Mössbauer spectroscopy study of aluminium substituted nickel-ferrites

Abstract

Powders of Al substituted Ni-ferrites (NiAl x Fe 2−x O 4 x = 0, 0.5, 1.0 and 1.5) were prepared using the calcination method. Mössbauer spectroscopy results of all samples show two well defined magnetic sextets corresponding to Fe 3+ ions in the A (tetrahedral) and B (octahedral) sites of the spinel structure. In addition, a quadrupole doublet with quadrupole splitting of (∼0.53 mm/s) starts evolving upon Al substitution. This doublet is associated with a new Fe-Al-oxide phase. The X-ray diffraction patterns show, in addition to the original peaks, new peaks evolve and increase in intensity as the Al concentration increases, confirming the evolution of this new phase.

Aluminum substituted nickel ferrite (Ni–Al–Fe): a ternary metal oxide adsorbent for arsenic adsorption in aqueous medium

“…The shi in the peaks observed in the Ni-Al-Fe adsorbent as compared to pure nickel ferrite lattice (JCPDS le no: 742081) is due to the Al 3+ ions substitution for Fe 3+ ions. 39 Additional bands observed in IR around 490, 750 and 960 cm À1 are the vibrations related to the asymmetric, symmetric and interactive stretching vibrations of Al-O type structures. 1(b).…”

“…Other bands around 3460 and 1644 cm À1 are corresponding to O-H stretching and bending vibrations of water molecules. 39 Additional bands observed in IR around 490, 750 and 960 cm À1 are the vibrations related to the asymmetric, symmetric and interactive stretching vibrations of Al-O type structures. 40 Raman spectrum of freshly prepared Ni-Al-Fe was recorded which shows a broad shoulder as it was reported for the pure nickel ferrite.…”

The influence of Al content and CaO–SiO2 on the magnetic and structural properties of Al-substituted Ni ferrites

“…Densification is noticeable when a small amount of liquid wets the grain boundary area. Many grain growth promoting dopants melt or form a lowmelting eutectic with the host material at sintering temperatures [4]. It is shown that the segregation of CaO and SiO 2 at grain boundaries and exaggerated grain growth can be explained from the view of liquid phase sintering [4].…”

“…Many grain growth promoting dopants melt or form a lowmelting eutectic with the host material at sintering temperatures [4]. It is shown that the segregation of CaO and SiO 2 at grain boundaries and exaggerated grain growth can be explained from the view of liquid phase sintering [4]. As a consequence of deviation from the stoichiometric state, a small amount of aluminum oxide can be segregated at grain boundaries [8][9][10].…”

“…The Al-substituted Ni ferrite is one of the most significant ferrites which have a wide range of applications at radio and microwave frequencies, where electrical and magnetic losses are required to be minimum [3][4][5][6][7][8][9]. Ni ferrite and those of the substituted are technologically crucial materials, which were synthesized for the first time about 50 years ago, and which have been studied in many experimental and theoretical works [10][11][12][13].…”