Structure evolution and magnetic property of cobalt-modified Bi0.9Gd0.1FeO3 nanocrystal at morphotropic phase boundary

• 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.

Cobalt-modified Bi0.9Gd0.1FeO3 nanocrystal was prepared by facile co-precipitation method. The Rietveld refinement results show that minor Co-substitution concentration (x ∼ up to 0.05) in Bi0.9Gd0.1Fe1−xCoxO3 gradually promotes the structural transition from R3c to Pn21a and their magnetic performances are also enhanced. The magnetization of the as-prepared Bi0.9Gd0.1Fe1−xCoxO3 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.