Shape-controlled microwave hydrothermal synthesis of antiferromagnetic GdVO4 nanowires for magnetocaloric materials

GdVO4 nanowires have been fabricated by a microwave-assisted hydrothermal method with the addition of EDTA (ethylenediaminetetraacetic acid) during synthesis. The GdVO4 nanowires have a lower antiferromagnetic (AFM) ordering temperature (T-N) and effective magnetic moment mu (eff) than them of bulk GdVO4. In a field-cooled mode, upward magnetization was found below T-N in the magnetization-temperature measurements because of surface effects, where uncompensated surface spins were not ordered as AFM states. With a magnetic field change of 5 T, the maximum value of magnetic entropy change (- Delta S-M(max)) is 35.77 J kg(-1) K-1 at 2.3 K and the relative cooling power is 211.04 J kg (-1) with no hysteresis loss. The nanocrystalline GdVO(4 )nanowires produce a significant reversible magnetocaloric effect (MCE) and can be applied to hydrogen liquefaction as a cryogenic MCE material.