Structure and magnetic properties of TbMn6-xTixSn6

TbMn6-xTixSn6 compounds with x = 0, 0.5, 1.0, 1.5 and 2.0 have been studied in this paper. All compounds crystallize in the HfFe6Ge6-type structure (space group, P6/mmm). The substitution of Ti for Mn in TbMn6Sn6 results in a linear increase in the lattice constants and the unit-cell volume from a = 5.531 Angstrom, c = 9.025 Angstrom and V = 239.10 Angstrom(3) at x = 0, to a = 5.588 Angstrom, c = 9.150 Angstrom and V = 247.44 Angstrom(3) at x = 2.0. The ordering temperature and the reorientation temperature of the easy axis of these compounds decrease monotonically with Ti content from 423 K and 330 K at x = 0 to 362 K and 285 K at x = 2.0. In thermal magnetic curves a new transition was found at the temperature T-f at which the magnetization begin to increase and T-f increases from 37 K at x = 0 to 150 K at x = 2.0. The saturation magnetization at room temperature decreases linearly with increasing Ti content. The magnetization curves at 1.5 K in fields up to 70 kOe are given and the magnetization values at 1.5 K are derived from them.