Mössbauer studies of ?-Fe3?x
Ni
x
N and γ′-Fe4?y
Ni
y
N nanoparticles |
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Authors: | N S Gajbhiye Sayan Bhattacharyya |
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Institution: | (1) Department of Chemistry, Indian Institute of Technology, Kanpur, 208 016 UP, India;(2) Institute of Nanotechnology, Forschungszentrum Karlsruhe, P.O. Box 3640, 76021 Karlsruhe, Germany |
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Abstract: | Nanocrystalline ?-Fe3?x Ni x N (0.0?≤?×?≤?0.8) particles are synthesized by precursor technique and nitridation of decomposed products in NH3 (g) in the temperature range 673 K-823 K. For x?=?0.1–0.4 compositions, single phase ?-Fe3?x Ni x N hexagonal structure with space group P63/mmc is formed, while for x?=?0.5–0.8, fcc γ′-Fe4?y Ni y N phase is also precipitated. The room temperature Mössbauer spectrum for all the compositions shows the presence of superparamagnetic doublet, which is attributed to ?-Fe3?x Ni x N phase. For x?=?0.5–0.8 compositions, two additional sextets are observed corresponding to two different iron sites, the corner position (Fec) and the fcc position (Fef), in γ′-Fe4?y Ni y N. The added Ni atoms preferentially substitute the corner Fec positions. The isomer shift, quadrupole splitting and hyperfine field values are found to change with the Ni content. |
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Keywords: | nanoparticle M?ssbauer iron– nickel nitride atomic ordering |
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