a nersesse@ucla.edu; phone 1 310 825-9564; fax 1 310 206-2302; b swor@seas.ucla.edu; phone 1 310 825-9564; fax 1 310 206-2302; c carman@seas.ucla.edu; phone 1 310 825-6030; fax 1 310 206-2302; d mcall10@llnl.gov; phone 1 925 422-1499; fax 1 925 422-4665; e choe1@llnl.gov; phone 1 925 422-8717; fax 1 925 423-0238; f radousky1@llnl.gov; phone 1 925 422-4478; fax 1 925 423-0238; g vitkp@ameslab.gov; phone 1 515 294-8220; fax 1 515 294-9579; h pecharsky@ameslab.gov; phone 1 515 294-2728; fax 1 515 294-9579
ABSTRACTA -1200 ppm forced volume magnetostriction has been obtained in a [0-3], resin-bonded, Gd 5 Si 2 Ge 2 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 m. Bulk Gd 5 Si 2 Ge 2 was manufactured via arc melting and subsequently annealed at 1300 o 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 M s = -9.3 o C, M f = -14.6 o C, A s = -4.4 o C, and A f = -1.2 o 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.