Single-crystal calcium hexaboride nanowires: Synthesis and characterization

Catalyst-assisted growth of single-crystal calcium hexaborlde (CaB6) nanowires was achieved by pyrolysis of diborane (B2H6) over calcium oxide (CaO) powders at 860-900 degreesC and similar to155 mTorr in a quartz tube furnace. TEM electron diffraction and Raman spectroscopy indicate that the nanowires are single-crystal CaB6 and have a preferred [001] growth direction. Analysis of TEM/EDX/EELS data proves the nanowires consist of CaB6 cores and thin (1-2 nm) amorphous oxide shell material. The CaB6 nanowires have diameters of similar to15-40 nm, and lengths of similar to1-10 mum.