Rod-like incipient ferroelectric SrTiO3 polycrystal with crystal-axis orientation

Strontium titanate (SrTiO3, ST) is an incipient ferroelectric material. Generally, a one-dimensional (1D) ST polycrystal is difficult to obtain because of its high aspect ratio and directional orientation. We prepared a 1D ST polycrystal from a layered H2Ti4O9·H2O (HT) single crystal via a solvothermal soft chemical process. The 1D ST polycrystal fabricated from ST nanocrystals has a [010] crystal axis, implying that it is a mesocrystal. The ST nanocrystals were grown not only on the surfaces but also in the interlayers of the original HT matrix. The formation mechanism of the ST mesocrystal is based on a topochemical mesocrystal conversion process. ST ceramics fabricated from ST mesocrystal powder present a lossy capacitor response and excellent energy-storage capabilities owing to the presence of locally oriented ST nanocrystals with a lattice mismatch in the rod-like ST mesocrystals. The investigations performed in this study can set a new benchmark for the development of new electric ST-based materials.