Ferroelectrics

AbstractFerroelectrics can be utilized in various devices such as high permittivity dielectrics, ferroelectric memories, pyroelectric sensors, piezoelectric devices, electrooptic devices, and PTCR components. However, ferroelectric devices often fail to be commercialized in the cases where competitive materials exist. In the photo‐sensors, for example, semiconductive materials are superior to ferroelectrics in response speed and sensitivity. Magnetic devices and flash memories are much more popular in the memory field, and liquid crystals are typically used for optical displays. This is mainly due to a lack of systematic and comprehensive accumulation of knowledge on ferroelectricity. This article was authored to strengthen the theoretical background of ferroelectric devices, then, practical materials, and typical applications, and looks forward to the future progress in this field. The article covers (1) crystal structure and ferroelectricity, (2) origin of spontaneous polarization, (3) origin of field‐induced strain, (4) piezoelectric constitutive equations, (5) ferroelectric materials, and (6) applications of ferroelectrics. This article is primarily based on the author's textbook, “Ferroelectric Devices 2nd Edition”.