Nd-doped BiFeO_3 ceramics with antipolar order

摘要

Bi_(1-χ)Nd_χFeO_3 (0≤χ≤0.2) ceramics have been investigated using x-ray diffraction (XRD) and electron diffraction (ED). XRD patterns for x≤0.1 were consistent with rhombohedral BiFeO_3, whereas those for χ=0.15 and χ=0.2 exhibited peak splitting and superlattice reflections representative of orthorhombic, antiferroelectric PbZrO_3. ED for the latter samples confirmed the presence of 1/4 (hk0) superlattice reflections typical of a PbZrO_3-like structure but additional superlattice reflections were observed at 1/4(00l) yielding a 2~(1/2)a, 2 2~(1/2)a, 4a (where a is the pseudocubic lattice parameter) unit cell. The transition from rhombohedral BiFeO_3 to the PbZrO_3-like structure implies a modification from polar to antipolar behavior.