Mossbauer study of iron sulfides doped with 3d-transition metals

It is found by Mossbauer measurements on M0.025Fe0.975S (M=Sc, Ti, V, Cr, Mn, Co, Ni, Cu) that the 3d-transition metal impurities profoundly affect both the crystallographic and spin rotation transitions of iron sulfide. It is noteworthy that both V0.025Fe0.975S and Co0.025Fe0.975S have Morin transition temperatures T-M which are distinctly different from that of FeS; furthermore, the directions of changes of T-M are opposite for V0.025Fe0.975S and Co0.025Fe0.975S. A vanadium impurity of 2.5% of the metal atoms in the iron sulfide makes the crystallographic transition take place rapidly in a narrow temperature region of about 15 K, while the a transition in FeS takes place over a wide temperature range of about 200 K. It is also found that the a transition for V0.025Fe0.975S has a hysteresis width of 5 K. (c) 2005 Elsevier Ltd. All rights reserved.