Thermal expansion anomalies and spontaneous magnetostriction in R 2Fe 17C x intermetallic compounds

Abstract

The influence of interstitial solution of carbon on the spontaneous magnetostriction of R 2 Fe 17 ( R = Y, Tb, Tm) has been investigated by means of X-ray dilatometry in the temperature range 5–800 K. The basal-plane linear deformation λ a at 5 K increases with increasing C content for R = Y and Tb, whereas the uniaxial deformation λ c remains practically the same. In the Tm compounds both deformations increase with increasing C content. The volume effect ω s increases from 1.1 × 10 -2 to 2.0 × 10 -2 in the Y series, reaching similar values as in R 2 Fe 14B compounds, despite the fact that the average magnetic moment of Fe atoms μ Fe does not change with increasing C content. Similar behaviour is found in the Tb and Tm compounds. For all compounds studied, the temperature dependence of ω s is in a good agreement with μ 2 Fe( T) in Y 2Fe 17, which points to a dominating contribution of the Fe sublattice to the spontaneous magnetostriction.