Thermal-expansion anomalies and spontaneous magnetostriction of Lu2Fe17-xSix intermetallic compounds

The thermal expansion of Lu(2)Fe(17-x)Si(x) solid solutions has been measured by X-ray powder diffraction. The magnetic ordering in all compounds within the homogeneity range (x <= 3.4) is accompanied by a large spontaneous volume magnetostriction, distributed anisotropically over the principal axes of the hexagonal crystal structure. The volume effect omega(s) in the ground state reaches 14.7 x 10(-3) in Lu(2)Fe(17) and decreases monotonously to 8.9 x 10(-3) for x 3.4, following the reduction of magnetic moment. Despite a still large os, the Invar behavior observed in Lu(2)Fe(17) changes to a positive thermal expansion for x > 1 due to an increasing Curie temperature. (c) 2008 Elsevier B.V. All rights reserved.