Determination of the local structure of a cage with an oxygen ion in Ca₁₂Al₁₄O₃₃

The crystal structure of mayenite (12CaO·7Al₂O₃) has been investigated by single-crystal synchrotron diffraction with high resolution and accuracy, using a four-circle diffractometer equipped with an avalanche photodiode detector (APD) detector installed at PF14A in Tsukuba, Japan. Analysis revealed random displacements of ions by the electrostatic force of the O^2- ion (O3) clathrated in two out of 12 cages. O3 ions are located at general positions close to the site at the centre of each cage. The difference-density map revealed two large peaks corresponding to displaced Ca ions. The positive ions close to O3 are displaced and one-to-one correspondence was found between one of the four equivalent O3 ions and the displaced ions. When an O3 ion is present in the cage the Al ion at the 16c position moves 0.946 (3) Å toward the O3 ion. One of the Al-O bonds is broken and a new Al-O3 bond is created. The result is an AlO₄ tetrahedron that is quite deformed. The three O1 ions and the O2 ion of the destroyed AlO₄ tetrahedron are forcibly displaced. O1 and O2 have two and one displaced ions, respectively. The local structure of the cage occupied by one of the four O3 ions was determined by calculating the electrostatic potential and electric field in the deformed cage, although the position of one of the displaced O1 ions was not clearly identified.

Computing details

Data collection: BL14A diffractometer control software (Satow. Y. and Iitaka. Y., (1989). Sci. Instrum. 60, 2390-2393; Vaalsta, T. P. & Hester, J. R. (1997). DIFF14A Software. Photon Factory, Tsukuba, Japan. ); cell refinement: RSLC-3 UNICS system (Sakurai, T. & Kobayashi, K. (1979), Rep. Inst. Phys. Chem. Res. 55, 69-77); data reduction: sortref (Sakakura, T. (2008): private communication.); program(s) used to refine structure: MOLLY (Hansen, N. K. and Coppens. P. (1978) Acta Cryst. A34, 909-921.); molecular graphics: gluplot (Sakakura, T. (2008): private communication.).

Figures

(I)

Crystal data

Al14Ca12O33	Dx = 2.672 Mg m^−3
Mr = 1386.66	Synchrotron radiation, λ = 0.67954 Å
Cubic, I43d	Cell parameters from 24 reflections
Hall symbol: I -4bd 2c 3	θ = 34.7–36.1°
a = 11.989 (3) Å	µ = 1.99 mm^−1
V = 1723.2 (7) Å^3	T = 298 K
Z = 2	Sphere, orange
F(000) = 1372	0.07 × 0.07 × 0.07 × 0.03 (radius) mm

Data collection

Tsukuba BL14A four-circle diffractometer	Rint = 0.012
integrated intensities data from ω/2θ scans	θmax = 68.4°, θmin = 4.0°
Absorption correction: for a sphere Transmission coefficient for spheres tabulated in International Table II(1972) Table 5.3.6B was interpolated with Lagrangian method	h = −9→32
Tmin = 0.908, Tmax = 0.909	k = −9→24
10790 measured reflections	l = −31→31
3077 independent reflections	9 standard reflections every 200 reflections
3020 reflections with F > 3.0σ(F)	intensity decay: none

Refinement

Refinement on F	0 constraints
Least-squares matrix: full	w = 1/[σ^2(Fo) + (0.016P)^2] where P = (Fo^2 + 2Fc^2)/3
R[F^2 > 2σ(F^2)] = 0.016	(Δ/σ)max = 0.050
wR(F^2) = 0.024	Δρmax = 0.34 e Å^−3
S = 1.09	Δρmin = −0.39 e Å^−3
3020 reflections	Extinction correction: B-C type 2 isotropic
66 parameters	Extinction coefficient: 0.00006 (4)
0 restraints

