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.