Department of Materials Science and Engineering, Stanford University, Stanford, California 94305, USA.
Nat Commun. 2013;4:1369. doi: 10.1038/ncomms2385.
Superionic materials are multi-component solids with simultaneous characteristics of both a solid and a liquid. Above a critical temperature associated with a structural phase transition, they exhibit liquid-like ionic conductivities and dynamic disorder within a rigid crystalline structure. Broad applications as electrochemical storage materials and resistive switching devices follow from this abrupt change in ionic mobility, but the microscopic pathways and speed limits associated with this switching process are largely unknown. Here we use ultrafast X-ray spectroscopy and scattering techniques to obtain an atomic-level, real-time view of the transition state in copper sulphide nanocrystals. We observe the transformation to occur on a twenty picosecond timescale and show that this is determined by the ionic hopping time.
超离子材料是具有固体和液体双重特性的多组分固体。在与结构相转变相关的临界温度以上，它们表现出类似于液体的离子电导率和刚性晶体结构内的动态无序。这种离子迁移率的突然变化带来了电化学储能材料和电阻开关器件的广泛应用，但与这种开关过程相关的微观途径和速度限制在很大程度上仍是未知的。在这里，我们使用超快 X 射线光谱和散射技术，从原子级实时观察到硫化铜纳米晶体中的过渡态。我们观察到转变在二十皮秒的时间尺度上发生，并表明这是由离子跳跃时间决定的。