Special details

Experimental. Multiple diffraction was avoided using ψ-scan.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq	Occ. (<1)
Ca1	0.139339 (15)	0	0.25	0.00869 (3)	0.75
Al1	0.268614 (9)	0.268614 (9)	0.268614 (9)	0.00633 (3)	0.875
Al2	0.25	0.125	0.5	0.00679 (3)
O1	0.15052 (4)	0.03605 (3)	0.44234 (3)	0.01155 (7)	0.916666
O2	0.18510 (4)	0.18510 (4)	0.18510 (4)	0.01011 (7)	0.875
O3	0.3559 (6)	0.0614 (7)	0.2506 (7)	0.0163 (8)*	0.041667
Ca1a	0.16936 (16)	0.00673 (17)	0.2504 (2)	0.00987 (16)*	0.041667
Ca1b	0.20692 (12)	0	0.25	0.0128 (2)	0.083334
Ca1c	0.13537 (17)	0.0043 (3)	0.2354 (2)	0.00930 (3)	0.041667
Al1a	0.3041 (2)	0.1984 (2)	0.2619 (2)	0.0096 (3)*	0.041667
O1a	0.1302 (3)	0.0603 (3)	0.4329 (3)	0.0039 (3)*	0.041667
O1b	0.1718 (6)	0.0312 (5)	0.4352 (5)	0.0079 (6)*	0.041667
O2a	0.1996 (6)	0.1750 (8)	0.1893 (7)	0.00663 (7)	0.041667

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Ca1	0.00936 (4)	0.00981 (4)	0.00691 (4)	0	0	0.00090 (4)
Al1	0.00633 (4)	0.00633 (4)	0.00633 (4)	−0.000145 (19)	−0.000145 (19)	−0.000145 (19)
Al2	0.00774 (5)	0.00488 (5)	0.00774 (5)	0	0	0
O1	0.01081 (8)	0.01258 (9)	0.01128 (7)	−0.00569 (8)	0.00251 (7)	−0.00328 (6)
O2	0.01011 (8)	0.01011 (8)	0.01011 (8)	−0.00174 (6)	−0.00174 (6)	−0.00174 (6)
Ca1b	0.0176 (4)	0.0113 (3)	0.0094 (2)	0	0	0.0000 (2)
Ca1c	0.00936 (4)	0.00981 (4)	0.00691 (4)	0	0	0.00090 (4)
Al2a	0.00774 (5)	0.00488 (5)	0.00774 (5)	0	0	0

Geometric parameters (Å, º)

