Carregant...
Tipus de document
TesiVersió
Versió publicadaData de publicació
Llicència de publicació
Si us plau utilitzeu sempre aquest identificador per citar o enllaçar aquest document: https://hdl.handle.net/2445/185828
Giant caloric and multicaloric effects in magnetic alloys
Títol de la revista
Autors
Director/Tutor
ISSN de la revista
Títol del volum
Resum
[eng] The urgent need to reduce our footprint on the earth environment is leading to ever more stringent commitments to decrease greenhouse gases emissions, which entails one of the greatest challenges that mankind has to tackle. As a direct consequence, it is of utmost importance to develop novel, energy-efficient and environmentally-friendly refrigeration technologies that do not require the use of climate-damaging substances. In this regard, solid-state refrigerants based on the large thermal response exhibited by a variety of materials when field-inducing a ferroic phase transition are among the best alternatives. Specifically, materials undergoing a first-order phase transition are of particular interest as the latent heat associated with the phase transition contributes on enhancing the magnitude of the thermal response. Depending on the nature of the external field that drives the phase transition one distinguishes between magnetocaloric, electrocaloric, elastocaloric or barocaloric effects. In spite of all the intensive research devoted to the study of the diverse caloric effects, there are still a series of bottlenecks to overcome. Firstly, they require the application of strong external fields in order to induce a large thermal response. Secondly, the hysteresis associated with the phase transition can drastically reduce the efficiency and compromises its reversibility. A way out of such issues can be provided by materials exhibiting a strong coupling between the structural, magnetic or electronic degrees of freedom, denoted as multicaloric materials, which allow to drive their phase transition by the combination of diverse external fields, giving rise to multicaloric effects. Despite the high potential they exhibit, the research on multicaloric materials is germinal as it requires the use of non-commercial experimental systems. In this dissertation, we have focused on the study of materials displaying a magnetostructural first- order phase transition with a strong coupling between the structural and magnetic degrees of freedom. For such purpose, we have used distinct purpose-built calorimetric and adiabatic thermometry systems to investigate their caloric and multicaloric effects by direct methods. We have concentrated on two distinct families of multicaloric materials: Fe-Rh and Ni-Mn-based Heusler alloys. Our research is aimed at thoroughly characterizing the diverse advantages of multicaloric effects: showing that lower driving fields are required, that the operating temperature windows of the materials can be enlarged and discussing how their inherent hysteresis can be mastered or even exploited.
Descripció
Matèries
Matèries (anglès)
Citació
Citació
GRÀCIA CONDAL, Adrià. Giant caloric and multicaloric effects in magnetic alloys. [consulta: 10 de desembre de 2025]. [Disponible a: https://hdl.handle.net/2445/185828]