Conférence : « Les développements récents des matériaux magnétocaloriques : du matériau massif vers le nano »

Professeur qui invite : My Ali El Khakani

Résumé :  

Over the last two decades, magnetic refrigeration which is based on the magnetocaloric effect (MCE) has attracted worldwide attention because particularly of its potential higher thermodynamic efficiency and ecological benefits [1]. By using solid-state magnetic refrigerants, this technology enables us to build more compact cooling devices while fully eliminating the harmful synthetic refrigerants widely used in traditional refrigeration. Additionally, magnetocaloric refrigeration shows promise in several applications including domestic refrigeration, air-conditioning, hydrogen storage and on-chip micro refrigeration. Currently, most room-temperature magnetic cooling systems use the expensive and chemically instable gadolinium (Gd)-based alloys as refrigerants. Aiming to replace Gd in magnetic refrigerators, intensive investigations were conducted by the magnetocaloric community on both bulk materials and thin films leading to serious alternatives such as La_2/3Sr_1/3MnO₃, LaFe_13-xSi_x and MnFePSi-based materials [1]. However, despite their undeniable potential in magnetic refrigeration, these newly reported magnetocaloric materials face serious practical issues such as, mechanical brittleness, chemical instability, large hysteretic effects and limited MCEs in terms of the adiabatic temperature change (ΔT_ad).

In this talk, I will explain the principle of magnetic refrigeration and the driving mechanisms behind the magnetocaloric effect. Recent developments in magnetocaloric materials will be also discussed while underlying the major issues faced by magnetic cooling. On the other hand, some interesting routes for boosting research activities on magnetocalorics will be presented.    

[1] Balli et al., Appl. Phys. Rev. 4, 021305 (2017).

Biographie :

Mohamed Balli is a full professor at the International University of Rabat (Morocco), professeur-associé at Université de Sherbrooke (Qc, Canada), and adjunct-professor at Mississippi State University (USA). His research focuses on the development of functional materials, understanding their structure properties relationships, and their application in our various sectors, such as clean and efficient refrigeration/heating, hydrogen storage, solar cells, and batteries. Prof. Balli received his PhD degree (2007) in physics of materials, from Joseph Fourier University, prepared at Néel Institute (CNRS). He has occupied several academic and research positions in France, Switzerland and Canada. His research work has received numerous awards including, « Rising star researcher award » given by the Research Fund: Nature and Technology, Canada (2014) and the “Research and Innovation Prize 2015” from Sherbrooke University. He was selected in 2024 among the top 2% world scientists by Stanford University ranking.