Structure and magnetic properties of TbFe 6−xGa 6+x compounds

Abstract

The TbFe 6 −x Ga 6+ x compounds ( x=0, 0.5, 1.0 and 1.45) have been prepared and studied by X-ray powder diffraction and magnetization measurements. The structure of the compound TbFe 6 −x Ga 6+ x transfers from the orthorhombic ScFe 6Ga 6-type structure (space group Immm) ( x=0 and 0.5) to the tetragonal ThMn 12-type structure (space group I4/mmm) ( x=1.0 and 1.5) and the volume of the unit cell increases as Ga content increases. The lattice parameters are a=0.85551, b=0.8626 and c=0.50717 nm for TbFe 6Ga 6, and a=0.86938 and c=0.50918 nm for TbFe 4.55Ga 7.45. The magnetization measurements indicate all the TbFe 6 −x Ga 6+ x compounds have magnetic ordering. The Curie temperatures decrease from 492 K for TbFe 6Ga 6 to 327 K for TbFe 4.55Ga 7.45. The magnetization of the TbFe 6−x Ga 6+ x decreases with temperature decreases below its magnetic ordering temperature due to the increasing Tb-sublattice magnetization which is antiparallel to the Fe-sublattice magnetization.