论文信息 - Analysis of Bulk and Thin Film Model Samples Intended for Investigating the Strain Sensitivity of Niobium-Tin

Analysis of Bulk and Thin Film Model Samples Intended for Investigating the Strain Sensitivity of Niobium-Tin

Bulk samples and thin films were fabricated and characterized to determine their suitability for studying the effect of composition and morphology on strain sensitivity. Heat capacity and resistivity data are used to determine the critical temperature distribution. It is found that all bulk samples contain stoichiometric Nb3Sn regardless of their nominal Nb to Sn ratio. Furthermore, in bulk samples with Cu additions, a bi-modal distribution of stoichiometric and off-stoichiometric Nb-Sn is found. Thus the nominally off-stoichiometric bulk samples require additional homogenization steps to yield homogeneous off-stoichiometric samples. A binary magnetron-sputtered thin film has the intended off-stoichiometric Nb-Sn phase with a mid-point critical temperature of 16.3 K. This type of sample is a suitable candidate for investigating the strain sensitivity of A15 Nb1-βSnβ, with 0.18 <; β <; 0.25. The strain sensitivity of Nb-Sn as a function of composition and morphology is important for an in-depth understanding of the strain sensitivity of composite Nb3Sn wires.

[1] Hellman,et al. Specific heat of thin-film A15 superconductors: An anomalous inhomogeneity discovered. , 1987, Physical review. B, Condensed matter.

[2] H. Kate,et al. State of the art powder-in-tube niobium–tin superconductors , 2008 .

[3] G. Rickayzen. Theory of Superconductivity , 1965 .

[4] M. Sadovskii,et al. Superconductivity in the , 2004 .

[6] D. R. Dietderich,et al. Nb3Sn research and development in the USA – Wires and cables , 2008 .

[7] A Godeke,et al. A general scaling relation for the critical current density in Nb3Sn , 2006, cond-mat/0608404.

[8] A Review of the Properties of Nb3Sn and Their Variation with A15 Composition, Morphology and Strain State , 2006, cond-mat/0606303.

[9] A. Godeke,et al. An improved model for the strain dependence of the superconducting properties of Nb3Sn , 2009 .

[10] A. Godeke,et al. Properties of homogeneous binary and ternary HIP-processed Nb₃Sn bulk , 2009 .

[11] H. Kate,et al. The strain dependence of the critical properties of Nb3Sn conductors , 1999 .

[12] C. Senatore,et al. Specific heat of Nb3Sn wires , 2006 .

[13] D. Larbalestier,et al. The upper critical field of filamentary Nb3Sn conductors , 2004, cond-mat/0410463.

[14] J. Ekin,et al. Unified scaling law for flux pinning in practical superconductors: I. Separability postulate, raw scaling data and parameterization at moderate strains , 2010 .