High-pressure synthesis of superconducting Nb{1-x}B2 (x = 0-0.48) with the maximum Tc = 9.2 K

Abstract

Superconductivity with Tc above 9 K was found in metal-deficient NbB2 prepared under 5 GPa, while no clear superconductivity was observed down to 3 K in stoichiometric NbB2. The superconductivity was observed above x = 0.04 in Nb1-xB2. and the lattice parameters also changed abruptly at x = 0.04. As x increased, the transition temperature Tc slightly rose and fell with the maximum value of 9.2 K at x = 0.24 for the samples sintered at 5 GPa and 1200 C. The Tc-value changed in the range from 7 K to 9 K, depending on the sintering pressure. A series of Ta1-xB2 (0 =< x =< 0.24) was also synthesized under high pressure to examine a special effect of high-pressure synthesis.

24 pages including 2 tables and 7 figures, accepted for publication in Physica C

References in corpus (4)

• Electronic structure of superconducting MgB2 and related binary and ternary borides
• Effect of lattice strain and defects on the superconductivity of MgB2
• Electron Transport in Diborides: Observation of Superconductivity in ZrB2
• Electronic structure and weak electron-phonon coupling in TaB${}_2$

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