Surface ferromagnetism and superconducting properties of nanocrystalline niobium nitride

Shipra, R and Kumar, Nitesh and Sundaresan, A (2013) Surface ferromagnetism and superconducting properties of nanocrystalline niobium nitride. In: Materials Chemistry and Physics, 139 (2-3). pp. 500-505.

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Abstract

Nanocrystalline delta-NbNx samples have been synthesized by reacting NbCl5 and urea at three different temperatures. A comparison of their structural, magnetic, transport and thermal properties is reported in the present study. The size of the particles and their agglomeration extent increase with increasing reaction temperature. The sample prepared at 900 degrees C showed the highest superconducting transition temperature (T-c) of 16.2 K with a transition width, similar to 1.8 K, as obtained from the resistivity measurement on cold-pressed bars. Above T-c, magnetization measurements revealed the presence of surface ferromagnetism which coexists with superconductivity below T-c. Heat capacity measurements confirm superconductivity with strong electron-phonon coupling constant. The sample prepared at 800 degrees C shows a lower T-c (10 K) while that prepared at 700 degrees C exhibit no superconductivity down to the lowest temperature (3 K) measured.

Item Type:	Journal Article
Publication:	Materials Chemistry and Physics
Publisher:	Elsevier Science
Additional Information:	Copyright of this article belongs to Elsevier Science.
Keywords:	Nitrides; Nanostructures; Superconductivity; Surface Properties
Department/Centre:	Division of Mechanical Sciences > Chemical Engineering
Date Deposited:	21 Jun 2013 05:14
Last Modified:	22 Oct 2018 10:02
URI:	http://eprints.iisc.ac.in/id/eprint/46683

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