Doping effects on structural and magnetic evolutions of orthoferrite SmFe_(1−x)Al_xO₃

The structural and magnetic properties of SmFeO₃ with B site substitution of non-magnetic atom Al are investigated. The x-ray diffraction patterns show that SmFe_(1−x)Al_xO₃ remains an orthorhombic structure within the whole doping range, and the unit-cell volume decreases monotonically with the increase of doped Al concentration. Besides, the octahedral tilting distortions of FeO₆ are found to be alleviated while the tolerance factor increases. However, the relationship between the lattice parameters and Al concentration is observed to deviate from Vegard's rule, and this may be caused by magnetostriction effects. For the doping content values in a range 0 ≤ x ≤ 0.6, the ferromagnetism, antiferromagnetism, and paramagnetism are observed to occur continuously. Moreover, the magnetization and the spin reorientation temperature (T_k) decrease monotonically as Al content value increases. With the doping content values being x = 0.8 and 1.0, these compounds only show paramagnetic behavior.