Wydarzenia

Seminarium Międzynarodowego Laboratorium Silnych Pól Magnetycznych i Niskich Temperatur PAN

Influence of carbon, neodymium and cerium on the critical current density J_c and the critical temperature T_c in MgB₂ samples

Grzegorz Gajda

In the presentation will be shown results of the critical current, the fields irreversibility and the critical temperature for MgB₂ bulks (cylinders), which were doped with carbon and magnetic molecules (cerium and neodymium). The samples had cylindrical shapes with dimensions of 6x6 [mm]. These samples were annealed at 800 ℃ for 1 h and at the pressure of 1GPa. The MgB₂ materials were made at the Institute of High Pressure Physics in Warsaw. Measurements of the critical temperature and the hysteresis loop were done at International Laboratory of High Magnetic Fields and Low Temperatures, using a vibrating magnetometer (VSM). Research of the microstructure were performed at the Institute of High Pressure Physics and at the Institute of Radiology. The critical current density was calculated from the Bean model. The obtained results show that doping (carbon, cerium and neodymium) affect the number of intergranular connections and creates pinning centers at the grain boundaries. The results of sample with cerium show that cerium slightly reduces the critical temperature.