A Mössbauer study of Al and Ga substituted magnetite

Abstract

Rosenberg, M.; Deppe, P.; Janssen, H.U.; Brabers, V.A.M.; Li, F.S.; Dey, S.

The Influence of Aluminum on Iron Oxides: XIV. Al-Substituted Magnetite Synthesized at Ambient Temperatures

“…To our knowledge, Al-for-Fe substitution in magnetites has so far only been achieved by reducing (Fe,AI)203 with H2 at 400~ (Michel and Pouillard, 1949) or by sintering mixed A1 and Fe salts at about 1300~ in a controlled atmosphere (Dehe et aL, 1975;Rosenberg et aL, 1985). The present investigation was therefore undertaken to answer the following questions: (1) Does A1 inhibit magnetite formation under alkaline conditions at ambient temperatures?…”

Analysis of Magnetic After-Effects in Gallium Ferrites

“…2b, 5). This conclusion brings, in our eyes, the decision in favour of the second of two controversial argumentations concerning the substitution of Ga 3 ions on B-sites either (a) only for higher contents x b 0X3 as proposed by Dehe et al [17] from Mo È ûbauer spectroscopy in combination with neutron diffraction and saturation magnetization, or b) already for low contents x 0X1 as deduced, alternatively, on the basis of again Mo È ûbauer spectroscopy [18], magnetic anisotropy and magnetostriction [19] and magneto-elastic relaxation [20].…”

“…Cylindrical mono-crystals of gallium ferrite (length 35 mm, diameter 5 mm) have been prepared using a floating zone melting technique, as described previously [1,18,19], with their axes oriented along h110i or h100i. Samples covering Ga contents 282 F. Walz and V. A. M. Brabers 1 Respective lattice distortions, revealed in the spectra of electron (e À )-irradiated magnetite, have been cogently attributed to the presence of radiation-induced intrinsic interstitials which, upon reorientations of their anisotropy axes, are inducing process IV.…”

“…Valuable insights, enlightening this problem of ionic distributions in the spinel, are available by means of high-sensitivitiy MAE spectroscopy. Such specific information, deducible from MAE analyses, is of use also for an adequate interpretation of the results obtained by alternative techniques such as, e.g., electric conductivity [16], Mo È ssbauer spectroscopy [17,18], magnetic anisotropy and magnetostriction [19], magneto-elastic relaxation [20], etc.…”

Nuclear magnetic resonance of 57Fe in Al-, Ga- and Ti-substituted magnetite above Verwey temperature

“…From this analysis follows that preference of Ga for B-sites is lower than the ratio 1:2 given in Ref. [3]. …”