Magnetocaloric effects on TbCo3-XAlX compounds

The TbCo3-xAlx compounds with x < 1 crystallize in a rhombohedral structure having R (3) over barm space group. The saturation magnetizations, at 4.2 K, increase as cobalt is replaced by aluminium from 3.8 mu(B)/f.u. (x=0) to 6.14 mu(B)/f.U. (x=1) in agreement with antiparallel ordering of Tb and Co sublattices. The magnetic behaviour of cobalt was analyzed in the spin fluctuation model. The adiabatic magnetic entropy changes, vertical bar Delta S vertical bar, were determined from magnetization data. The largest magnetic entropy change, vertical bar Delta S vertical bar(max), was obtained for the sample with x=0.99 which have the Curie temperature around 300 K.