Figure 4. Direct verification of growth rate difference in a nanorod.

(a) Snapshot DF TEM images to observe the growth kinetics in a nanorod of ∼17 nm with a narrow region (∼9 nm, denoted by orange arrows) in diameter. The dotted line in the top image outlines the nanorod morphology. The grain growth rate is estimated by measuring the lateral expansion of the crystalline grain front, reflected as the change of imaging contrast (yellow dashed lines). Note that the growth front passes through the neck at ∼370 °C. (b) Quantification of the crystalline grain growth rate. The grain growth rate is suppressed at the narrow region of the nanorod during crystallization. The growth rate for the thicker region is ∼65 and ∼180 nm s⁻¹ at 330 and 394 °C, respectively, and the rate for the thinner region is 4.5, 0.3 and 11 nm s⁻¹, at 360, 370 and 380 °C, respectively. The detailed experimental condition is described in Supplementary Note 2.