Synthesis, structure and magnetic properties of DyAl2 nanoparticles

DyAl2 nanoparticles have been prepared by means of arc discharge in a mixture of argon and hydrogen gas. The structure of DyAl2 nanoparticles is studied by means of X-ray diffraction, X-ray photoelectron spectroscopy, and high-resolution transmission electron microscopy. X-ray photoelectron spectroscopy shows that the as-prepared DyAl2 nanoparticles are coated with a layer of Al2O3 phase on the surface, and their sizes vary from 20 nm to about 100 nm. The DyAl2 nanoparticles exhibit ferromagnetic properties that are different from bulk DyAl2 compound. The gradual decrease of the magnetization with increasing temperature in a wide temperature range reveals the size distribution of the DyAl2 nanoparticles. The magnetic-entropy changes are derived from the isothermal magnetization curves measured at different temperatures. The magnetic-entropy change of the DyAl2 nanoparticles is lower than that of the bulk DyAl2 material but has a broadened peak.