Reactive single-step hot-pressing and magnetocaloric performance of polycrystalline Fe2Al1.15−xB2GexGax (x = 0, 0.05) MAB phases

B. Beckmann, T. A. El-Melegy, D.Koch, U. Wiedwald, M. Farle, F. Maccari, J. Snyder, K. P. Skokov, M. W. Barsoum, O. Gutfleisch

Energy-efficient and environmentally friendly cooling technology is imperative to face the rising energy demand for cooling as well as the interconnected challenges of climate change, population growth and world-wide rising standard of living. Magnetic refrigeration is considered to be a promising, environmentally friendly and more energy efficient alternative to conventional vapor-compression refrigeration. Currently, high-purity Gd is the benchmark material for magnetocaloric devices operating at room temperature. However, the high cost and high criticality of Gd make its widespread commercial usage challenging.

In this work, we focus on hot-pressed, low-cost and low-criticality Fe2Al1.15B2 and Fe2Al1.1B2Ge0.05Ga0.05 MAB phases, showing a second-order magnetic phase transition with favorable magnetocaloric properties around room temperature. For the very first time, we directly measure the adiabatic temperature change caused by the magnetic field application in this material system. In addition, we demonstrate that hot-pressing provides a much faster, more scalable and processing cost reducing alternative compared to conventional synthesis routes for the production of heat exchangers for magnetic cooling devices. Overall, our criticality assessment shows that hot-pressed Fe-based MAB phases show a promising compromise of material and processing cost, criticality and magnetocaloric performance, demonstrating the potential for low-cost and low-criticality magnetocaloric applications around room temperature.

J. Appl.Phys. 133, 173903 (2023)

DOI: 10.1063/5.0143037