Formation and characterization of an Al-rich metastable phase in the Al–B phase diagram

Vacuum heat treatment of mechanically alloyed powders of boron and aluminium leads to the formation of a metastable Al-rich phase, which can be quenched. Its structure, composition and thermal stability are established. With the chemical formula Al_1.28B the rhombohedral phase is unusually rich in Al. The parameters of the unit cell determined from X-ray powder diffraction are a = 18.3464 (19), c = 8.9241 (9) Å, V = 2601.3 (6) ų, space group R3. It is stable on heating to 630°C. It is suggested that this phase is an important intermediate step in the formation of AlB₂ and, eventually, of other borides; its nucleation and thermal stability are explained by high elastic energy hindering the formation of equilibrium phases at low temperatures.

Computing details

Program(s) used to solve structure: simulated annealing (Zhukov et al., 2001); program(s) used to refine structure: MRIA; molecular graphics: PLATON (Spek, 2009); software used to prepare material for publication: MRIA, SHELXL97 (Sheldrick, 2008).

(I)

Crystal data

Al6.31B4.94	Dx = 2.570 Mg m^−3
Mr = 223.65	Cu Kα radiation, λ = 1.5418 Å
Hexagonal, R3	T = 295 K
a = 18.3464 (19) Å	Particle morphology: no specific habit
c = 8.9241 (9) Å	dark grey
V = 2601.3 (6) Å^3	flat_sheet, 15 × 1 mm
Z = 18	Specimen preparation: Prepared at 295 K and 101 kPa
F(000) = 1921

Data collection

Empyrean diffractometer	Data collection mode: reflection
Radiation source: line-focus sealed tube	Scan method: continuous
Specimen mounting: thin layer on the non-diffracting silicon plate	2θmin = 10.011°, 2θmax = 119.995°, 2θstep = 0.008°

Refinement

Refinement on Inet	Profile function: split-type pseudo-Voigt (Toraya, 1986)
Least-squares matrix: full with fixed elements per cycle	65 parameters
Rp = 0.033	0 restraints
Rwp = 0.043	13 constraints
Rexp = 0.026	Weighting scheme based on measured s.u.'s
RBragg = 0.087	(Δ/σ)max = 0.003
13749 data points	Background function: Chebyshev polynomial up to the 5th order
Excluded region(s): none	Preferred orientation correction: none

Special details

Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes.

Refinement. Two-phase Rietveld refinement with cubic Al structure as a second phase.

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

	x	y	z	Uiso*/Ueq	Occ. (<1)
Al1	0.2721 (2)	0.1289 (2)	0.0570 (4)	0.033 (2)*
Al2	0.1186 (2)	0.0576 (3)	0.4165 (5)	0.033 (2)*	0.69 (2)
B2	0.1186 (2)	0.0576 (3)	0.4165 (5)	0.033 (2)*	0.31 (2)
Al3	0.33680 (19)	0.0557 (2)	0.3946 (5)	0.033 (2)*
Al4	0.1952 (2)	−0.00441 (18)	0.2497 (4)	0.033 (2)*
Al5	0.7832 (2)	−0.00018 (19)	0.2437 (4)	0.033 (2)*
Al6	0.1349 (2)	0.2697 (2)	0.4439 (4)	0.033 (2)*
Al7	0.0705 (3)	0.1168 (3)	0.0902 (6)	0.033 (2)*	0.62 (2)
B7	0.0705 (3)	0.1168 (3)	0.0902 (6)	0.033 (2)*	0.38 (2)
B8	0.3293 (7)	0.0721 (7)	0.163 (2)	0.033 (2)*
B9	0.2021 (8)	0.7981 (7)	0.4931 (15)	0.033 (2)*
B10	0.2043 (8)	−0.0027 (7)	0.4817 (19)	0.033 (2)*
B11	−0.0833 (8)	0.0641 (8)	0.1476 (13)	0.033 (2)*
B12	0.0000	0.0000	0.355 (4)	0.0357 (2)*	0.76 (3)

