A phenomenological qualitative model is proposed to understand the decrease of leakage current in Na doped BiFeO ₃ nanoparticles.

Hybrid improper ferroelectric Ca₃Ti₂O₇and Ca₃Ti₁₉Ru_0.1O₇ceramics were successfully synthesized by conventional solid-state reaction method. Two strongest diffraction peaks located around 2θ= 33° shifted towards the lower angle region with Ru substitution, reflecting structure variation. Grain growth and higher oxygen vacancy concentration after doping resulted in a reduction in the coercive field about 20 kV/cm. Optical bandgap estimated by UV-vis diffuse reflectance (DR) spectrum and X-ray photoelectron spectroscopy (XPS) valence band spectra showed a decreasing trend due to the existence of impurity energy level upon Ru doping, which was consistent with the results of first-principles calculations. The origin of the unexpected induced magnetic moments in Ru-dope Ca₃Ti₂O₇is also discussed.

Ruddlesden–Popper (RP) structural Li _2x Ca _3−2x Mn ₂ O ₇ ( x = 0–0.05) particles were successfully synthesized via a citrate sol–gel method. Li doping was investigated to have a positive influence on enhancing the magnetism of the system.