Abstract:
Hyperfine interactions of 57Fe nuclei in Fe100-xNix nanostructures synthesized in polymer
ion-track membranes were studied by Mössbauer spectroscopy. The main part of obtained
nanostructures was Fe100-xNix nanotubes with bcc structure for 0 ≤ x ≤ 40, and with fcc structure for
50 ≤ x ≤ 90. The length, outside diameter and wall thickness of nanotubes were 12 µm, 400 ± 10 nm
and 120 ± 5 nm respectively. For the studied nanotubes a magnetic texture is observedalong their
axis. The average value of the angle between the direction of the Fe atom magnetic moment and
the nanotubes axis decreases with increasing of Ni concentration for nanotubes with bcc structure
from ~50◦
to ~40◦
, and with fcc structure from ~55◦
to ~46◦
. The concentration dependences of the
hyperfine parameters of nanotubes Mössbauer spectra are qualitatively consistent with the data for
bulk polycrystalline samples. With Ni concentration increasing the average value of the hyperfine
magnetic field increases from ~328 kOe to ~335 kOe for the bcc structure and drops to ~303 kOe in
the transition to the fcc structure and then decreases to ~290 kOe at x = 90. Replacing the Fe atom
with the Ni atom in the nearest environment of Fe atom within nanotubes with bcc structure lead
to an increase in the hyperfine magnetic field by “6–9 kOe”, and in tubes with fcc structure—to a
decrease in the hyperfine magnetic field by “11–16 kOe”. The changes of the quadrupole shift and
hyperfine magnetic field are linearly correlated with the coefficient −(15 ± 5)·10−4 mm/s/kOe.