Geometric parameters (Å, º)

Al1—B8	2.044 (17)	Al6—B9^xviii	2.178 (17)
Al1—B9^i	2.067 (14)	Al6—B10^vii	2.284 (13)
Al1—B11^ii	2.162 (17)	Al6—B9^xix	2.415 (14)
Al1—B8^iii	2.332 (13)	Al6—Al4^xvii	2.704 (5)
Al1—Al3^iii	2.606 (5)	Al6—Al2^vii	2.705 (5)
Al1—Al4	2.734 (5)	Al6—Al3^vii	2.736 (6)
Al1—Al1^iii	2.772 (7)	Al6—Al5^v	2.799 (5)
Al1—Al7^iv	2.797 (6)	Al6—Al6^x	2.825 (7)
Al1—Al5^v	2.838 (5)	Al7—B11^ii	1.871 (15)
Al2—B12	1.964 (10)	Al7—B11^iv	2.213 (13)
Al2—B2^vi	2.403 (7)	Al7—B9^xix	2.445 (17)
Al2—Al2^vi	2.403 (7)	Al7—B7^iv	2.467 (8)
Al2—B2^vii	2.403 (7)	Al7—Al7^iv	2.467 (8)
Al2—Al2^vii	2.403 (7)	Al7—B7^xx	2.467 (8)
Al2—B10	2.402 (18)	Al7—Al7^xx	2.467 (8)
Al2—B11^ii	2.452 (13)	Al7—B11	2.535 (15)
Al2—B10^vii	2.517 (15)	Al7—Al5^v	2.741 (6)
Al2—Al4	2.661 (7)	Al7—Al4^xvii	2.765 (7)
Al2—Al6^vi	2.705 (5)	Al7—Al1^xx	2.797 (6)
Al2—Al5^v	2.982 (6)	B8—Al5^xxi	2.050 (14)
Al3—B8	2.100 (18)	B8—Al3^xi	2.184 (14)
Al3—B8^viii	2.184 (14)	B8—Al1^iii	2.332 (13)
Al3—B10	2.249 (14)	B9—Al1^xxii	2.067 (14)
Al3—B9^ix	2.534 (13)	B9—Al4^x	2.130 (12)
Al3—Al4	2.603 (5)	B9—Al6^xxiii	2.178 (17)
Al3—Al1^iii	2.606 (5)	B9—Al5^xxiv	2.205 (12)
Al3—Al4^viii	2.685 (6)	B9—Al6^xxv	2.415 (14)
Al3—Al6^vi	2.736 (6)	B9—Al7^xxv	2.445 (17)
Al4—B10	2.076 (17)	B9—Al3^xxvi	2.534 (13)
Al4—B9^x	2.130 (12)	B10—Al6^ii	2.128 (12)
Al4—B8	2.272 (12)	B10—Al6^vi	2.284 (13)
Al4—B11^ii	2.366 (12)	B10—Al5^xv	2.459 (17)
Al4—Al3^xi	2.685 (5)	B10—Al2^vi	2.517 (15)
Al4—Al6^ii	2.704 (5)	B11—B7^xvii	1.871 (15)
Al4—Al7^ii	2.765 (7)	B11—Al7^xvii	1.871 (15)
Al5—B8^xii	2.050 (14)	B11—Al1^xvii	2.162 (17)
Al5—B9^xiii	2.205 (12)	B11—Al7^xx	2.213 (13)
Al5—B11^xiv	2.289 (13)	B11—Al5^xxvii	2.289 (13)
Al5—B10^xv	2.459 (17)	B11—Al4^xvii	2.366 (12)
Al5—Al7^xvi	2.741 (6)	B11—Al2^xvii	2.452 (13)
Al5—Al6^xvi	2.799 (5)	B12—B2^xvii	1.964 (10)
