Papers by Keyword: AC Losses

Abstract: Structural and magnetic characteristics of (La,Sr)MnO₃ nanoparticles synthesized by different methods have been studied in the work. The specific loss power which is released on the exposure of an ensemble of synthesized particles to alternating magnetic field was calculated and measured experimentally. The contributions to the specific loss power resulted from different heating mechanisms have been discussed. The directions to enhance the heating efficiency of various kinds of magnetic nanoparticles are outlined

Abstract: Measurements of complex AC susceptibility χ = χ + χ as a function of temperature have been carried out on Sn-doped Bi_1.6Pb_0.4Sr₂(Ca_1-xSn_x)₂Cu₃O_δ superconductor samples prepared via the conventional solid state reaction method. All the samples exhibit perfect diamagnetism below 109 K. The χ (T) curves display two-step features, indicating the presence of mixed phases and therefore weakening of the grains' coupling. The amount of shielded volume in Sn-free samples is greater than that in Sn-doped samples. The intrinsic peak due to the small AC losses within the grain was not observed in the χ (T) curves for all samples. However, the coupling peak, T_P, for Sn-free samples at an applied field of 1.0 Oe was observed at 89 K and shifted to a lower temperature ranging from 59 K to 64.2 K in Sn-doped samples. The amounts of hysteresis losses above the T_P in all doped samples were smaller than that of the Sn-free sample. Therefore, the effect of Sn doping suppressed the inter-granular critical current, J_cm, and the presence of weak links that coupled the superconducting grains.Keywords: BSCCO, AC Losses, Sn-doped, Superconductor

Abstract: The results of experimental study of the critical current and AC losses in high pressure-synthesized MgB₂ bulk superconductors are presented. The method is based on the use of the transformer configuration and suitable for samples in the form of hollow superconducting cylinders and rings. It was shown that the critical current measured by the transformer method is an order of magnitude lower than the value given by the magnetization technique. The obtained dependencies of the losses on current and frequency reveal the deviations from the critical state model behavior and reflect structural peculiarities of the investigated MgB₂ samples.