The crystal structure with the idealized formula Mg3(OH)5Cl·4H2O, the so-called F5 phase according to 5Mg(OH)2·MgCl2·8H2O in the system MgCl2-MgO-H2O, has been solved ab initio from high-quality laboratory powder diffraction data at room temperature. The F5 phase is structurally related to 3Mg(OH)2·MgCl2·8H2O (F3 form). The F5 phase consists of infinite triple chains with one Mg(OH)6 and two Mg(OH)4(OH2)2 octahedra as building units intercalated by chlorides, which are partly substituted by disordered hydroxides in the real structure. The F5 phase is of technological importance as the most important binder phase in Sorel cements. Knowledge of the crystal structure enables the full quantitative phase analysis of magnesia cements for the first time, which turns out to be very helpful in the search for possible causes of broken or bleached magnesia floors. Two real-life examples are given.
Supporting information
Trimagnesium pentahydroxide triaqua chloride monohydrate
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Crystal data top
ClH13Mg3O9 | V = 230.44 (3) Å3 |
Mr = 265.46 | Z = 1 |
Monoclinic, p2/m | Dx = 1.913 Mg m−3 |
a = 9.6412 (5) Å | Cu Kα1 radiation, λ = 1.54059 Å |
b = 3.1506 (2) Å | T = 295 K |
c = 8.3035 (5) Å | white |
β = 113.986 (6)° | ?, ? × ? × ? mm |
Data collection top
Bruker D8 advance diffractmeter diffractometer | Data collection mode: transmission |
Specimen mounting: glass capillary | Scan method: continuous |
Refinement top
Rp = 0.042 | Profile function: fundamental parameters convolution-based |
Rwp = 0.060 | 16 parameters |
Rexp = 0.019 | H-atom parameters not defined |
χ2 = NOT FOUND | |
? data points | |
Crystal data top
ClH13Mg3O9 | β = 113.986 (6)° |
Mr = 265.46 | V = 230.44 (3) Å3 |
Monoclinic, p2/m | Z = 1 |
a = 9.6412 (5) Å | Cu Kα1 radiation, λ = 1.54059 Å |
b = 3.1506 (2) Å | T = 295 K |
c = 8.3035 (5) Å | ?, ? × ? × ? mm |
Data collection top
Bruker D8 advance diffractmeter diffractometer | Data collection mode: transmission |
Specimen mounting: glass capillary | Scan method: continuous |
Refinement top
Rp = 0.042 | ? data points |
Rwp = 0.060 | 16 parameters |
Rexp = 0.019 | H-atom parameters not defined |
χ2 = NOT FOUND | |
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top | x | y | z | Uiso*/Ueq | Occ. (<1) |
Mg1 | 0.8063 (16) | 0 | 0.694 (2) | 0.0623 (4)* | |
Mg2 | 0.5 | 0.5 | 0.5 | 0.0623 (4)* | |
Cl1 | 0.6826 (19) | 0.5 | 0.114 (2) | 0.0623 (4)* | 0.5 |
O1 | 0.715 (3) | 0.5 | 0.523 (3) | 0.0623 (4)* | |
O2 | 0.600 (4) | 0 | 0.683 (3) | 0.0623 (4)* | |
O3 | 1.023 (3) | 0 | 0.685 (3) | 0.0623 (4)* | |
O4 | 0.861 (2) | 0.5 | 0.884 (3) | 0.0623 (4)* | |
O5 | 0.6826 (19) | 0.5 | 0.114 (2) | 0.0623 (4)* | 0.5 |
H1 | 0.7324 | 0.5 | 0.412 | 0.0623 (4)* | |
H2 | 0.5862 | 0 | 0.7936 | 0.0623 (4)* | |
H3 | 1.1057 | −0.1875 | 0.7587 | 0.0623 (4)* | 0.5 |
