Refinement of the crystal structure of γ-Ca2SiO4

Udagawa, Shigekazu; Urabe, Kazuyori; Natsume, M.; Yano, Toyohiko

doi:10.1016/0008-8846(80)90070-8

Cited by 66 publications

(35 citation statements)

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“…The -form is a metastable monoclinic phase at room temperature. 18 The -phase, is stable at ambient temperature and it crystallizes in an orthorhombic olivine-type structure [19][20][21][22] , but is essentially nonreactive with water. ' L and ' H orthorhombic phases are stable at high temperatures.…”

Section: Introductionmentioning

confidence: 99%

“…Moreover, the crystal structures of ' H -and -polymorphs have calcium cations in both eight and nine irregular coordination. 16,21 It is important to know that there are experimental evidences that an increase of the calcium coordination number seems to enhance the water reactivity. 29 Nevertheless, crystal chemical stabilization is obtained by the addition of suitable "stabilizers" which are responsible of the actual reactivity.…”

Section: Introductionmentioning

confidence: 99%

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Mechanism of stabilization of dicalcium silicate solid solution with aluminium

et al. 2014

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KEYWORDS: PC-SOFC, Mixed oxide and proton conductor, aluminum doped dicalcium silicate ABSTRACT:Stoichiometric dicalcium silicate, Ca 2 SiO 4 , displays a well-known polymorphism with temperature.When this phase is doped by a range of elements generates belite, one of the main phases of cements. Here, we thoroughly study the aluminum doping of dicalcium silicate. This type of study is important for cement characterization and also from a basic point of view.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Mechanism of stabilization of dicalcium silicate solid solution with aluminium

et al. 2014

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“…7, supplementary materials 1 ). This deviation is characteristic of calcio-olivine (Smith et al 1965;Czaya 1971;Udagawa et al 1980;Mumme et al 1995;Gobechiya et al 2008, Yamnova et al 2011) and other Ca humite-group minerals (Kirfel et al 1983;Galuskina et al 2009Galuskina et al , 2012). Because the relatively rigid SiO 4 tetrahedra share three edges with the large CaO 6 octahedra, there are large angular distortions of the O-Ca-O angles.…”

Section: Crystal Structure Of Edgrewite and Hydroxyledgrewite And H-bmentioning

confidence: 90%

Edgrewite Ca9(SiO4)4F2-hydroxyledgrewite Ca9(SiO4)4(OH)2, a new series of calcium humite-group minerals from altered xenoliths in the ignimbrite of Upper Chegem caldera, Northern Caucasus, Kabardino-Balkaria, Russia

