Thermally induced transformations at an ion implanted α–Fe2O3/α–Al2O3 interface: A Mössbauer spectroscopy study

Abstract

Thermally induced chemical transformations at the interface between a 100 nm α–Fe2O3 and a polycrystalline α–Al2O3 substrate are studied and compared for the cases of the as-formed and ion bombarded interfaces. The thermal annealings are carried out under vacuum at 450 °C for different time durations and the transformations are examined by conversion electron Mössbauer spectroscopy. It is shown that in the sample prebombarded with 110 keV Ar+ ions, the formation of Fe3−xAlxO4, FeAl2O4, and FeO phases is favored at variance with a nonbombarded sample in which primarily a defective Fe3O4-y phase is produced with some amount of FeO. This difference is explained in terms of the annealing process of the oxygen vacancies produced during Ar implantation near the interfacial region.

Epitaxial growth of Fe3O4 (111) on SrTiO3 (001) substrates

“…In this thickness range, oxygen diffusion into the a-Fe 2 O 3 layer is inhibited, and during annealing, Fe deficient Fe 3 O 4 is formed due to the reduction of a-Fe 2 O 3 . Similar transformation has been reported by Bhagwat et al [18] in which thin film a-Fe 2 O 3 Ja-Al 2 O 3 , upon vacuum annealing for 6 hours, corresponds to a highly stoichiometric Fe 3 O 4 . It is possible that the (111) orientation in Fe 3Àx O 4 observed in this study is due to the transformation of rhombohedral a-Fe 2 O 3 to spinel Fe 3Àx O 4 (111) , which involves less rearrangement of chemical bonding compared to Fe 3 O 4 (0 0 1) with a lower symmetry.…”

Phase evolution and magnetic properties of a high-energy ball-milled hematite–alumina system

“…13 The great technological and academic interest in these composites is due to numerous potential applications, mainly in electronics, metallurgy, and catalysis of ammonia synthesis. 9,14 Surprisingly, so far, in spite of the immense technological and academic importance of the hematitealumina system, no research concerning the systematic study of this system, prepared through the high-energy ball-milling technique, has been reported in the literature. Actually, the influence of the substitution of aluminum ions on hematite or other iron oxides has already been largely studied.…”

High-energy ball-milled (α-Fe2O3)(α-Al2O3) system: A study on the milling time effects

“…In addition, the hematite magnetic behaviour is very sensitive to impurities, strain and external fields [10][11][12][13]. Taking the great technological and academic importance of the hematite-alumina system into account, as well as its numerous potential applications in electronics, metallurgy and catalysis of ammonia synthesis [5,14], it is worth exploring and understanding the mechanosynthesis effects provided by HEBM on its physical properties.…”