Al5—Al1^xvi	2.838 (5)	B12—Al2^xvii	1.964 (10)
Al5—Al2^xvi	2.982 (6)	B12—B2^ii	1.964 (10)
Al6—B10^xvii	2.128 (12)	B12—Al2^ii	1.964 (10)
B8—Al1—B9^i	122.8 (6)	B10^xv—Al5—Al2^xvi	54.1 (3)
B8—Al1—B11^ii	110.0 (5)	Al7^xvi—Al5—Al2^xvi	72.17 (17)
B9^i—Al1—B11^ii	107.3 (6)	Al6^xvi—Al5—Al2^xvi	81.05 (17)
B8—Al1—B8^iii	101.7 (5)	Al1^xvi—Al5—Al2^xvi	87.63 (15)
B9^i—Al1—B8^iii	114.4 (6)	B10^xvii—Al6—B9^xviii	115.2 (6)
B11^ii—Al1—B8^iii	97.7 (5)	B10^xvii—Al6—B10^vii	118.2 (8)
B8—Al1—Al3^iii	132.7 (3)	B9^xviii—Al6—B10^vii	112.8 (5)
B9^i—Al1—Al3^iii	64.5 (4)	B10^xvii—Al6—B9^xix	97.9 (5)
B11^ii—Al1—Al3^iii	110.8 (3)	B9^xviii—Al6—B9^xix	104.3 (5)
B8^iii—Al1—Al3^iii	50.0 (4)	B10^vii—Al6—B9^xix	105.6 (5)
B8—Al1—Al4	54.5 (3)	B10^xvii—Al6—Al4^xvii	49.1 (5)
B9^i—Al1—Al4	129.3 (4)	B9^xviii—Al6—Al4^xvii	122.1 (4)
B11^ii—Al1—Al4	56.3 (3)	B10^vii—Al6—Al4^xvii	123.0 (4)
B8^iii—Al1—Al4	115.2 (4)	B9^xix—Al6—Al4^xvii	48.8 (3)
Al3^iii—Al1—Al4	161.6 (2)	B10^xvii—Al6—Al2^vii	61.4 (5)
B8—Al1—Al1^iii	55.5 (4)	B9^xviii—Al6—Al2^vii	140.9 (4)
B9^i—Al1—Al1^iii	138.4 (5)	B10^vii—Al6—Al2^vii	56.8 (4)
B11^ii—Al1—Al1^iii	111.5 (4)	B9^xix—Al6—Al2^vii	114.8 (4)
B8^iii—Al1—Al1^iii	46.2 (4)	Al4^xvii—Al6—Al2^vii	86.39 (16)
Al3^iii—Al1—Al1^iii	87.64 (16)	B10^xvii—Al6—Al3^vii	139.1 (5)
Al4—Al1—Al1^iii	85.99 (18)	B9^xviii—Al6—Al3^vii	60.8 (3)
B8—Al1—Al7^iv	125.8 (3)	B10^vii—Al6—Al3^vii	52.3 (4)
B9^i—Al1—Al7^iv	58.1 (5)	B9^xix—Al6—Al3^vii	123.0 (3)
B11^ii—Al1—Al7^iv	51.1 (4)	Al4^xvii—Al6—Al3^vii	170.9 (2)
B8^iii—Al1—Al7^iv	128.4 (4)	Al2^vii—Al6—Al3^vii	95.43 (19)
Al3^iii—Al1—Al7^iv	98.5 (2)	B10^xvii—Al6—Al5^v	125.2 (5)
Al4—Al1—Al7^iv	83.14 (16)	B9^xviii—Al6—Al5^v	115.1 (3)
Al1^iii—Al1—Al7^iv	162.5 (3)	B10^vii—Al6—Al5^v	56.8 (4)
B8—Al1—Al5^v	116.0 (5)	B9^xix—Al6—Al5^v	49.3 (3)
B9^i—Al1—Al5^v	121.0 (4)	Al4^xvii—Al6—Al5^v	85.78 (16)
