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A comprehensive study of superconducting and normal state properties of Nb2Pd(S0.9Te0.1)5 system which consists of solid chunks embedded with mesh of fibers has been presented here. Below the superconducting transition temperature, in different iso-magnetic fields, the motion of vortices in mixed state has been analyzed using thermally activated flux flow (TAFF) model and the obtained thermal activation energy (TAE) follows Kramer’s scaling which suggests the dominance of mechanism similar to grain boundary pinning in these fibers. Bulk nature of superconductivity is clearly seen in specific heat data, however with a jump of ∼0.97, less than the BCS estimate, places these fibers in weak coupling strength limit. Low temperature electronic heat capacity down to 2 ​K point towards a fully gapped s-wave superconductivity in these fibers. Moreover, normal state study using thermoelectric power data suggests a hole dominated transport in this system.

The superconducting transition temperature of niobium silicon oxynitride (Nb0.87Si0.09□0.04)(N0.87O0.13) exhibits a gradual reduction from 16.8 K to around 11 K under an increasing applied magnetic field of up to 14 T. This relatively small Tc reduction under an applied magnetic field suggests a robustness of its superconducting behavior in comparison to that in the parent niobium oxynitride. It was similar to the flux pinning effect observed in the large magnetic hysteresis of the niobium-silicon oxynitrides in our previous study. Both Si K-edge XANES and 29Si MAS-NMR indicated that the local structure of pinning centers around the silicon atoms close to cationic vacancies was similar to that of Si in amorphous SiO2 in the rock-salt structure of niobium oxynitride.

Niobium compounds continue to be an interesting family of superconductors, with the recent addition of oxynitrides to it, which can be categorized as low-Tc superconductors (LTS) because they exhibit superconductivity below Tc∼17 K. In this paper, we report the superconducting properties of three members of the family of niobium oxynitrides, viz. (Nb0.89Al0.11)(N0.84O0.16), (Nb0.95Mg0.05)(N0.92O0.08) and (Nb0.87Si0.09□0.04)(N0.87O0.13). Low temperature dc and ac magnetization measurements have been performed. In addition, heat capacity has been recorded at low temperature under applied magnetic fields. A detailed analysis of the data is presented.