Comprehensive evaluation of formation kinetics in preparation of ternesite from different polymorphs of Ca2SiO4

• Published in: Journal of solid state chemistry 2020-12, Vol.292, p.121725, Article 121725
• Main Authors: Jing, Guojian, Zhang, Jinpu, Lu, Xiaolei, Xu, Jiankai, Gao, Yang, Wang, Shuxian, Cheng, Xin, Ye, Zhengmao
• Format: Article
• Language: English
• Subjects: Activation; Ca2SiO4; Ca5(SiO4)2SO4; Eu3; Formation kinetics
• ISSN: 0022-4596; 1095-726X
• DOI: 10.1016/j.jssc.2020.121725

Ca2SiO4 is an essential intermediate phase in the formation process of Ca5(SiO4)2SO4, and the polymorph change of Ca2SiO4 would seriously influence the relevant reaction kinetics. Herein, the reaction activities of three Ca2SiO4 polymorphs (αL’, β and γ phases) in preparation of Ca5(SiO4)2SO4 are studied in detail. The results indicate there is almost no generation of Ca5(SiO4)2SO4 from αL’-Ca2SiO4, and by contrast, β- and γ-Ca2SiO4 phases can successfully form the target product. Moreover, β-Ca2SiO4 manifests a higher reactivity than that of the γ one, and the relevant reaction rate constant is about 1.6 times larger than that of the γ one. Meanwhile, the ion activation mechanism is investigated in the formation process of Ca5(SiO4)2SO4 by Eu3+ fluorescence labeling. The reaction sites containing Eu3+ ions preferentially form Ca5(SiO4)2SO4 due to the introduced oxygen defects or calcium vacancies by doping Eu3+ ions, especially for the low-temperature sintering. In combination with the polymorph influence, the activation effect from ion doping further contributes to the formation of Ca5(SiO4)2SO4. The findings in this research provide a guidance for the synthesis and application development of Ca5(SiO4)2SO4 and offer a deeper understanding of the ion doping effect in cement minerals. [Display omitted] •The formation kinetics of Ca5(SiO4)2SO4 from three Ca2SiO4 polymorphs are studied.•The β-Ca2SiO4 is easier to form Ca5(SiO4)2SO4 than γ-Ca2SiO4.•The activated mechanism of ions doping is explored by Eu3+ fluorescent labeling.•The reaction sites containing Eu3+ ions preferentially form Ca5(SiO4)2SO4.