Effects of stoichiometry, purity, etching and distilling on resistance of MgB2 pellets and wire segments

Abstract

We present a study of the effects of non-stoichiometry, boron purity, wire diameter and post-synthesis treatment (etching and Mg distilling) on the temperature dependent resistance and resistivity of sintered MgB2 pellets and wire segments. Whereas the residual resistivity ratio (RRR) varies between RRR \~ 4 to RRR > 20 for different boron purity, it is only moderately affected by non-stoichiometry (from 20% Mg deficiency to 20% Mg excess) and is apparently independent of wire diameter and presence of Mg metal traces on the wire surface. The obtained set of data indicates that RRR values in excess of 20 and residual resistivities as low as rho{0} ~ 0.4 mu Ohm cm are intrinsic material properties of high purity MgB2.

References in corpus (7)

• Boron Isotope Effect in Superconducting MgB${}_2$
• Superconductivity in Dense $Mg{B}_2$ Wires
• Thermodynamic and Transport Properties of Superconducting $M{g}^{10}{B}_2$
• Superconducting properties of well-shaped MgB2 single crystal
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• Effects of Boron Purity, Mg Stoichiometry and Carbon Substitution on Properties of Polycrystalline MgB${}_2$
• Superconducting and Normal State Properties of Neutron Irradiated MgB2
• Two band/two gap superconductivity in carbon-substituted MgB2 evidenced by point-contact spectroscopy
• Superconductivity of magnesium diboride
• Sonochemical Modification of the Superconducting Properties of MgB2
• Synthesis of Mg(B${}_{1-x}$C${}_x$)${}_2$ Powders
• Carbon Doping in MgB_2 : Role of Boron and Carbon p_x(y) Bands
• Formation of MgB2 at low temperatures by reaction of Mg with B6Si
• Magnetic Field Induced Density of States in Superconducting MgB${}_2$: Measurement of Conduction Electron Spin-Susceptibility