Fig. 4 | Nature Communications

Fig. 4

From: Interface-mediated Kirkendall effect and nanoscale void migration in bimetallic nanoparticles during interdiffusion

Fig. 4

Void formation and migration in Au–Pd–Au sandwich NPs at elevated temperatures. a In situ STEM (upper) and EDX (lower) images of the as-synthesized NP morphology and after heating to 500 °C. The images indicate that the voids formed in these NPs are larger than the bi-layer NPs. Voids are denoted by dashed squares. bd In situ TEM image sequences of void migration in a Au–Pd–Au NP after heating to 500 °C, 600 °C (Supplementary Movie 4), and further to 650 °C (Supplementary Movie 5). The time-stamps in c and d are pegged to time in the supplementary movies. Note that void 1 increased in size between t= 0 s and t= 180 s at 600 °C. It can be seen from Supplementary Movie 4 that this increase was due to two void coalescence events between t= 60–80 s. Void 2 got annihilated at the surface between t= 180 s and t= 360 s at 600 °C (Supplementary Movie 4), resulting in a small hole on the NP surface. The sequence at 650 °C shows the extended migration of void 1 (Supplementary Movie 5). Movie 5 is recorded 70 s after the end of Movie 4

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