Tricalcium silicate Ca₃SiO₅superstructure analysis: a route towards the structure of theM₁polymorph

Abstract

M 1 alite / Polymorphism / Powder diffraction structure analysis / X-ray diffraction Abstract. In this paper, we present a structural model for the M 1 polymorph of tricalcium silicate Ca 3 SiO 5 from Powder X-Ray Diffraction (XRD) data, including weak intensity superstructure Bragg lines. As no single crystal is available, this structural model has been deduced using the structural relationships found between the previously known triclinic and monoclinic M 3 polymorphs.We find that the better starting set of atomic positions for Rietveld refinement is the triclinic set and not the monoclinic set. A key observation is that the monoclinic M 1 structure is closer to the low temperature triclinic T 3 structure (within the Golovastikov model) than to the higher temperature monoclinic M 3 structure.The unit cell and the set of atomic positions of the two best models, called 3hMiPc and 3hTiPn models, are provided. We prefer the 3hMiPc model for it better reproduces the weak characteristic Bragg lines of the superstructure.pure: T 1 ÀÀÀ! 620 C T 2 ÀÀÀ! 920 C T 3 ÀÀÀ! 980 C M 1 ÀÀÀ! 990 C M 2 ÀÀÀ! 1070 C R doped (mainly Zn or Mg): M 1 ÀÀÀ! 990 C M 2 ÀÀÀ! 1060 C M 3 ÀÀÀ! 1070 C R

Hydration of polyphase Ca3SiO5‐Ca3Al2O6 in the presence of gypsum and Na2SO4

“…One of the major challenges in using XRD in this study is the presence of C 3 S in its monoclinic M1 form. Since a well‐tested crystal structure is lacking for this polymorph, the crystal model proposed by de Noirfontaine et al 63 was used. For the Rietveld refinements, the structures ICSD 202220 for portlandite, ICSD 1841 for C 3 A cubic, ICSD 409581 for gypsum, and ICSD 155395 for ettringite from the Inorganic Crystal Structure Database 64 were used.…”

The Effect of Magnesium and Zinc Ions on the Hydration Kinetics of C3S

“…The diffractograms were refined with the documented structures of the T1, T2, T3, M1, M3,, and R polymorphs and the best fit was retained. Rietveld quantitative analysis was used to determine the content of alite and the presence of residual free lime, periclase, and zinc oxide.…”

New minerals with a modular structure derived from hatrurite from the pyrometamorphic Hatrurim Complex. Part I. Nabimusaite, KCa12(SiO4)4(SO4)2O2F, from larnite rocks of Jabel Harmun, Palestinian Autonomy, Israel

“…Nabimusaite, KCa 12 (SiO 4 ) 4 (SO 4 ) 2 O 2 F, is the first of a series of minerals discovered in pyrometamorphic rocks of the Hatrurim Complex with a modular layered structure derived from the hatrurite, Ca 3 SiO 5 , structure. The compound Ca 3 SiO 5 has also been known in industry and material science by the unofficial name 'alite'; it is an important clinker phase in Portland cement (de Noirfontaine et al, 2012). 'Alite' exists in various polymorphous forms but all are strongly pseudo-rhombohedral (R3m) with a ≈ 7.0, c ≈ 25 Å (Jeffery, 1952).…”