Al1^i—O1^ii	1.7746 (4)	Ca1^xii—O1a^ii	2.311 (3)
Al1^i—O1^iii	1.7746 (4)	Ca1^i—O1^xiii	2.3500 (3)
Al1^i—O1^iv	1.7746 (4)	Ca1^i—O1^xiv	2.5143 (4)
Al1^i—O1a^ii	1.739 (4)	Ca1^i—O1^i	2.3500 (3)
Al1^i—O1b^iii	2.009 (7)	Ca1^i—O1^xv	2.5143 (4)
Al1^i—O2^i	1.7342 (4)	Ca1^i—O2^xvi	2.4148 (4)
Al1^i—O2a^i	1.688 (9)	Ca1^i—O2^i	2.4148 (4)
Al1^i—O3^i	2.704 (8)	Ca1^i—O2a^i	2.335 (9)
Al1a^i—O1^ii	1.673 (3)	Ca1^i—O3^i	2.699 (7)
Al1a^i—O1^iii	2.709 (3)	Ca1^xvii—O2^i	2.4148 (4)
Al1a^i—O1^iv	1.839 (3)	Ca1^xvii—O2a^i	2.387 (8)
Al1a^i—O1a^ii	1.431 (5)	Ca1^xi—O1^iii	2.5143 (4)
Al1a^i—O1b^iii	2.936 (7)	Ca1^xi—O1^iv	2.3500 (3)
Al1a^i—O2^i	1.705 (3)	Ca1^xi—O1b^iii	2.380 (6)
Al1a^i—O2a^i	1.551 (8)	Ca1^xv—O2^i	2.4148 (4)
Al1a^i—O3^i	1.762 (9)	Ca1^xv—O2a^i	2.626 (8)
Al2—O1^iv	1.7428 (4)	Ca1a^i—O1^xiii	2.378 (3)
Al2^ii—O1^ii	1.7428 (4)	Ca1a^i—O1^xiv	2.841 (2)
Al2^ii—O1^v	1.7428 (4)	Ca1a^i—O1^i	2.339 (3)
Al2^ii—O1^vi	1.7428 (4)	Ca1a^i—O1^xv	2.805 (2)
Al2^ii—O1^i	1.7428 (4)	Ca1a^i—O1a^ii	3.221 (4)
Al2^ii—O1a^ii	1.820 (4)	Ca1a^i—O2^xvi	2.434 (2)
Al2^iii—O1^iii	1.7428 (4)	Ca1a^i—O2^i	2.285 (2)
Al2^iii—O1b^iii	1.657 (6)	Ca1a^i—O2a^i	2.177 (9)
Ca1—O1	2.3500 (3)	Ca1a^i—O3^i	2.331 (8)
Ca1—O1^vii	2.3500 (3)	Ca1b—O1	2.4416 (5)
Ca1—O1^viii	2.5143 (4)	Ca1b—O1^vii	2.4416 (5)
Ca1—O1^ix	2.5143 (4)	Ca1b—O1^viii	3.2227 (14)
Ca1—O2	2.4148 (4)	Ca1b—O1^ix	3.2227 (14)
Ca1—O2^ii	2.4148 (4)	Ca1b—O2	2.3661 (5)
Ca1—O3^i	3.141 (7)	Ca1b—O2^ii	2.3661 (5)
Ca1^x—O1^ii	2.5143 (4)	Ca1b—O3^i	2.361 (8)
Ca1^x—O1^x	2.3500 (3)	Ca1c^x—O1^ii	2.381 (2)
Ca1^x—O1^vi	2.5143 (4)	Ca1c^x—O1^x	2.517 (3)
Ca1^x—O1^iii	2.3500 (3)	Ca1c^x—O1^vi	2.578 (2)
Ca1^x—O1a^ii	2.905 (4)	Ca1c^x—O1^iii	2.192 (3)
Ca1^x—O1b^iii	2.285 (6)	Ca1c^x—O1a^ii	2.768 (4)
Ca1^x—O2^iii	2.4148 (4)	Ca1c^x—O1b^iii	2.134 (7)
Ca1^x—O2^xi	2.4148 (4)	Ca1c^x—O2^iii	2.533 (3)
Ca1^xii—O1^ii	2.3500 (3)	Ca1c^x—O2^xi	2.328 (3)
Ca1^xii—O1^iv	2.5143 (4)
O1^ii—Al1^i—O1^iii	101.039 (19)	O1^i—Ca1a^i—O3^i	92.8 (2)
O1^ii—Al1^i—O1^iv	101.039 (19)	O1^xv—Ca1a^i—O1^xiii	63.18 (6)
