Table S1. Atomic coordinates and isotropic equivalent displacement parameters (Å2) for ettringite.
Atom / Occupancy / x / y / z / Ueq(Uiso)Ca1 / 1 / 0.00704(3) / 0.81120(4) / 0.87233(3) / 0.01813(8)
Ca2 / 1 / 0.99730(7) / 0.19097(5) / 0.12197(3) / 0.02155(10)
Al1 / Al0.61Si0.39 / 0 / 0 / –0.00357(8) / 0.01445(18)
Al2 / Al0.79Si0.21 / 0 / 0 / 0.24736(8) / 0.0164(2)
S1 / S0.529(4)C0.471(4) / 1/3 / 2/3 / 0.48746(7) / 0.0199(4)
S2 / S0.968(4)Cr0.032(4) / 1/3 / 2/3 / 0.74455(9) / 0.02660(19)
S3 / S0.280(6)Cr0.320(6) / 1/3 / 2/3 / 0.00234(6) / 0.0140(3)
C3 / 0.110(3) / 1/3 / 2/3 / –0.0132(13) / 0.000(4)*
S4 / 0.586(4) / 1/3 / 2/3 / 0.25274(16) / 0.0466(7)
O1 / 1 / 0.99638(13) / 0.12792(15) / 0.94263(7) / 0.0167(4)
H1 / 1 / 1.023(2) / 0.179(2) / 0.9798(8) / 0.027**
O2 / 1 / 0.00401(18) / 0.8687(2) / 0.05093(7) / 0.0250(5)
H2 / 1 / 0.0156(18) / 0.8259(13) / 0.0052(8) / 0.036
O3 / 1 / –0.00191(16) / 0.1312(2) / 0.80035(6) / 0.0191(5)
H3 / 1 / –0.011(2) / 0.2019(19) / 0.7792(12) / 0.031
O4 / 1 / 0.00094(18) / 0.8712(2) / 0.19084(7) / 0.0190(4)
H4 / 1 / –0.002(2) / 0.795(2) / 0.2182(13) / 0.030
Ow5 / 1 / –0.00784(19) / 0.3404(2) / 0.03926(10) / 0.0433(6)
H5A / 1 / 0.0757(10) / 0.423(2) / 0.0277(15) / 0.066
H5B / 1 / –0.0874(11) / 0.353(2) / 0.0360(15) / 0.066
Ow6 / 1 / 0.0061(2) / 0.6647(3) / 0.95794(12) / 0.0369(6)
H6A / 1 / –0.026(2) / 0.623(3) / 0.9186(6) / 0.060
H6B / 1 / 0.015(2) / 0.607(2) / 0.9888(8) / 0.060
Ow7 / 1 / 0.0021(2) / 0.3372(2) / 0.20888(12) / 0.0358(6)
H7A / 1 / 0.0849(10) / 0.425(2) / 0.2091(17) / 0.053
H7B / 1 / –0.0788(10) / 0.343(2) / 0.2048(16) / 0.053
Ow8 / 1 / 0.0052(3) / 0.6620(3) / 0.79125(15) / 0.0519(9)
H8A / 1 / –0.0789(10) / 0.587(3) / 0.7724(16) / 0.076
H8B / 1 / 0.0842(11) / 0.653(3) / 0.7782(16) / 0.076
Ow9 / 1 / 0.2517(3) / 0.4000(2) / 0.62020(9) / 0.0464(7)
H9A / 1 / 0.2457(16) / 0.4829(16) / 0.6356(10) / 0.072
H9B / 1 / 0.312(2) / 0.438(2) / 0.5810(9) / 0.072
Ow10 / 1 / 0.74065(17) / 0.59340(18) / 0.37146(14) / 0.0408(5)
H10A / 1 / 0.722(3) / 0.558(2) / 0.3301(5) / 0.059
H10B / 1 / 0.704(3) / 0.515(2) / 0.4020(7) / 0.059
Ow11 / 1 / 0.2418(2) / 0.3980(2) / 0.12385(11) / 0.0452(7)
H11A / 1 / 0.3327(11) / 0.4076(19) / 0.1273(13) / 0.071
H11B / 1 / 0.246(2) / 0.468(2) / 0.0954(12) / 0.071
