Magnetocaloric effect in Tb-5(SixGe1-x)(4)

The magnetocaloric effect has been investigated in a series of the R-5(SixG e1-x)(4) pseudobinary alloys with R=Tb and x=0.0, 0.5, and 1.0. In Tb5Si4 a nd Tb5Ge4, a maximum magnetic entropy change of 9.8 and 3.7 J/kg K, respect ively, has been found at their ordering temperatures for a magnetic field c hange of 50 kOe. In the case of Tb5Ge4, we have observed the existence of a previously unreported magnetic transition below the Neel temperature. Tb-5 (Si0.5Ge0.5)(4) has been successfully synthesized, and a large entropy chan ge of 21.8 J/kg K (DeltaH=50 kOe) is achieved at a first-order para- to fer romagnetic transition, T(C)congruent to 105 K. This study demonstrates that Tb-5(SixGe1-x)(4) alloys are good candidates for magnetic refrigeration an d that very exciting phenomenology in these systems awaits further investig ation. (C) 2001 American Institute of Physics.