O1^ii—Al1^i—O2^i	116.97 (2)	O1^xv—Ca1a^i—O1^xiv	58.45 (4)
O1^ii—Al1^i—O3^i	68.26 (18)	O1^xv—Ca1a^i—O2^xvi	114.17 (8)
O1^iii—Al1^i—O1^iv	101.039 (19)	O1^xv—Ca1a^i—O2a^i	78.5 (3)
O1^iii—Al1^i—O2^i	116.97 (2)	O1^xv—Ca1a^i—O3^i	141.4 (2)
O1^iii—Al1^i—O3^i	169.27 (18)	O1^xiii—Ca1a^i—O1^xiv	105.39 (8)
O1^iv—Al1^i—O2^i	116.97 (2)	O1^xiii—Ca1a^i—O2^xvi	96.45 (8)
O1^iv—Al1^i—O3^i	82.41 (18)	O1^xiii—Ca1a^i—O2a^i	83.6 (3)
O2^i—Al1^i—O3^i	69.34 (18)	O1^xiii—Ca1a^i—O3^i	98.8 (2)
O1^iv—Al1a^i—O3^i	114.7 (3)	O1^xiv—Ca1a^i—O2^xvi	71.19 (6)
O1^iv—Al1a^i—O1a^ii	107.0 (2)	O1^xiv—Ca1a^i—O2a^i	122.5 (3)
O1^iv—Al1a^i—O1b^iii	68.72 (16)	O1^xiv—Ca1a^i—O3^i	155.2 (2)
O1^iv—Al1a^i—O2a^i	117.5 (3)	O2^xvi—Ca1a^i—O2a^i	165.9 (3)
O3^i—Al1a^i—O1a^ii	88.2 (3)	O2^xvi—Ca1a^i—O3^i	101.0 (2)
O3^i—Al1a^i—O1b^iii	171.9 (3)	O2a^i—Ca1a^i—O3^i	65.2 (3)
O3^i—Al1a^i—O2a^i	94.2 (4)	O1—Ca1b—O1^vii	147.84 (7)
O1a^ii—Al1a^i—O1b^iii	83.7 (2)	O1—Ca1b—O1^viii	55.81 (2)
O1a^ii—Al1a^i—O2a^i	129.2 (4)	O1—Ca1b—O1^ix	93.51 (4)
O1b^iii—Al1a^i—O2a^i	90.3 (3)	O1—Ca1b—O2	96.54 (2)
O1^i—Al2^ii—O1^v	104.553 (17)	O1—Ca1b—O2^ii	79.913 (17)
O1^i—Al2^ii—O1^vi	111.985 (17)	O1—Ca1b—O3^i	88.24 (18)
O1^i—Al2^ii—O1a^ii	104.51 (12)	O1^vii—Ca1b—O1^viii	93.51 (4)
O1^v—Al2^ii—O1^vi	111.985 (17)	O1^vii—Ca1b—O1^ix	55.81 (2)
O1^v—Al2^ii—O1a^ii	105.73 (12)	O1^vii—Ca1b—O2	79.913 (17)
O1^vi—Al2^ii—O1a^ii	117.04 (12)	O1^vii—Ca1b—O2^ii	96.54 (2)
O1^ii—Al2^ii—O1^i	111.985 (17)	O1^vii—Ca1b—O3^i	123.85 (19)
O1^ii—Al2^ii—O1^v	111.985 (17)	O1^viii—Ca1b—O1^ix	50.65 (2)
O1^ii—Al2^ii—O1^vi	104.553 (17)	O1^viii—Ca1b—O2	102.88 (5)
O1^i—Al2^ii—O1^v	104.553 (17)	O1^viii—Ca1b—O2^ii	64.99 (3)
O1^i—Al2^ii—O1^vi	111.985 (17)	O1^viii—Ca1b—O3^i	137.97 (18)
O1^v—Al2^ii—O1^vi	111.985 (17)	O1^ix—Ca1b—O2	64.99 (3)
O1—Ca1—O1^vii	173.462 (14)	O1^ix—Ca1b—O2^ii	102.88 (5)
O1—Ca1—O1^viii	68.456 (11)	O1^ix—Ca1b—O3^i	167.14 (19)
O1—Ca1—O1^ix	117.555 (12)	O2—Ca1b—O2^ii	167.31 (7)
O1—Ca1—O2	97.711 (12)	O2—Ca1b—O3^i	102.16 (19)
