ESTIMATION OF THE EXCHANGE CONSTANTS IN THE FE SUBLATTICE OF THE Y2FE17 AND Y2FE17N3-DELTA COMPOUNDS FROM THE ANALYSIS OF MOSSBAUER MEASUREMENTS

From the analysis of Mossbauer data for Y2Fe17 and Y2Fe17N3-delta at various temperatures the hyperfine fields for 4f, 6g, 12j, 12k iron sites were estimated as a function of temperature. The reduced magnetizations calculated from the values of the hyperfine fields are fitted with a mean field model for four interacting sublattices using a computer program. The estimated exchange interaction from the fitting procedure between the 4f sites is found strongly negative (antiferromagnetic) in Y2Fe17 whereas in Y2Fe17N3-delta it increases and becomes weak negative following a modified Slater-Neel curve. The rest of the exchange interactions are found positive or weak negative depending on the distances between the Fe atoms.