Fundamental principles that govern the copper doping behavior in complex clinker system

Abstract

Understanding the doping behavior of impurity ions in clinker phases is crucial for controlling the doping effect on clinker compounds, which, however, has not yet been fully demonstrated due to the composition complexity. Herein, we employ the state‐of‐the‐art ab initio calculation to uncover the substitution mechanism of Cu ions in 4 dominant clinker crystals. The defect formation energies indicate Cu ions energetically prefer to substitute Fe ions in ferrite, which is in accord with the experiments. The bond order difference is innovatively postulated to interpret the energy barriers of Cu substitution in comparison with the ionic radius criterion. The high potential barriers of Cu substituting Ca, Si, and Al ions are ascribed to their bond order mismatch, while the tendency of Cu replacing Fe is due to their bond order similarity. Namely, the Cu doping in clinker phases follows the “bond order conformity” principle. In‐depth electronic structure analysis reveals that the bond order is more effective than the ionic radius to estimate potential barriers of Cu substitution in complex clinker system mainly because the latter underestimates the influence of electronic structure differences while the bond order directly measures the bonding structure related to interatomic charge transfer.

The impact of Fe dosage on the ettringite formation during high ferrite cement hydration

“…The defect formation energy evaluates the possibility and stability of atomic substitution, 38,39 with large positive values meaning unfavorable substitution and vice versa. Generally speaking, the defect formation energy increases with the increase in defect concentration (Figure 11), namely AFt with high Fe uptake is energetically unfavorable and unstable.…”

Atomic occupancy mechanism in brownmillerite Ca2FeAlO5 from a thermodynamic perspective

“…Furthermore, the identification of the specific configuration of brownmillerites is particularly significant for the theoretical investigation based on atomistic simulation since it requires very unambiguous structural models with specific coordinate of each atom. 31,32 Our proposed configuration of Ca 2 Fe 2-x Al x O 5 brownmillerite facilitates the further simulation of its properties and the methodology is supposed to be an important reference for investigating other brownmillerites.…”

Screening Out Reactivity-Promoting Candidates for γ-Ca2SiO4 Carbonation by First-Principles Calculations

“…A kinetic energy cutoff of 580 eV was adopted based on multiple tests as posted in the Supplementary Material S1. More computational details can be found in our previous studies (Tao et al, 2018a(Tao et al, , 2019a.…”