanent magnetizations decreased with the addition of MgO phase. dM/dH curves showed a weak magnetic coupling between the hard magnetic BaFe12O19 and the soft magnetic MgFe2O4. [ABSTRACT FROM AUTHOR]

The structural, mechanical, optical, and magnetic properties of RE3+ (Nd3+and Sm3+) doped cadmium zinc ferrites were investigated. The purpose of the rare-earth dopants is to deduce the possible applications for the prepared samples. The Cd0.5Zn0.5RExFe2-xO4 ferrite (x = 0.00, 0.01, 0.08) was synthesized using the wet chemical co-precipitation method. The structural investigations were done using X-ray diffraction (XRD) fitted using Rietveld refinement. The analysis confirmed the spinel structure's crystallinity belonging to the Fd3m space group. The cation distribution and many other structural parameters were estimated from the XRD data. Cation distribution calculations were done using a custom-built Python program that proved the normal structure of the prepared ferrites. The mechanical properties were calculated using the data extracted from Fourier transform infrared (FTIR) spectra, which showed an increase in porosity, weakening of elastic moduli, increase in ionic distances, and expansion of the unit cell. The optical properties were studied using Photoluminescence (PL) spectroscopy and Ultraviolet–Visible (UV–Vis) spectroscopy, which allowed the evaluation of the energy gaps that are found to range between 3.24 and 3.27 eV for the direct energy gap. The results confirmed the quantum confinement effect due to the decrease of crystallite size with the increase of the energy band gap. Optical analysis also showed that the prepared ferrites are good candidates for optoelectronics and nonlinear optical applications. Mössbauer spectroscopy and vibrating sample magnetometer (VSM) investigate the magnetic and structural properties that verified the superparamagnetic behavior in all samples. [ABSTRACT FROM AUTHOR]

In this work, spinel zinc ferrite (ZnFe2O4), manganese oxide (Mn2O3) nanoparticles (NPs) as well as a series of ZnFe2O4/Mn2O3 nanocomposites (NCs) with varying Mn2O3 ratio from 10 to 50 wt. % were synthesized by co-precipitation route. The structural, optical, electrical, and magnetic properties of ZnFe2O4/Mn2O3 NCs were examined by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, transmission electron microscopy (TEM), ultraviolet–visible (UV–Vis) spectroscopy, photoluminescence (PL) emission, DC electrical conductivity, and vibrating sample magnetometer (VSM). The XRD analysis demonstrated the existence of Mn2O3 and ZnFe2O4 phases, in addition to the formation of spinel ZnMn2O4 and α-Fe2O3 as secondary phases. The chemical interactions between the Mn2O3 and ZnFe2O4 have been confirmed by the shift in the position of the metal–oxygen (M–O) stretching modes in the FTIR spectra. The TEM images revealed the presence of cubic and spherically shaped nanoparticles in the ZnFe2O4/Mn2O3 NCs with an average size in the range of 15.52 to 19.22 nm. The nanocomposites showed strong absorption in the UV region with a calculated bandgap ranging between 3.22 and 3.26 eV. However, the nanocomposite with 10 wt. % Mn2O3 exhibited the highest photocatalytic activity under UV-irradiation as confirmed by PL spectroscopy. Moreover, the nanocomposite structure exhibited a significantly enhanced DC conductivity compared to ZnFe2O4 and attained a maximum value at 10 wt. % Mn2O3. The room temperature M-H curves of ZnFe2O4/Mn2O3 NCs displayed weak ferromagnetic behavior. The magnetization increases with increasing Mn2O3 content up to 10 wt. % and then decreases with further increase in the wt.%. [ABSTRACT FROM AUTHOR]

Tricobalt tetroxide (Co3O4) nanoparticles were synthesized by co-precipitation method. The structure, morphology, purity, real compositions, and functional groups of the prepared nanoparticles were determined by X-ray diffraction (XRD), transmission electron microscope (TEM), energy-dispersive X-ray (EDX) analysis, and Fourier transform infrared (FTIR) spectroscopy, respectively. The results confirm the formation of pure spinel structure of the Co3O4 nanoparticles with space group Fd3m and average spherical particle size of 58 nm. The optical properties were explored by ultraviolet–visible spectroscopy (UV–vis) and photoluminescence spectroscopy (PL). Two absorption peaks were aroused in ultraviolet and visible ranges accompanied by two band gap energies and an Urbach energy. Moreover, two emission peaks in agreement with the calculated band gap energies were observed in the PL spectrum. A weak ferromagnetic behavior was investigated by magnetic hysteresis (M-H) loop at room temperature. The electrical conductivity was measured in the temperature range 313–573 K. A normal semiconductor behavior was detected. The dielectric properties were studied under the variation of temperature and frequency. Then, the dielectric constant, dielectric loss, ac conductivity, relaxation process, and Nyquist plots were discussed. [ABSTRACT FROM AUTHOR]

Effect of Nd3+ and Ca2+ ion substitutions in Y3Ba5Cu8O18 (Y-358) was studied using X-ray diffraction (XRD), scanning electron microscopy (SEM), electrical resistivity, and ac magnetic susceptibility measurements. Superconducting samples of type Y3 − xNdxBa5 − yCayCu8O18 (with 0 ≤ x, y ≤ 0.4) were synthesized by the standard solid-state reaction technique. XRD patterns revealed that all the samples were mainly composed of Y-358 phase with orthorhombic structure. SEM micrographs showed that Nd3+ and Ca2+ ion substitutions had the ability to alter the grain morphology of Y-358 to irregular randomly oriented grains with smaller average grain sizes. The temperature-dependent electrical resistivity curves indicated that the superconducting transition temperature Tc was decreased from 96.51 to 87.41 K as the substitution contents were increased from 0 to 0.4. Detailed AC magnetic susceptibility measurements were done using a quantum design physical property measurement system (PPMS) at different dc fields (B = 0.5–20 kG) and frequency of 1 kHz. A comparison between electrical resistivity and AC magnetic susceptibility data was performed. It was found that Tcs obtained from AC magnetic susceptibility were much lower than those obtained from the resistivity measurements, for all studied samples. This was discussed in terms of filamentary paths that could produce sharp pronounced drops in diamagnetism. Generally, the depression in Tc was attributed to the decrease in relative volume fraction of Y-358 or due to trapping of mobile holes or other mechanism connected with oxygen vacancy disorder. Werthamer–Helfand–Hohenberg (WHH) theory was employed to study the temperature dependence of the upper critical magnetic field Bc2(T) for the samples. The relative importance of both orbital and paramagnetic effects in the suppression of superconductivity was described with the aid of Maki parameter (κM). The estimated values of the upper critical magnetic field at 0 K, Bc2(0), were found to decrease from 37.3 to 13.5 T as Nd3+ and Ca2+ contents were increased from 0 to 0.4. This decrement was attributed to the weak electron–phonon coupling and to the orbital as well as spin pair breaking mechanisms. Furthermore, Ginzburg–Landau coherence length ξGL of Y3 − xNdxBa5 − yCayCu8O18 was found to increase with the increase of the Nd3+ and Ca2+ contents. Therefore, Nd3+ and Ca2+ ions play an important role in the pair-breaking mechanism and in suppressing superconductivity of the Y-358 phase. [ABSTRACT FROM AUTHOR]

The excess conductivity and magnetoconductivity of (NiO)x(Bi,Pb)-2223 were analyzed using the Aslamazov and Larkin (AL model) in order to obtain the coherence lengths ξab(0), ξc(0) at 0 K and the anisotropic parameter Γ. Both ξab(0) and ξc(0) values increase with the addition of NiO nanoparticles The anisotropic parameter values Γ in this study are less than those reported due to the polycrystalline nature of these samples. [ABSTRACT FROM AUTHOR]

