VP11-14: Laser Synthesis of FeRh Microstructures for Enhanced Magnetocaloric Refrigeration

Magnetocaloric refrigeration is a promising alternative to gas-based cooling systems, providing enhanced energy efficiency and reduced environmental impact. FeRh is a standout magnetocaloric material with the largest magnetocaloric effect due to the AFM-FM phase transition. The desired magnetocaloric response in FeRh structures depends on the composition and processing conditions.[1] In this contribution we present a comprehensive pathway for creating FeRh magnetocaloric microstructures by laser processing (Fig. 1). γ-FeRh nanoparticles with reduced oxidation are synthesized via picosecond pulsed laser ablation in ethanol (Fig. 1a).[2] These nanoparticles are employed to create 1 wt.% ethanol-FeRh ink which is then dispersed on PVP-coated glass substrates and subsequently patterned using a continuous wave laser (Fig. 1b and c). Laser-based direct writing facilitates sintering into custom structures (Fig. 2a) and partially induces the γ-FeRh to B2-FeRh phase transition.[3,4] A 52% partial phase transformation can be achieved, resulting in a significant magnetization increase of ca. 35 Am2/kg during the field-induced AFM-FM transition (Fig. 2b). Notably, laser sintering demonstrates a remarkable sixfold enhancement of the achieved magnetization compared to furnace annealed FeRh ink which measured ca. 6Am2/kg. This study presents a robust and efficient approach to generate magnetocaloric structures. Laser synthesis and sintering enable the production of diverse FeRh-based microstructures with high spatial resolution, in-situ annealing, and design flexibility (Fig. 2a). These advancements hold promise for the development of miniaturized devices like magnetic microcoolers, thermal sensors, and magnetic micropumps, leveraging pronounced magnetocaloric effects at a small scale.References: [1] S.Nikitin, G.Myalikgulyev, A.Tishin, Physics Letters A 148, 363–366 (1990) [2] R. Nadarajah, S.Tahir and J. Landers, Nanomaterials., 10 (12), 2362 (2020). [3] R. Nadarajah, J.Landers, S.Salamon, B.Gökce, Scientific Reports., 11 (1), 13719 (2021). [4] S.Tahir, J.Landers, S.Salamon, Advanced Engineering Materials, 2300245 (2023)