Potassium substitution effects in YBa2Cu3O7- & delta superconductor

  YBa2-xKxCu3O7-δ compound with x = 0, 0.1, 0.15, 0.2, 0.3, 0.5, 0.8, 1 was prepared. The samples were characterized by XRD, Tc, oxygen content and room temperature thermopower measurements. The results shows that by increasing the potassium, the samples go to the underdoped regime. This is due to the depletion of oxygen from the samples. By post annealing of the sample with x = 0.2 and Tc = 78 K in oxygen, the Tc increased up to 93 K which means it is possible to put back the oxygens into the structure

The study of the dependency of critical current density on cross section of sample in Bi1.6Pb0.4Sr2Ca2Cu3Oy and YBa2Cu3O7-& delta ceramic superconductors

 In this paper, the effect of the cross-section on the critical current density (Jc) of a sample in ceramic superconductors YBa2Cu3O7-­δ (YBCO) and Bi1.6Pb0.4Sr2Ca2cu3Oy (BPSCCO) has been studied. Five orthorhombic bar samples of YBCO with cross-sections of 6.25, 7.67, 9.25, 11.76, 14.67 mm2­ and also five orthorhombic bar samples of BPSCCO with cross-section of 6.4, 9.01, 11.88, 13.86, 14.98 mm2­ with the same synthesis conditions by the solid state reaction method were prepared. After the preparation of the samples, the Meissner effect, the critical temperature (Tc), and the critical current density (Jc) measurements, XRD and SEM have been done on the samples. The results of XRD show that the dominant phase in YBCO and BPSCCO are 123 and 2223, respectively. The results of Jc measurements in 77 K show that in both superconductors, the Jc decreases with increasing of cross-section (A). The type of dissipation obeys a power law with the relation . For a given cross-section, Jc of the BPSCCO sample is smaller than the YBCO sample

Bi-based superconductor

  In this paper, Bi-Sr-Ca-Cu-O (BCSCCO) system superconductor is made by the solid state reaction method. The effect of doping Pb, Cd, Sb, Cu and annealing time on the critical temperature and critical current density have been investigated. The microstructure and morphology of the samples have been studied by X-ray diffraction, scanning electron microscope and energy dispersive X-ray. The results show that the fraction of Bi-2223 phase in the Bi- based superconductor, critical temperature and critical current density depend on the annealing temperature, annealing time and the kind and amount of doping

Magnetic and structure properties of Cd doping Bi-2223 superconductor

In this paper, Bi1.64-xPb0.36CdxSr2Ca2Cu3Oy (BPCSCCO) superconductor with x = 0.0, 0.02, 0.04 and 0.06 is made by the solid state reaction method. The magnetic susceptibility measurements were performed using AC susceptometer. The microstructure and morphology of the samples have been studied by X-ray diffraction, scanning electron microscope and energy dispersive X-ray. The results show that the partial substitution of Pb for Bi in the Bi-based superconductor increases the volume fraction of Bi-2223 phase. We also found that by doping of Cd, the high Tc phase is promoted and stabilized in the Bi-Pb-Sr-Ca-Cu-O system. The results of the X-Ray diffraction patterns and magnetic susceptibility measurements show that the low amount of Cd and long annealing time enhance the fraction of Bi-2223 phase. The maximum value volume fraction of Bi-2223 phase for sample with annealing time of 270 hours and 0.04 of Cd doping is obtaine

Structure and properties of YBa2Cu3O7-δ superconductor doped with bulk cadmium oxide

In this paper, the Y1-xCdxBa2Cu3O7-δ superconductor with x=0, 0.05, 0.1, 0.15, 0.2, 0.3, 0.4, 0.5 are prepared using the solid state method and the structure, electrical resistance, critical current density and critical temperature of it, have been studied. The results show that these doping do not affect so much on the structure and lattice parameters. The electrical resistance of samples increased with doping. A little amount of doping cadmium improve critical current density such that the sample x=0.1 has a maximum critical current density among the samples. The critical temperature with doping cadmium up to x=0.2 has little fluctuation and its variation can be ignored, but by increasing up to x=0.5 the critical temperature decreases gradually

Codeposition of Fe 3 O 4 nanoparticles sandwiched between g-C3N4 and TiO2 nanosheets: Structure, characterization and high photocatalytic activity for efficiently degradation of dye pollutants

