Ceramics-Silikáty 54 (2) 133-138 (2010)

NANOPARTICLES AND SUPERCONDUCTORS

V. Bartůněk, O. Smrčková

Limiting parameters for cuprate Bi(Pb)SrCaCuO and YBaCuO superconductors are critical current density, critical external magnetic field and critical temperature. Since technology of cooling of superconductors by liquid nitrogen is well mastered, crucial limiting parameter is critical current density (with critical field linked). For II. type superconductors (including cuprates) mixed state where magnetic field penetrates to the mass of superconductor exists. Magnetic flux penetrates in form of moving vortices. Vortices could be pinned on pieces of nonsuperconducting phase and such process increases critical current density of superconductor. Possible pinning centres are nanoparticles in sizes to 10 nm but problem is chemical stability in material. In this work system of choosing of suitable materials has been developed. Firstly selected materials were tested to stability via thermodynamics calculations by using program FactSage. Two materials survived test and were tested experimentally. In₂O₃ was not inert to Bi(Pb)SrCaCuO superconductor but CeO₂ (in form of nanoparticles about 3 nm in diameter) was. Therefore CeO₂ seems to be good material for both purpose of research and for possible industrial use.

Keywords: Superconductor, Pinning centres, Nanoparticles