Spontaneous volume magnetostriction in R 2Fe 14B compounds

Abstract

We have measured the thermal expansion in ternary compounds of the type R 2Fe 14B (R  La, Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er and Lu) in the temperature range 4.2–1000 K. Data were also obtained above room temperature for Th 2Fe 14B. At temperatures well above the corresponding Curie temperatures we found a linear high temperature slope of Δ l l equal to α = 16 × 10 −6 K −1, excepting Ce 2Fe 14B for which the slope was slightly higher ( α = 20 × 10 −6 K −1). The spontaneous volume magnetostriction derived from our data extends to temperatures considerably above the corresponding Curie temperatures. The spontaneous volume magnetostriction at 4.2 K ranges from 2.5% to 3.5% in the various compounds investigated and consists of contributions due to the iron sublattice and the rare earth sublattice.