Superstructure in a Triclinic Phase of Tricalcium Silicate

Abstract

A triclinic phase of tricalcium silicate (TI) was investigated using transmission electron microscopy (TEM). Electron diffraction patterns were analyzed by introducing a subcell with the cell parameters of a ‫؍‬ 7.081 Å, b ‫؍‬ 7.043 Å, c ‫؍‬ 25.230 Å, ␣ ‫؍‬ 89.97°, ␤ ‫؍‬ 90.37°, and ␥ ‫؍‬ 119.44°. It was proven that the coordinates of all the reflections can be expressed to be ha* ؉ kb* ؉ lc* ؎ m/6(a* ؉ 2b* ؉ 2c*), where m ‫؍‬ 0, 1, 2, and 3. The result indicates that the structure modulation in TI is a one-dimensional type with a structural modulation normal to (122). The modulated structure could be observed in a highresolution TEM image as wavy contrast streaking parallel to the plane with an interval of six times the (122) spacing.

Structural Modulations in Monoclinic Tricalcium Silicate Solid Solutions Doped with Zinc Oxide, M(I), M(II), and M(III)

“…3). 10,11 The specimen doped with 4.8% ZnO was inhomogeneous, and SAD patterns were different on a grain-by-grain basis. Some of the grains showed SAD patterns for T(I) or T(II), and others exhibited those for M(III).…”

“…High-resolution transmission electron microscopy (HRTEM) has been applied to detect the modulation wave in T(I), and the modulation wave could be imaged as wavy contrasts. 10 The purpose of this study is to describe the superstructures of the monoclinic modifications in solid solutions doped with various amounts of ZnO. New indexes for describing the reflections attributable to the superstructures are introduced for expressing the orientations and sequences of the structural modulations in relation to the subcells.…”

Tricalcium Silicate T1 and T2 Polymorphic Investigations: Rietveld Refinement at Various Temperatures Using Synchrotron Powder Diffraction

“…In these refinements the internal T 1 structure was fixed to that of Golovastikov et al 3 fingerprint regions unique to different polymorphs. Bigaré et al 2 and more recently Urabe et al 12 presented laboratory XRD studies on the tricalcium silicate type T 1 . Both studies found characteristic reflections in the fingerprint regions that resembled T 1 of this study (shown in insets in Figs.…”

Lattice parameter measurement using Le Bail versus structural (Rietveld) refinement: A caution for complex, low symmetry systems

“…Subsequently, Rietveld fitting was performed with the model ofGolovastikov et al ͑1975͒ of T 1 triclinic tricalcium silicate. Despite the inadequacy of this model, which does not account for many small superstructure reflections arising from structural modulation ͑Peterson etal., 2004;Urabe et al, 2000;Peterson, 2003͒, the lattice parameters obtained from the Rietveld fits are internally consistent, and differ significantly from the Le Bail fits, as shown inFigures 3-5. The fact that the Le Bail and fullstructural Rietveld derived results do not match in any singular case indicates that at least one of them is incorrect.…”