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

Electrical transport, microstructure and optical properties of Cr-doped In2O3 thin film prepared by sol–gel method

High transparent In2O3 and Cr-doped In2O3 (In2−xCrxO3) nanocrystalline thin films were prepared using a simple sol–gel method followed by a spin coating technique. The effect of Cr concentration on the structural, microstructure, electrical and optical properties of In2−xCrxO3 were systematically investigated using X-ray diffractometer (XRD), atomic force microscopy (AFM), UV–vis spectroscopy, field emission scanning electron microscopy (FESEM) and Hall effect technique. The films have good crystallization with preferred orientation to (2 2 2) direction. The lattice parameters, a, of In2O3 system increased at lowest dopants (x = 0.025) and decreased as the dopant was further increased. The optical transmittance of films increased up to 98% for x = 0.05 and decreased for further Cr concentrations. From AFM measurement the films nanocrystals morphology was depending on Cr concentrations. The band gap was around 3.76 eV for pure and with x ⩽ 0.075 however it increased. The effect of Cr concentrations on conducting mechanisms of In2O3 film has been investigated from 80 to 300 K using thermal activated conduction band and hopping models. The films, at x = 0.0–0.075, have typical semiconductor behaviour. Three different conducting mechanisms have been estimated. All thermal activation energies and conduction hopping parameters have been determined and analysed in details

Grain - matrix mosaic contribution to ac losses in Ni-doped BSCCO cylinders.

The measurements of ac susceptibility χ = χ′+iχ′′is performed to determine the characteristics of intergranular components in sintered Bi1.6Pb0.4Sr2(Ca1-xNix)2Cu3Oδ, (x = 0.0 – 0.05) polycrystalline cylinders prepared by the conventional route. Theoretical values of for idealized cylinder were calculated in the range " χ max ≤ k ≤10 , correspondence of the Bean and the simplified Kim critical state models. Magnetization curve for various stages in the specimens is hence approximated. It is found that Ni content in BSCCO system changes the effective volume fraction of the grains, field dependence of the intergranular critical current density, transition temperature, and the intergranular pinning property

Effects of annealing temperature on magnesium deficient in MgB2 superconductor

The Mg-deficient Mg0.8B2 superconductors were prepared using the solid-state reaction method at different annealing temperature between 650 °C and 800 °C. The x-ray diffraction patterns indicated that magnesium diboride (MgB2) is a major phase and magnesium oxide (MgO) is the secondary phase. However, no unreacted Mg was detected by XRD at all annealing temperatures. The SEM images showed hexagonal grain structures with nano thickness distributions. The highest critical current density (Jc) at 5 K and 20 K was found in sample annealed at 700 °C. At 5 K and 6 T, the highest Jc achieved was 1.2×104 A/cm2 . At 20 K, the highest Jc achieved by 3.6×103 A/cm2 . The values of the onset superconducting transition temperature, Tc for all Mg0.8B2 were 37.0 K. The samples annealed at 700° C showed a sharper diamagnetic drop with ∆Tc = 3.0 K compared to all samples

Simple preparation and characterization of bismuth ferrites nanoparticles by thermal treatment method

In the present work, nanoparticles of multiferroic bismuth ferrites (BiFeO3) were synthesized via a simple thermal treatment method. BiFeO3 was prepared from an aqueous solution containing bismuth nitrate and iron nitrate as starting materials, polyvinyl pyrrolidone (PVP) as a capping agent and nitric acid to dissolve the bismuth nitrate, respectively. It is followed by thermal treatment at various calcination temperatures at 350, 450 and 550 °C. The samples were characterized by thermogravimetric analysis, X-ray diffractometer (XRD), transmission electron microscope (TEM), vibrating sample magnetometer and electron spin resonance (ESR) spectroscopy. XRD results indicate that the samples, calcined at 350, 450 and 550 °C, crystalized in rhombohedral crystal structure (space group R3c). The crystallinity of samples increased with increasing calcination temperature. Morphology study using TEM confirmed the growth of BiFeO3 nanoparticles with the average particle’s size increases from ~30 nm up to ~80 nm with the increasing of calcination temperature from 350 to 550 °C. Magnetic saturation Ms, of samples decreased from 2.15 to 0.25 emu/g while the coercivity Hc, increased from 54.41 to 272 G when the calcination temperature increased from 350 to 550 °C. ESR revealed increment of g-factor value from 2.14 to 2.64 and peak-to-peak linewidth from 129.33 to 201.61 Oe with the increasing of calcination temperature from 350 to 550 °C. The results demonstrate that by using thermal treatment method, the BiFeO3 nanoparticles can be obtained at low temperature, i.e. 350 °C

High transparency iron doped indium oxide (In2—xFexO3, x = 0.0, 0.05,0.25, 0.35 and 0.45) films prepared by the sol-gel method

High quality indium oxide and iron doped indium oxide nanocrystalline films were prepared by the sol-gel method followed by a spin coating technique. The samples were characterized by an X-ray diffractometer, an atomic force microscopy and a UV-vis spectroscopy. All samples had good crystallinity with a preferred orientation in the (222) direction. The crystallite size increased from 12.1 nm for the pure sample to 16.1 nm for the sample with x=0.35 and then decreased to 12.1 nm for the sample with x=0.45. All samples contained nanometer grain sizes with a smooth surface. All films showed a high transmission of over 91% in the wavelength range of 200-800 nm

Conducting mechanisms and magnetic behaviours of Fe-doped In2O3 nanocrystalline films

The relation between conducting mechanism and magnetic behaviour of Fe-doped In2O3 thin films was investigated. The films were prepared by sol gel method followed by spin coating techniques and characterized by X-rays diffractions, field emission electron microscopy, transmission electron microscopy, Hall Effect at room and low temperature, X-ray photoelectron spectroscopy and vibrating sample magnetometer. Films’ lattice parameter decreased with increasing of Fe content. Average grain size of films ranged between 8.4 and 13 nm. Oxygen vacancies of films tended to reduce with increasing of Fe doping. Films with x = 0.025 and 0.05 showed typical semiconducting behaviour while transition from metallic- to semiconducting-like behaviour was observed at 190 K and 230 K for films with x = 0.075 and x = 0.15, respectively. No trend had been found between films saturation magnetization, Ms, and free charge carriers. The magnetic behaviour of films has a correlation with localized electrons of Nearest-Neighbour Hopping conduction. Keywords: NNH conductivity, Magnetic behaviour, BMP, Carrier mediate, Localize electro

Conducting mechanisms and magnetic behaviours of Fe-doped In₂O₃ nanocrystalline films

The relation between conducting mechanism and magnetic behaviour of Fe-doped In2O3 thin films was investigated. The films were prepared by sol gel method followed by spin coating techniques and characterized by X-rays diffractions, field emission electron microscopy, transmission electron microscopy, Hall Effect at room and low temperature, X-ray photoelectron spectroscopy and vibrating sample magnetometer. Films’ lattice parameter decreased with increasing of Fe content. Average grain size of films ranged between 8.4 and 13 nm. Oxygen vacancies of films tended to reduce with increasing of Fe doping. Films with x = 0.025 and 0.05 showed typical semiconducting behaviour while transition from metallic- to semiconducting-like behaviour was observed at 190 K and 230 K for films with x = 0.075 and x = 0.15, respectively. No trend had been found between films saturation magnetization, Ms, and free charge carriers. The magnetic behaviour of films has a correlation with localized electrons of Nearest-Neighbour Hopping conduction