Effects of vanadium impurities on the crystallographic and spin-rotation transitions of iron sulfide

It is found by M\"ossbauer measurements on VₓFe_1-xS that the vanadium impurities profoundly affect both the crystallographic and spin-rotation transitions of iron sulfide. When the vanadium concentration is increased to 2.5% of the metal atoms, the crystallographic α transition proceeds an order of magnitude more rapidly than for iron sulfide, and the separation between the spin rotation and the α-transition temperatures increases by as much as 114 K compared with that for iron sulfide. The Morin transition temperature for V0.025{Fe}0.975$S was measured as 486 K, which is 86 K higher than the ${α}$-transition temperature. It was also found that the ${α}$ transition for ${V}0.025Fe0.975S has a hysteresis width of 4 K.