Charge Transfer between Fe and Ti Induced by <i>Ln</i> Substitution and Temperature in the <i>B</i>-Site-Disordered Perovskites <i>Ln</i>₂(FeTi)O₆ (<i>Ln</i> = La, Pr, and Nd)

Newly synthesized B-site-disordered perovskites Ln2(FeTi)O6 (Ln = Pr and Nd) were found to show charge transfer between Fe and Ti ions, which was in contrast to the robust Fe3+/Ti3+ state in the isostructural Ln = La compound La2(Fe3+Ti3+)O6. The charge distribution for Ln = Pr and Nd can be expressed as Ln2(Fe3+0.8Ti3+0.8Fe2+0.2Ti4+0.2)O6 at room temperature, and the amount of Fe2+/Ti4+ increases with decreasing temperature. In addition, the charge transfer resulting in Ln-dependent valence states at the B site strongly affects magnetic properties, including the magnetic transition temperatures and the ground states.