Cation distribution and entropic disordering in mixed spinel ferrite Ga0.4Fe0.6NiCr1-yAlyO4

Moessbauer measurements (4.2≤T≤2980 K) indicate the presence of entropic disordering in (Ga0.43+Fe0.6-p3+Alp3+)[Ni2+Cr1-y3+Aly-p3+Fep3+]O4 and a linear increase in p with y between 0(y=0) and 0.11(y=1). Entropic spins are located only on A-sites indicating relatively large A-sublattice frustration. Weak A-B coupling could explain this separate sublattice behaviour. Magneton number, along with Moessbauer p values, shows B-site canting which increases with y revealing weakness of A-B interaction. Present system can be called a 'frustrated ferrimagnet' or 'entropic ferrimagnet' where ferrimagnetic and frustrated (entropic) spins are coexisting. (orig.)