Charge states of Ca atoms in β-dicalcium silicate

Mori, Kazuhiro; Kiyanagi, Ryoji; Yonemura, Masao; Iwase, Kenji; Sato, Takashi; Itoh, Keiji; Sugiyama, Masaaki; Kamiyama, Takashi; Fukunaga, Toshiharu

doi:10.1016/j.jssc.2006.06.018

Cited by 29 publications

(18 citation statements)

References 21 publications

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“…In the bulk model, oxygen atoms covalently bond to silicon atoms forming [SiO 4 ] 4− tetrahedra, and calcium atoms are in an ionic state. The optimized lattice parameters a , b , and c of the β‐C 2 S bulk unit cell are reported in Table and are in agreement with experimental measurements and previous DFT calculations …”

Section: Computational Detailssupporting

confidence: 86%

Molecular and dissociative adsorption of a single water molecule on a β‐dicalcium silicate (100) surface explored by a DFT approach

Zhang

et al. 2017

J Am Ceram Soc

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The adsorption of water on a C2S surface initiates belite to hydrate. In the present work, the adsorption behavior of single water molecule on a β‐C2S (100) surface is explored using density functional theory (DFT) due to the lack of alternative approaches for direct observation. Four possible calcium atom sites on the β‐C2S (100) surface slab are considered in our calculations. The results show that water can adsorb on the 2 five‐coordinated calcium sites only via molecular adsorption with adsorption energies of 0.59 and 0.85 eV, respectively, but can dissociate on the other 2 six‐coordinated calcium sites with higher adsorption energies of 0.96 and 0.99 eV, respectively. The energy barriers to the dissociative adsorption of water at the Ca(III) site(0.10 eV) is much lower than that at the Ca(IV) site, indicating that water prefers to adsorb and dissociate on Ca(III) sites. The dissociative adsorption of water causes more obvious surface calcium shifts and Si–O bond length increases than molecular adsorption. The dissociative adsorption of a water molecule changes the electron distribution, and the overlap between Ca 2p and O 2s orbitals leads to new Ca–O bond formations.

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Section: Computational Detailssupporting

confidence: 86%

Molecular and dissociative adsorption of a single water molecule on a β‐dicalcium silicate (100) surface explored by a DFT approach

Zhang

et al. 2017

J Am Ceram Soc

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“…Figure 5 shows the relationship between the PL intensity and annealing temperature in green-emitting (Ca 1.95 Eu 2+ 0.02 □ 0.03 )(Si 0.94 P 0.06 )O 4 phosphors. The broad excitation spectra were composed of the four bands at 310 nm, 340 nm, 360 nm, and 400 nm, each of which could be attributed to the location of an Eu 2+ ion in the crystal structures of the β- and α’ L -phases [16,17]. The differences in peak shapes of the excitation spectra are caused by the differences in crystal structures of the host materials.…”

Section: Resultsmentioning

confidence: 99%

“…The emission peak wavelength decreased with increasing annealing temperature. This is caused by the expansion of Eu–O bond lengths by phase transition [17], because the 4f-5d transition of the Eu 2+ ion must be closely related to the crystal field. We observed the highest PL intensity for the specimen annealed at 1473 K, of which the phase composition was both β and α’ L .…”

Section: Resultsmentioning

confidence: 99%

The Effect of Heat Treatment on the Emission Color of P-Doped Ca2SiO4 Phosphor

et al. 2017

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In a series of (Ca2–x/2–yEuy□x/2)(Si1–xPx)O4 (x = 0.06, 0.02 ≤ y ≤0.5), various color-emitting phosphors were successfully synthesized by a solid-state reaction. These phosphors were characterized by photoluminescence (PL) spectroscopy, X-ray powder diffractometry, transmission electron microscopy, and X-ray absorption fine structure spectroscopy. We evaluated the effect of heat treatment on PL properties with various annealing temperatures at 1373–1773 K for 4 h before/after reduction treatment from Eu3+ to Eu2+. In the red-emitting (Ca1.95Eu3+0.02□0.03)(Si0.94P0.06)O4+δ phosphor, the highest PL intensity exhibited when it was annealed at 1773 K. On the other hand, in the green-emitting (Ca1.95Eu2+0.02□0.03)(Si0.94P0.06)O4 phosphor, the highest PL intensity was realized when it was annealed at 1473 K and consequently treated under a reductive atmosphere. With increasing annealing temperature, the emission peak wavelength steadily decreased. Furthermore, with increasing Eu2+ content, the emission peak wavelength increased, with the color of emitting light becoming yellowish. Thus, the PL properties of the phosphors were affected by both the structural change from β to α’L, which occurred by heat treatment, and the amount of doped Eu ions.

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“…1-b) are consistent with the crystal structure of this compound. 56 The maxima of spectral intensities are at about 46 and 29 ppm. These positions, however, are not the isotropic chemical shift since the signals are visibly affected by the second order quadrupolar interactions.…”

Section: Cement Compoundsmentioning

confidence: 97%

“…This is the first experimental report of 43 Ca 24 The structure of b-C 2 S is known to be built of isolated SiO 4 tetrahedra in an environment of two distinct Ca ions. 53 The calcium atom in site 1, Ca(1) (here and further we use the same notation as in the original crystallographic publications), is coordinated to six oxygen atoms with Ca (1) 56 All Ca-O distances for both Ca sites are very irregular, with no local symmetry in the oxygen environment. This observation suggests a significant deviation of asymmetry parameter Z from 0.…”

Section: Cement Compoundsmentioning

confidence: 99%

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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Charge states of Ca atoms in β-dicalcium silicate

Cited by 29 publications

References 21 publications

Molecular and dissociative adsorption of a single water molecule on a β‐dicalcium silicate (100) surface explored by a DFT approach

Molecular and dissociative adsorption of a single water molecule on a β‐dicalcium silicate (100) surface explored by a DFT approach

The Effect of Heat Treatment on the Emission Color of P-Doped Ca2SiO4 Phosphor

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

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