Acoustic shock wave impact on stability aspects of crystal structure–functional properties—A case study of corundum-type structure of α-Cr2O3 nanoparticles

Subjecting solid-state materials to shock conditions is one of the most familiar subjects in condensed matter research, helping to understand the usual and unusual behaviors of materials through their phase transitions and functional property changes. Highly stable materials under extreme conditions are typically considered for technological applications, and high-pressure researchers always try to find such materials to build a world of strong and stable materials science. In this context, we are inclined to investigate the corundum-type structure of α-Cr2O3 NPs under dynamic acoustic shock conditions and compare it with previously reported α-Fe2O3 NPs. From the structural point of view, under acoustic shock conditions, α-Cr2O3 NPs remain the same with the R3-c space group even at the 200-shocked condition, whereas in α-Fe2O3, the α-Fe2O3 (R3-c)-to-Fe3O4 (Fd-3m) transition is observed. For both these oxides, supporting evidence for the results is also presented via vibrational, optical, magnetic, thermal, electrical, and electrochemical properties. In addition, a possible mechanism is proposed, implementing a thermal conductivity-driven superheating approach to justify the stability order for both oxides. According to the observed static compression results and the current acoustic shock wave-induced results of these two oxides, the structural stability order is α-Cr2O3>α-Fe2O3. Due to the impressive results of structural stability under static and dynamic shock conditions, α-Cr2O3 is a more suitable candidate for extreme conditions such as aerospace and defense applications.