+ Site Statistics
+ Search Articles
+ PDF Full Text Service
How our service works
Request PDF Full Text
+ Follow Us
Follow on Facebook
Follow on Twitter
Follow on LinkedIn
+ Subscribe to Site Feeds
Most Shared
PDF Full Text
+ Translate
+ Recently Requested

Dehydration/ recrystallization mechanisms, energetics, and kinetics of hydrated calcium silicate minerals; an in situ TGA/ DSC and synchrotron radiation SAXS/ WAXS study

Dehydration/ recrystallization mechanisms, energetics, and kinetics of hydrated calcium silicate minerals; an in situ TGA/ DSC and synchrotron radiation SAXS/ WAXS study

Chemical Geology 167(1-2): 141-159

The dehydration and recrystallization of the natural hydrated calcium silicates xonotlite [Ca (sub 6) Si (sub 6) O (sub 17) (OH) (sub 2) ], 11Aa anomalous tobermorite [Ca (sub 5) Si (sub 6) O (sub 16) (OH) (sub 2) .4H (sub 2) O], and hillebrandite [Ca (sub 2) SiO (sub 3) (OH) (sub 2) ] were studied in situ by dynamic heating (5 degrees C min (super -1) ) differential scanning calorimetry/thermogravimetric analysis (TGA/DSC) and synchrotron small- and wide-angle X-ray scattering (SAXS/WAXS). All have structures based on silicate chains with a repeat unit of three tetrahedra ("dreierketten"). Room-T infrared data for the tobermorite sample suggest that it is essentially (OH)-free and that it is likely to contain double chains in addition to the normal single chain units. The in situ techniques allow the mechanisms and kinetics of dehydration and recrystallization processes to be studied directly or deduced. Xonotlite and tobermorite recrystallise to low-temperature (T)-wollastonite (CaSiO (sub 3) ) with two-phase regions existing over the temperature ranges 780-835 degrees C and 835-855 degrees C, respectively. Hillebrandite breaks down via a two-phase region between 520 degrees C and 590 degrees C to form larnite (beta -Ca (sub 2) SiO (sub 4) ) which appears to retain some (OH) in its structure. This hydroxylated larnite in turn recrystallises to alpha (sub L) '-Ca (sub 2) SiO (sub 4) between 775 degrees C and 900 degrees C. The presence of (OH) in the hydroxylated larnite appears to extend its stability limit to higher Ts than those shown for anhydrous larnite. In each case, the widths of the two-phase regions are dependent on the extents of structural changes involved. DSC data for xonotlite, hillebrandite and hydroxylated larnite give a mean energy for dehydroxylation/recrystallization of 4000+ or -1200 J/g (OH as H (sub 2) O) lost. Radius of gyration values for hillebrandite provide estimates of particle sizes up to about 640 Aa; this is believed to represent the lengthscale of domains between zones of defects formed by displacements of structural units along the dreierketten chains.

Please choose payment method:

(PDF emailed within 0-6 h: $19.90)

Accession: 018688770

Download citation: RISBibTeXText

DOI: 10.1016/s0009-2541(99)00206-5

Related references

Silk fiber assembly studied by synchrotron radiation SAXS/WAXS and Raman spectroscopy. Journal of the American Chemical Society 130(50): 17070-4, 2008

Preliminary study of human breast tissue using synchrotron radiation combining WAXS and SAXS techniques. Applied Radiation and Isotopes 68(4-5): 799-803, 2010

Structural elucidation of rapid solution-mediated phase transitions in pharmaceutical solids using in situ synchrotron SAXS/WAXS. Molecular Pharmaceutics 9(9): 2787-2791, 2012

In situ observations of particle size evolution during the hydrothermal crystallization of TiO2 A time-resolved synchrotron SAXS and WAXS study. Journal of Crystal Growth 344(1): 0-58, 2012

High-pressure potato starch granule gelatinization: synchrotron radiation micro-SAXS/WAXS using a diamond anvil cell. Biomacromolecules 8(7): 2092-2097, 2007

Study of temperature dependence of crystallisation transitions of a symmetric PEO-PCL diblock copolymer using simultaneous SAXS and WAXS measurements with synchrotron radiation. European Physical Journal. E Soft Matter 27(4): 357-364, 2008

Kinetics and mechanisms of dehydration and recrystallization of serpentine, 2, Spectrum of activation energies for recrystallization. Pages 49-54 1964, 1964

Synchrotron SAXS and WAXS study of the interactions of NSAIDs with lipid membranes. Journal of Physical Chemistry. B 115(24): 8024-8032, 2011

Solid-state (13)C NMR and synchrotron SAXS/WAXS studies of uniaxially-oriented polyethylene. Solid State Nuclear Magnetic Resonance 72: 27-40, 2015

Orientational distribution of parentdaughter structure of isotactic polypropylene: a study using simultaneous synchrotron WAXS and SAXS. Journal of Materials Science 43(19): 6459-6467, 2008

Effects of sugars on lipid bilayers during dehydration--SAXS/WAXS measurements and quantitative model. Journal of Physical Chemistry. B 113(8): 2486-2491, 2009

Using in situ synchrotron radiation wide angle X-ray scattering (WAXS) to study CaCO3 scale formation at ambient and elevated temperature. Faraday Discussions 136: 355-65; Discussion 395-407, 2007

Fundamental insights into barium sulfate precipitation by time-resolved in situ synchrotron radiation wide-angle X-ray scattering (WAXS). Chemical Engineering Science 133: 140-147, 2015

The transformation of ACC to vaterite; an in situ SAXS/WAXS study. Mineralogical Magazine 75.3: 559, 2011

In situ SAXS study on cationic and non-ionic surfactant liquid crystals using synchrotron radiation. Journal of Synchrotron Radiation 12(Pt 6): 717-720, 2005