The effect of samarium and lanthanum fluorides (SmF3 and LaF3) on the structural and superconducting properties of Tl0.8Hg0.2Ba2Ca2−xRxCu3O9-δ-yFy superconducting phase (Tl, Hg)-1223, where R = Sm or La and x = 0.00, 0.025, 0.050, 0.075, and 0.10 was investigated. The solid-state reaction method was used to synthesize the superconducting samples. The phase formation percentages and lattice parameters were calculated using X-ray powder diffraction (XRD). Images taken with a scanning electron microscope (SEM) show that the presence of both Sm and La increases the grain size and inter-grain connectivity up to x=0.025. The successful substitution of Sm and La elements in the crystal structure of (Tl, Hg)-1223 is confirmed by energy-dispersive X-ray (EDX) analysis. The oxidation states of the elements in the prepared samples are revealed by X-ray photoelectron spectroscopy (XPS) spectra. I–V and resistivity measurements were used to investigate the electrical properties of the (Tl, Hg)-1223 system with Sm and La substitutions. The superconducting transition temperature (Tc) and transport critical current density (Jc) have steadily improved up to x = 0.025, above which they dropped significantly. Furthermore, as temperature increased, the temperature dependence of fluctuation conductivity (Δσ), revealed distinct zones. The zero-temperature coherence length (ξc(0)), effective layer thickness of the two-dimensional system (d), interlayer coupling (I), Fermi velocity (vf), and Fermi energy (Ef) were determined. ξc(0) and d decrease until x= 0.025, then increase as x increases. All estimated I values show weak coupling between CuO2 planes and a transition from three-dimensional (3D) to two-dimensional (2D) regions. [ABSTRACT FROM AUTHOR]

The influence of barium tin oxide nanoparticles addition on the structural and superconducting properties of the $$\hbox {Cu}_{0.5}\hbox {Tl}_{0.5}\hbox {Ba}_{2}\hbox {Ca}_{2}\hbox {Cu}_{3}\hbox {O}_{10{-}\delta }$$ phase, (CuTl)-1223, was studied. A different wt% of $$\hbox {BaSnO}_{3}$$ , ranging from 0.00 to 1.50, were added into (CuTl)-1223 phase, and this composite was synthesized using the solid-state reaction technique. The phase formation and lattice parameters were calculated from X-ray powder diffraction measurements. The grain connectivity and surface morphology were identified using scanning electron microscope. Energy dispersive X-ray spectroscopy gave the real elemental composition of the prepared samples. Superconducting transition temperature $$({T_\mathrm{c}})$$ and critical current density $$({J_\mathrm{c}})$$ were determined from the electrical resistivity and I-V measurements, respectively. A complete study about the vibration modes of different atoms was carried out using Fourier transform infrared (FTIR) absorption spectroscopy of $$(\hbox {BaSnO}_{3})_\mathrm{x}/\hbox {CuTl-1223}$$ composite. The increase in $${T_\mathrm{c}}$$ and $${J_\mathrm{c}}$$ up to $$x=0.25$$ wt% is an evidence for improving the superconducting properties of $$(\hbox {BaSnO}_{3})_\mathrm{x}/\hbox {CuTl-1223}$$ composites by enhancing both the inter-grains coupling and volume fraction of the (CuTl)-1223 phase. [ABSTRACT FROM AUTHOR]

YBaCuO superconducting samples were synthesized at different ball-milling times, 0≤ t≤180 min, through the solid-state reaction technique. A comparison between the samples prepared by hand grinding and those prepared by high-speed ball-milling was studied. The variation of relative volume fraction, the lattice parameters, and the average crystallite size with t were examined using X-ray powder diffraction (XRD). The result is that the relative volume fraction of Y-123 phase increases by increasing t up to 15 min, and then it decreases with further increase in t. Moreover, the average crystallite size decreases as t increases from 0 to 60 min and then it increases with further increase in t. In addition, the surface morphology was studied through both scanning and transmission electron microscopes (SEM and TEM). Small crystallite grains, ranging from 25 to 70 nm, were detected between the matrices of Y-123 superconducting phase. The electrical resistivity and transport critical current density for Y-123 samples with different ball-milling time were measured by standard dc four-probe method. The superconducting transition temperature T and the transport critical current density J considerably enhance by increasing t to 15 and 30 min, respectively, beyond which they decrease. The suppression in both T and J may be due to decrease in relative volume fraction or degradation of the crystallite Y-123 matrix, causing increase in grain boundaries resistance. The Vickers microhardness for the prepared samples was measured, and the results indicate that the Vickers microhardness number H increases as the ball-milling time increases. [ABSTRACT FROM AUTHOR]

Solid-state reaction method was used to prepare superconductor samples with nominal composition of (SnO)(BiPb)SrCaCuO, (SnO)(Bi,Pb)-2223 composite, where 0.0 ≤ x ≤ 0.2 wt%. The prepared samples were characterized by X-ray diffraction (XRD) as well as scanning electron microscopy (SEM). XRD patterns proved that the addition of nano-SnO particles to (Bi,Pb)-2223 did not affect the tetragonal structure and the lattice parameters of this phase. Vickers microhardness measurements ( H ) for these samples were carried out at room temperature as a function of applied load, heating temperatures, and dwell time. However, to clarify the indentation size effect (ISE) behavior of these composite materials and to estimate the true microhardness values ( H ), different models including Meyer's law, Hays and Kendall (energy dissipation) model, elastic/plastic deformation model, as well as proportional specimen resistance model were applied. Some important mechanical parameters, such as Young's modulus ( E), yield strength ( Y), fracture toughness ( K), and brittleness index ( B), were estimated from the microhardness curves. It was found that the incorporation of a proper concentration of nano-SnO particles has proved their efficiency to enhance the mechanical properties of superconductors. Moreover, it was noted that dwell time and Vickers microhardness were inversely proportional. Indentation creep experiments showed that the operative creep mechanisms in the studied samples were dislocation creep in addition to dislocation interaction. [ABSTRACT FROM AUTHOR]

The electrical resistivity of normal and superconducting states for SmBaCuRuO (Sm-123) phase with 0.00 ≤ x ≤ 0.50, prepared by the conventional solid-state reaction technique, was studied. X-ray powder diffraction (XRD), scanning electron microscope (SEM), particle-induced X-ray emission (PIXE), Rutherford backscattering spectroscopy (RBS) and electrical resistivity measurements were performed in order to investigate the effect of Ru ions substitution in Sm-123 phase. Both the phase formation and superconducting transition temperature T enhance up to x = 0.05. For x > 0.05, suppression of both the phase formation and T is observed and the superconductivity is completely destroyed around x = 0.50. The normal-state electrical resistivity was analyzed by the two- and three-dimensional variable range hopping (2D-VRH and 3D-VRH) and Coulomb gap CG. The dominant mechanism for Sm-123 phase is CG with x ≤ 0.20 while is 3D-VRH for x ≥ 0.30. [ABSTRACT FROM AUTHOR]

(CoFe O) GdBa Cu O superconducting samples were synthesized using a conventional solid-state reaction technique with 0≤ x≤0.1 wt%. Characterization of the prepared samples was carried out using X-ray powder diffraction (XRD) and scanning electron microscopy (SEM). The effect of adding CoFe O to the Gd-123 phase, which acts as a flux pinning center, was investigated by measuring the ac magnetic susceptibility at different applied dc magnetic fields. Both the superconducting transition temperature T and the critical current density J increased up to x=0.01 wt%, and then, they decreased with further increase in x. The temperature dependence of the irreversibility line was investigated by the logarithmic plot of the irreversibility field H versus (1− T/ T(0)). This plot shows a crossover at a field of 1000 Oe, indicating 3D to 2D flux creep fluctuations. Furthermore, the H- T curves are well fitted according to a theoretical model proposed by Matsushita, based on the depinning mechanism caused by thermally activated flux creep. [ABSTRACT FROM AUTHOR]

To compare between the effect of partial substitution of lead ions (Pb4+ and Pb2+) at thallium (Tl) site in Tl0.8-xHg0.2PbxBa2Ca2Cu3O9−δ superconductor; two different compounds, lead (II) oxide (PbO) and lead (IV) oxide (PbO2), were used for the synthesis of the superconducting samples. Samples with nominal compositions Tl0.8-xHg0.2PbxBa2Ca2Cu3O9−δ, with x = 0.00, 0.05, 0.10, 0.15, and 0.20, were synthesized via solid state reaction technique. The x-ray diffraction (XRD) results showed that the partial substitution of both lead ions has not affected the tetragonal structure. Moreover, the volume fraction was increased from 75.95% to 90.38% and 89.41% as x increased up to 0.20 for PbO and PbO2 substitutions, respectively. The scanning electron microscopy (SEM) images demonstrated better grain connectivity and rectangular-shaped plates, supporting the phase formation of (Tl,Hg)-1223. The energy-dispersive x-ray (EDX) analysis revealed good agreement between the nominal and real compositions. Moreover, the elemental composition and oxidation states were proved by x-ray photoelectron spectroscopy (XPS). Both the superconducting transition temperature (Tc) and critical current (Jc) showed enhancement at x = 0.5 and 0.1 for PbO and PbO2 substituted samples, respectively. Vickers microhardness (Hv) measurements were used to examine the mechanical properties of the composites under a range of applied loads (0.49–9.8 N). All the prepared composites revealed the normal indentation size effect. The proportional sample resistance model proved to be the best model for interpreting the experimental data for the prepared samples. [ABSTRACT FROM AUTHOR]

