Electron Microscopy Study of Organic Intercalation Complexes in NbSe₂

Abstract

There has been much interest recently in transition metal dichalcogenides with layer structures, primarily as a result of the superconductivity exhibited by many of these compounds. The structural, optical and electrical properties of the group as a whole have been reviewed by Wilson and Yoffe¹. Considerable effort has been devoted to the study of complexes formed by intercalation of these materials with organic molecules² and alkali metals^3,4. Such controlled introduction of foreign species into the Van der Waals gap between the layers of the host chalcogenide affords a potentially powerful means of altering their optical and electrical properties. For example, the superconducting transition temperature in 2H TaS₂ is increased from 0.8 K to 3.5 K on intercalation with pyridine⁵, although with most materials based on group V metals, T_c is depressed following intercalation.