Structural and magnetic investigations of CaBaCo_4−xFe_xO₇ solid solutions

Solid solutions of CaBaCo_4−xFe_xO₇ (x=0, 0.05, 0.2, 1, 2) were synthesized by glycine-nitrate combustion process. Their structural and magnetic properties were characterized by means of x-ray diffraction and magnetization measurements. In the examined range of the solid solutions, their crystal lattice symmetry changes from orthorhombic with space group Pbn2₁ (03mc (x>0.5). The magnetic measurements revealed that even small doping (x=0.05) of the transition metal sublattice noticeably suppresses ferrimagnetism of the parent compound and induces an AF transition at 88 K. An increase in the doping concentration lowers the frustration parameter |θ_CW|/T_C from 17.2 (for x=0.05) to 13.7 (for x=2) and strengthens the antiferromagnetic interactions, which manifests itself in the Curie–Weiss temperature (θ_CW) growth. The samples with x=0.05 and x=0.2 also show an additional magnetic transition at temperatures T_g (55 and 70 K respectively). The temperature irreversibility between the ZFC and FC magnetization curves may suggest the formation of a spin-glass state below that temperature. - Highlights: • CaBaCo_4−xFe_xO₇ solid solutions were synthesized by glycine-nitrate process. • At x=1 symmetry became hexagonal instead orthorhombic. • Fe-doping abruptly suppresses ferrimagnetism of CaBaCo₄O₇. • Increase of x is followed by enhancing of antiferromagnetic interactions.