One-Step Sintering Process for the Production of Magnetocaloric La(Fe,Si)13-Based Composites

Abstract

A one-step sintering process was developed to produce magnetocaloric La(Fe,Si)13/Ce-Co composites. The effects of Ce2Co7 content and sintering time on the relevant phase transformations were determined. Following sintering at 1373 K/30 MPa for 1–6 h, the NaZn13-type (La,Ce)(Fe,Co,Si)13 phase formed, the mass fraction of α-Fe phase reduced and the CeFe7-type (La,Ce)(Fe,Co,Si)7 phase appeared. The mass fraction of the (La,Ce)(Fe,Co,Si)7 phase increased, and the α-Fe phase content decreased with increasing Ce2Co7 content. However, the mass fraction of the (La,Ce)(Fe,Co,Si)7 phase reduced with increasing sintering time. The EDS results showed a difference in concentration between Co and Ce at the interphase boundary between the 1:13 phase and the 1:7 phase, indicating that the diffusion mode of Ce is reaction diffusion, while that of Co is the usual vacancy mechanism. Interestingly, almost 100 % single phase (La,Ce)(Fe,Co,Si)13 was obtained by appropriate Ce2Co7 addition. After 6 h sintering at 1373 K, the Ce and Co content in the (La,Ce)(Fe,Co,Si)13 phase increased for larger Ce2Co7 content. Therefore, the Curie temperature increased from 212 K (binder-free sample) to 331 K (15 wt.% Ce2Co7 sample). The maximum magnetic entropy change (−∆SM)max decreased from 8.8 (binder-free sample) to 6.0 J/kg∙K (15 wt.% Ce2Co7 sample) under 5 T field. High values of compressive strength (σbc)max of up to 450 MPa and high thermal conductivity (λ) of up to 7.5 W/m∙K were obtained. A feasible route to produce high quality La(Fe,Si)13 based magnetocaloric composites with large MCE, good mechanical properties, attractive thermal conductivity and tunable TC by a one-step sintering process has been demonstrated.

Study on the Magnetocaloric Effect of Room Temperature Magnetic Refrigerant Material La0.5Pr0.5(Fe1−xCox)11.4Si1.6 and the Effect Arising from Co Doping on Its Curie Temperature

“…Considering Equations ( 16), ( 17) and (19), it was concluded that n Fe 2 J Fe−Fe + n Co 2 J Co−Co + 2n Fe n Co J Fe−Co would increase. Next, considering that the fourth term −2n Fe n R J Fe−R in Equation (15), and as n Co increases, n Fe decreases while n R remains unchanged, −2n Fe n R J Fe−R would increase. In general, it can be obtained that all four terms in Equation ( 15) increase with the increase of n Co .…”

“…Moreover, in order to improve the magnetic entropy change of the compound, other rare earth elements can be used to partially replace the La element in the compound, but this will further reduce the Curie temperature. This is very unfavorable to the practical application of the compound [13][14][15]. To address the mentioned problem, our research group has selected low-silicon compound LaFe 11.4 Si 6 as the research object and prepared La 0.8 Ce 0.2 (Fe 1−x Co x ) 11.4 Si 1.6 (x = 0.02, 0.04, 0.06) by partially replacing La and Fe with rare earth element Ce and transition metal Co [16].…”

Advances in Metal-Containing Magnetic Materials and Magnetic Technologies

“…Magnetocaloric and magnetostrictive materials have also attracted significant attention. Zhong et al [7] prepared magnetocaloric La(Fe,Si) 13 /Ce-Co composites via a one-step sintering process. Using 15 wt.% Ce 2 Co 7 as a dopant and binder, the Curie temperature (T C ) increased from 212 K to 331 K, and the change in the maximum magnetic entropy (−∆S M ) max decreased from 8.8 to 6.0 J/kg•K under a 5 T field.…”

Magnetic and magnetocaloric effect of Er20Ho20Dy20Cu20Ni20 high-entropy metallic glass

“…La(Fe, Si) 13 -based compounds are considered as promising magnetic refrigeration materials for room temperature refrigeration and have received extensive attention and research, while there are still relatively fewer magnetic refrigeration candidates for the liquid hydrogen temperature region. [9][10][11] The Ericsson cycle is considered to be the optimal thermodynamic cycle for hydrogen liquefaction, which consists of two isothermal processes and two isomagnetic processes. Therefore, the development of magnetic refrigeration materials with table-like magnetic entropy changes for hydrogen liquefaction is essential.…”