Charge-balanced synthesis and characterization of SnTiO₃: toward a lead-free ferroelectric material

Abstract The stabilization of divalent tin (Sn 2+ ) in perovskite SnTiO 3 remains a key challenge in developing Pb-free ferroelectrics with performance comparable to BaTiO 3 . We investigated the valence stability of Sn 2+ in SnTiO 3 synthesized via the solid-state reaction method, focusing on its thermal behavior under various annealing conditions. X-ray absorption near-edge structure spectroscopy reveals that the TiO 6 octahedra retain structurally robust across the annealing range (300 °C–700 °C), as evidenced by the pre-edge features of the Ti K-edge. In contrast, the Sn K-edge spectra reveal a significant sensitivity of the Sn oxidation state to thermal processing, highlighting the necessity of precise temperature control to prevent Sn 2+ → Sn 4+ conversion. X-ray diffraction analysis and Raman spectroscopy were employed to elucidate the structural instability of the SnTiO 3 phase. These findings establish a reliable framework for synthesizing Sn 2+ -stabilized SnTiO 3 , not only advancing the development of functional Pb-free ferroelectrics but also providing new opportunities for photocatalytic activities.