Effect Of Magnetic Nanoparticle Addition On The Superconducting Properties Of Bi-Pb-Sr-Ca-Cu-O

The effect of magnetic nanoparticle additions on the (Bi1.6Pb0.4Sr2Ca2Cu3O10+δ)1-x-(nano M)x with M= Sm2O3, Ho2O3, Nd2O3 and x= 0.0-0.05 systems, sintered at 850°C for 30 hours were investigated by X-ray diffraction techniques, critical temperature measurement, scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX). Magnetic nanoparticles, M= Sm2O3, Ho2O3 and Nd2O3 with 14.8 nm, 18 nm and 49-64 nm particle sizes respectively, were mixed with Bi1.6Pb0.4Sr2Ca2Cu3O10+δ precursor powder prepared by solid state reaction method before the final step heat treatment process. The phase purity, lattice parameters, superconducting properties, surface morphology and grain size were found to be dependent on the magnetic nanopatricles concentration in the sample. The XRD result indicate that the dominant high Tc (Bi2223) phase decrease due to the increase of low Tc phase (Bi2212) with the presence of magnetic nanoparticles with 0<x≤0.02 and the later phase become significant for further addition. The lattice parameters calculated from XRD data show a slight decrease in the c-axis while a-axis increase for initial nanoparticale addition. Lattice parameters decrease monotonically with x≥0.02. The scanning electron microscopy viewing shows platelets like-grain for all samples which is a signature of Bi2223 and Bi2212 phases. The existence of large oriented platelet-like grains that have been observed in pure sample surface, are maintained for sample with 0<x<0.02. Further more the previous samples have small, randomly oriented platelet-like grains that increase with the increase in magnetic nanoparticles content. For x≥0.02 the sample surface becomes more porous with large amount of randomly oriented platelet grains. The elemental analysis by EDX measurement of sample with x=0.05 reveals the existence of nanoparticles that homogeneously distributed in BSCCO matrix. The chemical formula of sample’s elements composition that has been estimated from EDX measurements is in good approximation to that of Bi2223 system with noticeable excess in oxygen ratio which may be due to the existence of magnetic oxide nanoparticles in the sample. All samples exhibit normal metallic behavior above superconducting transition temperature. Zero resistivity temperature Tc (R=0) which is around 102 K for pure sample was found to gradually decrease to lower temperature with magnetic nanoparticle additions and decrease to that of the low-Tc(2212) with x≥0.02. The onset transition temperature Tc is almost the same for sample with 0.005≤x≤0.02 and become lower with higher concentration of addition. The superconducting transition width becomes wider with increase in the magnetic nanoparticles addition. The hole concentration, p, of pure sample under preparation condition is around 0.13. The introduction of magnetic nanoparticles causes a decrease in the hole concentration of Bi2223 system. This decrease characterize by two steps. For initial addition of magnetic nanoparticle, the reduction of hole concentration per change in magnetic nanoparticles addition, Δp/Δx, is more than when x>0.02 for Ho2O3 and Nd2O3 and at x>0.03 for Sm2O3 addition

Synthesis, optical and magnetic behavior of (BiFeO3)1−x(α-Fe2O3)x nanocomposites

(BiFeO3)1−x(α-Fe2O3)x nanocomposites were synthesized from dried gels of BiFeO3 and α-Fe2O3. Samples with x = (0.00 (BiFeO3), 0.25, 0.50 and 1.00 (α-Fe2O3)) were studied using X-rays diffractions (XRD), UV–vis spectroscopy, photoluminescence spectroscopy (PL), electron spin resonance (ESR) and vibrating sample magnetometer (VSM). Amounts of α-Fe2O3 phase were 23 and 35% for samples x = 0.25 and 0.50, respectively. Microstrain of BiFeO3 phase tended to decrease with increasing α-Fe2O3. Optical band gap reduced from 2.42 eV for BiFeO3 to 2.35 eV for sample x = 0.25 and then increased to 2.56 eV for sample x = 0.50. From PL, intensity of near band emission peak of BiFeO3 increased with increasing α-Fe2O3 content. From ESR and VSM, the g-value and magnetization saturation were enhanced with embedding of α-Fe2O3 into BiFeO3

Effects of rare earth nanoparticles (M = Sm2O3, Ho2O3, Nd2O3) addition on the microstructure and superconducting transition of Bi1.6Pb0.4Sr2Ca2Cu3O10+δ ceramics

The effect of rare earth nanoparticles, M=Sm2O3, Nd2O3 and Ho2O3 added to (Bi1.6Pb0.4Sr2Ca2Cu3O10+δ)1-x(M)x, where x = 0.00 - 0.05, superconductor were studied by X-ray diffraction technique (XRD), resistivity (R), scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDX). The volume fraction of high-Tc phase, Bi-2223, decreased from 84% for pure sample to 48, 30 and 23% at x = 0.05 for Sm2O3, Ho2O3 and Nd2O3 additions, respectively. The critical temperature Tc(R=0) that is 102 K for the pure sample decreased to 78, 73 and 69 K at x = 0.05 for samples with Sm2O3, Nd2O3 and Ho2O3 nanoparticles additions, respectively. The additions of rare earth nanoparticles decreased the grain size and increased the random orientation of the grains. The results showed that the phases’ formations, variations of lattice parameters and electrical properties are sensitive to the size of nanoparticles and magnetic properties of its ions

