Insulating `nanocablesʹ: Invar Fe–Ni alloy nanorods inside BN nanotubes

Here we present the results on synthesis, structural and chemical analysis of insulating boron nitride (BN) nanotubes (NTs) which have been filled with conducting Invar Fe–Ni alloy (∼60 at.% Fe; ∼40 at.% Ni) nanorods. The result was accomplished by a two-step process: (i) carbon (C) NTs containing Invar alloy nanoparticles placed at the tube tips were synthesized by plasma-assisted chemical vapor deposition (CVD) on an Invar Fe–Ni alloy substrate; and (ii) the material was heated to the melting point of the alloy (1723 K) in a flow of B2O3 and N2 gases and held for 30 min. During this second stage, simultaneous filling of NTs with the Fe–Ni melt through capillarity and chemical modification of C tubular shells to form BN tubules occurred.