Superconducting samples of the type (ZnFeO)GdBaCuO were synthesized by the conventional solid-state reaction technique. The nanosized (ZnFeO) content x varied from 0 to 0.1 wt% of the samples' total mass. The prepared samples were characterized using X-ray powder diffraction (XRD) and scanning and transmission electron microscopes (SEM and TEM). The effect of ZnFeO addition, which acts as flux pinning centers, was investigated using ac magnetization at different applied dc magnetic fields. It was found that addition of the nanosized (ZnFeO) up to 0.06 wt% enhances the critical current density J and the superconducting transition temperature T. On the other hand, the superconducting properties of these samples are deteriorated for x > 0.06 wt%. The irreversibility line was thermally activated. The logarithmic plot of H versus (1 − T/ T(0)) shows a crossover at about 500 Oe, reflecting the transition from two- to three-dimensional vortex fluctuations. The B- T curves are well fitted according to Matsushita's model, which is based on the de-pinning mechanism caused by thermally activated flux creep. [ABSTRACT FROM AUTHOR]

Superconductor samples of type (CoFeO)GdBaCuO, 0.0≤ x≤0.1 wt.%, were synthesized by the conventional solid-state reaction technique. The prepared samples were investigated using X-ray diffraction (XRD), scanning electron microscope (SEM), electrical resistivity, AC magnetic susceptibility, and Vickers microhardness. Phase examination by XRD indicated that the orthorhombic structure of Gd-123 is not affected by nanosized ferrite CoFeO addition, whereas the volume fraction of Gd-123 increased with x up to 0.01 wt.%. Morphological investigations by SEM revealed that the porosity among grains decreased as x increased from 0.0 to 0.1 wt.%. The superconducting transition temperature T was estimated from electrical resistivity and the AC magnetic susceptibility measurements. A reduction in T was observed as x increased from 0.0 to 0.1 wt.%, consisting with the effect of adding magnetic impurities to HTSCs. Room temperature microhardness measurements were carried out at different applied loads (0.5-10 N) for the study of the mechanical performance of the studied samples. The experimental results were analyzed using Meyer's law, Hays-Kendall approach, elastic/plastic deformation model, and proportional specimen resistance model. The results showed that all the samples exhibited normal indentation size effect, and Vickers microhardness values were increased as nanosized CoFeO addition increased. The analysis showed that the proportional specimen resistance model is the best model for computing the load-independent microhardness values of our samples. [ABSTRACT FROM AUTHOR]

The magnetoresistance behavior of (CuF2)x-substituted (Cu0.5−x, Tl0.5)Ba2Ca2Cu3Oy superconducting samples with x = 0.1, 0.2, 0.3, and 0.4 was investigated by varying the flux pinning mechanism. A pronounced broadening of resistive transitions, ΔT, was observed by applying external magnetic fields ranging from 0.29 to 4.40 kOe. The thermally activated flux creep, TAFC, and Ambegaokar–Halperin, AH, models have been studied to explain the broadening of the resistive transition and magnetoresistance. The results revealed that the flux pinning energy, U(H), was reduced as the magnetic field increased while it was raised with increasing (CuF2)x substituted up to an optimum concentration of x = 0.2. Moreover, the critical current density, Jc, and the upper irreversibility field, Hirr, were enhanced with (CuF2)x—substituted in the (Cu0.5−x, Tl0.5)Ba2Ca2Cu3Oy phase, showing a strong flux pinning for x = 0.2 at different magnetic fields. [ABSTRACT FROM AUTHOR]

Study design:Prospective clinical study.Objectives:To assess fasting and postprandial (PP) perception of rectal distension and its correlation with symptoms in patients with spinal cord injury (SCI) and neurogenic bowel dysfunction compared to ten healthy subjects (HS).Setting:Experimental Medicine and Motility Unit, Mexico General Hospital and National Institute of Rehabilitation.Methods:Twenty patients with complete SCI at cervical, thoracic and lumbar levels [American Spinal Injury Association (ASIA) A] were studied. Rectal sensitivity was evaluated with a barostat.Results:In SCI patients, while lower the rectal tone more time was used for defecate (R=0.50, P=0.048) and more PP episodes of fecal incontinence occur (R=0.54, P=0.030). The thresholds for non-noxious stimuli of first (23.6 mmHg, CI 19.5-27.7) vs 14.0 (CI 10.9-17.1), P=0.004; gas (27.9 mmHg, CI 19.9-35.8) vs 17.9 mmHg (CI 14.25-21.69), P=0.02 and urge-to-defecate sensation (33.2 mmHg, CI 27.5-38.8) vs 22.4 mmHg (CI 17.9-26.9), P=0.01 were reported by SCI patients at higher pressure than HS, respectively. SCI patients reported PP pain sensation at a lower pressure than controls (27.8 mmHg, CI 21.5-34.2 vs 36.5 mmHg, CI 31.8-41.2), P=0.04.Conclusion:SCI patients preserve rectal sensation, present rectal hyposensitivity for non-noxious stimuli and PP hypersensitivity. Lower rectal tone was related to the time used for defecate and with fecal incontinence. The results suggest that an intact neural transmission between the spinal cord and higher centres is indispensable for noxious stimulus, but not for non-noxious stimuli. Also, barostat sensitivity studies can complement ASIA criteria to verify a complete injury. [ABSTRACT FROM AUTHOR]

In this study, superconducting samples of type CuTlBaCaCuO added by SnO and InO in nano-scale were prepared by a solid-state reaction technique. The concentrations of both SnO and InO were 0.0, 0.1, 0.2, 0.4, 0.6 and 1.0 wt% of the sample's total mass. The prepared samples were characterized using X-ray powder diffraction (XRD) and scanning electron microscopy (SEM) for phase analysis and microstructure examination. The elemental content of the prepared samples was determined using energy dispersive X-ray (EDX) and particle induced X-ray emission (PIXE). The results of elemental content, determined from EDX and PIXE, were compared and discussed. In addition, The oxygen content of these samples was obtained using non Rutherford backscattering spectroscopy (RBS) at 3 MeV proton beam. It was found that the Oxygen-content of (CuTl)-1223 phase was not affected by both SnO and InO nano-oxides addition. The electrical resistivity of the prepared samples was measured by the conventional four-probe technique from room temperature down to the zero superconducting transition temperature ( T). An increase in the superconducting transition temperature T from 106 to 119 K was observed as x was varied from 0.0 to 0.6 wt% for (SnO)CuTlBaCaCuO, followed by a systematic decrease with increasing nano-SnO addition. On the other hand, the T values for (InO)CuTlBaCaCuO show a small variation with x. Moreover, the variation rate of T with x, for both nano-additions, was found to be directly proportional to the variation of the volume fraction of the prepared samples. [ABSTRACT FROM AUTHOR]

The Vickers microhardness of BiPbSrCaCuO superconducting phase with added SnO nano-particles was investigated. The concentration of SnO nano-particles x varied from 0.0 to 2.0 of the sample's total mass. The experimental data of the Vickers microhardness were analyzed using Meyer's law, the elastic/plastic deformation model, Hays-Kendall's approach and the proportional specimen resistance model. The Vickers microhardness number H increased as x increased up to 0.4 wt%. The load dependence of H exhibited a normal indentation-size effect, H increased as the applied load increased. Moreover, this dependence was well fitted with the Hays-Kendall approach rather than the elastic/plastic deformation and proportional specimen resistance models. In addition, we calculated Young modulus, yield strength, fracture toughness and brittleness index as a function of both applied load and SnO nano-particle concentration. [ABSTRACT FROM AUTHOR]

