Professor Kan Zhang from the College of Materials Science and Engineering at Jilin University, in collaboration with international researchers, recently published a research article titled “Core Electron Count As A Versatile And Accurate New Descriptor For Sorting Mechanical Properties Of Diverse Transition Metal Compounds” in Advanced Materials. This work reports a novel discovery that the core electron count (CEC) plays a critical and previously underestimated role in the bonding behavior of transition metal–light element (TM–LE) compounds. Combined with valence electron concentration (VEC), this new VEC–CEC dual-descriptor enables accurate prediction of mechanical property trends in transition metal nitrides (TMNs) and diborides (TMB₂).

Mechanical properties are among the most fundamental and essential characteristics of materials, greatly influencing their applications and service life. As advanced technologies demand materials with increasingly refined mechanical performance, identifying effective descriptors that correlate with these properties becomes vital for high-throughput screening, classification, and design.

TM–LE compounds are widely studied due to their excellent chemical inertness, thermal stability, oxidation resistance, and high hardness — often reaching superhard levels. However, due to the diversity of transition metal elements and the multi-component nature of TM–LE systems, there exists a critical need for precise descriptors of their mechanical behavior. Previous work showed that VEC captures overall property trends across different structures (such as TMB₂, TMN, and TMC), indicating structural universality. However, as a standalone descriptor, VEC has limitations: compounds with the same VEC often exhibit widely scattered mechanical values, and those with similar VEC may have overlapping property ranges.

To address this, the research team proposed an approach linking full electronic structure with mechanical properties, introducing CEC as a complementary descriptor to VEC. The resulting VEC–CEC dual-descriptor accurately describes the trends in TMN and TMB₂ systems, with prediction accuracies of 95.06% (TMN) and 92.59% (TMB₂). The analysis shows that with increasing VEC, TMNs and TMB₂s transition from brittle to ductile behavior. Moreover, at the same VEC, increasing the CEC of solute atoms enhances electronic delocalization due to inner shell electron shielding, strengthening d–d interactions and improving ductility.

This dual-descriptor approach provides a new and generalizable framework for predicting mechanical properties across broader material systems, offering a promising pathway toward the rational design of materials with targeted strength and toughness.

Rui Zhang and Xinlei Gu, PhD candidates at Jilin University, are co-first authors of this study. Professor Kan Zhang and Dr. Chang Liu are the corresponding authors, with Professor Changfeng Chen from the University of Nevada, Las Vegas, also contributing to the research. This work was supported by the National Natural Science Foundation of China, the Natural Science Foundation of Jilin Province, and the Jilin University “Golden Seed” Project.

Related article:
Rui Zhang†, Xinlei Gu†, Kan Zhang*, Xinxin Gao, Chang Liu*, and Changfeng Chen,
“Core Electron Count As A Versatile And Accurate New Descriptor For Sorting Mechanical Properties Of Diverse Transition Metal Compounds”,
Advanced Materials, 202304729 (2023).
https://doi.org/10.1002/adma.202304729