Phase Transitions and Magnetic Properties of Transition Metal Based Magnetocaloric Materials
H. Gai (TU Delft - RST/Fundamental Aspects of Materials and Energy)
E. H. Brück – Promotor (TU Delft - RST/Fundamental Aspects of Materials and Energy)
Niels Harmen H. Dijk – Promotor (TU Delft - RST/Fundamental Aspects of Materials and Energy)
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Abstract
Efficient energy utilization has been central to human progress, with each new energy source driving societal and technological advancements. While fossil fuels like coal, oil, and natural gas currently dominate, their environmental impact and finite availability underscore the urgent need for sustainable alternatives. Developing environmentally friendly and efficient energy conversion processes is vital to addressing the challenges of resource scarcity and climate change. Magnetocaloric materials (MCMs) are at the forefront of research in advanced cooling technologies due to their ability to exhibit a magnetocaloric effect (MCE). This area of study holds both significant fundamental scientific interest and critical application potential. From a scientific point of view, MCMs are highly intriguing due to their ability to exhibit a giant magnetocaloric effect (GMCE). Uncovering the underlying mechanisms of first-order magnetic transitions (FOMT) plays a pivotal role in advancing research and development in this field [1–6]. From an application perspective, related research primarily focuses on developing 3D-printed bulk materials to achieve gradient composites manufacturing of MCMs with enhanced heat transfer coefficients [7]. This approach is particularly relevant given the narrow operating range of FOMTs, which necessitates multiple material layers to achieve optimal efficiency [8]. However, for the successful commercialization of magnetic cooling and heat pump technologies, the primary future challenge lies in ensuring mechanical stability of GMCMs, which is a critical prerequisite. This thesis explores the unique structure and thermomagnetic properties of Fe2Pbased and potential novel MCM systems using techniques such as magnetization, heat capacity, Mössbauer spectroscopy, Density Functional Theory (DFT), X-ray and neutron diffraction.