Bulk superconducting samples of type TlPbSrBaCaCuRuO, (Tl,Pb)/Sr-1212, with 0.0≤ x≤0.525 were synthesized by the conventional one-step solid-state reaction technique via a short time, using SrO instead of SrCO. X-ray powder diffraction XRD, scanning electron microscope SEM and the electrical resistivity measurements at different applied dc magnetic fields (0.0-4.4 kG) were performed in order to investigate the effect of Ru ions substitution on (Tl,Pb)/Sr-1212 phase. Enhancement of the phase formation, the superconducting transition temperature T and the hole carriers concentration P was observed up to x=0.075, and they decreased for further increase in x. The magnetoresistance data of these samples were analyzed within the thermally activated flux creep TAFC model and the Ambegaokar and Halperin AH theory. The derived flux pinning energy U, the critical current density J(0) and the upper critical magnetic field B(0) enhanced up to x=0.075, beyond which they decreased for further increase in Ru-content. The coherence length at 0 K ζ(0) decreased up to x=0.075 and increased with x>0.075. In addition, we reported a comparison between the effect of Ru substitution on the physical properties for Gd-123, (Bi,Pb)-2223 and (Tl,Pb)/Sr-1212 phases. [ABSTRACT FROM AUTHOR]

Superconducting samples of type BiPbSrCaCuRuO, (Bi, Pb)-2223, with 0.0≤ x≤0.4 and type TlPbSrBaCaCuRuO, (Tl, Pb)/Sr-1212, with 0.0≤ x≤0.525 were synthesized using the standard solid-state reaction technique. The lattice parameters and the surface morphology for these samples were determined using X-ray powder diffraction (XRD) and scanning electron microscope (SEM) measurements, respectively. All element-contents of the samples prepared were estimated from the electron dispersive X-ray (EDX) technique, and their results were compared with those obtained from particle-induced X-ray emission (PIXE). In addition, the oxygen-content was determined using elastic Rutherford backscattering spectroscopy (RBS) technique at 3 MeV proton beam. The superconducting transition temperature T and the hole carrier concentration P were determined from the electrical resistivity measurement. The data of both T and P for BiPbSrCaCuRuO and TlPbSrBaCaCuRuO phases increased up to x=0.05 and 0.075, respectively and then they decreased as x increased. The superconductivity was completely destroyed around x=0.4 and 0.525 for (Bi, Pb)-2223 and (Tl, Pb)/Sr-1212 phases, respectively. The normal-state electrical resistivity data were analyzed using the two and three dimensional variable range hopping (2D-VRH and 3D-VRH) and the Coulomb gab (CG). [ABSTRACT FROM AUTHOR]

Bulk superconducting samples of type GdBaCuRuO, Gd-123, with x=0.0-0.3 were prepared by the conventional solid-state reaction technique. X-ray powder diffraction (XRD), scanning electron microscope (SEM), electron dispersive X-ray (EDX) and electrical-resistivity measurements were performed in order to investigate the effect of Ru ions substitution on Gd-123 phase. Enhancement of both phase formation and the superconducting transition temperature T for GdBaCuRuO phase up to x=0.05 was observed from XRD and electrical-resistivity measurement, respectively. This enhancement was confirmed with the calculated relative volume fraction. For x>0.05, suppression of both phase formation and T was obtained and the superconductivity was completely destroyed around x=0.3. The normal-state electrical resistivity was analyzed by the two- and three-dimensional variable range hopping (2D-VRH and 3D-VRH) and Coulomb gap CG. The results showed that the dominant mechanism was CG for x≤0.075, while was 3D-VRH for x≥0.15. [ABSTRACT FROM AUTHOR]

CuTlBaCaPrCuO superconducting samples, with 0≤ x≤0.15, were prepared by a single-step solid state reaction on a form of rectangular bar. The prepared samples were characterized using X-ray powder diffraction (XRD) and scanning electron microscope (SEM). The room temperature Vickers microhardness was measured at different loads (0.25-3 N). The experimental results were analyzed using Meyer's law, Hays-Kendall approach, elastic/plastic deformation model, proportional specimen resistance model, and the indentation-induced cracking (IIC) model. Surprising results were obtained and showed that all samples in the form of rectangular bars exhibited reverse indentation size effect in contrary with those in the form of discs. Vickers microhardness values were decreased as Pr-content increased that consisting with the porosity results. Furthermore, the Young's modulus was determined using the dynamic resonance technique. A relation between Young's modulus ( E) and Vickers microhardness ( H) was obtained. [ABSTRACT FROM AUTHOR]

Series of superconducting samples of type CuTl BaCaRCuO, where R=Pr and La with 0≤ y≤0.20, were prepared in a sealed quartz tube via a single-step solid-state reaction technique. The prepared samples were characterized by X-ray powder diffraction (XRD), scanning electron microscope (SEM), and electron dispersive X-ray (EDX). XRD studies indicated that the tetragonal structure of (CuTl)-1223 phase does not change by Pr or La-substitutions whereas the lattice parameters a and c do. The elemental compositions analysis, determined from EDX, indicated that both Pr and La were successfully introduced into the microstructure of (CuTl)-1223 phase. The electrical resistivity ρ( T) was measured as a function of temperature using conventional dc four-probe technique. The fluctuation conductivity Δ σ, above the superconducting transition temperature T, was analyzed as a function of temperature using Aslamazov and Larkin model. It exhibits four different fluctuation regions namely critical (cr), three-dimensional (3D), two-dimensional (2D), and short-wave (sw). The zero-temperature coherence length, effective layer thickness of the two-dimensional system and inter-layer coupling strength were estimated as a function of the substitution-content y. Furthermore, the thermodynamics critical field, lower critical magnetic field, upper critical magnetic field, critical current density and Fermi energy were calculated from the Ginzburg number. The data indicated that both Pr and La-substitutions have quite similar behaviors. [ABSTRACT FROM AUTHOR]

High-temperature superconductor phase of (CuTlPb)-1223 was synthesized by solid-state reaction technique and characterized using X-ray powder diffraction (XRD). XRD analysis revealed that the prepared sample was nearly monophase and exhibited tetragonal structure with space group P4/mmm. Nano-zinc-oxide, prepared by Co-precipitation method, was added to the sample. ZnO-concentrations y varied from 0.0 to 2.0 wt.% of the sample's mass. The prepared samples were investigated through XRD, scanning electron microscope (SEM), energy dispersive X-ray (EDX), particle size analyzer (PSA), differential scanning calorimeter (DSC), electrical resistivity and transport critical current density measurement. X-ray data analysis showed that the nano-Zn addition does not affect the tetragonal structure of (CuTlPb)-1223 phase, whereas the lattice parameters showed an insignificant variation. The results of the superconducting transition temperature, the transport critical current density and melting point of the prepared samples were found to depend on nano-ZnO concentrations. [ABSTRACT FROM AUTHOR]

The effect of nano-size MgO (40–60 nm) addition on the physical properties of polycrystalline (Cu0.25Tl0.75)-1234 was studied. The MgO-concentration ( x) varied from 0.0 to 1.0 wt.% of the sample’s total mass. X-ray analysis, granular structure examination, energy dispersive X-ray spectroscopy, electrical resistivity, critical current density at different applied magnetic fields and Vickers microhardness measurements were carried out to study the performance of these samples. Phase examination by X-ray diffraction indicated that MgO-addition enhanced the (Cu0.25Tl0.75)-1234 phase formation till x=0.6 wt.%. Granular investigation by scanning electron microscope reveled that both number and size of voids decreased as x increased from 0.0 to 0.6 wt.%. These results were supported by the sample’s porosity calculation. The superconducting transition temperature and critical current density were found to have optimum values at x=0.6 wt.%. Furthermore, the Vickers microhardness increased till x=0.6 after that it decreased with further increase in x. [ABSTRACT FROM AUTHOR]

This work uses the co-precipitation method for the synthesis of Zn1-xRuxO nanoparticles, with (0 ≤ x ≤ 0.04). Structurally, Rietveld refinement of X-ray powder diffraction data revealed the hexagonal wurtzite crystal structure, for all samples, with minor traces of RuO2 for x > 0.01. Fourier transform infrared spectroscopy confirmed the formation of ZnO wurtzite structure with a broad peak at 441 cm−1 and a shoulder at 565 cm−1. Optical band gap (Eg) was investigated through UV–visible spectroscopic analysis. Eg showed an enhancement with the increase of Ru content verifying the decrease in the crystalline size from XRD results. Magnetic properties were investigated by the vibrating sample magnetometer. Ferromagnetism in ZnO was justified by the formation of bound magnetic polarons (BMPs). It shows an enhancement with Ru doping, verified by the increase of both Mr and Ms, attributed to the stabilization of Zn vacancy as well as magnetic defects. [ABSTRACT FROM AUTHOR]

