Ternary chalcogenides of vanadium and chromium

A Powder Neutron Diffraction Study of the Magnetic Structure of FeV2S4

“…These observations indicate that electrons reside in narrow bands. This is consistent with the suggestion of Holt et al (31) that the delocalized nature of the electrons associated with the VS unit arises from the formation of a narrow band derived from direct overlap of cation t g orbitals which, for a formal oxidation state of V(III):d, is incompletely "lled. Substitution of ca.…”

A Powder Neutron Diffraction Study of Structure and Magnetism in NiCr2S4

“…Activation energies derived from a simple activated conduction plot are similar to those previously obtained for Cr S -type phases (8,9). However, the material clearly lies close to the metal-insulator divide and data suggest that a further electronic transition may occur at higher temperatures ('300 K).…”

Phase behaviour, magnetic and electronic properties in the series Co1 − xNixCr2S4 (0 ≤ x < 1)

“…One-electron one-molecule energy level diagrams for AB 2 S 4 materials with the spinel 32 and Cr 3 S 4 33 structures show that metallic behaviour can result from direct overlap of the t 2g orbitals, or from the formation of partially ®lled narrow energy bands of antibonding s A * or s B * states, produced by covalent mixing of cation d states and anion s and p states. In ACr 2 S 4 materials, the Cr±Cr distances are always larger than R c , the critical distance for t 2g direct orbital overlap, leading to localisation of the t 2g states.…”