High-quality single crystal growth of Bi-based perovskite ferroelectrics based on defect chemistry

Abstract

We present the O2-blowing method for the growth of high-quality single crystals of Bi-based perovskite ferroelectrics, in which O2 gas is directly introduced inside crucibles during crystal growth. The O2-blowing method is demonstrated to be effective for enhancing polarization and piezoelectric properties as well as reducing leakage current for (Bi,Na)TiO3-BaTiO3 crystals. The superior properties are suggested to originate from the reduced reorientation of non-180° domains. Ab initio calculations suggest that the interaction between spontaneous polarization and defect dipole composed of Bi vacancy and O vacancy is the origin of the reorientation of non-180° domains.

Electric-field-induced giant strain in Bi0.5Na0.5TiO3-based single crystals: Influence of high-oxygen-pressure annealing

“…The carrier of the leakage current for BNT 89) and BNT-BT 90) has been reported to be h • generated by the oxidation reaction (Eq. (2) …”

“…81),82), 90) The direction normal to 90° domain walls is defined by the x axis. In the profile of the Ps component along x, Ps(x) is suppressed near the domain walls due to the spatial modulation of the Ps vector caused by ferroelastic distortion inside the 90° domain walls.…”

“…In the profile of the Ps component along x, Ps(x) is suppressed near the domain walls due to the spatial modulation of the Ps vector caused by ferroelastic distortion inside the 90° domain walls. 81),82), 90) The lower value of Ps(x) at the domain walls leads to an electrostatic potential drop across the domain walls. This potential drop induces a charged double layer 81) and the depolarization field near the domain walls exceeds 1 MV/cm in BaTiO3.…”

Enhanced polarization properties of ferroelectric (Bi_1/2Na_1/2)TiO₃–Ba(Mg_1/3Nb_2/3)O₃ single crystals grown under high-pressure oxygen atmosphere

“…There have been several reports on the crystal growth of BNT-based single crystals: the Bridgeman method, 76),77) the flux method, 78),79) the O 2 -blowing flux method, 80) the zone-melting technique, 81) and the top-seeded solution growth (TSSG) method. 82)84) Although large-sized BNT-based crystals were obtained, their polarization and piezoelectric properties were relatively inferior compared with those expected from ceramics.…”

“…This is probably due to the high leakage current and domain clamping caused by defects generated during the crystal growth process. 80) To elucidate the detailed properties and crystal structures in response to external field applied along specific directions, single-crystals studies are advantageous. To the best of our knowledge, there has been no report on the crystal growth and the property measurements on BNTBMN single crystals, probably because of a difficulty in growing high-quality crystals.…”