Weak Ferromagnetism in BiFeO[sub 3] - NdFeO[sub 3] Solid Solutions

Abstract

There are three phases in the pseudobinary solid solution Bi1−xNdxFeO3 — the rhombohedral ferroelectric BiFeO3 phase for x ≤ 0.1, a tetragonal phase near x = 0.15, and the orthorhombic NdFeO3 structure for x ≥ 0.2. Intrinsic weak ferromagnetism is present in all three phases. In rhombohedral Bi.9Nd.1FeO3, the room temperature moment is about 3 mμ B/formula unit after thermomagnetic annealing. The moment increases fairly smoothly with increasing Nd content through all three phases, at least up to x = 0.5. The presence of weak ferromagnetism in the BiFeO3 phase is explained on the basis of the effect of Nd in regularizing the Fe‐O distances, thus affecting superexchange at least locally. These results are compared with those found by others for Bi1−xLaxFeO3 and Bi1−xPrxFeO3.