Grain size effect on electrical properties of Ag6PS5I-based ceramic materials

Micro- and nanocrystalline powders were prepared by grinding of pre-synthesized Ag6PS5I in an agate mortar and a planetary ball mill, which were further investigated using XRD and SEM methods. Appropriate ceramic materials in the form of disks with a relative density of (91…94) ± 1% of the theoretical one were made using the cold pressing method for the obtained powders with subsequent annealing at the temperature 923 K. The values of the ionic and electron components of the total electrical conductivity were obtained analyzing the corresponding frequency dependences of the total electrical conductivity on the Nyquist plots using electrode equivalent circuits. It has been ascertained that reduction of crystallite sizes in Ag6PS5I-based ceramic materials leads to a slight increase in ionic conductivity and a significant increase in the electronic one, resulting in a decrease of the ratio between them.