Influence of recrystallization process on ionic conductivity of Ag6.75P0.25Ge0.75S5I based ceramic materials

This paper presents the results of research on ceramic materials based on Ag6.75(P0.25Ge0.75)S5I nanopowders with different grain size. Nanopowders with an average grain size of ∼100 and ∼160 nm, obtained by ball mill grinding, were characterized by XRD, SEM and diffuse reflectance methods. Ag6.75(P0.25Ge0.75)S5I ceramic samples were obtained by annealing pre-pressed disks at a pressure of 400 MPa. The microstructure and chemical composition of the obtained Ag6.75(P0.25Ge0.75)S5I ceramics were determined by SEM and EDS methods. The prepared Ag6.75(P0.25Ge0.75)S5I ceramics are chemically homogeneous with an average crystallite size of ∼1.99 and ∼2.29 μm and a low porosity of ∼6.4%. The electrical parameters of the investigated ceramics were characterized by the electrochemical impedance spectroscopy method. For both ceramics, there is an increase in total electrical conductivity with increasing frequency. It was established that the values of ionic conductivity of nanoceramic samples exceed the corresponding value of the bulk single crystalline sample. The influence of the recrystallization process and grain size on the electrical parameters of Ag6.75(P0.25Ge0.75)S5I ceramics is explained.