Chemically-invariant percolation in silver thioarsenate glasses and two ion-transport regimes over 5 orders of magnitude in Ag content

Ionic conductivity σ i measurements of AgY−As 2 S 3 (Y = Br, I) glasses, covering 13 orders magnitude in ( x ) over 5 silver content , confirm two drastically different ion transport regimes halide thioarsenate glasses. As expected, the ionic critical percolation domain, 20 ppm < ≤ at.% Ag, follows a power-law dependence, T ∝ 0 / where temperature is related to connectivity glassy host. Moreover, we show that chemically invariant domain. Three glass families, AgY- and Ag S-As reveal identical within experimental uncertainty three . The diverges modifier-controlled region, > 7-10 difference between AgI- glasses approaches 4 magnitude. Random distribution shown by DFT modeling neutron high-energy x-ray diffraction data, key observed invariance. When cation leaves residence site travels throughout network, characterized average Ag-Ag separation distance 12 Å or more, memory its original chemical form (sulfide halide) vanishes rapidly with increasing mean square displacement. A non-random modifier controlled region implying formation preferential conduction pathways via direct contacts edge- corner-sharing chalcogenide chalcohalide polyhedra rules out this possibility. Chemically-invariant seems be common feature any disordered system random mobile ions having similar size charge carriers.