Enhanced refrigerant capacity in Gd-Al-Co microwires with a biphase nanocrystalline/amorphous structure

"A class of biphase nanocrystalline/amorphous Gd(50+5x)Al(30-5x)Co20 (x = 0, 1, 2) microwires fabricated directly by melt-extraction is reported. High resolution transmission electron microscopy and Fourier function transform based analysis indicate the presence of a volume fraction (similar to 20%) of similar to 10nm sized nanocrystallities uniformly embedded in an amorphous matrix. The microwires possess excellent magnetocaloric properties, with large values of the isothermal entropy change (-Delta S-M similar to 9.7 J kg(-1) K-1), the adiabatic temperature change (Delta T-ad similar to 5.2K), and the refrigerant capacity (RC similar to 654 J kg(-1)) for a field change of 5 T. The addition of Gd significantly alters T-C while preserving large values of the Delta S-M and RC. The nanocrystallites allow for enhanced RC as well as a broader operating temperature span of a magnetic bed for energy-efficient magnetic refrigeration.