Oxygen-free nitride materials with the perovskite structure and stoichiometry could underpin a host of applications, including new types of mechanical energy harvesters and low-power memory devices. The applications require integrating the perovskites with silicon or other semiconductors while excluding oxygen, because its presence can diminish device performance. Theoretical studies predict that these materials would be thermodynamically stable, asymmetric (and therefore polar), and would have the required electronic properties to enable those applications. But researchers have been unable to prepare pure nitride perovskites and analyze their properties. One challenge is that traditional solid-state chemistry methods often yield oxynitrides. So a team led by Geoff L. Brennecka of the Colorado School of Mines and Andriy Zakutayev of the National Renewable Energy Laboratory took a different tack. To minimize oxygen contamination and maximize the nitrogen content of perovskite thin films, the group grew them in vacuum using a vapor deposition method with a nitrogen plasma source. The approach worked, yielding lanthanum tungsten nitride, LaWN3, a polar, crystalline perovskite (Science 2021, DOI: 10.1126/science.abm3466). One key finding that may signal future applications came from scanning probe analysis. Those measurements indicate that the new material exhibits a large piezoelectric response, which is the key property at work in ultrasound equipment, microphones, and other devices.