Structural and magnetic properties of Pr-3(Fe1-xCox)(27.5)Ti-1.5 (x = 0.0,0.1, 0.2, 0.3)

A novel class of Go-substituted 3:29 materials, Pr-3(Fe1 - xCox)(27.5)Ti-1. 5 (x = 0, 0.1, 0.2, 0.3) have been synthesized. Rietveld analysis of X-ray powder diffraction patterns for the x = 0, 0.1 and 0.2 compositions showed that nearly all of the compounds are formed in monoclinic symmetry, with A2 /m space group with traces of alpha-Fe, whereas, in x = 0.3, additional tra ces of a (Co/Fe)-Ti (1 : 12) phase are also seen. The saturation magnetizat ion increases with Co concentration both at 5 and 300 K and is explained on the basis of a rigid band model. A magnetic transition is observed for x = 0.1 near 240 K. A large increase in Curie temperature, of about 180 K for x = 0.1 and about 110 K for the other concentrations, is discussed on the b asis of the strengthening of TM-TM exchange by the preferential occupation of Co in some of the Fe sites originally participating in antiferromagnetic bonds. (C) 1998 Elsevier Science B.V. All rights reserved.