Dopant effects on thermodynamic stability and oxygen vacancy formation in CaMnO3 perovskites for chemical-looping combustion

Artikel i vetenskaplig tidskrift, 2026

The thermodynamic properties and phase stability of doped CaMnO3-δ perovskites have been investigated over a range of oxygen non-stoichiometry (δ), from 1/16 to 6/16, to assess their suitability as oxygen carriers for chemical-looping combustion. The computational framework combines machine-learning interatomic potentials for structural relaxation, cluster expansions for configurational energetics, phonon calculations for vibrational contributions, and Monte Carlo simulations for configurational entropy. Doping was explored at the A-site (Ce, Sr, La, Bi) and B-site (Ti, Fe, Si, Cr, Cu, Mo, Mg) at substitution levels ranging from 1/16 to 6/16. Phase stability was evaluated using multi-component equilibrium calculations based on thermodynamic data derived from the calculated enthalpy, entropy, and heat capacity. Ce and Sr (A-site), Fe and Ti (B-site), were identified as promising dopants. Ce and Ti enhanced the overall thermodynamic stability of CaMnO3, whereas Fe and Sr promoted oxygen vacancy formation, reflecting a trade-off between reducibility and thermodynamic stability. Where experimental data is available, these trends show good agreement with previously reported studies. These results demonstrate that targeted doping enables systematic tuning of thermodynamic behavior in CaMnO3-based perovskites, providing guidance for balancing thermodynamic stability and oxygen release in chemical-looping applications.