High-Performance Thermomagnetic Gd–Si–Ge Alloys
Saurabh Singh, Na Liu, Yu Zhang, Amin Nozariasbmarz, Sumanta Kumar Karan, Lavanya Raman, Gagan K. Goyal, Shweta Sharma, Wenjie Li, Shashank Priya, Bed Poudel
Abstract
Exploring low-grade waste heat energy harvesting is crucial to address increasing environmental concerns. Thermomagnetic materials are magnetic phase change materials that enable energy harvesting from low-temperature gradients. To achieve a high thermomagnetic conversion efficiency, there are three main material requirements: (i) magnetic phase transition near room temperature, (ii) substantial change in magnetization with temperature, and (iii) high thermal conductivity. Here, we demonstrate a high-performance Gd 5 Si 2.4 Ge 1.6 thermomagnetic alloy that meets these three requirements. The magnetic phase transition temperature was successfully shifted to 306 K by introducing Ge doping in Gd 5 Si 4, and a sharper and more symmetric magnetization behavior with saturation magnetization of M max = 70 emu/g at a 2 T magnetic field was achieved in the ferromagnetic state. The addition of SeS 2, as a low-temperature sintering aid, to the Gd–Si–Ge alloy improved the material’s density and thermal conductivity by ∼45 and ∼275%, respectively. Our results confirm that the (Gd 5 Si 2.4 Ge 1.6 ) 0.9 (SeS 2 ) 0.1 alloy is a suitable composite material for low-grade waste heat recovery in thermomagnetic applications.