Ow12 / 1 / 0.76055(18) / 0.6004(2) / 0.86882(17) / 0.0496(6)
H12A / 1 / 0.7049(15) / 0.6497(12) / 0.8572(17) / 0.072
H12B / 1 / 0.691(2) / 0.5025(12) / 0.8596(17) / 0.072
O13 / 0.529(4) / 1/3 / 2/3 / 0.4172(3) / 0.0235(13)
O14 / 0.652(8) / 1/3 / 2/3 / 0.8131(3) / 0.065(2)
O14' / 0.348(8) / 1/3 / 2/3 / 0.6703(3) / 0.0165(16)*
O15 / 0.770(10) / 1/3 / 2/3 / 0.0702(2) / 0.0508(18)
O16 / 0.627(5) / 0.1949(3) / 0.6167(3) / 0.50708(19) / 0.0471(10)
O16' / 0.373(5) / 0.3204(12) / 0.7707(10) / 0.4914(4) / 0.219(3)
O17 / 0.742(6) / 0.1922(3) / 0.6171(4) / 0.7262(2) / 0.0823(17)
O17' / 0.314(5) / 0.1950(4) / 0.5698(4) / 0.76672(18) / 0.0052(8)*
O18 / 0.890(3) / 0.1935(3) / 0.5658(3) / –0.02191(12) / 0.0447(9)
O18' / 0.110(3) / 0.2526(12) / 0.5252(11) / –0.0080(5) / 0.012(2)*
O19 / 0.652(12) / 1/3 / 2/3 / 0.3236(3) / 0.063(3)
O20 / 0.927(6) / 0.1988(3) / 0.6205(3) / 0.23282(14) / 0.0603(11)
* Atoms marked by asterisks are refined in isotropic approximation.
** Temperature factors for H atoms equal to those for O atoms multiplied by 1.5.
Table S2. Selected interatomic distances (Å) and angles (°) in ettringite.
Ca1–O1 / 2.4328(14) / Ca2–O2 / 2.4560(18)
Ca1–O3 / 2.4392(17) / Ca2–O4 / 2.3977(18)
Ca1–O3 / 2.4727(15) / Ca2–O4 / 2.4110(18)
Ca1–OW6 / 2.451(3) / Ca2–OW5 / 2.452(2)
Ca1–OW8 / 2.397(3) / Ca2–OW7 / 2.455(3)
Ca1–OW10 / 2.6308(16) / Ca2–OW9 / 2.590(2)
Ca1–OW12 / 2.5917(18) / Ca2–OW11 / 2.561(2)
Al1–O1(3×) / 1.8525(19) / Al2–O3(3×) / 1.863(2)
Al1–O2(3×) / 1.893(2) / Al2–O4(3×) / 1.884(2)
S1–O13 / 1.493(5) / O16–S1–O16(3×) / 111.80(15)
S1–O16(3×) / 1.425(3) / O13–S1–O16(3×) / 107.02(16)
S1–O16'(3×) / 1.250(9) / O16'–S1–O16'(3×) / 119.56(10)
S2–O14 / 1.457(6) / O14–S2–O17(3×) / 105.7(2)
S2–O17(3×) / 1.446(4) / O17–S2–O17(3×) / 112.98(17)
S2–O14' / 1.579(8) / O14–S2–O14' / 180
S2–O17'(3×) / 1.459(4) / O14'–S2–O17'(3×) / 108.85(17)
O17'–S2–O17'(3×) / 110.09(16)
S3–O15 / 1.443(5) / O15–S3–O18(3×) / 110.18(11)
S3–O18(3×) / 1.495(2) / O18–S3–O18(3×) / 108.76(11)
C3–O18'(3×) / 1.385(11) / O18'–C3–O18'(3×) / 119.4(3)
S4–O19 / 1.507(7) / O19–S4–O20(3×) / 107.68(19)
S4–O20(3×) / 1.395(3) / O20–S4–O20(3×) / 111.20(17)
Table S3. Hydrogen bonds in the Cr-rich ettringite structure in comparison with neutron diffraction data [41].
