Crystal structure, piezoelectric and magnetic properties of BiMn_1-xFe_xO₃ (x ≤ 0.4) solid solutions

The crystal structure, piezoelectric and magnetic properties of BiMn_1-xFe_xO₃ (x ≤ 0.4) solid solutions synthesized using different solid state reactions from a stoichiometric mixture of simple oxides at high pressures and temperatures have been studied. The structure of the composition undergoes a concentration phase transition from the monoclinic to the orthorhombic structure. The formation of the orthorhombic phase is observed at the concentration x ≈ 0.2 and is accompanied by the destruction of the d_z2 orbitals of the Mn³⁺ ions causing the stabilization of a homogeneous magnetic state. The solid solutions containing 0.2 ≤ x ≤ 0.4 exhibit a non-zero piezoresponse and may have ferroelectric or magnetic domain structures, the ferroelectric switching voltage decreasing with an increase in the iron concentration while the remanent magnetization decreases. The highest piezoresponse signal is observed for the BiMn_0.7Fe_0.3O₃ solid solution. The relationship between the chemical composition, type of crystal structure, piezoelectric and magnetic properties of the BiMn_1-xFe_xO₃ solid solutions has been verified. Due to the combination of magnetic and electric dipole ordering these materials show good promise for practical applications.