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The aim of this investigation is to study the grain size effect of the precursor SiC on the superconductivity and flux pinning and to further investigate the origin of the enhanced pinning is presented. It is found that very fine SiC powder plays an important role in the reaction between Mg+B and SiC.

Discussing the study on the transport current and its field dependence for the nanometer-size SiC doped MgB2 wires. The results reveal that the nanometer size SiC doped MgB2/Fe wires can carry higher transport I(sub c) and J(sub c) in the magnetic fields ever reported for any form of MgB2.

Uranium compound doping of Bi-Sr-Ca-Cu-O/Ag superconducting tapes was investigated to determine microstructural variations.

Uranium doped BiSCCO tapes were irradiated using thermal neutrons and flux pinning was improved.

Uranium doping and thermal neutron irradiation effects on flux-pinning of silver Bi-Sr-Ca-Cu-O tapes were studied.

Sandwich rolling and flat rolling in the processing of Ag/Bi-2223 tapes were compared.

The flat rolling, sandwich rolling and pressing of magneto-optical images of Ag/Bi-2223 tapes is reported.

Measurements were conducted on the critical current density distribution in Ag-sheathed Bi2212 tapes' superconducting cores. Results show that the critical current density on tape edges was higher by about a factor of 3 as compared to the central area. The Ag-sheath/core boundary also exhibited a thin interface layer with no secondary phase. The interface layer is believed to be vital to the tapes' supercurrent-carrying ability.

Graphical abstract Highlights • Facilesynthesis of inorganic Bi(OH) 3 nanoparticles. • High biocompatibility in human skin and dog kidney cells in vitro. • Ultraviolet filter capable of reducing the photocatalytic activity of TiO 2 and ZnO. • Preparation of TiO 2 /Bi(OH) 3 and classical TiO 2 /ZnO sunscreen formulations. • Significantly improved photoprotection and photostability compared to TiO 2 /ZnO. Abstract In this study we investigate readily synthesised Bi(OH) 3 nanoparticles as a novel, multifunctional ultraviolet filter for sunscreen. The absorbance of Bi(OH) 3 NPs in the ultraviolet region is comparable to that of both ZnO and TiO 2 NPs used in commercial sunscreens. In vitro photoprotection results show that the combination of TiO 2 /Bi(OH) 3 is more efficient than TiO 2 /ZnO over the whole UV range, with an increase in sun protection factor of 28%. The emulsions show rheological properties comparable to those of commercial sunscreens. The combination of TiO 2 /Bi(OH) 3 led to insignificant damage on pre-painted steel panels after exterior exposure for twelve weeks. We also demonstrate that the addition of Bi(OH) 3 NPs reduces the degradation of crystal violet by photocatalytically active TiO 2 or ZnO NPs under ultraviolet exposure. Finally, assessment of the biocompatibility of Bi(OH) 3 with HaCaT keratinocytes and Madin-Darby Canine Kidney (MDCK) cells in vitro is described. [ABSTRACT FROM AUTHOR]

TiO2 nanoparticles are typically used in sunscreens; however, they have been shown to exhibit cyto- and genotoxicity, which is related to the photocatalytic activity and the subsequent formation of reactive oxygen species when exposed to ultraviolet radiation. In this study, we synthesised nanocomposite materials consisting of TiO2 nanoparticles and homogeneously attached (BiO)2CO3 clusters with a size ＜10 nm onto their surfaces. The nanocomposites were prepared using a facile precipitation approach with different atomic ratios of Bi/Ti of 0.02, 0.04, and 0.08. The TiO2/(BiO)2CO3 nanocomposites exhibit an absorbance in the ultraviolet-visible range that is similar to that of TiO2 nanoparticles and photocatalytic activity that is reduced by up to 60% when exposed to ultraviolet and visible light. In addition, the nanocomposites show high biocompatibility in healthy HaCaT human skin cells and Madin–Darby canine kidney cells in vitro, and more importantly, they are capable of reducing the photo-generated toxicity of TiO2 in HaCaT cells upon irradiation with simulated sunlight. Such multifunctional nanocomposites could potentially be applied as alternative ultraviolet filter components in sunscreen formulations, reducing potential adverse effects associated with TiO2 nanoparticles. [ABSTRACT FROM AUTHOR]

We report the use of the spray pyrolysis method to design self-assembled isotropic ternary architectures made up of reduced graphene oxide (GO), functionalized multiwalled carbon nanotubes, and nickel oxide nanoparticles for cost-effective high-performance supercapacitor devices. Electrodes fabricated from this novel ternary system exhibit exceptionally high capacitance (2074 Fg−1) due to the highly conductive network, synergistic link between GO and carbon nanotubes and achieving high surface area monodispersed NiO decorated rGO/CNTs composite employing the liquid crystallinity of GO dispersions. To further assess the practicality of this material for supercapacitor manufacture, we assembled an asymmetric supercapacitor device incorporating activated carbon as the anode. The asymmetric supercapacitor device showed remarkable capacity retention (>96%), high energy density (23 Wh kg−1), and a coulombic efficiency of 99.5%. [ABSTRACT FROM AUTHOR]

The dependence of properties in YBa2Cu3O7 (YBCO) films grown by pulsed laser deposition at different distances from the target to a substrate has been systematically studied. The target to substrate distance DTS is shown to enable simple means for tunability of the critical current density and microstructure of the YBCO films. The variation of structural and electromagnetic properties in the films as a function of DTS has been explained in terms of laser plume propagation model and thin film formation mechanism. [ABSTRACT FROM AUTHOR]

