Structural phase evolution and superconductivity in the non-stoichiometric intermetallic compound niobium diboride

Zhi An Ren, Sogo Kuroiwa, Yoko Tomita, Jun Akimitsu

Research output: Contribution to journalArticlepeer-review

14 Citations (Scopus)

Abstract

The structural changes and superconductivity in the layered non-stoichiometric niobium diboride compound were systematically studied for both of niobium-deficient and boron-deficient phases by X-ray diffraction analysis and magnetic susceptibility measurements. The niobium and boron vacancies were found to have different effects on the crystal lattice parameters and superconducting properties; superconductivity only exists in niobium-deficient phases with a clear enhancement of inner-plane B-B bonding and the increase of inter-plane distance, while boron vacancies have the opposite effect of enhancing the Nb-B bonding and breaking the superconductivity. A main superconducting phase with Nb0.83B2 composition was obtained with Tc ∼ 9.3-9.9 K, and a = 3.102(1) Å and c = 3.322(2) Å under the optimum sintering conditions. The low temperature specific heat was measured for three high-pressure synthesized superconducting samples to reveal the origin the increase of Tc with the niobium deficiencies.

Original languageEnglish
Pages (from-to)411-416
Number of pages6
JournalPhysica C: Superconductivity and its applications
Volume468
Issue number5
DOIs
Publication statusPublished - Mar 1 2008
Externally publishedYes

Keywords

  • Niobium diboride
  • Non-stoichiometric phase
  • Specific heat
  • Superconductivity

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Energy Engineering and Power Technology
  • Electrical and Electronic Engineering

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