MAGNETIC, MAGNETOCALORIC AND ELECTRICAL PROPERTIES IN BULK NANOCRYSTALLINE Gd METALS

摘要

Magnetic, magnetocaloric, electrical properties of nanocrystalline and coarse-grained gadolinium (Gd) metals were compared in the present work. The bulk nanocrystalline matels have been consolidated from Gd nanoparticles using spark plasma sintering technique. With the decrease of Gd grain size from micrometer to nanometer range, Curie temperature of the nanocrystalline Gd shifts by more than 6 K below that of coarse-grained and the magnetic moment per Gd atom at 5 K dropped noticeably from 7.81ub to 6.31ub. Magnetic entropychange of crystalline Gd drops surprising from 10.07 to 4.47 Jkg~(-1)- K~(-1) at ΔH=5 T; adiabatictemperature change drops from 3.5 K to 1.1 K with ΔH=1.5 T. However, magnetocaloriceffect of the nanocrystalline metals exhibit a more constant tendency. The room temperature electrical resistivity increases from 209.68 to 333.04 uΩ cm, while the low temperature electrical resistivity is found to increase surprisingly from 16.51 to 126.30 uΩ cm.