SEM and EDXS analysis of the reaction products of compounds AxM6X8 (A = Tl, K; M = V, Ti; X = S, Se) with I2/CH3CN and H2O

Abstract

The ternary transition metal chalcogenides AxM6X8 (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 TlxTi6Se8 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.