Abstract
Single-crystalline, hexagonal coaxial-shaped ZnO nanocolumns have been synthesized in a large quantity on steel alloy substrate via catalyst-free thermal evaporation of metallic zinc powder at
490
°
C
. The optical-phonon
E
2
mode at
437
cm
−
1
in Raman spectrum and a strong UV emission at
381
nm
in photoluminescence spectrum showed that the synthesized ZnO nanocolumns have a good crystal quality, with a wurtzite hexagonal phase and exhibited a good optical property. A layer-by-layer three-step growth mechanism was proposed for the formation of hexagonal coaxial-shaped ZnO nanocolumns.