Magnetic and crystallographic properties of SmMn6-xFe xGe6 intermetallics

The magnetic and crystallographic properties of induction-melted SmMn_6-xFe_xGe₆ compounds, where x is 0, 0.5, 1.0, and 1.5, have been studied using X-ray diffraction and bulk magnetic measurements between 30 and 490 K. All of the samples crystallized in the YCo₆Ge₆-type structure with the space group P6/mmm. A small amount, less than 9 mol%, of Sm(MnFe) ₂Ge₂ was present as an impurity in all samples. The unit cell volume decreases with increasing iron content at an average rate of 2.4% per substituted atom at room temperature. The a and c lattice parameters decrease at an average rate of 1.1 and 0.1% per substituted atom at room temperature, respectively. The magnetic properties deteriorate rapidly as the iron concentration increases beyond x=0.5. Magnetic behavior of SmMn₅Fe₁Ge₆ and SmMn_4.5Fe _1.5Ge₆ is indicative of antiferromagnetic or ferrimagnetic coupling. According to X-ray diffraction patterns of magnetically aligned powders, the easy direction of magnetization at room temperature for all of the samples lies close to the basal plane of the unit cell