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One of the main phases formed at the beginning of the carbonation reaction of cementitious building materials is the calcium hemicarboaluminate (abbreviated as Hc). This AFm (shorthand for hydrated calcium aluminate phases structurally related to hydrocalumite) phase was synthesized, crystallized and then studied by synchrotron X-ray powder diffraction and micro-Raman spectroscopy. At room temperature and standard experimental conditions two major cementitious phases were detected, the Hc phase (as a major phase) and carbonated calcium hemicarboaluminate (abbreviated as cHc). By increasing the temperature the Hc form transforms into cHc. The crystal structures of these important AFm phases were successfully solved and refined in the R\bar 3c space group of the trigonal crystal system. Hc has the unit-cell parameters a = 5.7757 (1) and c = 48.812 (2) Å, and cHc the unit-cell parameters a = 5.7534 (1) and c = 46.389 (1) Å. The two crystal structures are composed of positively charged main layers, [Ca4Al2(OH)12]2+, and negatively charged interlayers, [OH2n(CO3)1 - n·4H2O]2-. The structure of the main layers is typical of the AFm family. Conversely, the interlayer region has a characteristic structure built up from water molecules and statistically distributed anions. In the interlayer, the Hc carbonate and hydroxyl anions are distributed in a 0.25:0.5 ratio, whereas the ratio of the anions in the cHc interlayers is 0.4:0.2.

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S010876811203042X/eb5017sup1.cif
Contains datablocks global, cHc, Hc

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S010876811203042X/eb5017Hcsup2.hkl
Contains datablock Hc

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S010876811203042X/eb5017cHcsup3.hkl
Contains datablock cHc

rtv

Rietveld powder data file (CIF format) https://doi.org/10.1107/S010876811203042X/eb5017297Ksup4.rtv
Contains datablock 297K

rtv

Rietveld powder data file (CIF format) https://doi.org/10.1107/S010876811203042X/eb5017347Ksup5.rtv
Contains datablock 347K