O1–H1···Ow5 / 0.931(15) / 2.37(2) / 3.167(3) / 143(2) / 2.340
O2–H2···Ow6 / 1.121(12) / 2.026(9) / 3.036(3) / 148.0(14) / 2.235
O3–H3···Ow7 / 0.962(16) / 2.081(18) / 3.005(3) / 160(2) / 2.347
O4–H4···Ow8 / 1.019(17) / 2.185(18) / 3.193(4) / 170(3) / 2.130
Ow5–H5A···O18 / 0.963(14) / 1.82(2) / 2.736(3) / 157(3) / 1.824
Ow5–H5A···O18' / 0.963(14) / 1.886(18) / 2.792(11) / 156(2) / –
Ow5–H5B···O16 / 0.977(15) / 1.83(2) / 2.763(3) / 158(2) / 1.894
Ow5–H5B···O16' / 0.977(15) / 1.73(2) / 2.590(9) / 145(3) / –
Ow6–H6A···O16 / 0.936(14) / 2.82 / 2.733(4) / 75.02 / 1.813
Ow6–H6B···O16 / 0.961(15) / 2.26(2) / 2.733(4) / 109.1(16) / –
Ow6–H6B···O18 / 0.961(15) / 2.28(3) / 2.859(4) / 117.7(19) / 1.769
Ow6–H6B···O18' / 0.961(15) / 2.51(3) / 2.749(13) / 94.0(15) / –
Ow7–H7A···O20 / 0.960(13) / 1.97(2) / 2.868(3) / 154(2) / 2.218
Ow7–H7B···O17 / 0.945(14) / 1.96(2) / 2.830(4) / 152(2) / 2.019
Ow7–H7B···O17' / 0.945(14) / 2.01(3) / 2.743(4) / 133(3) / –
Ow8–H8A···O20 / 0.982(15) / 1.86(2) / 2.809(4) / 161(2) / 1.752
Ow8–H8B···O17 / 0.979(16) / 1.83(2) / 2.763(5) / 158(3) / 2.025
Ow8–H8B···O17' / 0.979(16) / 1.91(2) / 2.844(5) / 158(3) / –
Ow9–H9A···O14' / 1.020(15) / 1.934(15) / 2.863(4) / 150.0(15) / –
Ow9–H9A···O17 / 1.020(15) / 2.36(2) / 2.867(5) / 109.7(15) / 1.708
Ow9–H9B···O16 / 1.023(15) / 2.08(2) / 3.003(5) / 149(2) / 1.764
Ow10–H10A···O14 / 0.946(13) / 2.30(3) / 2.887(3) / 119.5(17) / 2.070
Ow10–H10A···O17' / 0.946(13) / 1.867(18) / 2.761(5) / 157(2) / –
Ow10–H10B···O18 / 1.003(14) / 1.843(14) / 2.771(4) / 152(2) / 1.882
Ow10–H10B···O18' / 1.003(14) / 2.012(17) / 2.858(10) / 140.4(17) / –
Ow11–H11A···Ow9 / 0.973(11) / 2.232(19) / 2.963(3) / 130.9(15) / 1.863
Ow11–H11B···O15 / 0.977(15) / 2.007(18) / 2.891(3) / 149.5(19) / 1.906
Ow12–H12A···Ow10 / 1.051(14) / 1.995(17) / 2.994(3) / 158(3) / 2.078
Ow12–H12B···O13 / 0.999(13) / 2.16(2) / 2.828(3) / 123(2) / 2.224
Ow12–H12B···O19 / 0.999(13) / 1.937(18) / 2.804(3) / 144(2) / –
* Powder neutron diffraction data [41].