Theory of Ferroelectrics: A vision for the next decade and beyond

Compositional range and electrical properties of the morphotropic phase boundary in the Na0.5Bi0.5TiO3–K0.5Bi0.5TiO3 system

“…The trend of an increasing piezoelectric constant towards the MPB was already demonstrated for other solid-solution systems, especially in the case of PZT. 1,2 The reason for the enhanced piezoelectric response at the MPB is in the easier dipole alignment due to the large number of possible directions of polarization, and this is the same for the highest remanent polarization of the material. According to our experiences with the synthesis of NBTbased 16,44 and KBT 40 ceramics, the preparation conditions are very important because of the presence of highly volatile and hygroscopic elements.…”

“…It is known from the literature that materials in the vicinity of polymorphic phase transitions, or in the MPB regions, exhibit enhanced electromechanical coupling properties. 1,2 Many studies have been made on B-site cation-substituted perovskites, whereas A-site cation-substituted perovskites are relatively less investigated, but nevertheless important, since alkali cations contribute to the greater polarizability of the materials. Na 0.5 Bi 0.5 TiO 3 (NBT) is an A-site cation-substituted perovskite, which was first reported by Smolenskii and Agranovskaya in 1960.…”

“…An appropriate alternative to piezoelectric materials containing lead could be systems in the form of solid solutions with complex perovskite structures. 1,2 Among the potential materials that could substitute for lead-based piezoelectric ceramics are Na 0.5 Bi 0.5 TiO 3 -and K 0.5 Na 0.5 NbO 3 -based perovskite materials. [3][4][5][6][7] The electrical properties of these two compounds can be modified by the formation of solid solutions with K 0.5 Bi 0.5 TiO 3 , 8 18 LiSbO 3 , etc., 19 where the A-or B-site cations in the ABO 3 structure are substituted.…”

Towards an accurate description of perovskite ferroelectrics: exchange and correlation effects

“…A key challenge is the fact that complex behavior such as order-disorder transitions and domain wall motion typically require a large number of atoms in order to adequately simulate this behavior. Thus, some of the most common tactics for efficiently studying ferroelectric phase transitions include: (1) Monte Carlo simulations employing DFT parameterized effective Hamiltonians11121314151617 or (2) molecular dynamic simulations with atomistic potentials, such as the shell-model181920 or bond-valence212223 approach. While the above methods correctly reproduce the overall sequence of phase transitions for various perovskite oxides, the values of transition temperatures were generally underestimated relative to the experiments111224.…”

Hydrothermal synthesis of lead free piezoelectric materials

“…Contemporary studies of ferroelectrics based on first-principle calculations suggest that the ferroelectric response is more than just lattice distortions [89][90][91]. Cohen suggests that the origin of ferroelectricity, observed in the lead titanate system he was studying, is connected to the important hybridization between 3d states of the "B" cation and 2p states of the "X" anion [90].…”