Revealing the doping mechanism of barium in sulfoaluminate cement clinker phases.

The doping mechanism of Ba in sulfoaluminate cement (SAC) clinker was systematically studied. Results from density functional theoretical simulations, backscattered electron diffraction and X-ray diffraction show that Ba ions prefer to incorporate into the mineral C 4 A 3 S ¯ by substituting Ca atoms while little enter into the other two minerals, C 2 S and C 4 AF. Such doping preference was also certified by the results of individual mineral of C 4 A 3 S ¯ and C 4 AF, respectively. Further analyses from partial density of states, electron density difference and local distortions indicate that the Ba-doping preference in C 4 A 3 S ¯ is attributed to the efficiency of newly formed bonds, which is enhanced by electronic structure matching and small local distortions. The understandings are essential in guiding the production of Ba-bearing SAC clinker by utilizing industrial barium slags, thus should be very important in sustainable production of SAC clinkers, environmental governance and industrial collaborative disposal of waste. [Display omitted] • Ba ions prefer to incorporate into the mineral C 4 A 3 S̅ by substituting Ca atoms. • Almost no Ba ions enter into the other two minerals of C 2 S and C 4 AF. • The small local distortion between Ca–O/Ba–O determines the preference in C 4 A 3 S̅. • It provides a possibility of producing sulfoaluminate cement with Ba-bearing waste. [ABSTRACT FROM AUTHOR]