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The application of magnetic cenospheres including ferrospinel nanoparticles as a “transport container” in medicine and biology is quite attractive. Their nanoscale size, high porosity, and well pronounced magnetic properties provide good consumer choice. In this contribution, we report on the magnetic properties of microspheres from energetic ashes of Ekibastuz coals.

Phase composition of six narrow size fractions of microspheres extracted from fly ashes of Ekibastuz coals has been determined by Mossbauer spectroscopy. The basic phase is defect magnetite substituted by Al, Mg, and Ti ions. The magnetic properties of microspheres depend on the content of iron and its distribution over spinel positions.

The preliminary results of the investigation of magnetic properties of a novel low-density superconducting material Bi1.8Pb0.3Sr2Ca2Cu3Ox with a low density and microfoam structure are presented. The temperature, magnetic field, and time dependences of magnetization M have been measured. The experimental hysteresis loops M(H) are well described in the framework of the Val’kov-Khrustalev theory developed for type II granular superconductors.

We have studied the magneto-resistive effect in bulk Y3/4Lu1/4Ba2Cu3O7 + CuO composites prepared by the fast-sintering technique. It has been found that the composites exhibit large magnetoresistance in low magnetic fields ( jc (where jc is the critical-current density), large values of the magnetoresistance R0, up to thousands percent, are obtained in the range of weak magnetic fields (tens of oersteds) at 77 K. This effect is attractive for practical applications of these composite materials as active elements of magnetic-field sensors. The sign of the magneto-resistive effect is positive in contrast to that of manganese oxides. This may be important for some devices.

The current-voltage characteristic (CVC) of break junction made from polycrystalline Bi_{1.8}Pb_{0.3}Sr_{1.9}Ca_2Cu_3O_x is investigated. The experimental CVC has hysteretic feature that reflects a part of a curve with negative differential resistance. The CVC is discussed within the framework of the Kummel-Gunsenheimer-Nicolsky theory considering multiple Andreev reflections in superconductor/normal-metal/superconductor junctions., 5 pages, 1 figure