Preparation, crystal structure, magnetic and magnetothermal properties of (GdxR5-x)Si-4, where R=Pr and Tb, alloys

The series of alloys (GdxTb5-x)Si-4 (x=0,2.5,3,3.5,4,4.5,5) and (GdxPr5-x)S i-4 (x=4,4.25,4.5) have been prepared. Their room temperature crystal struc ture has been established, and dc magnetization and ac magnetic susceptibil ity have been measured in the temperature range from 4.2 to 550 K and in dc magnetic fields up to 50 kOe. The magnetocaloric effect has been calculate d from the magnetization data and, for one of the alloys, from the heat cap acity data. The magnetocaloric effect values from the two different measure ments are in excellent agreement. The (GdxTb5-x)Si-4 alloys exhibit magneto caloric effects in low magnetic fields (<20 kOe) comparable to that of Gd m etal and, therefore, they represent a new class of promising magnetic refri gerant materials. (C) 2001 American Institute of Physics.