Polycrystalline samples of the new superconductor MgB_(2) are prepared by solid state reaction using Mg and B powders.The resistance measurement shows that the onset transition temperature and zero resistance transiti...Polycrystalline samples of the new superconductor MgB_(2) are prepared by solid state reaction using Mg and B powders.The resistance measurement shows that the onset transition temperature and zero resistance transition temperature are Tonsetc=43.8 K and Tc0=37 K,respectively.The Tc0 depends on measuring current strongly.The diamagnetic transition temperature of~38 K is obtained by the ac susceptibility measurement.X-ray powder diffraction spectra of MgB_(2) can be indexed using hexagonal structure with space group P6/mmm and lattice parameters a=0.30864 and c=0.35212 nm.A second phase,probably MgO,is also found.展开更多
基金Supported by the Ministry of Science and Technology of China(NKBRSF-G1999064602)the National Natural Science Foundation of China under Grant No.59872043the Fundamental Research Bureau,Chinese Academy of Sciences.
文摘Polycrystalline samples of the new superconductor MgB_(2) are prepared by solid state reaction using Mg and B powders.The resistance measurement shows that the onset transition temperature and zero resistance transition temperature are Tonsetc=43.8 K and Tc0=37 K,respectively.The Tc0 depends on measuring current strongly.The diamagnetic transition temperature of~38 K is obtained by the ac susceptibility measurement.X-ray powder diffraction spectra of MgB_(2) can be indexed using hexagonal structure with space group P6/mmm and lattice parameters a=0.30864 and c=0.35212 nm.A second phase,probably MgO,is also found.
