Magnetic and structural properties of Nd2Fe17−xMnx solid solutions

A series of ${\mathrm{Nd}}_{\mathrm{2}}{\mathrm{Fe}}_{\text{17−x}}{\mathrm{Mn}}_x$ solid solutions with $x$ values between 0 and 6 were prepared and analyzed using magnetic measurements, neutron diffraction, and Mössbauer spectroscopy. All of the ${\mathrm{Nd}}_{\mathrm{2}}{\mathrm{Fe}}_{\text{17−x}}{\mathrm{Mn}}_x$ samples crystallized in the ${\mathrm{Th}}_{\mathrm{2}}{\mathrm{Zn}}_{\text{17−x}}$ -type rhombohedral structure. The lattice parameters and unit cell volumes decrease with increasing manganese content up to $\mathrm{\sim x}$ equal to 2, and then increase for higher manganese content. The magnetizations of ${\mathrm{Nd}}_{\mathrm{2}}{\mathrm{Fe}}_{\text{17−x}}{\mathrm{Mn}}_x$ decrease with increasing manganese content and ${\mathrm{Nd}}_{\mathrm{2}}{\mathrm{Fe}}_{\text{17−x}}{\mathrm{Mn}}_x$ is paramagnetic at room temperature for $x$ greater than 3. The Curie temperature in ${\mathrm{Nd}}_{\mathrm{2}}{\mathrm{Fe}}_{\text{17−x}}{\mathrm{Mn}}_x$ solid solutions is maximum for $x$ equal to 0.5 and decreases at a rate of ∼10° per substituted manganese up to $x$ equal to 3, after which it drops sharply. These results are discussed in terms of the manganese site occupancies in ${\mathrm{Nd}}_{\mathrm{2}}{\mathrm{Fe}}_{\text{17−x}}{\mathrm{Mn}}_x.$