The Synthesis and Characterisation of the High-Hardness Magnetic Material Mn2N0.86

Abstract

High-quality P6322 Mn2N0.86 samples were synthesised using a high-pressure metathesis reaction, and the properties of the material were investigated. The measurements revealed that the Vickers hardness was 7.47 GPa, which is less than that predicted by commonly used theoretical models. At low air pressure, Mn2N0.86 and MnO coexist at 500 to 600 °C, and by excluding air, we succeeded in producing Mn4N by heating Mn2N0.86 in nitrogen atmosphere; we carefully studied this process with thermogravimetry and differential scanning calorimetry (TG-DSC). This gives a hint that to control temperature, air pressure and gas concentration might be an effective way to prepare fine Mn-N-O catalysis. Magnetic measurements indicated that ferromagnetism and antiferromagnetism coexist within Mn2N0.86 at room temperature and that these magnetic properties are induced by nitrogen vacancies. Ab intio simulation was used to probe the nature of the magnetism in greater detail. The research contributes to the available data and the understanding of Mn2N0.86 and suggests ways to control the formation of materials based on Mn2N0.86.

Heterogeneous Catalyst-Modified Anode in Solid Oxide Fuel Cells for Simultaneous Ammonia Synthesis and Energy Conversion

“…The absence of metallic Mn 0 indicates its full nitriding. Zhang et al reported that Mn 2 N 0.86 transforms to Mn 4 N in the presence of N 2 at a high temperature; however, Mn 2 N 0.86 oxidizes to MnO in the absence of N 2 at >500 °C . Therefore, upon nitriding the reduced Mn x N y , the NRR activity of the catalyst improves owing to the formation of higher ε-Mn 4 N contents.…”

“…Zhang et al reported that Mn 2 N 0.86 transforms to Mn 4 N in the presence of N 2 at a high temperature; however, Mn 2 N 0.86 oxidizes to MnO in the absence of N 2 at >500 °C. 34 Therefore, upon nitriding the reduced Mn x N y , the NRR activity of the catalyst improves owing to the formation of higher ε-Mn 4 N contents. The overall change in the Mn x N y catalyst composition after single-step exposure to a H 2 /N 2 1:1 atm in cell operating conditions is shown in Figure S1.…”