Magnetic reversibility accompanied by thermal hysteresis in magnetocaloric materials: A lock-in thermography study
Lock-in infrared thermography (LIT) was used to obtain the reversible adiabatic temperature change (ΔTrev ad ) from an oscillating magnetic field up to a maximum of 1.5 T. Several paradigmatic magnetocaloric materials exhibiting diverse thermomagnetic phase transitions were studied: (1) Gd, undergoi...
| Autores: | , , , , , |
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| Tipo de recurso: | artículo |
| Estado: | Versión publicada |
| Fecha de publicación: | 2025 |
| País: | España |
| Institución: | Universidad de Sevilla (US) |
| Repositorio: | idUS. Depósito de Investigación de la Universidad de Sevilla |
| OAI Identifier: | oai:idus.us.es:11441/178868 |
| Acceso en línea: | https://hdl.handle.net/11441/178868 https://doi.org/10.1016/j.matdes.2025.114372 |
| Access Level: | acceso abierto |
| Palabra clave: | Magnetocaloric effect Direct characterization measurements Lock-in thermography Hysteresis Reversibility Dynamic conditions |
| Sumario: | Lock-in infrared thermography (LIT) was used to obtain the reversible adiabatic temperature change (ΔTrev ad ) from an oscillating magnetic field up to a maximum of 1.5 T. Several paradigmatic magnetocaloric materials exhibiting diverse thermomagnetic phase transitions were studied: (1) Gd, undergoing a second-order transition; (2) LaFe11.38Mn0.28Si1.34-H undergoing a magneto-elastic first-order transition; and (3) Ni48.6Mn35.9In15.5 and (4) Ni36Co14Mn35Ti15 Heusler alloys, both undergoing magneto-structural first-order transition with varying degrees of overlap with the second-order transition of austenite and associated hysteresis. LIT increases ΔTrev ad resolution by two orders of magnitude compared to traditional thermography. This advanced capability facilitates the detection of features in the responses that would otherwise be challenging to identify. Furthermore, the phase Φ with respect to the excitation serves as an indicator of the phase transition dynamics. Importantly, while the ΔTrev ad measurements remain reversible against field oscillations, first-order thermomagnetic phase transitions driven by non-saturating fields show different behaviors for heating and cooling curves, manifesting thermal hysteresis and the irreversibility of the transition under those conditions. This highlights the significance of direct characterization methods of the magnetocaloric response over indirect approaches and its usefulness for the design of materials for efficient refrigeration devices. |
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