Compositional dependence of structural parameters, polyhedral distortion and magnetic properties of gallium ferrite

We show the effect of composition on the structure, polyhedral distortion and magnetic characteristics of pure phase polycrystalline Ga2−xFexO3 (GFO) for compositions between 0.8≤x≤1.3. X-ray analysis reveals that lattice parameters of GFO exhibit a linear dependence on Fe content in single phase region indicating manifestation of Vegard's law. Upon changing the composition, a rather small change in the overall unit cell volume (∼1%) appears to be an outcome of a competition between changing trends of various polyhedra. Increasing Fe content of the samples also leads to stretching of the bonds as indicated by the Raman peak shifts. Further, low temperature magnetic measurements show that the coercivity of the samples is maximum for Ga:Fe ratio of 1:1 driven by a competition between decreasing crystallite size and increasing magnetic anisotropy.

► Single phase polycrystalline Ga2−xFexO3 remains stable for compositions 0.8≤x≤1.3.
► Lattice parameter variation with varying composition follows Vegard's law over 0.8≤x≤1.3.
► Small unit cell volume change (∼1%) is due to complex polyhedral volume changes.
► Increasing x causes bond stretching and increase of magnetic transition temperature.
► Counteracting magnetic anisotropy and crystallite size forms maxima in the coercive field.