Researchers have built a chemical map to guide the exploratory synthesis of nitrides. If new nitrides are discovered it would the chemical science equivalent of discovering a new continent.
Before researchers could map the nitrides, however, they first needed to predict new nitride materials. Using high-throughput computational materials science, they first considered 6,000 potential nitride compounds by substituting known nitrides with new elements. After checking the stability of these possible nitrides, they predicted 203 new stable ternary nitride compounds. Until now, only 213 stable nitrides were known to exist.
Now possessed with a greater understanding of nitrides, researchers can move forward with determining their best uses. The Nobel Prize for physics in 2014 was awarded to a trio of researchers who combined several layers of gallium nitride to invent a blue LED. Coupling their blue light with efficient phosphors allowed the creation of long-lasting and energy-efficient white LED bulbs. The nitrides team sees even more applications on—and beyond—the horizon.
“Certainly, these materials have many possible new functional applications,” Sun said. “Some of them are semiconductors and others might be superconductors. Many of them might have applications we haven’t even dreamed of yet. There are a lot of directions for this to go.”
Other research funded by the center has discovered new ways to combine materials to form alloys, as well as to synthesize specific material polymorphs that could form the basis of next-generation semiconductors. The new nitrides research follows several years of investigating metastable materials and the potential to use them in various technologies, including semiconductors.
A groundbreaking research effort involving scientists at NREL; Lawrence Berkeley National Laboratory (LBNL); University of Colorado, Boulder (CU); and other partner institutions around the country recently published “A Map of the Inorganic Ternary Metal Nitrides,” which appears in Nature Materials. The paper features a large stability map of the ternary nitrides, highlighting nitride compositions where experimental discovery is promising, and other compositions where nitride formation would be unlikely. For chemists attempting to create new nitrides in the laboratory, this map will be a significantly valuable tool.
Exploratory synthesis in new chemical spaces is the essence of solid-state chemistry. However, uncharted chemical spaces can be difficult to navigate, especially when materials synthesis is challenging. Nitrides represent one such space, where stringent synthesis constraints have limited the exploration of this important class of functional materials. Here, we employ a suite of computational materials discovery and informatics tools to construct a large stability map of the inorganic ternary metal nitrides. Our map clusters the ternary nitrides into chemical families with distinct stability and metastability, and highlights hundreds of promising new ternary nitride spaces for experimental investigation—from which we experimentally realized seven new Zn- and Mg-based ternary nitrides. By extracting the mixed metallicity, ionicity and covalency of solid-state bonding from the density functional theory (DFT)-computed electron density, we reveal the complex interplay between chemistry, composition and electronic structure in governing large-scale stability trends in ternary nitride materials.