Fabrication and Raman Studies οf MgO/$SnO_2$ Core-Shell Heteronanowires

We have reported the fabrication of MgO core/$SnO_2$ shell nanowires, by a two-step evaporation process. Thermal annealing induced changes in morphology, in which the nanowire surface became rough by the agglomeration of $SnO_2$ shell layers and its crystallinity was enhanced. It was found that three fundamental modes (475, 634, 772 $cm^{-1}$) and an infrared (IR)-active mode (682 $cm^{-1}$) of rutile $SnO_2$ appeared in the Raman spectrum of MgO core/$SnO_2$ shell nanowires. By thermal annealing, the relative intensity of the $A_{2u}$ to the $A_{1g}$ line was reduced, presumably due to the disorder or size effects.