Pure and lanthanum-doped zinc oxide nanoparticles (Zn1-xLaxO), with atomic percentages ( x = 0, 1, 3, 5 and 7 at%) were prepared by chemical co-precipitation method. The synthesized samples have been characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), UV–visible spectroscopy, photoluminescence spectroscopy (PL) and M-H loop using vibrating sample magnetometer (VSM). XRD analysis reveals the wurtzite hexagonal crystal structure of ZnO structure with the detection of lanthanum oxide secondary phase (La2O3) for x ≥ 3 at%. The increase of the lanthanum content affects the particles size, energy bandgap and lattice parameters. The presence of functional groups and the chemical bonding is confirmed by FTIR spectra that shows the formation of additional peaks due to ZnO ions dopant. The direct energy bandgap was calculated, showing a noticeable change as the concentration of the lanthanum content increases. The photoluminescence spectra show 8 emission peaks due to different defects. The M-H curves exhibited a combination of both diamagnetic and ferromagnetic contributions. The antibacterial activity of the synthesized samples was studied against three gram-negative (Escherichia coli, Klebsiella pneumoniae, and Citrobacter braakii) and three gram-positive (Staphylococcus aureus, Staphylococcus haemolyticus, and Streptococcus intermedius) bacterial strains using agar well diffusion method. These nanoparticles exhibited various degrees of antibacterial activity against the investigated bacteria. [ABSTRACT FROM AUTHOR]

The effect of CdMnO addition on the physical properties of Bi-2212 superconductors was investigated. The conventional solid-state reaction technique was employed for the synthesis of (Cd0.95Mn0.05O)x Bi1.6 Pb0.4 Sr1.9 Ca1.1 Cu2.1 O8+δ samples with 0.00 ≤ x ≤ 0.10 wt.%. The X-ray diffraction confirms the formation of the orthorhombic phase of Bi-2212 superconductors. The lattice parameter a shows an increase with x, conversely the lattice parameters b and c show a decrease. The scanning electron microscope (SEM) images have shown an enhancement in the grain connectivity and a reduction of voids due to the CdMnO addition. The Fourier transform infrared (FTIR) spectroscopy analysis shows a remarkable shift in the wave number positions due to the addition of CdMnO nanoparticles. The superconducting transition temperature (Tc) and the critical current density (Jc) show an enhancement with CdMnO addition up to x = 0.05 wt.%. The elemental composition and oxidation state of all elements were determined from the X-ray photoelectron emission (XPS) analysis. The work suggests a correlation between the variations of the superconducting properties and the dynamics of the cationic equilibrium reactions among Pb2+ ions in Bi3+ or Cu2+ sites. These equilibrium reactions are induced by the variations in the oxygen content produced by the addition of CdMnO nanoparticles. [ABSTRACT FROM AUTHOR]

This study examined the impact of adding hard ferrite Ba0.5Sr0.5Fe12O19 (BSF) nanoparticles to the Bi1.8Pb0.4Sr2Ca2Cu3.2O10+δ (Bi, Pb)-2223) superconductor phase. The investigation specifically focused on evaluating the critical current density, fluctuation-induced conductivity, and magnetoresistance of nano-(BSF)x/(Bi, Pb)-2223 composite, where 0.00 ≤ x ≤ 0.20 wt.%. The results revealed that the critical current density, Jc, increased with the addition of nano-(BSF) up to x = 0.04 wt.%, reaching a value of 441.20 A/cm2. The Aslamazov and Larkin (A–L) approach has been evaluated the fluctuation-induced conductivity. Several superconducting parameters, including coherence length ζc(0), effective layer thickness d, penetration depth λpd(0), and Fermi energy E F showed improvement as the concentration of nano-(BSF) increased up to x = 0.04 wt.%. In addition to Ginzburg–Landau critical parameters, such as the thermodynamic critical field Bc(0), lower critical magnetic field Bc1(0), upper critical magnetic field Bc2(0), and critical current density Jc(0) demonstrated an increase up to x = 0.04 wt.%, followed by a decrease for higher concentrations. The magnetoresistance measurements were performed at various applied DC magnetic fields, with values ranging from 0.29 to 4.44 kG, and were analyzed using the thermally activated flux creep (TAFC) and Ambegaokar–Halperin (AH) models. The calculated flux pinning energy (U) increased with the addition of nano-(BSF) up to x = 0.04 wt.% and then decreased for x > 0.04 wt.%. Furthermore, the transition width (ΔT), was observed to increase as the applied magnetic field values increased. Moreover, the addition of nano-(BSF) increased the field-independent critical current density, Jc,0(0), up to x = 0.04 wt.%, after which it decreased for higher concentrations. [ABSTRACT FROM AUTHOR]

Pure and Gd-doped NiO nanoparticles capped by polyvinylpyrrolidone (PVP) were synthesized via the co-precipitation method, with different concentrations (x = 0.000, 0.005 and 0.010). Extensive experimental assessments were conducted to study the structural, optical and magnetic properties of the prepared nanoparticles. The X-ray diffraction patterns depicted the formation of pure NiO phase without impurities, assuring the adequate incorporation of Gd dopants into the lattice. The transmission electron micrographs showed the pseudospherical morphology of the pure and Gd-doped samples, with mean sizes, ranging between 28.09 and 22.84 nm. The vibrational spectroscopies confirmed the purity of the synthesized samples and gave insight into their structural properties. Moreover, the excitation dependence of the photoluminescence emission spectra was noticed due to the particles' size distribution. Some point defects, as the nickel and oxygen vacancies, were tuned upon the introduction of Gd dopants, leading to enhancements in the optical and magnetic properties. The optimum concentration of Gd dopants was x = 0.005 in Ni1-xGdxO nanoparticles since it attained the widened bandgap energy of 3.46 eV and highest saturation magnetization of 0.23 emu/g at an applied field of 20 kG. All the samples demonstrated weak ferromagnetic nature, which was deduced from the M-H loops after subtracting the linear magnetization of the antiferromagnetic contribution. The Belov–Arrot plot showed a second-order magnetic transition from antiferromagnetic to ferromagnetic nature. The improvements in PVP-capped Gd-doped NiO nanoparticles are fruitful for light-emitting devices and spintronic applications. [ABSTRACT FROM AUTHOR]

Solid-state reaction technique was used to prepare superconductor samples with nominal composition of (SnO2)x(Bi,Pb)-2223 and (NiO)x(Bi,Pb)-2223, where 0.0 ≤ x ≤ 0.2 wt%. The prepared samples were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The impact of SnO2 and NiO nanoparticles addition on the thermopower of (Bi,Pb)-2223 was measured using a standard differential technique. The Seebeck coefficient values in the presence of NiO nanoparticles were about 5–37.9% higher than those obtained with the addition of SnO2 nanoparticles. Higher values of Seebeck coefficients result in a wide variety of applications of these superconductors such as electronics and thermoelectric devices. The obtained results were analyzed according to the two-band model (Fermi-liquid model) and the two-band model with an extra linear term. The Fermi velocity (υF), Fermi energy, Fermi temperature (TF), Fermi wavenumber (KF), Fermi wavelength (λF) as well as the carrier concentration (N/V) values were calculated and discussed as a function of the nanoparticles content. [ABSTRACT FROM AUTHOR]

In this study, lanthanum La-doped Mg0.33Ni0.33Co0.33Fe2-xLaxO4 (0.00 ≤ x ≤ 0.08) nanoferrites were synthesized using the co-precipitation method. The physical properties of the samples were examined using X-ray diffraction (XRD), transmission electron microscope (TEM), selected area electron diffraction (SAED), Fourier transform infrared (FTIR) spectroscopy, Raman spectroscopy and vibrating sample magnetometer (VSM). The XRD results confirmed the formation of a single-phase spinel ferrite. Upon increasing the La3+ ions concentration, crystallite and particle sizes decreased as revealed from XRD and TEM analysis, respectively. The values of the lattice parameter estimated from the SAED are in harmony with those obtained from XRD patterns. The appearance of two bands in the FTIR spectra, mainly in the range of 592–595 and 387–422 cm−1, confirms the formation of the spinel structure. Furthermore, the red shift in A1g Raman mode, observed in La-doped nanoferrites, was attributed to the active motion of Fe3+ towards the A sites. The samples demonstrated a ferromagnetic behavior with a reducing saturation magnetization from 31.87 to 12.99 emu/g as x increased from 0.00 to 0.08, respectively. Different forms of the law of approach to saturation (LAS) were employed to fit M–H hysteresis curves of experimental data. Moreover, different parameters were investigated, including the exchange field, anisotropy field, Bohr magneton, and magnetocrystalline anisotropy. These parameters were further analyzed to check the accuracy of the fitting and the best-suited model. [ABSTRACT FROM AUTHOR]

