Structure and properties of MnNi$_{1-x}$Fe$_x$Ge (0.10 $\le x\le$ 0.25)

The magnetic and structural characteristics of the solid solutions MnNi$_{1-x}$Fe$_x$Ge (0.10 $\le x\le$ 0.25) have been investigated. At $T$ = 290 K, the solid solutions have a hexagonal structure of the Ni$_2$In type. The magnetic properties of MnNi$_{1-x}$Fe$_x$Ge (0.10 $\le x\le$ 0.25) weakly depend on the type of heat treatment. Based on the magnetometric and Mössbauer data, it has been found that, in the solid solutions MnNi$_{1-x}$Fe$_x$Ge (0.10 $\le x\le$ 0.25) with iron concentrations $x$ = 0.10–0.15, the iron atoms are statistically distributed over the octahedral and trigonal-bipyramidal positions. At concentrations above $x$ = 0.15, iron atoms replace only the manganese atoms in the octahedral positions, whereas nickel atoms in the trigonal-bipyramidal positions are not replaced by the iron atoms.