FeN foils by nitrogen ion-implantation

Abstract

Iron nitride samples in foil shape (free standing, 500 nm in thickness) were prepared by a nitrogen ion-implantation method. To facilitate phase transformation, the samples were bonded on the substrate followed by a post-annealing step. By using two different substrates, single crystal Si and GaAs, structural and magnetic properties of iron nitride foil samples prepared with different nitrogen ion fluences were characterized. α″-Fe16N2 phase in iron nitride foil samples was obtained and confirmed by the proposed approach. A hard magnetic property with coercivity up to 780 Oe was achieved for the FeN foil samples bonded on Si substrate. The feasibility of using nitrogen ion implantation techniques to prepare FeN foil samples up to 500 nm thickness with a stable martensitic phase under high ion fluences has been demonstrated. A possible mechanism was proposed to explain this result. This proposed method could potentially be an alternative route to prepare rare-earth-free FeN bulk magnets by stacking and pressing multiple free-standing thick α″-Fe16N2 foils together.

Effect of dopants on thermal stability and self-diffusion in iron-nitride thin films

“…By using processes such as physical vapor deposition or ion implantation, bcc-Fe lattice is strained to accommodate a much higher amount of interstitial N (up to 11 at. %) [19,20]. This intrinsically makes interstitial Fe-N a weakly stable system.…”

Preparation of high performance bulk Fe–N alloy by spark plasma sintering

“…Samples of bulk Fe-N alloy prepared by SPS have higher saturation magnetization (N 157 emu/g) and lower remanence ratio (b 0.35). The coercivity is around 50 Oe, higher than that of conventional bulk soft magnetic materials [48], but is much lower than that of some Fe-N films and foils [10,20,22]. This Fig.…”

“…indicates that the bulk Fe-N alloys prepared by SPS have few permanent magnetic properties. In comparison, the Fe-N alloy sintered at 750°C has better saturation magnetization and lower coercivity, being close to pure iron [22]. During the process of magnetization and demagnetization, changes of the crystal structure caused by nitrogen content can affect the motion of magnetic domains and increase the coercivity [10,20,22].…”

“…For example, pulsed laser deposition [14], molecular beam epitaxy (MBE) [15][16], facing target sputtering [17][18], magnetron sputtering [19][20], ion implantation [21][22], and RF reactive sputtering [23], were used to create Fe-N films at lower temperature. Mechanical alloying, chemical reaction, and nitriding were used to produce Fe-N powders from room temperature to 700°C [24][25][26].…”

Effects of Bias Voltage on Fen Films Prepared by Magnetron Sputtering

“…Many growth method, such as reactive magnetron sputtering, molecular beam epitaxy, nitrogen ion implantation and etc. have been applied on different substrate to grow iron nitride films which are mainly composed of α '' -Fe 16 N 2 , γ'-Fe 4 N orε-Fe 3 N [4][5][6] . The phase evolution of the iron nitride films induced by thermal treatment was also studied.…”