The substitution of vanadium by chromium in thallium pentavanadium octasulfide. Part III. Magnetic properties

The investigation of the magnetic properties of the substitution series TIV5−yCryS8 (1≤y≤4) revealed a complex magnetic behaviour due to the successive formation of Cr2-dimers. The Cr atoms within the dimers are antiferromagnetically coupled and with raising Cr content the coupling constant becomes more negative indicating stronger antiferromagnetic exchange interactions. The magnetic behaviour is further characterized by a Curie-Weiss like contribution from nearly isolated Cr atoms and a temperature independent paramagnetism (TIP) from delocalized conduction electrons. With increasing substitution of V by Cr the TIP decreases and the magnetic moment per Cr atom increases. In addition, the evaluation of the magnetic susceptibilities gives hints for a preferential occupation of the three different crystallographic sites by the Cr atoms.