Nanoscale Metastable ε-Fe₃N Ferromagnetic Materials by Self-Sustained Reactions

Abstract

A single-step method for the preparation of metastable ε-Fe3N nanoparticles by combustion of reactive gels containing iron nitrate (Fe­(NO3)3) and hexamethylenetetramine (C6H12N4) in an inert atmosphere is reported. The results of Fourier transform infrared spectroscopy (FTIR) and thermal analysis coupled with dynamic mass spectrometry revealed that the exothermic decomposition of a coordination complex formed between Fe­(NO3)3 and HMTA is responsible for the formation of ε-Fe3N nanoscale particles with sizes of 5–15 nm. The magnetic properties between 5 and 350 K are characterized using a superconducting quantum interference device (SQUID) magnetometer, revealing a ferromagnetic behavior with a low-temperature magnetic moment of 1.09 μB/Fe, high room temperature saturation magnetization (∼80 emu/g), and low remanent magnetization (∼15 emu/g). The obtained value for the Curie temperature of ∼522 K is close to that (∼575 K) for bulk ε-Fe3N reported in the literature.

Structural peculiarities of ε-Fe2O3/GaN epitaxial layers unveiled by high-resolution transmission electron microscopy and neutron reflectometry

“…To match the HRTEM image, the GaON lattice must be rotated 90° relative to the GaN substrate which seems unreasonable. Still, another candidate is the ε-Fe3N compound possessing a hexagonal close packed crystal structure with a = 4.77 Å, c = 4.38 Å [44]. All these compounds, though possess a similar lattice, have the interplanar distance quite different from the d = 4.8 Å observed in the present study and must be ruled out.…”

Biogas Reforming over Al-Co Catalyst Prepared by Solution Combustion Synthesis Method

“…Structures with a high concentration of defects, which is one of the reasons for the high activity of SHS catalysts, are formed under conditions of rapid rates of combustion and cooling reactions. Studies of the physicochemical and mechanical properties of a wide range of synthesized SHS and SCS catalysts have been reported in the literature [17][18][19][20][21][22]. As a result of these studies, SHS materials with high catalytic activity-promising for many industrial processes such as partial oxidation, reduction, carbon dioxide conversion of methane, etc.-have been developed [23][24][25].…”

Out-of-Plane Magnetic Anisotropy in Ordered Ensembles of FeyN Nanocrystals Embedded in GaN

“…However, the Ga incorporation is minimal, since the ternary GaFe N is weakly antiferromagnetic [ 15 ]. The same extrapolation method yields K for the layer grown on the Al Ga N buffer, which contains predominantly -Fe N NCs and a limited amount of ’-Ga Fe N. No quantitative conclusion about the of -Fe N NCs can be made, nevertheless it can be stated that its value is significantly greater than the previously reported 575 K [ 5 ] and (500–525) K [ 53 , 56 ]. This result is relevant, since despite the high potential of -Fe N for spintronics [ 5 ], the technological development of this material has been limited by its high chemical reactivity and by challenges in obtaining the required stoichiometry [ 57 ].…”