Figure 12.

TEM images of DWNTs (a) uncoated; (b) and after 100; and (c) 200 cycles of Al₂O₃ ALD coating The DWNTs showed nodular growth at 100 cycles. By 200 cycles some of the nodules had grown together to form a more continuous coating, however, many uncoated regions remained. The nodule radius was approximately 10 ± 2 nm for the 100 cycle sample. The film thickness for the 200 cycles sample had increased to approximately 21 ± 3 nm for the coated portions of the 200 cycle sample. This is consistent with nucleation on defects, followed by facile film growth with little additional film nucleation on this particular nanotube type.