Computing details top

Figures top
[Figure 1]
[Figure 2]
[Figure 3]
[Figure 4]
[Figure 5]
[Figure 6]
[Figure 7]
(cHc) Tetracalcium dialuminium dodecahydroxide hemicarbonate hydroxide n-hydrate top
Crystal data top
C0.4AlCa2O9.2Z = 6
Mr = 259.14F(000) = 774.0
Trigonal, R3cDx = 1.942 Mg m3
Hall symbol: -R 3 2"cSynchrotron radiation, λ = 0.8264 (3) Å
a = 5.7534 (1) ÅT = 347 K
c = 46.389 (1) Åwhite
V = 1329.84 (4) Å3?, ? × ? × ? mm
Data collection top
Synchrotron Diamond I11 (Great Britain)
diffractometer
Refinement top
Rp = 0.030χ2 = 40.069
Rwp = 0.050? data points
Rexp = 0.008
Crystal data top
C0.4AlCa2O9.2V = 1329.84 (4) Å3
Mr = 259.14Z = 6
Trigonal, R3cSynchrotron radiation, λ = 0.8264 (3) Å
a = 5.7534 (1) ÅT = 347 K
c = 46.389 (1) Å?, ? × ? × ? mm
Data collection top
Synchrotron Diamond I11 (Great Britain)
diffractometer
Refinement top
Rp = 0.030χ2 = 40.069
Rwp = 0.050? data points
Rexp = 0.008
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/UeqOcc. (<1)
Ca10.666670.333330.67930 (2)0.0231 (4)*
Al10000.0127 (5)*
O10.3051 (3)0.0586 (3)0.52121 (3)0.0151 (5)*
O20.666670.333330.93091 (6)0.0630 (10)*
O30.220 (3)00.750.025 (2)*0.40
C10.666670.333330.0833330.025 (2)*0.40
Geometric parameters (Å, º) top
Ca1—O1i2.374 (2)Al1—O1iv1.890 (2)
Ca1—O1ii2.450 (2)C1—O3v1.266 (4)
Ca1—O2iii2.619 (3)
O1iv—Al1—O1vi180.0O1xiii—Ca1—O1xiv146.32 (5)
O1vii—Al1—O1viii180.0O1xiv—Ca1—O1xii117.25 (3)
O1ix—Al1—O1x180.0O1i—Ca1—O1xiv117.25 (3)
O1iv—Al1—O1vii95.36 (6)O1i—Ca1—O1xii117.25 (3)
O1iv—Al1—O1ix95.36 (6)O1xi—Ca1—O1xiv86.21 (6)
O1vii—Al1—O1ix95.36 (6)O1xiii—Ca1—O1i86.21 (6)
O1vi—Al1—O1viii95.36 (6)O1ii—Ca1—O1xii86.21 (6)
O1vi—Al1—O1x95.36 (6)O1xiii—Ca1—O1xi83.35 (5)
O1viii—Al1—O1x95.36 (6)O1xiii—Ca1—O1ii83.35 (5)
O1iv—Al1—O1viii84.64 (6)O1xi—Ca1—O1ii83.35 (5)
O1iv—Al1—O1x84.64 (6)O1xiii—Ca1—O1xii63.65 (8)
O1vii—Al1—O1vi84.64 (6)O1xi—Ca1—O1i63.65 (8)
O1vii—Al1—O1x84.64 (6)O1ii—Ca1—O1xiv63.65 (8)
O1ix—Al1—O1vi84.64 (6)O1xii—Ca1—O2iii80.35 (4)
O1ix—Al1—O1viii84.64 (6)Al1iv—O1—Ca1xv104.00 (7)
O1xi—Ca1—O1xii146.32 (5)Ca1xiii—O1—Ca1xv93.79 (6)
O1ii—Ca1—O1i146.32 (5)O3v—C1—O3xvi120
Symmetry codes: (i) y+1/3, x+2/3, z+1/6; (ii) x+4/3, x+y+2/3, z+7/6; (iii) x+4/3, y+2/3, z+5/3; (iv) y, x, z+1/2; (v) x+2/3, y+1/3, z2/3; (vi) y, x, z1/2; (vii) xy, y, z+1/2; (viii) x+y, y, z1/2; (ix) x, x+y, z+1/2; (x) x, xy, z1/2; (xi) xy+1/3, y+2/3, z+7/6; (xii) x+1/3, xy1/3, z+1/6; (xiii) y+1/3, x1/3, z+7/6; (xiv) x+y+4/3, y+2/3, z+1/6; (xv) y+2/3, x+1/3, z1/6; (xvi) y+2/3, xy+1/3, z2/3.
(Hc) Tetracalcium dialuminium dodecahydroxide hemicarbonate hydroxide n-hydrate top
Crystal data top
C0.25AlCa2O9.25Z = 6
Mr = 258.13F(000) = 771.0
Trigonal, R3cDx = 1.824 Mg m3
Hall symbol: -R 3 2"cSynchrotron radiation, λ = 0.8264 (3) Å
a = 5.7757 (1) ÅT = 297 K
c = 48.812 (2) Åwhite
V = 1410.14 (7) Å3?, ? × ? × ? mm
