Adv. Mater. 2021, 33, 2005612 Mistakes in Figure 2a and Figure 5e are corrected here. 2a Figure (Figure presented.) Isothermal section of Ge–Sb–Te at 623 K superimposed with nominal compositions of thermally equilibrated alloys. 5e Figure (Figure presented.) Isoplethal section of pseudo-binary (GeTe)1−y(Sb2Te3)y, revealing the temperature and composition ranges of the phase decomposition and diffusion-less athermal transformation. The insets: Line-scan results for Sb concentration for y = 0.05 samples annealed at 773 and 723 K are shown as an inset, together with the Gibbs free energy curves (G) versus composition (y) for the spinodal decomposition (right panel, upper image) and the athermal transformation (right panel, lower image). The Sb concentration in the 773 K-annealed sample is nearly constant (≈7 at%Sb), while that for the sample that underwent phase decomposition can be as wide as 6–11 at%Sb from Sb-deficient to Sb-rich regions. i) In Figure 2a, the temperature should refer to 623 K, as is mentioned in the caption, instead of 723 K, which is in the published image. ii) In Figure 5e, in the lower right inset, the yellow atom represents Ge, rather than Sb as quoted in the originally published figure. The corrected figures are shown below.