100 years of ferroelectricity—A celebration.

Spreitzer I et al. i [96] provide a research update on the growth of ferroelectric oxide thin films on silicon, with a particular view toward their applications in piezoelectric micro electromechanical systems (MEMS), electro-optic devices for communications applications, and catalysis and a consideration of the complexities of the silicon-ferroelectric interface. The favored theory for oxide ferroelectrics is the soft-mode theory, and here, we have a perspective by Kamba[79] discussing the results of broadband dielectric, THz, and IR spectroscopic investigations of soft-mode phenomena in H-bonded ferroelectrics, BaTiO SB 3 sb , relaxors, and multiferroics. Domains are also of considerable interest in antiferroelectric materials, and An I et al. i [118] discuss the hierarchical nature of domains in PZT crystals with only 2 at. % Ti, close to the antiferroelectric PbZrO SB 3 sb composition, showing how this forms in the intermediate ferroelectric state and have a significant impact on the materials' physical properties. Subsequently, there has been shown to be a wide range of metal organic complex ferroelectrics, as reviewed by Hang I et al. i [123] In this collection, we have an overview by Yao I et al. i [124] of the potential for bandgap engineering in hybrid organic-inorganic perovskite (HOIP) ferroelectrics such as (MDABCO)(NH SB 4 sb )I SB 3 sb [MDABCO = I N i -methyl I N i '-diazabicyclo(2.2.2)octonium], with the potential for linking the excellent characteristics of the new perovskite materials for solar cells, such as methylammonium lead iodide (MAPbI SB 3 sb ),[125] with the photovoltaic effects seen in ferroelectrics. [Extracted from the article]