Structure and Properties of Multiferroic Oxygen Hyperstoichiometric BiFe_1−xMn_xO_3+δ

The structure and properties of materials in the BiFeO 3 -rich side of the pseudo-binary phase diagram BiFeO 3 −BiMnO 3 are reported. Manganese substitution ( x ) and oxygen hyperstoichiometry (δ) are demonstrated to strongly affect the crystallographic properties, electrical conductivity, and phase-transition temperatures of BiFe 1− x Mn x O 3+δ . Increasing the manganese content and oxygen hyperstoichiometry of the materials depresses the Néel temperature, the ferroelectric Curie temperature, and the transition temperature from the paraelectric, ferroelastic structure to the paraelastic, cubic perovskite structure. The thermodynamics of the ambient pressure solid solubility is discussed and a phase diagram for the system BiFe 1− x Mn x O 3+δ is presented, establishing the stability regions of three, two, one, and zero simultaneous ferroic properties. Finally, technological implications of the influence of manganese and excess oxygen are discussed.