Structure and magnetic phase diagram of mixed rare-earth Nd1−xTbxFe10.5Mo1.5 compounds

The structural and magnetic properties of Nd1−xTbxFe10.5Mo1.5 (x=0, 0.2, 0.4, 0.6, 0.8, 1.0) compounds have been investigated by means of X-ray diffraction and magnetic measurements. All the investigated compounds crystallize in the tetragonal ThMn12-type structure with I4/mmm space group. The lattice parameters a, c and the unit-cell volume V decrease with increasing x. The Curie temperatures TC are almost independent x. There exists a unique spin-reorientation transition for the end compositions of Nd1−xTbxFe10.5Mo1.5 compounds with x=0 and x=1, while two spin-reorientation transitions are observed for x=0.2-0.8. The room-temperature magnetocrystalline anisotropy of Nd1−xTbxFe10.5Mo1.5 compounds changes from uniaxial to planar with increasing x content. Based on magnetic measurements, a magnetic phase diagram of Nd1−xTbxFe10.5Mo1.5 compounds is constructed. By minimizing the magnetocrystalline anisotropy energy, a theoretical magnetic phase diagram for the Nd1−xTbxFe10.5Mo1.5 system is derived, showing a reasonable agreement with the observations.