The thermal energy is one of the most ubiquitous and large energy resources. Just consider that about 70% of all the energy produced by humanity is chucked as waste heat. The development of new technologies to capture and convert thermal energy is essential to push the transition to a fully sustainable resource-efficient and circular economy and to design new solutions for the generation of energy on a small-scale to allow self-sustaining operation of miniaturized smart devices and sensors, for the Internet of Things as well as mobile, wearable and implantable systems. Thermomagnetic generators (TMGs) are innovative and eco-friendly energy conversion systems that offer a chance to face this challenge. In the last decade, proof-of-concept TMG prototypes have been realized, demonstrating the prospective of this technology. However, to fully unleash its potential and make economic sense for wide-scale use, this technological innovation still requires the search of performant, sustainable, recyclable and cost-effective thermomagnetic (TM) materials and their efficient implementation in devices. The “Small-scale Thermomagnetic energy harvesters: from materials to devices” (STEve) project aims to boost the research on TMG technologies, developing advanced miniaturized TM materials, that can be efficiently exploited as active elements in innovative thermomagnetic oscillators (TMOs) for the harvesting of low-grade heat (from sources in the 20°-80°C temperature range) and production of electric power on a small-scale. The project is characterized by a multidisciplinary (physics, materials science and engineering) and multi-level perspective that look both at the optimization of physical properties of TM materials and at the definition of routes for their miniaturization in thin active elements with high TM, thermal and mechanical performances to boost the frequency of thermodynamic cycles. Two classes of rare-earth-free intermetallic alloys (Heusler alloys and High Entropy Alloys) based on non-critical, easily accessible, stable and easily recyclable 3d metals like Fe, Ni and Mn, will be investigated. The synthesis routes, based on arc-melting and microwave-assisted sintering, will be optimized to improve the functional properties of materials through the engineering of atomic order and microstructure. Two approaches will be used to prepare thin active elements with high thermal diffusivity and mechanical stability: synthesis of TM ribbons by melt spinning and preparation of functional composites based on powders of TM materials. The synthesis and engineering of materials will be supported by different characterization techniques (structural, morphological, magnetic, thermodynamic and mechanical), to assess the physical and functional properties of as prepared and shaped materials. A small-scale prototype of TMO will be developed to directly evaluate under operative
conditions the performance and endurance of TM materials.