Layered Double Perovskites

Abstract

Successful strategies for the design of crystalline materials with useful function are frequently based on the systematic tuning of chemical composition within a given structural family. Perovskites with the formula ABX3, perhaps the best-known example of such a family, have a vast range of elements on A, B, and X sites, which are associated with a similarly vast range of functionality. Layered double perovskites (LDPs), a subset of this family, are obtained by suitable slicing and restacking of the perovskite structure, with the additional design feature of ordered cations and/or anions. In addition to inorganic LDPs, we also discuss hybrid (organic-inorganic) LDPs here, where the A-site cation is a protonated organic amine. Several examples of inorganic LDPs are presented with a discussion of their ferroic, magnetic, and optical properties. The emerging area of hybrid LDPs is particularly rich and is leading to exciting discoveries of new compounds with unique structures and fascinating optoelectronic properties. We provide context for what is important to consider when designing new materials and conclude with a discussion of future opportunities in the broad LDP area. Expected final online publication date for the Annual Review of Materials Science, Volume 51 is August 2021. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Chemical Control of Magnetic Ordering in Hybrid Fe–Cl Layered Double Perovskites

“…Two Fe-based 3D double perovskites, namely, Cs 2 AgFeCl 6 and Cs 2 NaFeCl 6 are recently reported, − but their magnetic properties remain unknown. Additionally, the incorporation of long-chain organic cations results in dimensional reduction that generates hybrid layered double perovskites, − providing the opportunity to study the 2D magnetism in halide double perovskites. The development of new layered magnetic semiconductors is of great importance for both fundamental research and technological applications such as in spin- and valleytronic devices.…”

Bismuth/Silver-Based Two-Dimensional Iodide Double and One-Dimensional Bi Perovskites: Interplay between Structural and Electronic Dimensions

“…2D halide perovskites based on Pb 2+ dominate the field because of their favorable electronic structures thanks to the Pb s 2 lone pair. , In the efforts to expand the family and in part to eliminate the perceived toxic Pb, researchers have developed double perovskites where Pb 2+ is replaced by a +3 metal (such as Bi 3+ or In 3+ ) and a +1 metal (such as Ag + or Cu + ). − So far, most 3D double perovskites have been based on bromide or chloride because of a size limit that excludes the iodide structures. Because the octahedral ratio, μ = r (M III )/ r (X) (where r (M III ) and r (X) are the radii of the +3 metal and halogen, respectively), needs to be ≥ 0.41, it places the iodine with its large radius off limits because few +3 metals can meet the requirement. , However, using the dimensional reduction − as in Pb-based perovskites, 2D iodide double perovskites have been achieved recently . After the first report of iodide 2D double perovskites using aromatic diammonium cations, they were also synthesized with aliphatic diammonium cations − and monoammonium cations. , They have demonstrated interesting features such as ferroelectricity, X-ray detection, and even circularly polarized light detection …”

Factors Constituting Proton Trapping in BaCeO3 and BaZrO3 Perovskite Proton Conductors in Fuel Cell Technology: A Review

“…In a macroscopic perspective, the grain boundary resistance in proton-conducting electrolytes can be decremented by increasing the grain size using nanosized materials with better sinterability or employing uniform sintering additives. Post annealing of synthesized acceptor-doped proton conductors would minimize the proton trapping effect reflecting high proton conductivity. Thick electrolytes with standard cathodes affect electrochemical kinetics and electrocatalytic activity. Maintaining a suitable electrolyte dimension by constricting the electrolyte thickness adopting thin-film techniques such as pulse layer deposition subsidizes the cathode polarization resistance ( R p ) and ohmic resistance and revamps a fuel cell’s power density at intermediate temperatures. Layered double perovskites with two active B-sites, large proton incorporation, and fast proton diffusion have been gaining desirable attention as an alternative solution to doped single perovskite proton conductors . Meanwhile triple-conducting oxides have also gained importance displaying high mixed ion-electron conductivity for cathode materials. Substantial exploration indicates materialistic research gaps concerning the constituents in fuel cell storage systems.…”

“…• Layered double perovskites with two active B-sites, large proton incorporation, and fast proton diffusion have been gaining desirable attention as an alternative solution to doped single perovskite proton conductors. 199 Meanwhile triple-conducting oxides have also gained importance displaying high mixed ion-electron conductivity for cathode materials. • Substantial exploration indicates materialistic research gaps concerning the constituents in fuel cell storage systems.…”