Mudgel, Monika and Awana , V. P. S. and Kishan, H. and Felner, I. and Alvarez, G. A. and Bhalla, G. L. (2008) Superconductivity of various borides: The role of stretched c-parameter. Journal of Applied Physics, 105 (7). 07E313-1. ISSN 1089-7550

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The superconductivity of MgB2, AlB2, NbB2+x, and TaB2+x is intercompared. The stretched c-lattice parameter (c = 3.52 Å) of MgB2 in comparison to NbB2.4 (c = 3.32 Å) and AlB2 (c = 3.25 Å) decides empirically the population of their π and σ bands and as a result their transition temperature Tc values, respectively, at 39 and 9.5 K for the first two and no superconductivity for the later. The nonstoichiometry induces an increase in c parameter with Boron excess both in NbB2+x and TaB2+x. Magnetization (M-T) and resistivity measurements (ρ-T) in case of niobium boride samples show the absence of superconductivity in stoichiometric NbB2 sample (c = 3.26 Å) while a clear diamagnetic signal and a ρ = 0 transition for boron excess NbB2+x samples. On the other hand, superconductivity is not achieved in TaB2+x case. The probable reason behind is the comparatively lesser or insufficient stretching of c parameter.

Item Type: Article
Subjects: Physics
Depositing User: Ms Neetu Chandra
Date Deposited: 12 Oct 2012 12:10
Last Modified: 12 Oct 2012 12:10

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