Formation of SrSnO3 shell-like inclusions in the Bi2Sr2CaCu2O8+x superconductor via chemical reaction

P.E. Kazin, A.S. Karpov, Yu.D. Tretyakov, M. Jansen

Solid State Sciences (in print)

ABSTRACT. Superconducting composites Bi-2212 - SrSnO3 have been prepared by reacting between the Bi-Sr-Ca-Cu-O precursor and Sr2SnO4 or Ca2SnO4 at 800-950эC, followed by crystallisation of Bi-2212 from the partial melt at decreasing temperature. The samples have been characterised by powder X-ray diffraction, scanning electron microscopy and magnetic measurements. The materials consist of large Bi-2212 lamellae and complex-shaped fine inclusions of SrSnO3. The composite obtained using Sr2SnO4 contains almost all the SrSnO3 phase in the form of micron-sized spherical shells, which are partly included in Bi-2212 lamellae, partly agglomerated in-between. The shells are perforated that allows the Bi-2212 crystals to grow through them. It has been found that the shell-like grains form at an early stage of the precursor thermal treatment between 800 and 850эC. A mechanism of the SrSnO3 shell formation is proposed. The composites exhibit Tc in the range of 82-87K and reveal up to 5! times better magnetic flux pinning at T ( 30K in comparison with the undoped Bi-2212 sample prepared using the same experimental procedure.

Laboratory of Inorganic Materials Science