Impact of minor iron content on crystal structure and properties of porous calcium silicates during synthesis

Influence of foreign ions on calcium silicate hydrate under hydrothermal conditions: A review

“…This phenomenon is attributed to that the Fe incorporation leads to charge defects, which increases the formation of the amorphous phase. The destabilisation of xonotlite to tobermorite leads to an excess of CaO, which reacts with CO2 producing calcite [143]. Although the study seems to indicate that the presence of Fe stabilises tobermorite over xonotlite even at 200°C, it also could be a kinetic effect as the autoclaving duration was not stated in [143].…”

“…As for the influence of Fe incorporation, it is reported that the imperfection of tobermorite is intensified at 175 C after 4 h of autoclaving, but the crystallinity after 16 h is increased, characterised by improved silicate chain polymerisation and chain cross-linkage, leading to the morphology of tobermorite conversion from a typical platy shape to a fibre shape growing parallel to the b-axis (along the silicate chains) [134]. Conversely, in other literature, for the system CaO-SiO2-H2O (Ca/Si = 1) under 200 C, the number of Q 3 sites and the Q 3 /Q 2 ratio are observed to decrease with a higher Fe concentration, and the authors suggested that the existence of Fe 3+ leads to defect formation on the Q 3 sites of xonotlite and tobermorite, which contributes the space for the incorporation of foreign ions and the decrease in the crosslinking degree [143,144].…”

“…% based on EDX spectroscopy [38]. Labhasetwar et al [142] observed that Fe 3+ enters the tobermorite structure and takes the position of interlayer Ca 2+ without much loss of crystallinity, which was later confirmed by Haastrup et al [143].…”

Efficient Enhancement of Heat Storage Capacity of Polyethylene Glycol Phase Change Material Based on a Novel Fly Ash Support

“…Therefore, the obtained results indicate that the processing method proposed in this work of the −Si−O−Si− group (near 672 cm −1 ) is found. 24,25 The results indicate that MFA contains silicates. As mentioned above, the main chemical component of tobermorite is calcium silicate hydrate, and thus, it can be inferred that MFA is mainly composed of hydrated calcium silicate.…”

“…As shown in Figure , a broad absorption band in the range of 1308–749 cm –1 is observed in the CFA supporting material, mainly due to the overlap between the stretching vibration peak of the Si–O bond and the stretching vibration peak of the Al–O bond of [AlO 6 ] . For the MFA supporting material, the peak representing the stretching vibration of the Al–O bond of [AlO 6 ] (near 559 cm –1 ) is not detected, but the peak belonging to the vibration of the −Si–O–Si– group (near 672 cm –1 ) is found. , The results indicate that MFA contains silicates. As mentioned above, the main chemical component of tobermorite is calcium silicate hydrate, and thus, it can be inferred that MFA is mainly composed of hydrated calcium silicate.…”