Polycrystalline samples of the new superconductor MgB_(2) are prepared by solid state reaction using Mg and B *** resistance measurement shows that the onset transition temperature and zero resistance transition tempe...
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Polycrystalline samples of the new superconductor MgB_(2) are prepared by solid state reaction using Mg and B *** resistance measurement shows that the onset transition temperature and zero resistance transition temperature are Tonsetc=43.8 K and Tc0=37 K,*** Tc0 depends on measuring current *** 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.
High temperature superconductivity,up to 258K,was observed in the Y_(1)Ba_(2)Cu_(3)F_(2x)O_(7-x-δ)(0.2≤x≤1)bulk materials prepared by means of conventional ceramic-technique.X-ray diffraction analysis shows that th...
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High temperature superconductivity,up to 258K,was observed in the Y_(1)Ba_(2)Cu_(3)F_(2x)O_(7-x-δ)(0.2≤x≤1)bulk materials prepared by means of conventional ceramic-technique.X-ray diffraction analysis shows that these materials are *** is believed that to obtain a high Tc superconducting material with Tc near room temperature is possible,though the high Tc state of samples is now very unstable.
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