Novel ternary nanocomposite photocatalysts based on g-C3N4 /Fe3O4 /TiO2 nanosheet were synthesized using simple solid combustion, hydrothermal and wetness impregnation methods. The g-C3N4 nanosheet (2D)/ Fe3O4 /TiO2 nanosheet (2D) triad-interface nanocomposite arranged in the form of Fe 3 O 4 nanoparticle was sandwiched and effectively dispersed on the surface between g-C3N4 and TiO2 nanosheets. The synthesized composites were characterized by some specific techniques such as X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, field emission scanning electronic microscopy (FE-SEM), transmission electron microscope (TEM), vibrating sample magnetometer (VSM), specific surface area (SSA), and dynamic laser scattering (DLS) analyzer. The effect of Fe3O4 loading quantity on photocatalytic overall performance indicated that g-C3N4 nanosheets/Fe3O4/TiO2 nanosheets with 5% wt Fe3O4 nanoparticle exhibit the best photocatalytic ability. These composites showed excellent activities in the UV-light-driven degradation of direct blue (DB), methyl blue (MB) and safranin (SA). After irradiation for 210 min, the methylene blue (MB) degradation efficiency was 63% for g-C3N4 , 58% for TiO2 , 71% for g-C3N4-TiO2 , 85% for g-C3N4 -1% wt Fe3O4-TiO2 , 96% for g-C3N4 -5% wt Fe3O4 -TiO2 and 77% for g-C3N4-10% wt Fe3O4-TiO2 indicating that nanocomposites with 5 wt% Fe3O4 had the best photocatalytic performance. The SSA of the TiO2 , g-C3N4 , g-C3N4-TiO2 and g-C3N4-10% wt Fe3O4-TiO2 were determined using Sear's method. Finally, it is worth mentioning that the surface area of the g-C3N4-10% wt Fe3O4-TiO2 photocatalyst has been found to be 66.2 m 2 g -1

Superparamagnetic recoverable flowerlike Fe3O4@Bi2O3 core–shell with g-C3N4 sheet nanocomposite: synthesis, characterization, mechanism and kinetic study of photo-catalytic activity

In the present research study, a simple method was developed for the synthesis of three-dimensional flowerlike Fe3O4@Bi2O3 core–shell with g-C3N4 sheet nanocomposites. The X-ray diffraction, Fourier transform infrared spectroscopy, scanning electronic microscopy, transmission electron microscope, vibrating sample magnetometer, dynamic laser scattering analyzer and UV–Vis diffuse reflection spectroscopy were employed for the characterization of structure, purity and morphology of the resultant samples. The degradation of indigo carmine as a model of organic dye pollutant is applied for photo-catalytic activity. The parameters which are affecting the efficiency of various parameters, such as; pH (5–9), photo-catalyst dose (30–120 mg), initial concentration of dye (1.0 × 10−5–7.5 × 10−5 M) were studied. The results show that the high photo-degradation was obtained at pH 5, with 70 mg of photo-catalyst, for initial concentration of 1.0 × 10−5 M the indigo carmine. In the kinetic part of this study is found that the photo-degradation of the dye follows pseudo-first-order kinetics according to the Langmuir–Hinshelwood model. The radical scavenger measurement illustrates that the electron generated from Bi2O3 was carried to the surface of Fe3O4 and this electron was shifted to the surface positive hole of g-C3N4. The electron on g-C3N4 surface reacted with O2 and produced ·O2. The h+ of Bi2O3 reacted with OH¯ to produce ·OH. The ·O2−, ·OH and h+ were the main active species in the photo-catalytic process

Synthesis of ZnO–Ag2CO3–Fe3O4@rGO core–shell structure: magnetically separable photocatalyst for degradation of MB using the Box–Behnken design

In this work, a simple microwave method was utilized to prepare ZnO sheet linked with Fe3O4@rGO core–shell and of Ag2CO3 through formation of the quadri-photocatalytic with high activity. The microstructure, morphology, spectroscopic, and magnetic characteristics of the prepared samples were assessed using XRD, SEM, PL, TEM, FT-IR, DLS, and VSM analysis. The photocatalytic activity of the material was evaluated for photodegradation of methylene blue dye under the UV and visible light with home-made photoreactor. The response surface method in a Box–Behnken design was utilized to design the experiments. The parameters affecting the efficiency of the degradation including, pH (5–9), photocatalyst dose (50–150 mg), contact time (30–90 min), and radiation power (30–60 W) were studied and optimized. The optimum parameters were found to the initial concentration of 10 ppm, after a reaction time of 63.65 min, the amount of the catalyst of 150 mg, the pH of 8.99, and 94.99% of degradation (in the radiation power of 45 W)