The crystal structure of tricalcium aluminate, Ca3Al2O6

Mondal, Pritam; Jeffery, J. W.

doi:10.1107/s0567740875003639

Cited by 396 publications

(158 citation statements)

References 5 publications

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“…2 and Table 1). 48 The exact balance was confirmed through best structural fit in the simulation. Upon initial reaction with water, apical oxygen atoms form aluminol groups and hydroxide ions.…”

Section: Derivation and Interpretation Of Individual Parametersmentioning

confidence: 82%

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A force field for tricalcium aluminate to characterize surface properties, initial hydration, and organically modified interfaces in atomic resolution

et al. 2014

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Tricalcium aluminate (C 3 A) is a major phase of Portland cement clinker and some dental root filling cements. An accurate all-atom force field is introduced to examine structural, surface, and hydration properties as well as organic interfaces to overcome challenges using current laboratory instrumentation. Molecular dynamics simulation demonstrates excellent agreement of computed structural, thermal, mechanical, and surface properties with available experimental data. The parameters are integrated into multiple potential energy expressions, including the PCFF, CVFF, CHARMM, AMBER, OPLS, and INTERFACE force fields. This choice enables the simulation of a wide range of inorganic-organic interfaces at the 1 to 100 nm scale at a million times lower computational cost than DFT methods. Molecular models of dry and partially hydrated surfaces are introduced to examine cleavage, agglomeration, and the role of adsorbed organic molecules. Cleavage of crystalline tricalcium aluminate requires approximately 1300 mJ m −2 and superficial hydration introduces an amorphous calcium hydroxide surface layer that reduces the agglomeration energy from approximately 850 mJ m −2 to 500 mJ m −2 , as well as to lower values upon surface displacement. The adsorption of several alcohols and amines was examined to understand their role as grinding aids and as hydration modifiers in cement. The molecules mitigate local electric fields through complexation of calcium ions, hydrogen bonds, and introduction of hydrophobicity upon binding. Molecularly thin layers of about 0.5 nm thickness reduce agglomeration energies to between 100 and 30 mJ m −2 . Molecule-specific trends were found to be similar for tricalcium aluminate and tricalcium silicate. The models allow quantitative predictions and are a starting point to provide fundamental understanding of the role of C 3 A and organic additives in cement. Extensions to impure phases and advanced hydration stages are feasible.

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Section: Derivation and Interpretation Of Individual Parametersmentioning

confidence: 82%

“…1 and 2). 48 Four chemically distinct atom types can be identified similar to the concept of chemical equivalence in NMR spectroscopy. These include calcium, aluminum, apical oxygen, and ring oxygen.…”

Section: Derivation and Interpretation Of Individual Parametersmentioning

confidence: 99%

A force field for tricalcium aluminate to characterize surface properties, initial hydration, and organically modified interfaces in atomic resolution

et al. 2014

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“…The unit cell of C 3 A contains six inequivalent sites for calcium, 59 which can result in six distinct signals in the spectrum if all are resolved. Overlap in the signals can obviously reduce the number of observed components in the spectrum.…”

Section: Cement Compoundsmentioning

confidence: 99%

“…59 The structure is built of six-fold rings centered on three-fold axes and composed of two types of distorted AlO 4 tetrahedra. 59 Two out of six non-equivalent Ca atoms are found on threefold axes in hexagonal oxygen coordination to one type of oxygen atom in each hexagon. Such symmetry should reflect on the 43 Ca signals and result in a characteristic axially symmetric signal with Z close to 0.…”

Section: Cement Compoundsmentioning

confidence: 99%

“…The corresponding NMR parameters for the site are d i = 17.0 ppm and C q = 2.8 MHz. Although the average Ca-O distances for all the sites in the structure are known, 59 the assignment of four remaining Ca sites, however, is hampered by the very limited experimental data available for calcium aluminates, and would be too speculative. The lower symmetry of the oxygen environment for the remaining sites is expected to result in an increased Z, which is likely what is observed for the signal in the region B.…”

Section: Cement Compoundsmentioning

confidence: 99%

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Natural abundance high field 43Ca solid state NMR in cement science

Moudrakovski

Alizadeh

Beaudoin

2010

Phys. Chem. Chem. Phys.

