Using the strenght of R-R interactions deduced from the ordering temperatures of RNi2
compounds, the R-T exchange-coupling parameter (ART) in RmTn (R = rare earth, T = Co or Fe, m / n = 1
2; 1 3; 6 23; 1 5; 2 17; 1 12) and RmTnBk (m / n / k = 1/4/1; 2/14/1; 1/12/6) systems has been evaluated
from analyses of Curie temperatures. Whereas ARR, as deduced from the RNi2 compounds, increases by
almost an order of magnitude in a given series, ART is enhanced by a factor of only about three from the
heavy to the light rare earth compounds. These phenomena, already reported in literature, are based on 4f-5d
exchange interactions at R sites. In addition, for a given rare earth element, going from T-poor to T-rich
compounds, a tendency to decrease is found for both ARCo and ARFe; this variation is discussed in terms of
3d-5d hybridization. ?? 1993.
