Hu T, Wittenberg J S, Lindenberg A M
Department of Materials Science and Engineering, Stanford University, Stanford, CA 94305, USA. Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA.
Nanotechnology. 2014 Oct 17;25(41):415705. doi: 10.1088/0957-4484/25/41/415705. Epub 2014 Sep 24.
Superionic materials are multi-component solids in which one sub-lattice exhibits high ionic conductivity within a fixed crystalline structure. This is typically associated with a structural phase transition occurring significantly above room temperature. Here, through combined temperature-resolved x-ray diffraction and differential scanning calorimetry, we map out the nanoscale size-dependence of the Ag₂Se tetragonal to superionic phase transition temperature and determine the threshold size for room-temperature stabilization of superionic Ag2Se. For the first time, clear experimental evidence for such stabilization of the highly ionic conducting phase at room temperature is obtained in ∼2 nm diameter spheres, which corresponds to a >100 °C suppression of the bulk phase transition temperature. This may enable technological applications of Ag₂Se in devices where high ionic conductivity at room temperature is required.
超离子材料是多组分固体，其中一个子晶格在固定的晶体结构内表现出高离子导电性。这通常与在显著高于室温时发生的结构相变有关。在这里，通过结合温度分辨X射线衍射和差示扫描量热法，我们绘制出了Ag₂Se从四方相到超离子相转变温度的纳米尺度尺寸依赖性，并确定了超离子Ag₂Se在室温下稳定存在的阈值尺寸。首次在直径约2nm的球体中获得了在室温下稳定这种高离子导电相的明确实验证据，这对应于体相转变温度被抑制了>100°C。这可能使Ag₂Se在需要室温下高离子导电性的器件中得到技术应用。
