@article{Yao2025, 
author = {Yize Yao and Shuang Zhang and Huimin Xiang and Cheng Fang and Wei Xie and Yanchun Zhou},
title = {Direct experimental validation on the crystal structure, chemical bonding, and magnetic properties of CrB2},
year = {2025},
journal = {Journal of Advanced Ceramics},
volume = {14},
number = {9},
pages = {9221145},
keywords = {magnetic properties, crystal structure, chemical bonding, electron energy loss spectroscopy (EELS), CrB2, sp2 hybridization, scanning transmission electronic microscopy (STEM)},
url = {https://www.sciopen.com/article/10.26599/JAC.2025.9221145},
doi = {10.26599/JAC.2025.9221145},
abstract = {CrB2 crystallizes in an AlB2-type crystal structure, and the chemical bonding in CrB2 includes B sp2‒B sp2 covalent bonds in the graphite-analogous six-numbered B ring, B pz‒Cr 3d covalent‒ionic bonds, and Cr‒Cr metallic bonds from theoretical calculations. However, the crystal structure and chemical bonding properties have not been experimentally validated. To fill this research gap, herein, the crystal structure and chemical bonding of CrB2 were evaluated for the first time via aberration-corrected transmission electron microscopy (AC-TEM) coupled with electron energy loss spectroscopy (EELS). Combined with first-principles calculations based on density functional theory (DFT), CrB2 is confirmed to have an AlB2-type structure, where Cr bonds to each other in the (001) plane via metallic bonding and where B bonds in the form of a graphite-like six-membered ring in the (002) plane through sp2 hybridization, whereas Cr‒B ionic‒covalent bonding is formed in the (110) plane. A detailed analysis of the experimental and calculated results of the EELS of CrB2 shows that the hybridization of Cr 3d and B has a significant effect on the EELS of transition metal borides (TMB2). In addition, the hysteresis loop of CrB2 was tested for the first time on the basis of theoretical calculations, and the molar susceptibility of CrB2 was approximately 5.77×10−4 emu/mol. The present work is helpful for understanding the structure‒property relationships, which are essential for tailoring the properties from a crystal structure and chemical bonding point of view and promoting the practical application of TMB2 in extreme aerospace environments.}
}