Preferential site occupation of Fe and Co atoms in Nd2(Fe1-x, Cox)14B

The site preference of iron and cobalt atoms in Nd2(Fe,Co)14B and the local magnetic properties are examined by Mossbauer spectroscopy for specimen of (Fe1-xCox)75Nd16.5B8.5(x= 0\sim1). From the measurement of relative intensities of resonant⁵⁷Fe nuclei in the six sites, it is concluded that iron atoms preferentially occupy j1, and j2 sites and, instead, cobalt atoms k1 and k2 sites. The internal magnetic field of each site sharply decreases between x=1/3 and 1/2 of the specimens, suggesting the local magnetic moment of iron changes at this concentration range. For iron at the j2 site the largest values of internal magnetic field and quadrupole coupling (positive) are observed and most remarkable changes occur among the six sites. This behavior is interpreted to be caused by the effect of the special surroundings of the j2 site, the existence of the two hexagons of iron and cobalt atoms at the nearest positions.