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 C4A3S¯ by substituting Ca atoms while little enter into the other two minerals, C2S and C4AF. Such doping preference was also certified by the results of individual mineral of C4A3S¯ and C4AF, respectively. Further analyses from partial density of states, electron density difference and local distortions indicate that the Ba-doping preference in C4A3S¯ 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.