Thermally Reduced Soft Magnetic CuFe Nanoparticles for High-Performance Electrical Devices

Abstract

Developing economically soft magnetic materials for high-performance electrical devices is indispensable. Here, we present the structural and magnetic properties of thermally reduced soft CuFe nanoparticles. The fcc cubic structure of iron-rich Cu <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">37</sub> Fe <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">63</sub> and their composition was confirmed by Rietveld refinement. Cu <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">37</sub> Fe <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">63</sub> nanoparticles exhibited high saturation magnetization and coercivity of 127 emu/g (142 emu/g) and 4.3 Oe (31 Oe), respectively, at 300 K (5 K). They showed transitions at ~34 and ~249 K due to the Kondo temperature of CuFe and minor fraction of CuFe <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sub> , respectively. The exchange coupling between Cu and Fe was not significant, as demonstrated by field-cooled magnetization curves at 5 K. The magnetocaloric effect (MCE) in the range of fields and temperatures was estimated whereas the maximum MCE of -8.71 × 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-2</sup> J.kg <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> .K <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> was achieved at 222 K. These soft magnetic materials, which exhibited stable high saturation magnetization with less heating effect during magnetization and demagnetization cycles, would be suitable candidates for magnetic applications.