SEM and EDXS analysis of the reaction products of compounds A_xM₆X₈ (A = Tl, K; M = V, Ti; X = S, Se) with I₂/CH₃CN and H₂O

Abstract

The ternary transition metal chalcogenides A_xM₆X₈ (A=Tl, K; M=V, Ti; X=S, Se) build up a three dimensional framework with large hexagonal channels running parallel to the crystallographic c-axis. The electropositive elements thallium or potassium are confined within these channels. It is possible to remove the Tl or K atoms via a chemical redox reaction with an I₂/CH₃CN solution or with H₂O. Using SEM it is demonstrated that the host matrix “V₆S₈” is only slightly affected by the redox agent. In contrast the host matrix “Ti₆Se₈” of Tl_xTi₆Se₈ reacts with the I₂/CH₃CN solution. The results of the EDXS analyses clearly show that the removal of the electropositive elements proceeds only along the large channels and not through the host matrix.