Galuskin

Lazić

Armbruster

et al. 2012

American Mineralogist

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Members of the edgrewite Ca 9 (SiO 4 ) 4 F 2 -hydroxyledgrewite Ca 9 (SiO 4 ) 4 (OH) 2 series, structural analogues of clinohumite-hydroxylclinohumite series, Mg 9 (SiO 4 ) 4 (F,OH) 2 , were discovered in xenoliths of carbonate-silicate rock altered to skarn within ignimbrites of the Upper Chegem volcanic structure, Kabardino-Balkaria, Northern Caucasus, Russia. The new minerals occur sparingly in zones containing bultfonteinite, hillebrandite, jennite, and chegemite, as well as rare relics of larnite and rondorfite enclosed in a matrix of hydroxylellestadite. Edgrewite and hydroxyledgrewite are largely altered to jennite in places with admixed zeophyllite and trabzonite, and are preserved as elongate relics mostly 0.1-0.4 mm long in the central part of atoll-like pseudomorphs. The new minerals form a solid-solution series Ca 9 (SiO 4 ) 4 (F,OH) 2 , in which the content of the edgrewite end-member Ca 9 (SiO 4 ) 4 F 2 ranges from 74% (F = 3.64 wt%) to 31% (F = 1.52 wt%).Structure refinement of crystals containing 51% and 37% of the edgrewite end-member gave, respectively, R 1 = 3.03%, space group P2 1 /b11 (no. 14), Z = 2, a = 5.06870(10), b = 11.35790(10), c = 15.4004(2) Å, α = 100.5980(10)°, V = 871.47(3) Å 3 ; and R 1 = 1.61%, space group P2 1 /b11 (no. 14), Z = 2, a = 5.06720(10), b = 11.35450(10), c = 15.3941(2) Å, α = 100.5870(10)°, and V = 870.63(2) Å 3 .Minerals of the edgrewite-hydroxyledgrewite series are colorless, optically biaxial (+), 2V meas = 80(5)°; 2V calc = 78.7°; dispersion r > v, medium; orientation: Z = a, X ∧ c = 12(2)°; edgrewite: α = 1.621(2), β = 1.625(2), γ = 1.631(2); hydroxyledgrewite: α = 1.625(2), β = 1.629(2), γ = 1.635(2) (589 nm). The micro-hardness VHN 50 = 352-366 kg/mm 2 corresponds to the Mohs scale of 5.5-6. 5. FTIR spectra of edgrewite and hydroxyledgrewite show resolved bands at (edgrewite/hydroxyledgrewite, cm -1 ): 3558 and 3551 and 3543/3554, absent/3486, 1075/1075, 996/996, 980/982, 934/933, 917/918, 904/903, 890/884, 864/864, 842/842, 818/820. Raman spectra are characterized by the following bands (edgrewite/hydroxyledgrewite, cm -1 ) at: 921/923, 889/890, 839/840, and 815/814 (SiO 4 stretching), at: 556/559, 527/527, 423/419, 406/404, and 394/394 (SiO 4 bending), 309/295, 269/256, and 163/166 (CaO 6 ). In the OH stretching region three bands are noted at 3554, 3547, and 3540 cm -1 for edgrewite and two -3550 and 3475 cm -1 for hydroxyledgrewite confirming the corresponding IR spectra. The major difference in Raman and IR spectra of edgrewite and hydroxyledgrewite is the presence of two resolved peaks in the OH stretching region at ca. 3550 and 3480 cm -1 for hydroxyledgrewite.

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“…Stoichiometric C 2 S has five polymorphs varieties ( γ , β, α L , α H and α), stable at different temperatures [13,14]. The γ phase is the variety stable at room temperature it is, however, not hydraulically active [14,15]. The α −C 2 S form is less reactive than the β −C 2 S and α L −C 2 S forms [16].…”

Section: Introductionmentioning

confidence: 97%

Synthesis and Characterization of Belite Cement with High Hydraulic Reactivity and Low Environmental Impact

et al. 2014

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Cement industry is a large energy consumer and a major CO 2 producer. In cement manufacture, most of the CO 2 footprint is due to the decarbonation of limestone. The designing of new clinkers that require less limestone and less energy for their production is a means to significantly reduce the environmental impact of this binder, the most widely used in construction worldwide. The present study focuses on the elaboration and characterization of environmentally friendly cements of very low lime saturation factor, obtained at low burning temperatures with hydraulic properties similar to those of alite cement. Four types of complete belite cements of high hydraulic reactivity were obtained thanks to the stabilization of the most reactive phases of the belite using quick cooling associated to four different mineralizations. The obtained cements have been characterized for their burnability on the basis of the free lime content. Their chemical and mineralogical compositions were studied using Xray fluorescence, X-ray diffraction and optical microscopy. The composition and morphology of the belite were studied using scanning electron microscope coupled with EDAX. The compressive strength and hydration heat were determined according to French standards. The results show that the sintering temperature can be reduced to 1,100 • C which is 50 • C less than reported in similar researches and 350 • C less than alite cement, with an improvement of the chemical, mineralogical and structural properties of the belite. This results in a hydraulic reactivity comparable to that of ordinary alite cements, with 28-day compressive strength of 38 MPa.

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Refinement of the crystal structure of γ-Ca2SiO4

Cited by 66 publications

References 2 publications

Mechanism of stabilization of dicalcium silicate solid solution with aluminium

Mechanism of stabilization of dicalcium silicate solid solution with aluminium

Edgrewite Ca9(SiO4)4F2-hydroxyledgrewite Ca9(SiO4)4(OH)2, a new series of calcium humite-group minerals from altered xenoliths in the ignimbrite of Upper Chegem caldera, Northern Caucasus, Kabardino-Balkaria, Russia

Synthesis and Characterization of Belite Cement with High Hydraulic Reactivity and Low Environmental Impact

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