High-Performance Thermomagnetic Gd-Si-Ge Alloys

Exploringlow-grade waste heat energy harvesting is crucial toaddress increasing environmental concerns. Thermomagnetic materialsare magnetic phase change materials that enable energy harvestingfrom low-temperature gradients. To achieve a high thermomagnetic conversionefficiency, there are three main material requirements: (i) magneticphase transition near room temperature, (ii) substantial change inmagnetization with temperature, and (iii) high thermal conductivity.Here, we demonstrate a high-performance Gd5Si2.4Ge1.6 thermomagnetic alloy that meets these three requirements.The magnetic phase transition temperature was successfully shiftedto 306 K by introducing Ge doping in Gd5Si4,and a sharper and more symmetric magnetization behavior with saturationmagnetization of M (max) = 70 emu/g at a2 T magnetic field was achieved in the ferromagnetic state. The additionof SeS2, as a low-temperature sintering aid, to the Gd-Si-Gealloy improved the material's density and thermal conductivityby & SIM;45 and & SIM;275%, respectively. Our results confirmthat the (Gd5Si2.4Ge1.6)(0.9)(SeS2)(0.1) alloy is a suitable composite materialfor low-grade waste heat recovery in thermomagnetic applications.