First-principles study on the structural stability, radiation effect, and disorder-induced strengthening in A-site high-entropy spinel (Zn0.25Mn0.25Ca0.25Mg0.25)Al2O4

High-entropy spinel oxides (HESOs) exhibit exceptional properties, and selective cation site occupancy can significantly influence their structures and behaviors. In this study, the special quasi-random structure (SQS) method combined with density functional theory (DFT) was employed to model and analyze the A-site high-entropy spinel (Zn 0.25 Mn 0.25 Ca 0.25 Mg 0.25 )Al 2 O 4 and its various possible cation configurations. The transformation from normal to inverse spinel demonstrates a gradual order-disorder transition, accompanied by increased configurational entropy. Calculations reveal that HESOs are thermodynamically stable, with negative formation energies and favorable Gibbs free energy changes upon synthesis. Analysis of cation antisite defect formation energies and Al-vacancy migration barriers suggests enhanced resistance to amorphization. Furthermore, as the degree of disorder increases, both elastic moduli and hardness improve while anisotropy decreases. These findings elucidate the connection between structural disorder and mechanical strengthening, offering valuable guidance for the design of HESOs for use in extreme environments.