Evidence of Percolation transition in superionic conductor glasses

逾渗理论是解释超离子导体玻璃普遍频率响应的最有希望的理论之一。然而，目前还没有发现真实的玻璃表现出从离子导体到绝缘体的良好的逾渗阈值。在本研究项目中，作者在新开发的有机-无机混合离子导体玻璃如碘化银-烷基碘化铵中发现了从超离子导体到绝缘体的逾渗转变的明显证据。当AgI浓度较高时，玻璃是很好的离子导体，但在阈值φ =0.35以下，电导率低于10^<-8>S/cm，几乎为绝缘体.用中子小角散射研究了玻璃的中程结构，发现玻璃在纳米尺度上具有不均匀结构，其分维为2.8，接近逾渗理论的预测值.

Percolation theory is one of the promising candidates for explaining universal frequency response in superionic conductor glasses. However, there had been found no real glasses exhibiting a good percolation threshold from ionic conductor to insulator.In this research project, authors found a clear evidence of percolation transition from superionic conductor to insulators in newly developed organic-inorganic mixed ionic conductor glasses such as AgI-alkylammonium iodides. At higher concentration of AgI the glasses are very good ionic conductors, however below a thresholdphi=0.35 their conductivities are below 10^<-8> S/cm and are almost insulator.The intermediate range structure of the glasses were investigated by neutron-small angle scattering which revealed the inhomogeneous structure in nano meter scale with fractal dimension 2.8 close to the value predicted by the percolation theory.