Polar Nitride Perovskite LaWN_3‐δ with Orthorhombic Structure

Abstract

Nitride perovskite LaWN3 has been predicted to be a promising ferroelectric material with unique properties for diverse applications. However, due to the challenging sample preparation at ambient pressure, the crystal structure of this nitride remains unsolved, which results in many ambiguities in its properties. Here, the authors report a comprehensive study of LaWN3 based on high‐quality samples synthesized by a high‐pressure method, leading to a definitive resolution of its crystal structure involving nitrogen deficiency. Combined with theoretical calculations, these results show that LaWN3 adopts an orthorhombic Pna21 structure with a polar symmetry, possessing a unique atomic polarization along the c‐axis. The associated atomic polar distortions in LaWN3 are driven by covalent hybridization of W: 5d and N: 2p orbitals, opening a direct bandgap that explains its semiconducting behaviors. The structural stability and electronic properties of this nitride are also revealed to be closely associated with its nitrogen deficiency. The success in unraveling the structural and electronic ambiguities of LaWN3 would provide important insights into the structures and properties of the family of nitride perovskites.

Metal nitrides for seawater electrolysis

“…It is essential to note that X-ray photoelectron spectroscopy (XPS) is a near surface analysis technique and the accuracy of the results is highly dependent on instrument calibration and sample preparation. 183,184 The quantitative determination of N content can also be obtained through Rietveld analysis, which involves fitting crystal structure parameters to acquire precise crystallographic information. 185…”