Effect of Nonmagnetic Ion Substitution on Multiferroic Properties of BiFeO3

BiFeO3 is a ferroelectric and antiferromagnetic material at room temperature. In contrast to the weak ferromagnetism anticipated below TN = 640 K, it exhibits no macroscopic moment due to a cycloidal spin ordering. This study attempts to perturb the cycloidal spin ordering and improve the multiferroic properties by substitutions of Al and Sc at Fe site. The compounds BiFe1−xAlxO3 (0 ≤ x ≤ 0.3) and BiFe1−xScxO3 (0 ≤ x ≤ 0.2), synthesized at high pressures and temperatures, crystallize with perovskite structure in polar space group R3c. With increasing Al/Sc concentration, the compounds undergo marked changes in magnetic properties. While Al-substituted compounds were lossy and exhibited a Maxwell–Wagner effect, the Sc-substituted compounds exhibited ferroelectricity at room temperature.