B11^ii—Al1—Al5^v	52.4 (3)	Al2^vii—Al6—Al5^v	91.12 (17)
B8^iii—Al1—Al5^v	45.4 (4)	Al3^vii—Al6—Al5^v	85.28 (17)
Al3^iii—Al1—Al5^v	73.52 (16)	B10^xvii—Al6—Al6^x	116.4 (5)
Al4—Al1—Al5^v	88.16 (16)	B9^xviii—Al6—Al6^x	55.9 (4)
Al1^iii—Al1—Al5^v	74.49 (19)	B10^vii—Al6—Al6^x	122.0 (5)
Al7^iv—Al1—Al5^v	91.49 (18)	B9^xix—Al6—Al6^x	48.3 (4)
B12—Al2—B2^vi	78.3 (7)	Al4^xvii—Al6—Al6^x	81.18 (19)
B12—Al2—Al2^vi	78.3 (7)	Al2^vii—Al6—Al6^x	163.1 (2)
B2^vi—Al2—Al2^vi	0.0 (5)	Al3^vii—Al6—Al6^x	95.14 (15)
B12—Al2—B2^vii	78.3 (7)	Al5^v—Al6—Al6^x	76.68 (18)
B2^vi—Al2—B2^vii	85.6 (3)	B11^ii—Al7—B11^iv	119.3 (5)
Al2^vi—Al2—B2^vii	85.6 (3)	B11^ii—Al7—B9^xix	105.6 (5)
B12—Al2—Al2^vii	78.3 (7)	B11^iv—Al7—B9^xix	93.9 (6)
B2^vi—Al2—Al2^vii	85.6 (3)	B11^ii—Al7—B7^iv	59.5 (4)
Al2^vi—Al2—Al2^vii	85.6 (3)	B11^iv—Al7—B7^iv	65.3 (4)
B2^vii—Al2—Al2^vii	0.0 (3)	B9^xix—Al7—B7^iv	133.1 (4)
B12—Al2—B10	128.6 (3)	B11^ii—Al7—Al7^iv	59.5 (4)
B2^vi—Al2—B10	63.2 (4)	B11^iv—Al7—Al7^iv	65.3 (4)
Al2^vi—Al2—B10	63.2 (4)	B9^xix—Al7—Al7^iv	133.1 (4)
B2^vii—Al2—B10	127.3 (5)	B7^iv—Al7—Al7^iv	0.0 (3)
Al2^vii—Al2—B10	127.3 (5)	B11^ii—Al7—B7^xx	137.2 (5)
B12—Al2—B11^ii	84.4 (10)	B11^iv—Al7—B7^xx	46.7 (4)
B2^vi—Al2—B11^ii	137.7 (4)	B9^xix—Al7—B7^xx	114.8 (4)
Al2^vi—Al2—B11^ii	137.7 (4)	B7^iv—Al7—B7^xx	82.0 (3)
B2^vii—Al2—B11^ii	128.3 (4)	Al7^iv—Al7—B7^xx	82.0 (3)
Al2^vii—Al2—B11^ii	128.3 (4)	B11^ii—Al7—Al7^xx	137.2 (5)
B10—Al2—B11^ii	101.4 (5)	B11^iv—Al7—Al7^xx	46.7 (4)
B12—Al2—B10^vii	128.7 (5)	B9^xix—Al7—Al7^xx	114.8 (4)
B2^vi—Al2—B10^vii	120.3 (5)	B7^iv—Al7—Al7^xx	82.0 (3)
Al2^vi—Al2—B10^vii	120.3 (5)	Al7^iv—Al7—Al7^xx	82.0 (3)
B2^vii—Al2—B10^vii	58.4 (4)	B7^xx—Al7—Al7^xx	0.0 (3)
Al2^vii—Al2—B10^vii	58.4 (4)	B11^ii—Al7—B11	134.2 (8)
B10—Al2—B10^vii	100.7 (3)	B11^iv—Al7—B11	95.8 (4)