Facile synthesis and characterizations of polypyrrole/BiOCl hybrid composites

Polypyrrole(PPy)/BiOCl hybrid composites were synthesized for the first time via one-step chemical oxidation process by addition of Bi2O3 nanoparticle in an aqueous solution of pyrrole monomer/FeCl3 oxidant agent. X-ray diffractions (XRD), field emission scanning electron microscopy (FESEM), and thermogravimetric technique confirmed the growth of BiOCl in PPy matrix. From the XRD, the amount of BiOCl in PPy matrix increased with increasing of Bi2O3addition in pyrrole solution. The FESEM images indicated the presence of two phases related to PPy and BiOCl. Thermal stability of PPy/BiOCl hybrid composites has been improved in the range 300–800 K and degraded above 800 °C, i.e., decomposition point of BiOCl. Fourier transforms infrared spectroscopy point to a mutual interaction between PPy and BiOCl system. The characteristic optical absorption peaks of PPy shifted to higher wavelength in PPy/BiOCl(5%) composites and disappeared at PPy/BiOCl(20%). From electrical measurement, the PPy/BiOCl hybrid composites have higher conductivity than PPy, where the maximum conductivity observed was for PPy/BiOCl(5%). The conducting mechanism of PPy and PPy/BiOCl composites followed three-dimensional Mott variable range hopping in the range of 300–150 K and has involved fluctuation-assisted tunneling phenomenon below 150 K

Effects of aging time on microstructure, hydrophobic and optical properties of BiFeO3 thin films synthesized via sol-gel method

BiFeO3 (BFO) films were synthesized with the sol-gel method followed by the spin coating technique using 2-methoxyethanol as solvent and acetylacetone as chelating agent. The effects of aging time (t = 0, 1, 3, 6 days) of the BFO sol on the microstructure, wettability and optical properties of BFO films were investigated by means of X-ray diffraction (XRD), atomic force microscopy (AFM), contact angle (CA) measurement, Uv-vis and photoluminescence. The crystallinity of films was affected by t. Crystallite size of the films changed slightly in the range of 14.2 – 15.2 nm while the lattice parameters clearly varied with t. The average particle size of BFO films ranged between 45.9 and 52.7 nm while the mean square roughness (Rq) varied between 1.0 and 4.2 nm. The films showed maximum optical transmittance (81 – 90 %) in the range 600 – 800 nm. The band gap of the films was also affected with t, and it has a value of 2.85 to 2.76 eV. The films showed a hydrophobic property with CA ranging between 95.3 to 104.7 °. The best crystallinity, lowest Rq and highest Eg = 2.85 eV were obtained for the film with t = 1 day. The results demonstrate possible development of a superhydrophobic coating using BiFeO3 coating

Preparation and physical properties of polypyrrole / zeolite composites

Polypyrrole (PPy′)/zeolite composites were synthesized via chemical oxidation of pyrrole in the presence of zeolite. FeCl3 was used as an oxidant with the FeCl3-to-pyrrole molar ratio (MR) equal to 1. The zeolite contents were 0%, 5%, 10%, 15% and 20% of the total weight of PPy′. For comparison, pure PPy″ with FeCl3–pyrrole MR equal to 2 was also synthesized using the same method. The structural and physical properties of the samples were studied using X-rays diffraction (XRD), Fourier transform infrared spectroscopy, field emission electron scanning microscopy, thermogravimetric analysis, van Der Pauw technique and UV–VIS-NIR spectroscopy. The XRD of PPy′/zeolite (5%) revealed a presence of crystalline nature of zeolite in a spectrum of host amorphous PPy′. The XRD peaks increased, became stronger and shifted slightly to higher 2θ in PPy′/zeolite (10–20%) composites. Compared with PPy′, the composites were denser, more compact and had better thermal stability. The composites conductivity increased while their bandgap tended to reduce with increasing of zeolite. PPy′/zeolite (20%) composite had the highest conductivity value of 3.6 S cm−1 with an optical bandgap of 2.21 eV. The results showed that zeolite has been incorporated into PPy′ matrix and improved its physical properties

Physical properties of Fe doped In2O3 magnetic semiconductor annealed in hydrogen at different temperature