O1—Ca1—O2^ii	80.788 (12)	O2^ii—Ca1b—O3^i	89.97 (18)
O1—Ca1—O3^i	73.44 (14)	O1^x—Ca1c^x—O1^vi	65.04 (6)
O1^vii—Ca1—O1^viii	117.555 (12)	O1^x—Ca1c^x—O2^iii	75.39 (8)
O1^vii—Ca1—O1^ix	68.456 (11)	O1^x—Ca1c^x—O2^xi	95.49 (11)
O1^vii—Ca1—O2	80.788 (12)	O1^x—Ca1c^x—O1a^ii	117.97 (12)
O1^vii—Ca1—O2^ii	97.711 (12)	O1^x—Ca1c^x—O1b^iii	163.8 (2)
O1^vii—Ca1—O3^i	100.03 (14)	O1^vi—Ca1c^x—O2^iii	74.33 (9)
O1^viii—Ca1—O1^ix	66.496 (12)	O1^vi—Ca1c^x—O2^xi	127.57 (12)
O1^viii—Ca1—O2	126.549 (14)	O1^vi—Ca1c^x—O1a^ii	69.18 (9)
O1^viii—Ca1—O2^ii	77.556 (13)	O1^vi—Ca1c^x—O1b^iii	127.9 (2)
O1^viii—Ca1—O3^i	134.52 (14)	O2^iii—Ca1c^x—O2^xi	150.66 (10)
O1^ix—Ca1—O2	77.556 (13)	O2^iii—Ca1c^x—O1a^ii	127.95 (14)
O1^ix—Ca1—O2^ii	126.549 (14)	O2^iii—Ca1c^x—O1b^iii	97.7 (2)
O1^ix—Ca1—O3^i	157.65 (14)	O2^xi—Ca1c^x—O1a^ii	81.11 (12)
O2—Ca1—O2^ii	153.735 (16)	O2^xi—Ca1c^x—O1b^iii	83.41 (19)
O2—Ca1—O3^i	81.77 (14)	O1a^ii—Ca1c^x—O1b^iii	78.0 (2)
O2^ii—Ca1—O3^i	72.62 (14)	Ca1^x—O1^ii—Ca1^xii	98.221 (13)
O1^ii—Ca1^x—O1^iii	68.456 (11)	Ca1^x—O1^ii—Al1^i	92.368 (14)
O1^ii—Ca1^x—O1^x	117.555 (12)	Ca1^x—O1^ii—Al2^ii	94.475 (16)
O1^ii—Ca1^x—O1^vi	66.496 (12)	Ca1^xii—O1^ii—Al1^i	98.052 (16)
O1^ii—Ca1^x—O2^iii	126.548 (14)	Ca1^xii—O1^ii—Al2^ii	122.736 (17)
O1^ii—Ca1^x—O2^xi	77.556 (13)	Al1^i—O1^ii—Al2^ii	136.984 (19)
O1^iii—Ca1^x—O1^x	173.462 (14)	Ca1^xi—O1^iii—Ca1^x	98.221 (13)
O1^iii—Ca1^x—O1^vi	117.555 (12)	Ca1^xi—O1^iii—Al1^i	92.368 (14)
O1^iii—Ca1^x—O2^iii	97.711 (12)	Ca1^xi—O1^iii—Al2^iii	94.475 (16)
O1^iii—Ca1^x—O2^xi	80.788 (12)	Ca1^x—O1^iii—Al1^i	98.052 (16)
O1^x—Ca1^x—O1^vi	68.456 (11)	Ca1^x—O1^iii—Al2^iii	122.736 (17)
O1^x—Ca1^x—O2^iii	80.788 (12)	Al1^i—O1^iii—Al2^iii	136.985 (19)
O1^x—Ca1^x—O2^xi	97.711 (12)	Ca1^xii—O1a^ii—Al2^ii	121.03 (18)
O1^vi—Ca1^x—O2^iii	77.556 (13)	Ca1^xii—O1a^ii—Ca1c^x	88.38 (13)
O1^vi—Ca1^x—O2^xi	126.549 (14)	Ca1^xii—O1a^ii—Al1a^i	97.4 (2)
O2^iii—Ca1^x—O2^xi	153.735 (16)	Al2^ii—O1a^ii—Ca1c^x	83.19 (15)
O1^i—Ca1^i—O1^xv	117.555 (12)	Al2^ii—O1a^ii—Al1a^i	139.9 (3)
