Magnetic properties and magnetocaloric effects in amorphous and crystalline Gd55Co35Ni10 ribbons

Achieving table-like magnetocaloric effect and large refrigerant capacity around room temperature in Fe78−xCexSi4Nb5B12Cu1 (x=0–10) composite materials

“…For the magnetic refrigeration based on Ericsson-cycle, a magnetocaloric material (MCM) should possess a constant high ΔS M in the refrigeration temperature range, known as "table-like" MCE, with negligible thermal/magnetic hysteresis [6]. In this context, MCM which undergoes multiple successive magnetic phase transitions may meet these criteria as the presence of magnetic multiphase broadens the ΔS M (T) curve and consequently enhances the refrigeration capacity (RC) [7][8][9].…”

Observation of a Broadened Magnetocaloric Effect in Partially Crystallized Gd60Co40 Amorphous Alloy

“…We found that the maximum magnetic entropy change of Gd 60 Co 40 amorphous alloy (8.3 J•kg −1 •K −1 [17]) was higher than that of Gd 55 Co 35 Ni 10 (6.5 J•kg −1 •K −1 [15]) and Gd 55 Co 35 Mn 10 (6.47 J•kg −1 •K −1 [14]) amorphous counterparts with analogous Curie temperature (T C ). Additionally, according to the Gd-Co binary phase diagram [27], the constituent phases of Gd 60 Co 40 alloy after equilibrium solidification are Gd 4 Co 3 and Gd 12 Co 7 types.…”

“…Nevertheless, the broadened and flatten MCE with |∆S M | values of 6.65 ± 0.1 J•kg −1 •K −1 and 6.44 ± 0.1 J•kg −1 •K −1 within the temperature regions of 180-196 K and 177-196 K observed in samples annealed at 513 K for 40 min and 60 min, enable them to be more suitable for the Ericsson thermodynamic cycle [1]. In comparison with the table-like MCE in other alloys at analogous temperature ranges, such as Gd 55 Co 35 Mn 10 annealed at 600 K for 30 min (|∆S M | of 5.46 J•kg −1 •K −1 with a temperature range from 137 K to 180 K) [14] and fully crystallized Gd 55 Co 35 Ni 10 (620 K/30 min) ribbon (|∆S M | of 5.0 J•kg −1 •K −1 with a temperature range from 154 K to 214 K) [15], as listed in Table 1, the |∆S M | of the materials in this work are larger, but the temperature width of the plateau of |∆S M |-T is narrower. On another hand, when compared with single amorphous phase alloys, like Gd 75 (Fe 0.25 Co 0.75 ) 25 [24] and Gd 50 (Co 69.25 Fe 4.25 Si 13 B 13.5 ) 50 [25], the combined merits of larger or comparative |∆S M | and broader working temperature range can be observed in these Gd 60 Co 40 annealed samples.…”

“…The typical material for the latter group is heat-treated Gd 0.54 Er 0.46 NiAl compounds with hexagonal ZrNiAl-type crystal structure, which exhibit a nearly temperature independent |∆S M | of 13 J•kg −1 •K −1 over the temperature region of 15-45 K for a field change of 0-5.32 T [6]. While, for the former group, there are two common strategies to combine multiple phases undergoing neighboring phase transitions, one is manufacturing the composites by artificially mixing, bonding, pressing or sintering [7][8][9][10], and the other is preparing the multi-phase materials by traditional producing techniques, like casting and heat-treatment [11][12][13][14][15].…”

“…Gd-TM (TM = Co, Fe, Ni, and Mn) amorphous alloys with near-room temperature MCE have attracted more attention in recent years. Generally, the broadened |∆S M |-T profile can be observed in these materials, owing to the highly disordered structure of amorphous systems, which smears out the magnetic transition [1,11,15,[17][18][19][20][21][22][23][24][25][26]. In-situ crystallization treatment of the amorphous ribbons is also utilized to obtain multi-phase magnetic refrigerant, such as crystallized Gd 55 Co 35 Ni 10 ribbon containing Gd 4 (Co, Ni) 3 and Gd 12 (Co, Ni) 7 phases, and partially crystallized Gd 55 Co 35 Mn 10 with precipitation of the Gd 3 Co-type and Gd 12 Co 7 -type phases in the amorphous matrix, both of them possess broadened table-like MCE [14,15].…”