The effects of hydrogen-annealing at different temperatures (300, 400, 500 and 600°C) on physical properties of In2−xFexO3 (x=0.025) thin film were investigated. The structural measurement using XRD shows that the film has a single In2O3 phase structure when annealed in hydrogen at 300–500°C, however when annealed in hydrogen at 600°C the film has a mixed phase structure of In2O3 and In phases. The electrical measurements show that the carrier concentrations of the films decrease with the increase of hydrogen-annealing temperature in the range 300–500°C. The optical band gap of the films decreases with increasing hydrogen-annealing temperatures. The saturation magnetisation, Ms, and coercivity of films increase with the increment of hydrogen annealing temperature. The film annealed at 300°C has the lowest resistivity, ρ=0.03 Ω cm, and the highest carrier concentrations, n=6.8×1019 cm−3, while film annealed at 500°C has both good electrical (ρ=0.05 Ω.cm and n=2.2×1019 cm−3) and magnetic properties, Ms=21 emu/cm-3

Structural, electrical and magnetic properties of BiFe1-xYxO3 (0 ≤ x ≤ 0.6) ceramics

The effect of Y substitution on the microstructure, dielectric, magnetic and leakage current properties of BiFe1-xYxO3 (0 ≤ x ≤ 0.6) ceramics was investigated. The BiFeO3 phase that is dominant at x = 0.0 – 0.2 decreased with the increase of Y substitution. Other phases such as YFeO3 and Bi1.46Y0.54O3 emerged with Y substitution and became dominant in the range x = 0.3 – 0.4 and 0.5 – 0.6, respectively. The BiFe1-xYxO3 composites of rounded shape grains at x = 0.0 deformed at x = 0.1 – 0.3 and changed to melted-like grains at x = 0.4 – 0.6 with the incorporation of smaller grains at x = 0.5 and 0.6. The sample with x = 0.2 had the highest remnant magnetization (Mr = 0.09 emu/g) and saturation magnetization (Ms = 2.9 emu/g). The sample with x = 0.4 showed the highest dielectric constant of 104 and lowest loss tangent of 1.34 × 10-4. The leakage current was significantly reduced to a lower value of 2.80 × 10-8 A/cm2 at x = 0.6

Influence of tartaric acid concentration on structural and optical properties of CuSe nanoparticles synthesized via microwave assisted method

The influence of chelating agent on structural and optical properties of copper selenide nanoparticle has been the subject of ongoing debate in copper selenide based material research. In this project we developed a straightforward microwave irradiation technique for the synthesis of copper selenide nanoparticles. Copper selenide nanoparticles were successfully synthesized using CuCl2·2H2O and Na2SeO3 as copper and selenium sources respectively while, the reducing and chelating agents were hydrazine hydrate and tartaric acid respectively. The effect of concentration of tartaric acid on structural and optical properties of CuSe NPs were investigated. The as-prepared product were characterized by means of an X-ray diffraction (XRD), transmission electron microscopy (TEM), field emission scanning electron spectroscopy (FESEM), atomic force microscopy (AFM), energy dispersive X-ray spectroscopy (EDX), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), UV–visible absorption spectroscopy (UV–Vis.), Raman spectroscopy and photoluminescence spectroscopy (PL). XRD results reveal a hexagonal (Klockmannite) crystal structure with size in the range between 73.10 nm and 16.10 nm. The band gap of the as-prepared CuSe NPs were found to increase between 1.80 eV and 2.10 eV. The wavelength of the maximum PL emission was at 600 nm with 400 nm excitation wavelength. Three characteristics vibrational modes belonging to CuSe NPs were detected in the Raman spectra. Therefore, the results obtained in this study provide a new pathway of understanding the effect of tartaric acid concentration on structural and optical properties of CuSe NPs and can explain the use of this novel product as a potential candidate for optoelectronic and solar cell applications

Role of Nd2O3 nanoparticles addition on microstructural and superconducting properties of YBa2Cu3O7-δ ceramics

The effects of Nd2O3 nanoparticles addition on microstructure, transport and AC susceptibility properties of YBa2Cu3O7–δ (Y123) superconductors were systematically investigated using X-ray diffraction (XRD), scanning electron micrograph (SEM), four point probe measurement and AC spectrometer. It was found that the added samples were predominant by Y-123 phase beside small amount of Y-211 and unreacted Nd2O3 secondary phases. All added samples preserved the orthorhombic structure similar to the pure sample and no orthorhombic-to-tetragonal transition occurred. The samples became more porous and their grain size significantly decreased with addition of Nd2O3. The addition of nano-Nd2O3 disturbed the grain growth of Y123, thus resulting in the degradation of superconducting properties of the samples. The superconducting transition temperature (Tc onset) of samples decreased from 92 K for x=0.0 to 78 K for x=1.0 wt.%, which could be attributable to oxygen vacancy disorder. From AC susceptibility result, the inter- and intra-granular loss peaks became wider and broader with increase of Nd2O3 addition due to the weakening of grains coupling. On the other hand, the inter-granular critical current density, Jcm, was found to increase with Nd2O3 addition and had the highest value at x=0.6, confirming that Nd2O3 nanoparticles acted as pinning centers in Y123 matrix