In this study, the impact of adding samarium iron garnet (Sm3Fe5O12; SmIG) nanoparticles to the (Bi1.6Pb0.4)Sr1.9Ca0.9Y0.2Cu2.1O8+δ ((Bi, Pb)-2212) superconductor was investigated. The conventional solid-state reaction method was utilized to synthesize (SmIG)x(Bi, Pb)-2212 phase with different concentrations (x = 0, 0.25, 0.5, 0.75, 1, and 2 wt%). The structure, the morphology, and the elemental composition were tested using X-ray powder diffraction spectroscopy (XRD), scanning electron microscopy (SEM), and dispersive X-ray spectroscopy (EDX), respectively. Filling of pores and voids validated the impact of the added nano-SmIG on intergrain connections. The enhancement in oxygen content was verified by iodometric titration analysis. The superconducting transition temperature (Tc) and the critical current density (Jc) showed best enhancement with the addition of nano-SmIG up to x = 0.75 wt%, having values of 91.02 K and 373.95 A/cm2, respectively. The fluctuations in the superconducting properties were explained via X-ray photoelectron spectroscopy (XPS) by studying the elemental composition and oxidation states for all elements. Vickers microhardness (Hv) investigations were carried out at different applied loads and indentation time of 20 s, where Hv reached its highest value at x = 0.25 wt%. Based on Hv values, the modified proportional sample resistance (MPSR) model offered the most suitable theoretical model to elucidate the experimental data. [ABSTRACT FROM AUTHOR]

In the search for highly responsive dielectric materials, superconducting samples of type (Bi,Pb)-2223 were prepared using the standard solid-state reaction technique, with the addition of three different concentrations of ferrato and mangano-undecatungstosilicate (0.04, 0.12, and 0.20 wt%). The dielectric studies were performed by measuring the parallel capacitance C p as well as the dielectric loss factor using LCR HiTESTER. The studies were performed at temperature and frequency ranges starting from room temperature down to 98 K and from 50 kHz up to 5 MHz, respectively. The dielectric behavior was investigated by calculating both dielectric constants ( ε ′ and ε ″ ), loss tangent (Tanδ) and ac conductivity (σac) as a function of frequency, temperature and addition concentrations of the {FeSiW11} and {MnSiW11} polyoxometalates. The results revealed that the dielectric parameters decrease with increasing frequency at each temperature for all the {FeSiW11}x(Bi,Pb)-2223 and {MnSiW11}x(Bi,Pb)-2223 prepared samples. Moreover, ε ′ and σac showed a decreasing trend with an increase in temperature in contrast to the increasing trend shown by ε ″ and Tanδ. Additionally, ε ″ has decreased upon increasing temperature at low frequencies. Accordingly, low {MnSiW11} addition at 0.12 wt% exhibited the highest dielectric constant 1.99 × 10 7 and ac conductivity 61.449 (Ω.m)−1 with minimum dissipation (1.078). Furthermore, the ac conductivity was studied according to the power law, and the frequency exponent was found greater than one 1.654 ≤ S ≤ 1.759 for all the prepared samples. [ABSTRACT FROM AUTHOR]

Applying the coprecipitation technique, we synthesized PVA-capped Ni0.98RE0.02O (RE = Er md Pr) nanoparticles. Thermogravimetric analysis (TGA) was performed to study the thermal stability of the prepared samples to choose the calcination temperature accordingly. Thermal stability was attained at ~ 823 K with no further thermal decomposition beyond. The crystallinity and phase formation of the prepared samples were confirmed by powder X-ray diffraction XRD. Studying the effect of RE3+ doping on the structural parameters of NiO nanoparticles was facilitated by X-ray peak profile analysis, based on the Debye Scherer model, Williamson–Hall model and size strain plot. The doped samples exhibited smaller lattice parameter and strain, with the minimum strain along the (200) direction. Also, a smaller crystallite size was found for the doped samples, depending on the dopant's ionic radius, giving rise to higher dislocation density and specific surface area. Transmission electron microscopy (TEM) proved the nanoscale of the prepared samples, in agreement with the XRD outcomes, and revealed slight agglomeration of homogeneous nanoparticles. DC conductivity indicated the semiconducting behavior of the prepared samples, triggered by Ni2+ vacancies. Hopping mechanism was found to be the conduction process with two activation energies, depending on the temperature range of study. The dielectric behavior was explained by Maxwell–Wagner interfacial polarization, in agreement with Koop's theory. The correlated barrier hopping mechanism CBH was found to be the conduction mechanism. Moreover, the Nyquist plot was investigated. Doping by rare earth elements resulted in an increase in dielectric constant, AC and DC conductivities. [ABSTRACT FROM AUTHOR]

In this study, the effects of (K6[(H2O)MnSiW11O39]·21H2O, {MnSiW11}) polyoxometalate, with an average particle size of 48.46 nm, on (Bi1.8Pb0.4)Ca2Sr2Cu3O10+δ (Bi,Pb)-2223, superconducting samples, were investigated. Samples of type {MnSiW11}x(Bi1.8Pb0.4)Ca2Sr2Cu3O10+δ, 0.00 ≤ x ≤ 0.20 (wt%) were prepared using the conventional solid-state reaction technique. Manganese-containing polyoxometalates are considered as an attractive class of inorganic nanomaterials, because they have multiple oxidation states and many unpaired electrons. Consequently, the microstructure, morphology, optical and magnetic properties of the prepared {MnSiW11} nanoparticles were determined by powder X-ray diffraction (XRD), transmission electron microscopy, Fourier transform infrared spectroscopy and magnetic hysteresis loop measurements, respectively. The bulk of superconducting samples was characterised by XRD, scanning electron microscopy and energy dispersive X-ray spectroscopy. The XRD analysis showed that the addition of small amounts of {MnSiW11} nanoparticles improves (Bi,Pb)-2223 phase formation significantly. The lattice parameters (a and c) of (Bi,Pb)-2223 phase did not change with the addition of nanoparticles. Furthermore, the superconducting transition temperature (Tc) was determined from dc electrical resistivity (ρ − T) as a function of temperature measurements. Tc was enhanced as x increased up to x = 0.12 wt%, then decreased gradually with a further increase in the concentration of nanoparticles. The (E − J ) measurements were conducted at 77 K with 1 μV/cm. It showed that the critical current density (Jc) of the samples increased from about 301.9 to 728.4 A/cm2 as x increased from 0.00 to 0.12 wt%. The suppression in Tc and Jc for x > 0.12 wt% samples may be due to the decrease in the volume fraction of a high-Tc (Bi,Pb)-2223 phase and the increase of weak links connectivity among the grain boundaries. [ABSTRACT FROM AUTHOR]

We have been investigating the effect of (CoFe2O4)x and (ZnFe2O4)x (x is the wt%) nano-sized ferrites on the superconducting (SC) properties of the high-Tc SC compound GdBa2Cu3O7-δ (Gd123) prepared by the conventional solid-state reaction technique. In this work, the magnetic hysteresis for pure Gd123 samples and samples added with nano-sized ferrites was measured using a superconducting quantum interference device (SQUID) magnetometer using a dc field up to 30,000 Oe. The magnetic Jc was estimated using the extended Bean model. While a clear increase in Jc values with the addition of (CoFe2O4)x nano-sized ferrites is observed, a less clear positive effect on the Jc values is observed with the addition of (ZnFe2O4)x nano-sized ferrites. These results indicate an improvement of grain connectivity, decrease of voids between the grains, and decrease of porosity in Gd123 compound resulting from CoFe2O4 addition consistent with the mechanical properties measured before. (CoFe2O4)x nano-sized ferrite addition has thus resulted in an improvement in the SC properties of Gd123 high-Tc SC compound making it more convenient for applications. [ABSTRACT FROM AUTHOR]

