Top-seeded solid-state single crystal growth of 0.75(Na_0.5Bi_0.5)TiO₃-0.25SrTiO₃ single crystals in oxygen and their characterization

In this present work, 0.75(Na_0.5Bi_0.5)TiO₃-0.25SrTiO₃ single crystals were grown by top-seeded solid-state crystal growth under an oxygen atmosphere. Growth in oxygen resulted in improved single-crystal growth and density compared to single crystals previously grown in air. X-ray diffraction revealed the simultaneous presence of tetragonal and cubic phases in the crystal while Raman scattering suggested the presence of rhombohedral and tetragonal phases. Piezoresponse force microscopy and electrostatic force microscopy show that the single crystal is in an ergodic relaxor state and electrostatic force microscopy shows that ferroelectric domains can be induced by an electric field. Dielectric property measurements show behaviour typical of an (Na_0.5Bi_0.5)TiO₃-type relaxor material. Polarization and strain vs. electric field hysteresis measurements show that the single crystal is an incipient ferroelectric. A maximum strain of 0.48% was obtained at an electric field of 3.5 kV/mm, giving S_max/E_max = 1365 pm/V, which is an enhancement of 32% compared to 0.75(Na_0.5Bi_0.5)TiO₃-0.25SrTiO₃ single crystals grown in air.