Synthesis and Characterization of Diamine Intercalation Compounds of SnS2 Single Crystals

Abstract

Single crystals of SnS2 were intercalated with ethylenediamine (en) and propylenediamine (pn) by direct reaction. The resulting novel compounds were examined by different techniques including XRD, XPS, a.c. impedance, TG, and TPD measurements. The observed lattice expansion for both compounds, ca. 3.9 Å, is consistent with the location of the amine molecules at van der Waals gaps, with monolayers in the alkyl chain parallel to the sulfur layers. XPS data reveal that these complexes easily absorb moisture that binds strongly to sulfur to give hydrogen sulfide traces that were detected upon thermal deintercalation above 473 K. However, the charge transferred from the guest to the host is too small to be detected by this photoelectron technique. The en intercalate preserves the semiconductor behavior of the pristine compound, SnS2, but with two significant differences, viz. lower conductivity at low temperatures and an increased activation energy. These differences are ascribed to increased incoherent scattering of electrons resulting from the guest atoms acting as impurities and also to the lattice defects formed upon intercalation.