Direct observation of titanium-centered octahedra in titanium-antimony-tellurium phase-change material

Phase-change memory based on Ti 0.4 Sb 2 Te 3 material has one order of magnitude faster Set speed and as low as one-fifth of the Reset energy compared with the conventional Ge 2 Sb 2 Te 5 based device. However, the phase-transition mechanism of the Ti 0.4 Sb 2 Te 3 material remains inconclusive due to the lack of direct experimental evidence. Here we report a direct atom-by-atom chemical identification of titanium-centered octahedra in crystalline Ti 0.4 Sb 2 Te 3 material with a state-of-the-art atomic mapping technology. Further, by using soft X-ray absorption spectroscopy and density function theory simulations, we identify in amorphous Ti 0.4 Sb 2 Te 3 the titanium atoms preferably maintain the octahedral configuration. Our work may pave the way to more thorough understanding and tailoring of the nature of the Ti-Sb-Te material, for promoting the development of dynamic random access memory-like phase-change memory as an emerging storage-class memory to reform current memory hierarchy.