Effect of Cr and Mn ions on the structure and magnetic properties of GaFeO3: Role of the substitution site

Effect of substitution of Cr and Mn in the Fe and Ga sites of GaFeO3 on the structural parameters and magnetic properties has been investigated by preparing GaFe1-xCrx(Mn-x)O-3 and Ga1-xCrx(Mn-x)FeO3 starting with appropriate oxide precursors. It is shown that, starting with Cr or Mn substituted Ga2O3, one obtains Ga1-xCrx(Mn-x)FeO3, while reaction of Cr or Mn substituted alpha-Fe2O3 with Ga2O3 yields GaFe1-xCrx(Mn-x)O-3. The structural parameters and magnetic properties vary significantly with the substitution site of Cr showing a large decrease in the unit cell parameters as well as the T-C and other magnetic properties when the substitution is at the octahedral Fe (1, 2) site. Substitution of Cr at the octahedral Ga2 site results in marginal changes. Substitution of Mn in the Ga and Fe sites also show differences although the changes themselves are much smaller. First-principles calculations confirm such site-specificity and show how Cr substitution affects the properties differently when substituted at the Ga2 and Fe1 sites. (C) 2011 Elsevier Inc. All rights reserved.