Freestanding and flexible composites of magnetocaloric Gd5(Si,Ge)4 microparticles embedded in thermoplastic poly(methyl methacrylate) matrix.

The implementation of processed magnetic materials onto thermoplastics can be an approach for practical use of brittle intermetallic materials on device development with the advantage of enlarging the range of applications. In this paper, we present the evaluation on the effect of blending magnetocaloric Gd 5 Si 2.4 Ge 1.6 3.4 μm particles with in different weight fractions onto a flexible, transparent and non-magnetic poly(methyl methacrylate) (PMMA). A close to homogeneous grain distribution along the polymer surface were achieved by using a simple solvent casting method for their magnetocaloric properties studies. From XRD analysis, it was found a unit cell volume shrinkage by increasing the powder concentration followed by a reduction on the amount of secondary monoclinic phase as a result of interfacial interactions. As a consequence, a weakening of secondary phases effect on the composite magnetocaloric behavior is observed as a result of the effective hydrostatic pressure from the difference between thermal expansions of matrix and filler. Unlabelled Image • Particle size reduction of Gd 5 Si 2.4 Ge 1.6 bulk to 3.4 μm increases the detection on the amount of distorted monoclinic phase. • The solvent casting technique allows a close to homogeneous dispersion of the micropowder along the composite volume. • Inclusion of the micropowder into the thermoplastic converts the monoclinic phase into an orthorhombic-I phase. • PMMA matrix works as a pressure cell for the micropowder leading to a reduction on the magnetocaloric response of the monoclinic phase. [ABSTRACT FROM AUTHOR]