Crystallization of Co-rich amorphous ribbons annealed under a 10 Oe external magnetic field at the early 30 minutes from their glassy status to supercooled liquid status is investigated by high-resolution transmission microscope (HR-TEM), Selected Area Fourier Transform (SA-FT), X-ray diffraction (XRD) and differential scanning calorimetry (DSC). Results indicate that the short-rang ordering feature can be refined very well in specimen annealed under temperatures about 87.4 degrees C below their glass transition (Tg), showing refined salt-pepper morphologies with a mean length changing from 1.2 +/- 0.8 nm to 0.8 +/- 0.2 nm and a mean width shifting from 0.5 +/- 0.2 nm to 0.3 +/- 0.1 nm. When the amorphous ribbons are field-annealed at temperature near to Tg (i.e., 450 degrees C), ultra-fine nanocrystalline structures can be formed on the top surface of ribbons with size of 3.5 +/- 0.5 nm and inter-grain spacing of about 0.4 +/- 0.2 nm even though the inner parts of the ribbons are still in amorphous phases. The nanocrystalline areas are featured by the formation of doped hcp cobalt phase orientated along the c-axis, with the inter-plane spacing ranging from 4 A to 6 A. When the annealing temperature is above Tg, the grain sizes are increased dramatically with multi-phased nanocrystals precipitating from the amorphous substrate, and finally reaching almost complete crystallization at 600 degrees C, causing greatly coarsening of the nanocrystal structures.

To investigate the damage profiles of high-fluence low-energy proton irradiation on superconducting materials and related devices, Raman characterization and electrical transport measurement of 40-keV-proton irradiated YBa 2 Cu 3 O 7−x (YBCO) thin films are carried out. From micro-Raman spectroscopy and x-ray diffraction studies, the main component of proton-radiation-induced defects is found to be the partial transition of superconducting orthorhombic phase to the semiconducting tetragonal phase and non-superconducting secondary phase. The results indicate that the defects induced in the conducting CuO 2 planes, such as increased oxygen vacancies and interstitials, can result in an increase in the resistivity but a decrease in the transition temperature T C with the increase in the fluence of proton irradiation, which is confirmed in the electrical transport measurements. Especially, zero-resistance temperature T C0 is not observed at a fluence of 10 15 p/cm 2 . Furthermore, the variation of activation energy U 0 can be explained by the plastic-flux creep theory, which indicates that the plastic deformation and entanglement of vortices in a weakly pinned vortex liquid are caused by disorders of point-like defects. Point-like disorders are demonstrated to be the main contribution to the low-energy proton radiation damage in YBCO thin films. These disorders are likely to cause flux creep by thermally assisted flux flow, which may increase noise and reduce the precision of superconducting devices.

We report a newly developed simple one-step annealing process, namely the simultaneous texture (STEX) technique, for cheap and convenient fabrication of buffer layers on rolled Ni tapes. Textured CeO 2 buffer layers have been prepared using this new process from solutions of cerium nitrite in acetyl acetone. Ba x Sr 1 x TiO 3 buffer layers have also been prepared from solutions of strontium acetate, barium acetate, titanium (IV) butoxide in 2-metoxyethanol and acetic acid. For both cases, an analysis of X-ray diffraction omega and phi scans indicates that cube-on-cube texture formation takes place during STEX processing. The possible mechanisms related to the STEX method are analyzed and discussed. The preparation of multi-layer configurations, and of subsequent YBa 2 Cu 3 O 7 x (YBCO) film growth on STEX-prepared buffer layers is also reported.

Magnetic field gradient tensor measurement is an important technique to obtain position information of magnetic objects. When using magnetic field sensors to measure magnetic field gradient as the coefficients of tensor, field differentiation is generally approximated by field difference. As a result, magnetic objects positioning by magnetic field gradient tensor measurement always involves an inherent error caused by sensor sizes, leading to a reduction in detectable distance and detectable angle. In this paper, the inherent positioning error caused by magnetic field gradient tensor measurement is calculated and corrected by iterations based on the systematic position error distribution patterns. The results show that, the detectable distance range and the angle range of an ac magnetic object (2.44 Am 2 @1 kHz) can be increased from (0.45 m, 0.75 m), (0 • , 25 •) to (0.30 m, 0.80 m), (0 • , 80 •), respectively.

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