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.
Highlights
Over the past few decades, nanotechnology has become one of strategic directions of industrial and industrial development
Increased interest in this form is due from a fundamental point of view: that is associated with the miniaturization of dimensions and structural and magnetic properties, and with the wide possibilities of practical application of nanotubes; it is due to the fact that many properties, the magnetic texture and orientation of magnetic domains, are due to the phase composition, and to the geometric characteristics of the structure [26,27]
Extra subspectra of low intensity observed in experimental spectra presumably corresponds to the impurities of salts and magnetically ordered iron oxide compounds formed during synthesis
Summary
Over the past few decades, nanotechnology has become one of strategic directions of industrial and industrial development. The increased interest in nanostructures is based on the real possibility of their practical application in various fields of science and technology, ranging from microelectronics, catalysts, magnetic media, to alternative energy sources and targeted drug delivery [1,2,3,4,5]. Such interest is due to the unique properties of nanostructures, as well as the possibility of obtaining nanostructures with different shapes and geometries: wires, dendrites, cubes, tubes, spheres, etc. The possibility of controlling the magnetic and structural characteristics, studying the effect of the phase composition on the physical-chemical properties gives grounds for further research in this area [37,38,39,40,41,42,43]
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