Title: High curie temperature ferroelectrics

Abstract

High Curie temperatures of ferroic materials such as ferroelectrics, ferromagnetics, and ferroelastics have attracted much attention, while their physical origins are not yet clarified. The year 2020 marks hundred years since the discovery of the phenomenon of ferroelectricity. Ferroelectrics have a rich of functionality such as piezoelectric, electro-optic, nonlinear optic, electrocaloric, energy storage, pyroelectric properties. Ferroelectric materials with high Curie temperatures, TC, and tuning of the TC over a large temperature range are very important for the fundamental sciences and engineering. This paper reviews the various types of high-temperature ferroelectrics with perovskite, bismuth layered, tungsten bronze, and perovskite slab structures, especially Sr2Nb2O7 with TC = 1342oC and its family. The superior tunability of the TC is achieved by the substitution of cations in the A- and B-sites of perovskite-like structures. The origin of ferroelectricity with high TC is discussed.