Tetragonal-structural changes influenced the magnetic and ferroelectric properties of (Y, Fe)-codoped BaTiO3 ceramics

We present a detailed study on the structural characterization, electronic structure, and magnetic/electric-polarization properties of Ba1-xYxTi1-xFexO3 (BYxTFxO, x = 0–0.1) ceramic samples. These samples mainly crystalized in a tetragonal structure, and a small amount of a YFeO3-related secondary phase constituted as x ≥ 0.08. With increasing x, the lattice constant a increases while c decreases. Such structural changes reduce rapidly the intensity of characteristic Raman modes. Magnetization data have proved all BYxTFxO samples exhibiting ferromagnetism at room temperature. Both the saturation magnetization and coercivity tend to increase with increasing x. This is ascribed to an enhanced exchange interaction between Fe3+ ions, and the YFeO3-phase formation. Herein, the Fe3+ presence has been confirmed upon analyzing X-ray absorption spectra. Though all the samples exhibit ferroelectricity, the electric-polarization slightly decreases with increasing x. This is associated with an increased symmetry due to the changes in the lattice parameters towards the cubic structure.