A new intercalated iron sulfide (C 2 H 8 N 2 ) 0.4 Fe 2 S 2 from solvothermal route: Synthesis, structure and tunable magnetism

Abstract In this work, a new intercalated FeS compound: (C 2 H 8 N 2 ) 0.4 Fe 2 S 2 was synthesized via the solvothermal route. The product is stable in air and shows the micron-sized plate shape. Structure refinement indicates that (C 2 H 8 N 2 ) 0.4 Fe 2 S 2 adopts the I 4/ m space group with the lattice constants a  = 3.6906(6) and c  = 20.4215(11) A. The [FeS] layer crystallizes into the anti-fluorite structure with edge-sharing tetrahedrons and the C 2 H 8 N 2 molecules are inserted in between the layers. (C 2 H 8 N 2 ) 0.4 Fe 2 S 2 is the first intercalated FeS compound reported up to now that contains the electroneutral guest layers. This specific feature leads to the paramagnetic behavior without any magnetic transition in the measured temperature range. Furthermore, we find that the ferromagnetic interaction can also be easily induced in this compound by inserting the extra Fe in between the layers, indicating the controllable magnetism of the title compound. The absence of superconductivity in (C 2 H 8 N 2 ) 0.4 Fe 2 S 2 is mainly due to the external pressure on FeS layers induced by En intercalation.