Extended Data Fig. 6: Diffraction pattern analysis of the poly-crystalline SiTe_x filament by fast-Fourier transformation (FFT).

a. TEM image of the SiTe_x filament in set state. b-d. High-resolution TEM images of the grains in the filament, showing clear lattice fringes. e-g. FFT analyses conducted on the high-resolution TEM image in (b-d). h-j. The inverse-FFT results obtained from FFT results to measure the interatomic distance of each crystal. For the grains marked in the green (b and e) and pink (d and g) boxes, hexagonal diffraction patterns of the trigonal Te crystal (0 0 1) plane were obtained. The two nearest spots to the diffraction center (marked as yellow circles) represent (\(\bar{1}20\)) and (\(2\bar{1}0\)) planes of the Te crystal (e and g). The measured interatomic distances through inverse FFT on the FFT result were close to 0.22 nm, consistent with the interatomic distance of the trigonal Te crystal⁴⁶ (h and j). On the other hand, the grain marked in the blue box exhibited a diffraction pattern of the trigonal SiTe₂ crystal (0 0 1) plane with a 0.38 nm interatomic distance (f and i), indicating the grain is composed of trigonal SiTe₂ crystal⁴⁷. The two nearest spots to the diffraction center represent (0 1 0) and (1 0 0) planes and the second closest spot represents (\(\bar{1}20\)) plane of the SiTe₂ crystal. The diffraction patterns and interatomic distances indicate the formation of Te and SiTe₂ crystals in the poly-crystalline SiTe_x filament.