Structure evolution and magnetic property of cobalt-modified Bi_0.9Gd_0.1FeO₃ nanocrystal at morphotropic phase boundary

Cobalt-modified Bi_0.9Gd_0.1FeO₃ nanocrystal was prepared by facile co-precipitation method. The Rietveld refinement results show that minor Co-substitution concentration (x ∼ up to 0.05) in Bi_0.9Gd_0.1Fe_1−xCo_xO₃ gradually promotes the structural transition from R3c to Pn2₁a and their magnetic performances are also enhanced. The magnetization of the as-prepared Bi_0.9Gd_0.1Fe_1−xCo_xO₃ specimen (x = 0.05) at a 1.8 T testing magnetic field is 1.3450 emu/g, which is stronger than those of samples with x = 0 (0.3457 emu/g) and pure phase BiFeO₃ (0.0867 emu/g). The possible mechanism of magnetic transition would mainly be contributed to the substitution-induced suppression of spiral spin structure and magnetically active substitution ions. - Highlights: • Increasing Co-substitution promotes phase transition from R3c to Pn21a near MPB. • Increasing Co-substitution caused dramatic enhancement of magnetization. • The facile synthesis gives a strategy for efficiently modulating magnetoelectric property.