Data collection top
Synchrotron Diamond I11 (Great Britain)
diffractometer
Refinement top
Rp = 0.029χ2 = 27.384
Rwp = 0.040? data points
Rexp = 0.008
Crystal data top
C0.25AlCa2O9.25V = 1410.14 (7) Å3
Mr = 258.13Z = 6
Trigonal, R3cSynchrotron radiation, λ = 0.8264 (3) Å
a = 5.7757 (1) ÅT = 297 K
c = 48.812 (2) Å?, ? × ? × ? mm
Data collection top
Synchrotron Diamond I11 (Great Britain)
diffractometer
Refinement top
Rp = 0.029χ2 = 27.384
Rwp = 0.040? data points
Rexp = 0.008
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/UeqOcc. (<1)
Al10000.0127 (7)*
Ca10.666670.333330.67796 (4)0.0214 (4)*
O10.3012 (3)0.0484 (4)0.52040 (6)0.0224 (5)*
O20.666670.333330.93875 (8)0.063 (2)*
O30.219 (2)00.750.025 (4)*0.25
O40.5650.4740.0940.025 (7)*0.08333
C10.666670.333330.083330.025 (4)*0.25
Geometric parameters (Å, º) top
Ca1—O1i2.346 (3)C1—O3v1.265 (9)
Ca1—O1ii2.467 (3)C1—O41.324
Ca1—O2iii2.439 (4)O3—O4vi0.745 (3)
Al1—O1iv1.900 (3)O4—O4vii1.456
O1iv—Al1—O1viii180.0O1i—Ca1—O1xiv116.50 (5)
O1ix—Al1—O1x180.0O1i—Ca1—O1xvi116.50 (5)
O1xi—Al1—O1xii180.0O1xiv—Ca1—O1xvi116.50 (5)
O1xiii—Ca1—O1xiv148.60 (8)O1i—Ca1—O2iii79.08 (8)
O1xv—Ca1—O1xvi148.60 (8)O1xiv—Ca1—O2iii79.08 (8)
O1ii—Ca1—O1i148.60 (8)O1xvi—Ca1—O2iii79.08 (8)
O1xv—Ca1—O2iii128.85 (6)O3v—C1—O3xvii120.0
O1xiii—Ca1—O1i86.29 (9)O3v—C1—O3xviii120.0
O1xv—Ca1—O1xiv86.29 (9)O3xvii—C1—O3xviii120.0
O1ii—Ca1—O1xvi86.29 (9)O3xix—O3—O3xx60
Symmetry codes: (i) y+1/3, x+2/3, z+1/6; (ii) x+4/3, x+y+2/3, z+7/6; (iii) x+4/3, y+2/3, z+5/3; (iv) y, x, z+1/2; (v) x+2/3, y+1/3, z2/3; (vi) x+y+1/3, x+2/3, z+2/3; (vii) x+4/3, x+y+2/3, z+1/6; (viii) y, x, z1/2; (ix) xy, y, z+1/2; (x) x+y, y, z1/2; (xi) x, x+y, z+1/2; (xii) x, xy, z1/2; (xiii) y+1/3, x1/3, z+7/6; (xiv) x+y+4/3, y+2/3, z+1/6; (xv) xy+1/3, y+2/3, z+7/6; (xvi) x+1/3, xy1/3, z+1/6; (xvii) y+2/3, xy+1/3, z2/3; (xviii) x+y+2/3, x+1/3, z2/3; (xix) y, xy, z; (xx) x+y, x, z.

Experimental details

(cHc)(Hc)
Crystal data
Chemical formulaC0.4AlCa2O9.2C0.25AlCa2O9.25
Mr259.14258.13
Crystal system, space groupTrigonal, R3cTrigonal, R3c
Temperature (K)347297
a, c (Å)5.7534 (1), 46.389 (1)5.7757 (1), 48.812 (2)
V3)1329.84 (4)1410.14 (7)
Z66
Radiation typeSynchrotron, λ = 0.8264 (3) ÅSynchrotron, λ = 0.8264 (3) Å
Specimen shape, size (mm)?, ? × ? × ??, ? × ? × ?
Data collection
DiffractometerSynchrotron Diamond I11 (Great Britain)
diffractometer
Synchrotron Diamond I11 (Great Britain)
diffractometer
Specimen mounting??
Data collection mode??
Scan method??
2θ values (°)2θmin = ? 2θmax = ? 2θstep = ?2θmin = ? 2θmax = ? 2θstep = ?
Refinement
R factors and goodness of fitRp = 0.030, Rwp = 0.050, Rexp = 0.008, χ2 = 40.069Rp = 0.029, Rwp = 0.040, Rexp = 0.008, χ2 = 27.384
No. of data points??
No. of parameters??
No. of restraints??

 

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