SEM images of FeS
nanocrystals synthesized with different [S]/[Fe] ratios. (a) 1:1.5. (b) 1:0.75. (c) 2:1. (d) 2.5:1. (e) 3:1. (f) 3.75:1. The reaction time is 24 h for the nanocrystals in (a) and (b) and 48 h for the others. The inset in (a) and (b) is the TEM images of the nanocrystals. The scale bars for the SEM images is 1,000 nm. The scale bars for the TEM images is 100 nm.