H4 | 1.0496 | 0.1875 | 0.6078 | 0.0623 (4)* | 0.5 |
H5 | 0.8 | 0.5 | 0.9534 | 0.0623 (4)* | 0.75 |
H6 | 0.9659 | 0.5 | 0.9688 | 0.0623 (4)* | 0.75 |
H7 | 0.7679 | 0.5 | 0.0865 | 0.0623 (4)* | 0.5 |
H8 | 0.582 | 0.5 | 0.0186 | 0.0623 (4)* | 0.5 |
Geometric parameters (Å, º) top
Mg1—O1 | 2.066 (15) | Mg2—O1 | 2.00 (3) |
Mg2—O2 | 2.127 (13) | O1—H1 | 1.002 |
Mg1—O2 | 1.96 (3) | O2—H2 | 0.980 |
Mg2—O2i | 2.127 (13) | O3—H3 | 0.980 |
Mg1—O4 | 2.14 (2) | O3—H4 | 0.975 |
Mg2—O1ii | 2.00 (3) | O4—H5 | 0.973 |
Mg1—O1iii | 2.066 (15) | O4—H6 | 0.971 |
Mg2—O2ii | 2.127 (13) | O5—H7 | 0.939 |
Mg1—O4iii | 2.14 (2) | O5—H8 | 0.972 |
Mg2—O2iv | 2.127 (13) | | |
| | | |
O1iii—Mg1—O1 | 99.3 (8) | O2—Mg2—O2i | 95.6 (5) |
O1iii—Mg1—O2 | 79.9 (10) | O2—Mg2—O2ii | 84.4 (5) |
O1iii—Mg1—O3 | 97.3 (11) | O2—Mg2—O2iv | 180.0 |
O1iii—Mg1—O4iii | 81.6 (6) | O2i—Mg2—O2ii | 180.0 |
O1iii—Mg1—O4 | 168.0 (14) | O2i—Mg2—O2iv | 84.4 (5) |
O1—Mg1—O2 | 79.9 (10) | O2ii—Mg2—O2iv | 95.6 (5) |
O1—Mg1—O3 | 97.3 (11) | Mg1—O1—Mg1i | 99.3 (9) |
O1—Mg1—O4iii | 168.0 (14) | Mg1—O1—Mg2 | 101.6 (12) |
O1—Mg1—O4 | 81.6 (6) | Mg1i—O1—Mg2 | 101.6 (12) |
O2—Mg1—O3 | 175.7 (12) | Mg1—O2—Mg2iii | 101.0 (12) |
O2—Mg1—O4iii | 88.6 (9) | Mg1—O2—Mg2 | 101.0 (12) |
O2—Mg1—O4 | 88.6 (9) | Mg2iii—O2—Mg2 | 95.6 (8) |
O3—Mg1—O4iii | 94.5 (8) | Mg1—O4—Mg1i | 94.9 (11) |
O3—Mg1—O4 | 94.5 (8) | Mg1—O1—H1 | 116.6 |
O4iii—Mg1—O4 | 94.9 (9) | Mg2—O1—H1 | 118.1 |
O1—Mg2—O1ii | 180.0 | Mg1—O2—H2 | 118.4 |
O1—Mg2—O2 | 77.4 (10) | Mg2—O2—H2 | 118.4 |
O1—Mg2—O2i | 77.4 (10) | Mg1—O3—H3 | 122.3 |
O1—Mg2—O2ii | 102.6 (10) | Mg1—O3—H4 | 123.1 |
O1—Mg2—O2iv | 102.6 (10) | H3—O3—H4 | 114.6 |
O1ii—Mg2—O2 | 102.6 (10) | Mg1—O4—H5 | 114.2 |
O1ii—Mg2—O2i | 102.6 (10) | Mg1—O4—H6 | 113.9 |
O1ii—Mg2—O2ii | 77.4 (10) | H5—O4—H6 | 106.0 |
O1ii—Mg2—O2iv | 77.4 (10) | H7—O5—H8 | 118.9 |
Symmetry codes: (i) x, y+1, z; (ii) −x+1, y, −z+1; (iii) x, y−1, z; (iv) −x+1, y+1, −z+1. |
Experimental details
Crystal data |
Chemical formula | ClH13Mg3O9 |
Mr | 265.46 |
Crystal system, space group | Monoclinic, p2/m |
Temperature (K) | 295 |
a, b, c (Å) | 9.6412 (5), 3.1506 (2), 8.3035 (5) |
β (°) | 113.986 (6) |
V (Å3) | 230.44 (3) |
Z | 1 |
Radiation type | Cu Kα1, λ = 1.54059 Å |
µ (mm−1) | ? |
Specimen shape, size (mm) | ?, ? × ? × ? |
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Data collection |
Diffractometer | Bruker D8 advance diffractmeter diffractometer |
Specimen mounting | Glass capillary |
Data collection mode | Transmission |
Scan method | Continuous |
2θ values (°) | 2θmin = ? 2θmax = ? 2θstep = ? |
|
Refinement |
R factors and goodness of fit | Rp = 0.042, Rwp = 0.060, Rexp = 0.019, χ2 = NOT FOUND |
No. of data points | ? |
No. of parameters | 16 |
No. of restraints | ? |
H-atom treatment | H-atom parameters not defined |