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/npsi/ctrl?lang=en http://nparc.cisti-icist.nrc-cnrc.gc.ca/npsi/ctrl?lang=fr Access and use of this website and the material on it are subject to the Terms and Conditions set forth at http://nparc.cisti-icist.nrc-cnrc.gc.ca/npsi/jsp/nparc_cp.jsp?lang=en NRC Publications Archive Archives des publications du CNRCThis publication could be one of several versions: author's original, accepted manuscript or the publisher's version. / La version de cette publication peut être l'une des suivantes : la version prépublication de l'auteur, la version acceptée du manuscrit ou la version de l'éditeur. For the publisher's version, please access the DOI link below./ Pour consulter la version de l'éditeur, utilisez le lien DOI ci-dessous.http://dx.doi.org/10.1039/c000353kPhysical Chemistry Chemical Physics, 12, pp. 6961-6969, 2010-06-01 Natural abundance high field 43Ca NMR solid state NMR in cement science Moudrakovski, I.; Alizadeh, R.; Beaudoin, J. J. The material in this document is covered by the provisions of the Copyright Act, by Canadian laws, policies, regulations and international agreements. Such provisions serve to identify the information source and, in specific instances, to prohibit reproduction of materials without written permission. For more information visit http://laws.justice.gc.ca/en/showtdm/cs/C-42Les renseignements dans ce document sont protégés par la Loi sur le droit d'auteur, par les lois, les politiques et les règlements du Canada et des accords internationaux. Ces dispositions permettent d'identifier la source de l'information et, dans certains cas, d'interdire la copie de documents sans permission écrite. Pour obtenir de plus amples renseignements : http://lois.justice.gc.ca/fr/showtdm/cs/C-42 Natural abundance high field 43 Ca solid state NMR in cement sciencew This work is a systematic attempt to determine the possibilities and the limitations of the 43 Ca high field solid state NMR in the study of cement-based materials. The low natural abundance (0.135%) and small gyromagnetic ratio of 43 Ca present a serious challenge even in a high magnetic field. The NMR spectra of a number of cement compounds of known structure and composition are examined. The spectra of several phases important in cement science, e.g., anhydrous beta di-calcium silicate (b-C 2 S) and tri-calcium (C 3 S) silicate were obtained for the first time and the relation of spectroscopic and structural parameters is discussed. The method was also applied to the hydrated C 3 S and synthetic calcium silicate hydrates (C-S-H) of different composition in order to understand the state of calcium and transformations in the structure during hydrolysis. The spectra of hydrated C 3 S reveals a calcium environment similar to that of the C-S-H samples and 11 Å Tobermorite. These observations support the validity of using layered crystalline C-S-H systems as structural models for the C-S-H that forms in the hydration of Portland cement.

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Sr3(Al0.36Ga0.64)2O6 - a new Strontium Aluminum Gallate

Kahlenberg

2000

Cryst. Res. Technol.

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The new compound Sr3(Al0.36Ga0.64)2O6 has been synthesized and studied by single crystal X‐ray diffraction. The material crystallizes in the cubic space group Pa‐3 (No. 205) with Z = 24 and a lattice constant a = 16.0195(12)Å. The structure is isotypic with Ca3Al2O6 and is characterized by isolated, highly puckered, six‐membered (Al,Ga)O6 rings. The rings are linked by strontium cations which are coordinated by 6 to 9 oxygen ligands. Alternatively, the structure can be regarded as an example for a defect ABO3‐perovskite with 12.5% vacancies in the A‐sublattice and 25% oxygen vacancies.

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The crystal structure of tricalcium aluminate, Ca₃Al₂O₆

Cited by 396 publications

References 5 publications

A force field for tricalcium aluminate to characterize surface properties, initial hydration, and organically modified interfaces in atomic resolution

A force field for tricalcium aluminate to characterize surface properties, initial hydration, and organically modified interfaces in atomic resolution

Natural abundance high field 43Ca solid state NMR in cement science

Sr3(Al0.36Ga0.64)2O6 - a new Strontium Aluminum Gallate

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