Magnetic and magnetocaloric properties of Gd melt-spun ribbons

Abstract

Structural features, magnetic properties and magnetocaloric effect of pure Gd ribbons prepared by melt spinning method were carefully analyzed. The X-ray data show that there is no change in the cell parameters for the samples prepared at different copper-wheel speed. Average size of nanocrystalline grains was close to 30 nm. As compared to the bulk Gd sample, the Curie temperature was the same in the case of the ribbons. From the magnetic isotherms, the magnetic entropy change was derived using the Maxwell relation follow the standard procedure. Its value was comparable with the value of the bulk Gd. Good mechanical properties of fabricated Gd ribbon and their flexibility can be useful for design of flexible refrigerating elements.

Anomalous Nernst Effect in Flexible Co-Based Amorphous Ribbons

“…However, the employment of a flexible element, in turn, provides a path for modifications of the magnetic properties, especially in the case of magnetic materials having high magnetostriction coefficient [ 30 ]. A possible alternative to address this challenge is the use of flexible materials without substrates, such as amorphous ribbons or even ribbon-based composites [ 37 , 38 ]. For instance, previously, a number of studies were devoted to the design of GMI composites consisting of rapidly quenched magnetic ribbons, with thin-film coverings deposited by sputtering deposition [ 39 , 40 ].…”

Realization of Enhanced Refrigeration Capacity with Non-Hysteretic Behavior in Ni40Gd5Co5Mn37In12Si1 Alloy Near Room Temperature at 2T

“…The phase transition temperatures of all the samples are estimated from the minima of the plot of dM/dT versus T in the temperature range of 200−400 K and are presented in Figure 7, where NM alloy is seen to exhibit three transitions, (i) martensite−austenite structural transition (FOPT) near T M = ∼250 K, (ii) FM−PM transition (SOPT) known as austenite Curie transition T A = 333 K, and (iii) high-temperature transition T S = 358 K. The substitution of Gd at the Ni site in NM alloy completely resulting in changes on the double exchange interactions between Mn ions. 58 The small hump that appears near T S = 285 K, as seen in Figure 7, in GS well matches with pure Gd ribbon with T C = 282 K. 59 To further investigate the magnetic hysteresis, the isothermal M(H) data of NM, GS, and GA samples were recorded across the austenitic transition temperature regime, by increasing and decreasing magnetic fields from 0 to 2 T in the temperature range of 313−393 K, as shown in Figure 8a−c. At each temperature, the sample is magnetized from 0 to 2 T and then demagnetized from 2 to 0 T. The magnetization increases dramatically up to 0.5 T for all the samples.…”

“…The phase transition temperatures of all the samples are estimated from the minima of the plot of d M /d T versus T in the temperature range of 200–400 K and are presented in Figure , where NM alloy is seen to exhibit three transitions, (i) martensite–austenite structural transition (FOPT) near T M = ∼250 K, (ii) FM–PM transition (SOPT) known as austenite Curie transition T A = 333 K, and (iii) high-temperature transition T S = 358 K. The substitution of Gd at the Ni site in NM alloy completely vanishes the low-temperature martensite phase and also notably reduces the Curie temperature (SOPT) from T A = 333 to 317 K. Moreover, addition of Gd in NM alloy brings the austenite Curie temperature T A from 333 to 323 K with the secondary phase at T S = 374 K. The reduction in T C might be attributed to the crystallographic distortion caused by the substitution of larger rare-earth Gd 3+ ions at Ni 3+ in NM alloy, which might cause the decrease in the Mn–Mn bond distance, resulting in changes on the double exchange interactions between Mn ions . The small hump that appears near T S = 285 K, as seen in Figure , in GS well matches with pure Gd ribbon with T C = 282 K …”

Ball Milled Gd Flakes Subjected to Heat Treatments: Structure, Magnetic and Magnetocaloric Properties

“…Therefore, the well-known and highly productive conventional ball milling technique was used to obtain gadolinium powder for this study. Rapidly quenched gadolinium ribbons (3 mm wide and 70 µm thick [24]) were mechanically cut into small pieces a few mm long. These pieces of Gd ribbons were used as the primary material for the conventional ball milling fabrication of the flake powder samples.…”