In the present study, the synthesis, using the wet co-precipitation method, and characterization of Mg 1 / 3 Ni 1 / 3 Co 1 / 3 Fe 2 - x Gd x O 4 , with x = 0.00, 0.02 and 0.08 wt% nanoparticles were reported. The X-ray powder diffraction (XRD) and transmission electron microscopy (TEM) confirm the formation of nano-spinel ferrite. The crystallite size of Mg 1 / 3 Ni 1 / 3 Co 1 / 3 Fe 2 - x Gd x O 4 nanoparticles decreased, resulting from the microstrain induced by Gd3+ substitution. However, the lattice parameter "a" increased, in agreement with the difference between the ionic radii of Fe3+ and Gd3+ ions. X-ray photoelectric spectroscopy (XPS) measurements were conducted to verify the elemental composition, valency, and cationic distribution. Furthermore, Fourier-Transform Infrared spectroscopy (FTIR) was used in combination with XPS to estimate the force constants, elasticity parameters, and Debye temperature. Vickers microhardness measurements were carried out to investigate the mechanical behavior of the prepared samples and determine Young's modulus. The values of Young's modulus obtained from the microhardness measurements are larger than those obtained from FTIR measurements. However, the results, obtained from both techniques, showed an enhancement with Gd3+ doping. [ABSTRACT FROM AUTHOR]

Mn2O3 nanoparticles were synthesized at different pH values ranging from 10 to 13 by co-precipitation technique. The characterization of all samples were completed by X-ray diffraction (XRD), transmission electron microscopy (TEM), energy-dispersive X-ray (EDX), thermogravimetric analysis (TGA), Fourier transform infrared (FTIR), ultraviolet-absorption spectroscopy (UV), Raman spectroscopy, and M–H loop measurements. The XRD spectra show that the structure of Mn2O3 is cubic, and the lattice parameter a decreases as pH increases. Crystalline size, determined from TEM and XRD analyses, decreases as pH increases. TGA curves show that a mass loss is significantly affected as pH increases, indicating the decomposition of organic species besides the oxidation of Mn2O3 to Mn3O4. FTIR spectra indicate that the absorption peaks at 593.73 and 519.09 cm− 11 referred to the stretching vibration of Mn–O and Mn–O–Mn bonds during the synthesis of Mn2O3 nanoparticles. UV-visible spectroscopy is measured in the range 250–800 nm and showed a deviation to the lower wavelength in addition to an increase in the band-gap energy (Eg) values from 1.012 to 1.370 eV is obtained. Raman spectra shows a slight deviation to the left which is conversely proportional to the crystalline size. M–H loops for the prepared samples were measured and the results of retentivity (Ms) and coercivity (Hc) were discussed. [ABSTRACT FROM AUTHOR]

Pure and erbium-doped ZnO nanoparticles (Zn1−xErxO), (0.00 ≤ x ≤ 0.10), were synthesized by wet chemical co-precipitation method. The structural, optical, and magnetic properties of the prepared samples were investigated using x-ray powder diffraction (XRD), transmission electron microscopy (TEM), ultraviolet-visible spectroscopy (UV), Fourier transform infrared spectroscopy (FTIR), M-H magnetic hysteresis, and electron paramagnetic resonance (EPR). XRD studies exhibit the presence of a single ZnO wurtzite hexagonal crystal structure for 0.00 ≤ x ≤ 0.06. A secondary phase of Er2O3 appears for x > 0.06. This means that the solubility limit for doping Zn2+ ions by Er3+ ions is about x = 0.06 under our preparations condition. The lattice parameter a is not affected by the Erbium doping. On the other hand, the lattice parameter c and the unit cell volume V increase with the increase of x up to x = 0.06. This is attributed to the larger ionic size of Er3+ ions (0.88 Å) compared to Zn2+ ions (0.74 Å). Both c and V decrease for x > 0.06. TEM micrographs indicate that the shape and the size of the ZnO nanoparticles are modified by changing the doping level of Er. The UV measurements point out that band gap energy Eg decreases with the increase of x up to x = 0.06. Then, it increases for both x = 0.08 and 0.10. FTIR spectra confirm the presence of O-H and Zn-O stretching modes at 3451.963 and 428.901 cm− 1, respectively, in pure and doped ZnO samples. The Zn-O stretching mode shifts toward a lower wavenumber for x = 0.06 and toward a higher wavenumber for x = 0.10. M-H hysteresis analysis, at room temperature, reveals that the pure ZnO has a ferromagnetic signal combined with diamagnetic and paramagnetic contributions. This ferromagnetism is reduced for the doped samples up to x = 0.02, and an antiferromagnetic alignment appears for 0.04 ≤ x ≤ 0.10. The saturation magnetization (Ms), the coercivity (Hc), the retentivity (Mr), the anisotropy constant (Ka), and the magnetic moment (μm) were estimated and discussed in terms of erbium doping for the different samples. EPR spectra for Zn1−xErxO were measured at room temperature in order to study the effect of Er substitution on the g value, resonance field (Hr), peak to peak line width (ΔHpp) and spin-spin relaxation time constant (T2). [ABSTRACT FROM AUTHOR]

A correction to the article "Stoichiometry Analysis and Normal-State Properties of SmBa2Cu3-x RuxO7-8 Superconducting Phase" by M. ME. Barakat, R. Awad and M. Roumie published online on December 21, 2015 is presented.

To manifest the effect of hard magnetic Ba0.5Sr0.5Fe12O19 nanoparticles on the mechanical performance of the (Bi,Pb)-2223 superconducting phase, nano-(Ba0.5Sr0.5Fe12O19)x/Bi1.8Pb0.4Sr2Ca2Cu3.2O10+δ, with x = 0.00, 0.01, 0.02, 0.03, 0.04, 0.05, 0.10, and 0.20 wt%, were synthesized using a conventional solid-state reaction method. The X-ray diffraction (XRD) data revealed that adding nano-(Ba0.5Sr0.5Fe12O19) to the host (Bi,Pb)-2223 phase preserved the orthorhombic structure. The porosity (P%) calculations revealed a decrease until x = 0.04 wt%, which suggests that the addition of nano-(Ba0.5Sr0.5Fe12O19)x reduces the number of voids and improves inter-grain connections, as confirmed by SEM micrographs. The superconducting transition temperature (Tc) increased to 112 K with the inclusion of nano-(Ba0.5Sr0.5Fe12O19) up to x = 0.04 wt%. Vickers microhardness (HV) measurements were conducted at various applied loads (0.245–9.800 N) and a duration time of 45 s. The HV number increased with the addition of x up to x = 0.04 wt% but then decreased with further addition. Various models were employed for analysis and modelling of Vickers hardness (HV) versus test load (F), including Meyer's law, Hays–Kendall (H–K) model, the elastic/plastic deformation (EPD) model, the proportional sample resistance (PSR) model, the modified proportional sample resistance (MPSR), and indentation-induced cracking (IIC) model. It was found that the PSR model was the most appropriate theoretical model for describing the microhardness of nano-(Ba0.5Sr0.5Fe12O19)x/(Bi,Pb)-2223 composites. Moreover, the elastic modulus (E), yield strength (Y), fracture toughness (K), brittleness index (B), and elastic stiffness coefficient (C11) were estimated as a function of the inclusion of nano-(Ba0.5Sr0.5Fe12O19)x. Furthermore, the indentation creep test (time-dependent Vickers microhardness) revealed that the dislocation creep mechanism exists in composite samples with low concentrations (x < 0.05 wt%), whereas the dislocation climbs creep mechanism was observed for x ≥ 0.05 wt%. [ABSTRACT FROM AUTHOR]

