A new calcium-aluminate from a refractory inclusion in the Leoville carbonaceous chondrite

Valleriite is an unusual mineral, consisting of intergrowths of sulfide layers (corresponding in structure to the mineral smythite - Fe9S11) and hydroxide layers (corresponding to brucite - Mg(OH2)). It has a composition of approximately 1.526[Mg.68Al.32(OH)2].[Fe1.07Cu.93S2] and consists of two interpenetrating lattices, each of which retains its individual structural and diffraction characteristics parallel to the layering. The valleriite structure is related to that of tochilinite, an unusual iron-rich mineral that is of considerable interest for the origin of certain carbonaceous chondrite meteorites and to those of franckeite and cylindrite, two minerals that are of interest because of their unique morphological and crystallographic properties, e.g., the distinctive curved form of cylindrite and the perfect mica-like cleavage with unusual striations and the long-period wavy structure of franckeite.Our selected-area electron diffraction (SAED) patterns and high-resolution transmission electron microscope (HRTEM) images of valleriite provide new structural data. A basic structure and a new superstructure have been observed.

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An HREM study of superstructures in Ca4Al6SO16

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s042482010017846x ◽

1990 ◽

Vol 48 (4) ◽

pp. 1066-1067

Author(s):

Y.G. Wang ◽

H.Q. Ye ◽

K.H. Kuo

Keyword(s):

Calcium Aluminate ◽

Structural Model ◽

Bright Spot ◽

Sulphur Atom ◽

Synthetic Compound ◽

Space Group ◽

Lattice Images ◽

Cubic Structure ◽

Good Agreement

A synthetic compound Ca4Al6SO16 (usually abbreviated as C4A3S) obtained by mixing CaO, A12O3 and CaSO4 powders and finally sintered at 1380°C is a cement with excellent hydraulicity and greatly expanding in application. It is hydralysed rapidly by water to form predominatly calcium aluminate hydrates and therefore unlikly to occur naturally, although structurally it may be regarded as an end member of the sodalite-hauynite series of naturally occuring minerals. C4A3S has a cubic structure with ao=9.19Å and space group . Fig.1 is the projection viewed down axis, in which there are two sets of 8C position in , namely CaI and CaII, occupied by the calcium atoms, respectively, and the ratio of occupations in these two sets of positions is about 3:1. This suggests that the calcium atoms can freely occupy these sites in various degrees and usually they almost locates on the CaI positions. A through-focus series of the lattice images were found in good agreement with the simulated ones. Each bright spot in the image taken at Scherzer defocus correspounds to a colunm of sulphur atom in the structural model (Fig.1).

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Quick Setting Property and Hydration of Portland Cement with Accelerating Agent Based on Calcium Aluminate.

Journal of the Society of Materials Science Japan ◽

10.2472/jsms.49.209 ◽

2000 ◽

Vol 49 (2) ◽

pp. 209-214

Author(s):

Minoru TAKEHIRO ◽

Seishi GOTO ◽

Koji IOKU ◽

Hirotaka FUJIMORI

Keyword(s):

Portland Cement ◽

Calcium Aluminate ◽

Agent Based

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Preparation of near net size porous alumina‐calcium aluminate ceramics by gelcasting‐pore‐forming agent processs

Journal of the American Ceramic Society ◽

10.1111/jace.17075 ◽

2020 ◽

Vol 103 (8) ◽

pp. 4602-4610

Author(s):

Bian‐Lei Hao ◽

Ying Lang ◽

Da‐Qian Bian ◽

Chang‐An Wang

Keyword(s):

Calcium Aluminate ◽

Porous Alumina

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The Bencubbin stony-iron meteorite breccia: Electron petrography, shock-history and affinities of a “carbonaceous chondrite” clast

Meteoritics ◽

10.1111/j.1945-5100.1991.tb01023.x ◽

1991 ◽

Vol 26 (2) ◽

pp. 83-95 ◽

Cited By ~ 11

Author(s):

D. J. Barber ◽

R. Hutchison

Keyword(s):

Carbonaceous Chondrite ◽

Iron Meteorite

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Study by DTA/TG of the formation of calcium aluminate obtained from an aluminium hazardous waste

Journal of Thermal Analysis and Calorimetry ◽

10.1007/s10973-009-0597-z ◽

2009 ◽

Vol 99 (3) ◽

pp. 999-1004 ◽

Cited By ~ 11

Author(s):

A. López-Delgado ◽

F. A. López ◽

L. Gonzalo-Delgado ◽

S. López-Andrés ◽

F. J. Alguacil

Keyword(s):

Hazardous Waste ◽

Calcium Aluminate

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Physicochemical, Mineralogical, and Mechanical Properties of Calcium Aluminate Cement Concrete Exposed to Elevated Temperatures

Materials ◽

10.3390/ma14143855 ◽

2021 ◽

Vol 14 (14) ◽

pp. 3855

Author(s):

Amirmohamad Abolhasani ◽

Bijan Samali ◽

Fatemeh Aslani

Keyword(s):

Temperature Rise ◽

Calcium Aluminate ◽

Elevated Temperatures ◽

Ultrasonic Pulse Velocity ◽

Pulse Velocity ◽

Calcium Aluminate Cement ◽

Cement Concrete ◽

Sem Images ◽

Strength Deterioration ◽

Aluminate Cement

One commonly used cement type for thermal applications is CAC containing 38–40% alumina, although the postheated behavior of this cement subjected to elevated temperature has not been studied yet. Here, through extensive experimentation, the postheated mineralogical and physicochemical features of calcium aluminate cement concrete (CACC) were examined via DTA/TGA, X-ray diffraction (XRD), and scanning electron microscopy (SEM) imaging and the variation in the concrete physical features and the compressive strength deterioration with temperature rise were examined through ultrasonic pulse velocity (UPV) values. In addition, other mechanical features that were addressed were the residual tensile strength and elastic modulus. According to the XRD test results, with the temperature rise, the dehydration of the C3AH6 structure occurred, which, in turn, led to the crystallization of the monocalcium dialuminate (CA2) and alumina (Al2O3) structures. The SEM images indicated specific variations in morphology that corresponded to concrete deterioration due to heat.

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