Forced volume magnetostriction in composite Gd5Si2Ge2

Abstract

A -1200 ppm forced volume magnetostriction has been obtained in a [0-3], resin-bonded, Gd5Si2Ge2 particulate composite. The strain is a result of a magnetically induced phase transformation from a high volume (high temperature, low magnetic field) monoclinic phase to a low volume (low temperature, high magnetic field) orthorhombic phase. The particles used in the composite were ball-milled from a bulk sample and sieved to obtain a size distribution of ≤600 mm. Bulk Gd5Si2Ge2 was manufactured via arc melting and subsequently annealed at 1300°C for 1 hour to produce a homogenous, polycrystalline sample. The transformation temperatures of the bulk sample, as measured using a Differential Scanning Calorimeter (DSC), were Ms = -9.3°C, Mf = -14.6°C, As = -4.4°C, and Af = -1.2°C. The composite and the bulk samples were magnetically characterized using a SQUID magnetometer, and found to undergo a paramagnetic to ferromagnetic transition during the phase transformation, consistent with published results. The bulk sample was also found to possess a maximum linear magnetostriction of -2500 ppm.