KINETIC-PROPERTIES OF INTERCALATES AGXTAS2
Abstract The diffusion of the mobile silver ions in intercalates Ag x TaS 2 with electronic as well as ionic conduction was studied at temperatures above 440 K in a three electrode cell with AgI as solid electrolyte. Use was made of ac response and the galvanostatic intermittent current titration technique (GITT). Experiments were performed with samples prepared from the elements. ac response and GITT showed superionic conduction of silver ions in stage-1 Ag x TaS 2 (0.55⩽ x ⩽0.68) and stage-2 Ag x TaS 2 (0.22⩽ x ⩽0.35). The chemical diffusion coefficient, D , of silver for stage 1 from ac response is 7.5×10 −5 cm 2 s −1 at 500 K; the activation energy of D is 0.13 eV. D of the stage-2 phase, about 10 −6 cm 2 s −1 at 500 K, is smaller than in stage 1. The kinetics of intercalation in the stage-2 phase is slow, also because of the formation of a reaction layer at the interface with AgI. An island type domain structure for the stage-2 phase in which diffusion is accompanied by shear transformation might explain the much slower diffusion of silver in the stage-2 phase compared to diffusion in stage 1.