Pseudo-Polymorphism in Layered FeS Intercalates: A Competition between Charged and Neutral Guest Species

Abstract

Systematic synthesis studies of the formation of tetrahedral FeSethylenediamine intercalates resulted in the synthesis of a new compound, [Fe 9.4(2) S 10 ][Fe(en) 3 ] 0.6(1) •en 0.9(3) . The composition and complex crystal structure were determined based on a synergistic combination of elemental composition, decomposition behavior, high-resolution synchrotron X-ray diffraction and total scattering, 57 Fe Mossbauer spectroscopy, and electron diffraction. The structural model was derived based on a systematic comparison to the previously reported structures [Fe 8 S 10 ][Fe(en) 3 ] 1 •en 0.5 and tetragonal FeS. The new compound has flat Fe 9.4 S 10 layers, analogous to those in superconducting binary FeS. In the crystal structure of [Fe 9.4 S 10 ][Fe(en) 3 ] 0.6 •en 0.9 , the interlayer space is occupied by [Fe(en) 3 ] 2+ complexes and neutral ethylenediamine molecules in a ∼2:3 ratio. Interlayer species are not randomly oriented but ordered as evidenced by superstructural diffraction peaks in both high-resolution Xray diffraction and electron diffraction patterns. Magnetic studies reveal no superconducting transition down to 2 K, indicating that the presence of minute amounts (∼6%) of iron vacancies at the Fe-S layer in [Fe 9.4 S 10 ][Fe(en) 3 ] 0.6 •en 0.9 is still sufficient to shift the position of the Fermi level resulting in an adjustment of the properties. Our work shows the importance of detailed characterization of the crystal structure of intercalated compounds to understand the origin of the observed properties and develop proper structure− property relationships.

Twisting two-dimensional iron sulfide layers into coincident site superlattices via intercalation chemistry

“…This unit cell dimensions are in close agreement with literature reports on alkali metal and alkali metal-free ethylenediamine intercalated FeS. 14,15,24,59 There is one impurity peak seen in the PXRD due to excess Fe powder remaining from the in situ growth of FeS layers. To avoid excess Fe, we attempted syntheses using pre-reacted tetragonal FeS at 120 °C over 2–6 days, but were unsuccessful.…”

“…, semiconducting transition metal dichalcogenides) and because it is known to host a variety of guest species. For example, one can insert into its interlayer galleries alkali metal ions, 12 amines, 13 metal amine complexes, 14–16 and metal hydroxide layers. 17 This intercalation chemistry goes beyond a synthetic interest too.…”

Inducing Ferrimagnetic Exchange in 1D-FeSe2 Chains Using Heteroleptic Amine Complexes: [Fe(en)(tren)][FeSe2]2

“…The intercalation chemistry of larger organic–inorganic spacer molecules, such as ammonia, hydroxides, and linear diamines, in the interlayer space of Fe Q superconductors has been thoroughly investigated. − In certain instances, intercalation led to the occurrence of vacancies in the layers and loss of superconductivity, giving rise to moderate AFM nearest-neighbor interactions between Fe atoms in adjacent tetrahedra. − The same structural design was applied to 1D Fe chalcogenide chains to study the impact of host–guest interactions on the magnetic properties due to structural rearrangements. Distortion in the FeSe 2 chains was found to correlate with the type and strength of the intra chain magnetic interactions.…”

Tunable Salt-Inclusion Chalcogenides for Ion Exchange, Photoluminescence, and Scintillation

“…Advances in synthetic chalcogenide chemistry have accelerated the discovery of functional materials as well as stimulated the development of numerous technological applications for these materials, all helped by an increased understanding of composition–property relationships. , Chalcogenide-based compounds occupy a unique position in material chemistry due to the soft nature of the chalcogen elements and emerging covalent metal chalcogenide bonding, which results in a rich and diverse crystal chemistry. , In fact, the electronic structure of chalcogenide materials favors their applications as quantum materials, catalysts, ion-exchange materials, ion-conductors, luminophores, thermoelectric materials, and semiconductors. − Recent advances in developing convenient synthetic approaches have enabled the rational synthesis of new functional chalcogenide-based materials containing a wide range of elements, resulting in various material types, ranging from nanoparticles to large single crystals of pure inorganic compositions and hybrid structures. − Another new material type that has emerged from these investigations is salt-inclusion chalcogenide materials (SICs) , that exhibit novel framework topologies and possess ionic inserts (salt-inclusions).…”