Highly crystalline core-shell FeCo-CoFe₂O₄nanostructures

FeCo Nanowire–Strontium Ferrite Powder Composites for Permanent Magnets with High-Energy Products

“…The darker core of the nanowire is observed to be surrounded by a thin layer that appears slightly brighter in the image. This is consistent with the formation of a passivating oxide layer on the surface of the FeCo NWs, resulting in a core–shell type of structure that protects the metallic core from further oxidation . The diameter of the metallic core is D core = 35 nm.…”

“…The TGA curve in Figure e shows a very mild weight gain from RT to 300 °C, a temperature at which a more pronounced weight gain commences, reaching a maximum value of 25.3% at 520 °C and subsequently staying relatively constant up to 900 °C. Previous studies allow us to correlate this TGA curve with the oxidation of the FeCo bcc alloy nanoparticles to CoFe 2 O 4 (Co ferrite) under high-temperature annealing in air. , Assuming that is the case here if the FeCo NWs were 100% metallic, a 37% weight gain should be observed during the oxidation to Co ferrite. From the values of the length and outer/core diameter of the 50 nm NW, the volume of the metallic core in an average FeCo NW is calculated to be V core = 24.4 × 10 6 nm 3 , while that of the oxide shell is V shell = 20.5 × 10 6 nm 3 .…”

“…This is consistent with the formation of a passivating oxide layer on the surface of the FeCo NWs, resulting in a core−shell type of structure that protects the metallic core from further oxidation. 43 The diameter of the metallic core is D core = 35 nm. This value is in agreement with previous reports, 43,44 as a shell with a thickness of 7 nm is inferred by subtracting outer and inner diameters.…”

“…43 The diameter of the metallic core is D core = 35 nm. This value is in agreement with previous reports, 43,44 as a shell with a thickness of 7 nm is inferred by subtracting outer and inner diameters. The SEM image in Figure 2b shows that all FeCo NWs obtained in the batch present a diameter close to 50 nm, confirming a very narrow dispersion of values.…”

Synthesis and magnetic properties of cobalt-iron/cobalt-ferrite soft/hard magnetic core/shell nanowires

“…Under appropriate conditions, the thermal treatment can be used to transform CoFe 2 into CoFe 2 O 4 [29,30]. On the other hand, Paterson et al [31] reported core/shell CoFe/CoFe 2 O 4 nanowires using electrospinning technique that include several additional steps after the synthesis. Hereby a straightforward procedure for the synthesis of CoFe 2.7 /CoFe 2 O 4 core/shell nanowires is proposed.…”