Synthesis and magnetic properties of Sb added MnBi magnets for applications at sub-zero temperatures

Abstract

MnBi-LTP bulk magnets containing substitutional Sb element were fabricated using gas-atomizing process, surfactant-assisted wet magnetic compaction process, and thermal compaction process. Magnetic properties and microstructures were investigated according to the processing parameters. It was found that substitutional Sb element effectively refined the grain size of gas-atomized powders. The conventional ball milling process was able to pulverize these powders into fine particles with a single crystalline structure and minimize their phase decomposition, resulting in a (BH)(max) of 11.0 MGOe. By analyzing the effects of the compaction pressure on the density and magnetic alignment during the surfactant-assisted wet compaction process, Mn54Bi45.9Sb0.1 bulk magnet with H-c of 10.0 kOe at room temperature and temperature coefficient H-c of 0.68%/K was successfully fabricated. Furthermore, effects of Sb element on the temperature dependency of H-c in the bulk magnet were discussed. (C) 2021 Elsevier B.V. All rights reserved.