Nanostructured superconductors: from granular through wire towards high-T_c nanotubular 2D composites
by Vladimir Pokropivny
International Journal of Nanotechnology (IJNT), Vol. 1, No. 1/2, 2004

Abstract: Superconductivity in nanostructured materials, nanowires, nanotubes and their 2D crystals is briefly reviewed. Experimental data show both the decrease of a critical superconducting temperature T_c under transition from polycrystalline to nanogranular ceramics, and the increase of T_c under transition to one-dimensional (1D) nanowires, nanotubes and their 2D crystals. Theoretical requirements for ideal room-T_c superconductor is shown to point out on 2D crystals built from noncarbon nanotubes of superconducting layered material as the ideal media. Analysis of superconductivity in MgBE₂ is presented which point out on a key role of E_2g-vibrations of boron ions resulted in the mechanism of two-gap two-phonon superconductivity. Connected with the author's concept of nanotubular superconductivity, this model lay off a bridge for the novel joint model of a nanotubular multi-phonon multi-gap room-T_c superconductivity on base of gallery of whispering circular zero-points phonon modes (twistons, rotons), in particular E_2g-mode, resulting in resonant electron-phonon coupling. From a structural engineering point of view, a novel route in high-T_c and room-T_c superconductivity is advanced based on 2D crystals built from noncarbon MgB₂, NbSe₂, Sn, Bi or other superconducting nanotubes with expected record T_c. The suggested original model is in accordance with some recent experimental data confirming the effect of nanotubular superconductivity. Recent progress in synthesis of 2D nanochannel membrane and nanowire-brush templates, aligned nanotube arrays and nanotubular crystals are briefly reviewed as promising routes to fabricate these record nanotubular superconductors.

Online publication date: Wed, 03-Dec-2003

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