Orthorhombic Nitride Perovskite CeTaN 3‐ δ With Switchable and Robust Ferroelectric Polarization

ABSTRACT Perovskite‐type ternary nitrides with predicted exciting ferroelectricity and many other outstanding properties hold great promise to be an emerging class of advanced ferroelectrics for use in diverse technologically important devices. However, such nitride ferroelectrics have not yet been experimentally identified, mainly due to the challenging sample synthesis by traditional methods at ambient pressure. Here, we report the successful high‐pressure synthesis of a high‐quality ferroelectric nitride perovskite of CeTaN 3‐δ with nitrogen deficiency, adopting an orthorhombic Pmn 2 1 polar structure. This material is a semiconductor and exhibits switchable and robust electric polarization for producing ferroelectricity. Furthermore, a number of other extraordinary properties are also revealed in this nitride such as excellent mechanical properties and chemical inertness, which would make it practically useful for many device‐relevant applications and fundamentally important for the study of condensed‐matter physics.