Influence of Ion Substitution on the Properties of Apatite-Based Materials: Computational Predictions Using Density Functional Theory

Apatite-based materials have attracted recognition as promising candidates for catalytic applications because of their tunable properties that can be achieved through ionic substitutions and their compatibility with sustainability goals for environmentally friendly catalysts. However, a thorough understanding of their physicochemical properties at the atomic level remains insufficient. In this study, calculations based on density functional theory combined with Spearman's correlation are used to investigate the effects of cationic and anionic substitutions on the structural, energetic, and electronic properties of materials similar to apatite with Ca/P ratios ranging from 0.50 to 2.00. Our results reveal that substitutions with d-block elements, such as Zn and Cd, reduce the energy gap at the Γ-point and decrease the ionic character of the materials, leading to reduced stability. Additionally, d-p orbital hybridization within the PO₄ ^3-, AsO₄ ^3-, and VO₄ ^3- groups significantly influences structural stability. Using Spearman's correlation analysis, we identified significant trends, specifically indicating a strong correlation between net atomic charges, energy gaps, and cohesive energy. These results offer critical insights into how ionic substitutions influence the tunable characteristics of materials resembling apatite.