O1^i—Ca1^i—O1^xiii	173.462 (14)	Ca1c^x—O1a^ii—Al1a^i	111.1 (2)
O1^i—Ca1^i—O1^xiv	68.456 (11)	Ca1^xi—O1b^iii—Al2^iii	101.9 (3)
O1^i—Ca1^i—O2^i	97.711 (12)	Ca1^xi—O1b^iii—Ca1c^x	102.8 (2)
O1^i—Ca1^i—O2^xvi	80.788 (12)	Ca1^xi—O1b^iii—Al1a^i	89.4 (2)
O1^i—Ca1^i—O3^i	83.81 (16)	Al2^iii—O1b^iii—Ca1c^x	134.5 (4)
O1^xv—Ca1^i—O1^xiii	68.456 (11)	Al2^iii—O1b^iii—Al1a^i	130.6 (3)
O1^xv—Ca1^i—O1^xiv	66.496 (12)	Ca1c^x—O1b^iii—Al1a^i	87.2 (2)
O1^xv—Ca1^i—O2^i	77.556 (13)	Ca1^i—O2^i—Ca1^xvii	99.237 (15)
O1^xv—Ca1^i—O2^xvi	126.548 (14)	Ca1^i—O2^i—Ca1^xv	99.237 (15)
O1^xv—Ca1^i—O3^i	136.96 (16)	Ca1^i—O2^i—Al1^i	118.41 (2)
O1^xiii—Ca1^i—O1^xiv	117.555 (12)	Ca1^xvii—O2^i—Ca1^xv	99.237 (15)
O1^xiii—Ca1^i—O2^i	80.788 (12)	Ca1^xvii—O2^i—Al1^i	118.41 (2)
O1^xiii—Ca1^i—O2^xvi	97.711 (12)	Ca1^xv—O2^i—Al1^i	118.41 (2)
O1^xiii—Ca1^i—O3^i	89.89 (16)	Ca1^xvii—O2a^i—Ca1^xv	94.3 (3)
O1^xiv—Ca1^i—O2^i	126.549 (14)	Ca1^xvii—O2a^i—Ca1a^i	101.3 (4)
O1^xiv—Ca1^i—O2^xvi	77.556 (13)	Ca1^xvii—O2a^i—Al1a^i	111.2 (4)
O1^xiv—Ca1^i—O3^i	151.43 (16)	Ca1^xv—O2a^i—Ca1a^i	104.0 (3)
O2^i—Ca1^i—O2^xvi	153.735 (16)	Ca1^xv—O2a^i—Al1a^i	143.3 (5)
O2^i—Ca1^i—O3^i	62.07 (16)	Ca1a^i—O2a^i—Al1a^i	96.5 (4)
O2^xvi—Ca1^i—O3^i	91.79 (16)	Ca1a^i—O3^i—Ca1b	145.5 (4)
O1^i—Ca1a^i—O1^xv	107.60 (8)	Ca1a^i—O3^i—Al1a^i	85.6 (3)
O1^i—Ca1a^i—O1^xiii	168.36 (10)	Ca1b—O3^i—Al1a^i	128.8 (4)
O1^i—Ca1a^i—O1^xiv	62.98 (6)	Ca1—O3^i—Ca1^i	150.6 (3)
O1^i—Ca1a^i—O2^xvi	80.61 (8)	Ca1—O3^i—Al1^i	126.3 (3)
O1^i—Ca1a^i—O2a^i	102.0 (3)	Ca1^i—O3^i—Al1^i	83.0 (2)

Symmetry codes: (i) −x+3/4, −z+1/4, y+1/4; (ii) z, −x, −y+1/2; (iii) y+1/2, z−1/2, x+1/2; (iv) −x+1/2, y, −z+1; (v) x+1/4, z−3/4, y+1/4; (vi) −z+1, x−1/2, −y+1/2; (vii) x, −y, −z+1/2; (viii) −y, z−1/2, −x+1/2; (ix) −y, −z+1/2, x; (x) −y+1/2, −z, x+1/2; (xi) −x+1/2, −y, z+1/2; (xii) −z+1/2, −x, y+1/2; (xiii) −x+3/4, z−1/4, −y+1/4; (xiv) y+3/4, x−1/4, z−1/4; (xv) y+3/4, −x+1/4, −z+3/4; (xvi) −z+3/4, y−1/4, −x+1/4; (xvii) z+1/4, y+1/4, x+1/4.