A Predictive Theory for Domain Walls in Oxide Ferroelectrics Based on Interatomic Interactions and its Implications for Collective Material Properties

Abstract

Domain walls separating regions of ferroelectric material with polarization oriented in different directions are crucial for applications of ferroelectrics. Rational design of ferroelectric materials requires the development of a theory describing how compositional and environmental changes affect domain walls. To model domain wall systems, a discrete microscopic Landau–Ginzburg–Devonshire (dmLGD) approach with A‐ and B‐site cation displacements serving as order parameters is developed. Application of dmLGD to the classic BaTiO3, KNbO3, and PbTiO3 ferroelectrics shows that A–B cation repulsion is the key interaction that couples the polarization in neighboring unit cells of the material. dmLGD decomposition of the total energy of the system into the contributions of the individual cations and their interactions enables the prediction of different properties for a wide range of ferroelectric perovskites based on the results obtained for BaTiO3, KNbO3, and PbTiO3 only. It is found that the information necessary to estimate the structure and energy of domain‐wall “defects” can be extracted from single‐domain 5‐atom first‐principles calculations, and that “defect‐like” domain walls offer a simple model system that sheds light on the relative stabilities of the ferroelectric, antiferroelectric, and paraelectric bulk phases. The dmLGD approach provides a general theoretical framework for understanding and designing ferroelectric perovskite oxides.

Antiferroelectric-to-ferroelectric phase transition in hexagonal rare-earth iron oxides

“…It is noted that small c/a, which is obtained when the lattice constant parallel (perpendicular) to polarization decreases (increases), tends to reduce the DW formation energy. 43,44…”

Toward Ecofriendly Piezoelectric Ceramics—Reduction of Energy and Environmental Footprint from Conceptualization to Deployment

“…[30] In recent DFT studies, the lower energy state has been found to be the antiparallel B-site displacement direction when competing between being displaced in the parallel (single domain) and antiparallel (multiple domains) directions, as shown in Figure 3a. [31] These results have been explained using the simple argument of the minimization of electrostatic energy. In the AFE state, the electrostatic energy is reduced with the antiparallel arrangement while increasing the repulsion between the A-site and B-site.…”

“…Figure 3. a) Energy difference between AFE and FE phases as a function of lattice parameter c for BTO (BaTiO 3 ), KNO (KNbO 3) and PTO (PbTiO 3 ), wherein the energies have been calculated for structures with a fixed A-site and oxygen octahedron cage. Reproduced with permission [31]. Copyright 2021, John Wiley and Sons.…”

Bulk Photovoltaic Current Mechanisms in All-Inorganic Perovskite Multiferroic Materials

“…In traditional semiconductor p-n junction solar cells, the position of quasi Fermi level limits that the energy difference of electron hole pair in thermal equilibrium state that cannot exceed its bandgap (the Shockley and Queisser limit) (SQL) [ 6 ]. From this point of view, although the specific microscopic mechanism of BPE is still controversial [ 7 ], it must be different from the traditional p-n junction space depletion layer, because both theoretical calculation and experimental results show that [ 8 , 9 ], the open circuit voltage (Voc) of ferroelectric materials (or localized polar materials) [ 10 ] can exceed the limit of SQL, reaching two to four orders of magnitude higher than the bandgap [ 11 ], which enables ferroelectric photovoltaic devices with significant potential to be applied in multifunctional optical–electrical systems [ 12 ].…”