The structural properties of (x)CuO/(1-x)CdFe2O4 nanocomposites for x = 0.0, 0.1, 0.2, 0.3, 0.4, 0.5 and 1.0 were studied. The X-ray diffraction (XRD) patterns confirmed the existence of both phases with a secondary phase of α-Fe2O3. The Fourier-transform infrared spectroscopy (FTIR) characterization showed the vibrational bands of the synthesized samples. The high resolution transmission electron microscopy (HRTEM) micrographs revealed the presence of CuO, CdFe2O4, and α-Fe2O3 phases and showed the polycrystalline nature of the prepared nanocomposites. The scanning electron microscope (SEM) study exhibited the morphology of the prepared nanostructures and indicated the agglomeration between them. The energy-dispersive X-ray spectroscopy (EDX) results revealed the presence of all chemical elements within the synthesized nanocomposites. Emission peaks of the samples were analyzed via Photoluminescence (PL) deconvolutions which approved the interface defects. The Mössbauer study showed the presence of hematite impurity and the results were coherent with XRD findings. The obtained M-H loops from the vibrating-sample magnetometer (VSM) analysis depicted a paramagnetic nature of CuO and showed the ferromagnetic behavior of the nanocomposites. [ABSTRACT FROM AUTHOR]

This investigation studies the effect of Mn and Sm co-dopants on the properties of CdO nanostructures. With the aid of co-precipitation technique, Cd1–2xMnxSmxO (x = 0.00, 0.005, 0.01, 0.02, 0.03, and 0.04) nanostructures, denoted by CdO, co-0.5, co-1, co-2, co-3 and co-4, respectively were synthesized. The crystallinity and phase formation of the prepared samples were confirmed by X-ray powder diffraction. The doped samples exhibited larger lattice parameters and strain as compared to the pure sample. Transmission electron micrographs revealed the formation of nanowires for pure and low co-doped concentrations and nanowires with nanoclusters for higher co-doped concentrations. The Raman spectra disclosed the major phonon modes of CdO without any indicator from the co-dopants, proving that they were well integrated into the CdO lattice. The UV–Vis spectra revealed the tunable energy gap with the co-dopants' concentration. The photoluminescence spectroscopy indicated the abundance of Cd interstitials and O/Cd vacancies. The DC conductivity indicated the metallic behavior of the prepared samples, triggered by Cd2+ vacancies, and the semiconducting behavior at high temperatures for co-1 and co-2. CdO and co-0.5 showed a weak ferromagnetic behavior combined with diamagnetic behavior; however, superparamagnetic along with an antiferromagnetic behavior was detected for higher doping concentrations. The origin of ferromagnetism may be related to O/Cd vacancies. Remarkably, all the samples prevented the growth of bacteria and formed well-defined zones around the samples with a stronger antibacterial activity on gram-negative (Escherichia coli, Citrobacter Braakii, and Klebsiella pneumoniae) than that on gram-positive bacteria (Staphylococcus aureus, Staphylococcus epidermidis, and Streptococcus intermedius). [ABSTRACT FROM AUTHOR]

The impact of adding the orthoferrite NdFeO3, at the nanoscale, on the (Cu0.5Tl0.5)Ba2Ca2Cu3O10–δ phase formation, microstructure, electrical and mechanical performance was studied. The nano-(NdFeO3)x/(CuTl)-1223 composites, with x = 0.00, 0.25, 0.50, 0.75, 1.00, and 2.00 wt.%, were prepared using the solid-state reaction technique. The X-ray diffraction (XRD) confirmed that supplementing the host (CuTl)-1223 phase with nano-NdFeO3 did not alter the unit cell parameters (a and c) and preserved the tetragonal structure. SEM micrographs suggested that the inclusion of nano-NdFeO3 reduced the number of voids and boosted the inter-grain connections. The energy-dispersive X-ray (EDX) spectra revealed the elemental compositions of the various superconductor composites. The superconducting transition temperature (Tc) and the critical current density (Jc) increased with the inclusion of nano-NdFeO3 up to x = 0.50 wt.%. X-ray photoelectron spectroscopy (XPS) spectra analysis revealed the elemental composition and oxidation state of all elements. The Vickers microhardness (Hv) measurements were analyzed and compared with five different theoretical models. According to Hv measurements, the modified proportional sample resistance (MPSR) model provided the best theoretical analysis of Hv within the plateau limit regions. Moreover, various mechanical parameters were estimated as a function of the inclusion of nano-NdFeO3. The indentation creep test showed that the composite samples with high nanoparticle concentration (x > 0.50 wt.%) have dislocation creep mechanism, while those with x ≤ 0.50 wt.% followed a dislocation climbs creep mechanism. A comparison between NdFeO3 nanoparticles and other magnetic ferrites and nano-magnetic oxides was reported. [ABSTRACT FROM AUTHOR]

In the present work, the magnetoresistance behavior of (TlF)x-substituted (Cu0.5,Tl0.5)Ba2Ca2Cu3O10−δ superconducting samples, with x = 0.0, 0.1, 0.2, 0.3 and 0.4, was investigated. According to the thermally activated flux creep (TAFC) model, the flux pinning energies U(H, T) were calculated from the resistivity temperature (ρ–T) curves at applied DC magnetic fields ranging from 0.29 to 4.44 kOe. The results indicated that flux pinning energy was increased with increasing the F-substituting up to x = 0.1 and then decreased with increasing the applied field up to 4.44 kOe. Moreover, significant resistive broadening (ΔT) was observed with increasing the values of the applied magnetic fields. Furthermore, the (TlF)x substitution, boosting the transport critical current density Jc(0) and irreversibility magnetic field Hirr(0) up to x = 0.1 and then decreasing for x > 0.1 at various applied magnetic fields, demonstrates strong flux pinning for x = 0.1. [ABSTRACT FROM AUTHOR]

The characterization of Nanosized Ni0.5Zn0.5RuxFe2−xO4 (0.00 ≤ x ≤ 0.015), prepared by the wet chemical coprecipitation method, is reported in the current investigation. X-ray powder diffraction (XRD) analysis has confirmed the formation of a single phased spinel cubic structure. While transmission electron microscopy (TEM) studies have shown an increase in the particle size for high content of Ru3+ doping. The elemental composition of all samples was investigated using energy dispersive x-ray (EDX) measurements. The results showed a reciprocal relation between the Fe3+ and Ru3+ contents, suggesting the successful substitution of Ru3+in Fe3+ sites. UV–Vis spectroscopy studies, via Urbach energy analysis, proposed a perturbation in the band structure of Ni0.5Zn0.5Fe2O4 induced by Ru3+ substitution, affecting both the direct and indirect bandgap energies. Excitation wavelength-dependent photoluminescence (PL) studies, presented for the first time, have shown a strong dependence of the emission spectra on both the excitation wavelength and Ru3+ doping. The PL analysis suggests the utilization of Ni0.5Zn0.5RuxFe2−xO4 as a candidate for photocatalytic applications. Furthermore, VSM studies, have shown a transition from superparamagnetic to soft ferromagnetic for Ru3+ doped samples. The saturation magnetization, coercivity, and effective anisotropy were enhanced as a result of Ru3+ doping. Finally, photocatalysis experiments have shown an enhancement of the degradation rate of nitrobenzene for the sample with x = 0.0125 with the ability of magnetic recycling, in agreement with the PL and VSM studies. [ABSTRACT FROM AUTHOR]

Superconductor samples of type BiPbSrCaCuO added with nano ZnO and FeO were synthesized by the conventional solid-state reaction technique. The samples were characterized using X-ray powder diffraction (XRD), scanning electron microscope (SEM), differential scanning calorimetry (DSC) and electrical resistivity measurements. Excess conductivity analysis of the investigated samples was carried out as a function of temperature using Aslamazov and Larkin (AL) model. The analysis showed four different fluctuation regions namely critical (cr), three-dimensional (3D), two-dimensional (2D) and short-wave (sw). The zero temperature coherence length along c-axis, effective layer thickness of the two-dimensional system and inter-layer coupling strength were estimated as a function of nano-oxides concentration. In addition, the thermodynamics, lower and upper critical magnetic fields as well as critical current density were calculated from the Ginzburg number N. It was found that the low concentration of nano-ZnO addition up to x=0.2 wt.% improved the physical properties of (Bi,Pb)-2223 phase. In contrary, these properties were deteriorated for x>0.2. These results indicated that the addition of a low amount of nano-ZnO during the final processing of (Bi,Pb)-2223 samples can be effectively improved the flux pinning ability, while the addition of a high amount of nano-ZnO decreased the volume fraction and increased the resistance of grain boundaries. Moreover, the addition of nano-FeO had a negative effect on the superconducting parameters of the (Bi,Pb)-2223 phase. This behavior was attributed to the decrease in the volume fraction of (Bi,Pb)-2223 phase with the increasing of nano-FeO. [ABSTRACT FROM AUTHOR]