Eugene B. Gordon
Principal Scientist of IPCP and Professor of Chemical Physics in MUPT. Russia
Title: The bottom-up design of thin nanowires in superfluid helium
Biography
Biography: Eugene B. Gordon
Abstract
The quasi-1D quantized vortices appeared in superfluid helium (He II) represent an ideal template for growing the nanowire from any metal embedded to He II. Using the laser ablation for the metal introduction into He II we have grown at T = 1.5 - 2.0 K the nanowires made of many metals and alloys. Their diameters D dependent on the metal thermodynamic properties ranged from 8 nm for fusible metals to 2 nm for refractory ones, and the structure and shape of nanowires were quite perfect. Generally, the product of our synthesis represents a 3D web of nanowires interconnected by metallic manner. The total area of web grown in one experiment is up to 10 cm2.
Nanowires with thickness of few nanometers are of interest for many applications. In particular they appear to be excellent nanocatalysts: the efficiencies of nanowebs made of gold, palladium, platinum and niobium as the catalysts for CO oxidation were found to be higher than those for the nanoparticles immobilized on alumina. Niobium nanowires demonstrated the size suppression of superconductivity by the mechanism of quantum phase slip; thus they can be used for the qubits and pointed SQUID creation. For alloys the different metals separation along the wire core led to formation of nano-heterostructures with unique properties.
The thin (D <4 nm) nanowires possess unexpectedly low thermal stability: they decay to the chains of separate nanoclusters at temperatures 3 times lower than the melting temperature. The ways to overcome this defect have been outlined.