The vortex pinning model based on the presence of the large number of edge dislocations in high quality YBa2Cu3O7 (YBCO) films and multilayers has been refined. By introducing the pinning potential of a chain of individual edge dislocations, we have been able not only to describe the critical current density dependence on the applied magnetic field over its entire range, but also to extract the microstructural parameters in the films, such as interdislocation spacing and average domain size, without employing sophisticated microstructural analysis. The model applicability and its results have been verified with the help of microstructural characterization combined with magneto-optical imaging in YBCO films and multilayers with different properties. [ABSTRACT FROM AUTHOR]

Much denser YBa2Cu3O7 (YBCO) superconducting films at least 1 μm thick with smooth surfaces have been obtained after introducing (Y/Nd)BCO multilayered structures. A significant enhancement of current carrying abilities has been achieved in these pulsed laser deposited films. The critical current density (Jc) has been increased by a factor of up to three in the entire field range. The imitation of the (Y/Nd)BCO multilayered structure by using YBCO ‘interlayers’ has also exhibited a considerable improvement in the current carrying ability. Similarities and differences between these two ‘multilayering’ approaches, leading to the observed effects, are discussed. The presence of interfaces even without element variation is likely to be the key to the improvements observed. In order to further promote Jc enhancement, small ‘multilayered’ additions of silver (Ag) to the films and multilayers provide various results: (i) rather strong enhancement for rather thin films and low addition levels, (ii) considerable degradation for large addition levels, and (iii) much less pronounced effect for thicker films. The enhancement of Jc is observed in zero and low magnetic fields, but has almost no effect at higher fields. All these experimental observations are discussed in terms of pinning, transparency and structural modifications introduced during the deposition of the film structures. [ABSTRACT FROM AUTHOR]

Significant differences in superconducting and microstructural properties between two types of MgB2 films prepared by pulsed laser deposition were determined. A very high Hc2 — T slope of 1.1 T/K was achieved in the in situ film. The Jc — H curves of the in situ film also show a much weaker field dependence than that of the ex situ film. The magneto-optical (MO) images show that at 4 K the flux penetrates the in situ MgB2 film through random paths, while for the ex situ film, the flux penetration pattern is mostly repeatable, indicating a defect-controlled flux penetration. Microstructural study (transmission electron microscopy and atomic force microscopy) revealed a relatively big grain size in the ex situ film. The correlation between the super- conducting properties, microstructure and preparation conditions is discussed with regard to the two types of films. [ABSTRACT FROM AUTHOR]

The nano-SiC doped MgB[sub 2]/Fe wires were fabricated using a powder-in-tube method and an in-situ reaction process. The depression of T[sub c] with increasing SiC doping level remained rather small due to the counterbalanced effect of Si and C co-doping. The high level SiC co-doping allowed creation of the intra-grain defects and nano-inclusions, which act as effective pinning centers, resulting in a substantial enhancement in the J[sub c](H) performance. The transport J[sub c] for all the wires is comparable to the magnetic J[sub c] at higher fields despite the low density of the samples and percolative nature of current. The transport I[sub c] for the 10wt% SiC doped MgB[sub 2]/Fe reached 660A at 5K and 4.5T (J[sub c] = 133 000A/cm²) and 540A at 20K and 2T (J[sub c] = 108 000A/cm²). The transport J[sub c] for the 10wt% SiC doped MgB[sub 2] wire is more than an order of magnitude higher than for the state-the-art Fe-sheathed MgB[sub 2] wire reported to date at 5K and 10T and 20K and 5T respectively. There is a plenty of room for further improvement in J[sub c] as the density of the current samples is only 50%. [ABSTRACT FROM AUTHOR]

SiC doped MgB[sub 2] polycrystalline samples were fabricated by in-situ reaction using different grain sizes (20 nm, 100 nm, and 37 µm) of SiC and different doping levels (0, 8, 10, 12, 15 wt%). Phases, microstructures, superconductivity, critical current density and flux pinning have been systematically investigated using XRD, SEM, TEM, and magnetic measurements. Results show that grain sizes of the starting precursors of SiC have a strong effect on the critical current density and its field dependence. The smaller the SiC grains are, the better the J[sub c] field performance is. Significant enhancement of J[sub c] and the irreversibility field H[sub irr] were revealed for ali the SiC doped MgB[sub 2] with additions up to 15 wt%. A J[sub c] as high as 20,000 A/cm² in 8 Tesla at 5 K was achieved for the sample doped with 10 wt% SiC with a grain size of 20 nm. Results indicate that the nano-inclusions and substitution inside MgB[sub 2] are responsible for the enhancement of flux pinning. [ABSTRACT FROM AUTHOR]

Evaluates the use of sandwich rolling and flat rolling in the processing of Ag/Bi-2223 superconducting tapes. Critical current density measurements; X-ray diffraction patterns of the tapes; Association between microcracks and reductions in critical currents of the tapes.

Much smoother surfaces and significantly improved superconducting properties of relatively thick YBa2Cu3O7 (YBCO) films have been achieved by introducing a multilayered structure with alternating main YBCO and additional NdBCO layers. The surface of thick (1 μm) multilayers has almost no holes compared to YBCO films. Critical current density (Jc) has been drastically increased up to a factor >3 in 1 μm multilayered structures compared to YBCO films over entire temperature and applied magnetic field range. Moreover, Jc values measured in thick multilayers are even larger than in much thinner YBCO films. The Jc and surface improvement have been analyzed and attributed to growth conditions and corresponding structural peculiarities. [ABSTRACT FROM AUTHOR]