B11^ii—Al2—B10^vii	100.7 (5)	B9^xix—Al7—B11	99.7 (5)
B12—Al2—Al4	107.0 (7)	B7^iv—Al7—B11	122.8 (3)
B2^vi—Al2—Al4	93.81 (19)	Al7^iv—Al7—B11	122.8 (3)
Al2^vi—Al2—Al4	93.81 (19)	B7^xx—Al7—B11	52.5 (3)
B2^vii—Al2—Al4	174.4 (2)	Al7^xx—Al7—B11	52.5 (3)
Al2^vii—Al2—Al4	174.4 (2)	B11^ii—Al7—Al5^v	55.7 (4)
B10—Al2—Al4	48.1 (4)	B11^iv—Al7—Al5^v	117.9 (4)
B11^ii—Al2—Al4	54.9 (3)	B9^xix—Al7—Al5^v	49.9 (3)
B10^vii—Al2—Al4	117.6 (4)	B7^iv—Al7—Al5^v	101.5 (3)
B12—Al2—Al6^vi	168.8 (9)	Al7^iv—Al7—Al5^v	101.5 (3)
B2^vi—Al2—Al6^vi	94.6 (3)	B7^xx—Al7—Al5^v	161.3 (3)
Al2^vi—Al2—Al6^vi	94.6 (3)	Al7^xx—Al7—Al5^v	161.3 (3)
B2^vii—Al2—Al6^vi	92.5 (3)	B11—Al7—Al5^v	133.1 (4)
Al2^vii—Al2—Al6^vi	92.5 (3)	B11^ii—Al7—Al4^xvii	130.5 (4)
B10—Al2—Al6^vi	52.7 (3)	B11^iv—Al7—Al4^xvii	105.1 (4)
B11^ii—Al2—Al6^vi	106.5 (4)	B9^xix—Al7—Al4^xvii	47.8 (3)
B10^vii—Al2—Al6^vi	47.9 (3)	B7^iv—Al7—Al4^xvii	169.9 (3)
Al4—Al2—Al6^vi	81.94 (17)	Al7^iv—Al7—Al4^xvii	169.9 (3)
B12—Al2—Al5^v	110.2 (7)	B7^xx—Al7—Al4^xvii	88.92 (19)
B2^vi—Al2—Al5^v	171.0 (3)	Al7^xx—Al7—Al4^xvii	88.92 (19)
Al2^vi—Al2—Al5^v	171.0 (3)	B11—Al7—Al4^xvii	52.8 (3)
B2^vii—Al2—Al5^v	93.1 (2)	Al5^v—Al7—Al4^xvii	85.74 (17)
Al2^vii—Al2—Al5^v	93.1 (2)	B11^ii—Al7—Al1^xx	114.2 (5)
B10—Al2—Al5^v	111.3 (3)	B11^iv—Al7—Al1^xx	49.5 (5)
B11^ii—Al2—Al5^v	48.6 (3)	B9^xix—Al7—Al1^xx	45.8 (3)
B10^vii—Al2—Al5^v	52.3 (4)	B7^iv—Al7—Al1^xx	96.5 (3)
Al4—Al2—Al5^v	86.60 (15)	Al7^iv—Al7—Al1^xx	96.5 (3)
Al6^vi—Al2—Al5^v	76.53 (15)	B7^xx—Al7—Al1^xx	86.2 (3)
B8—Al3—B8^viii	124.8 (6)	Al7^xx—Al7—Al1^xx	86.2 (3)
B8—Al3—B10	106.0 (6)	B11—Al7—Al1^xx	110.9 (4)
B8^viii—Al3—B10	113.5 (6)	Al5^v—Al7—Al1^xx	75.17 (15)
B8—Al3—B9^ix	105.6 (5)	Al4^xvii—Al7—Al1^xx	78.40 (19)
B8^viii—Al3—B9^ix	102.5 (5)	Al1—B8—Al5^xxi	112.1 (7)
B10—Al3—B9^ix	101.8 (5)	Al1—B8—Al3	128.1 (8)
B8—Al3—Al4	56.6 (3)	Al5^xxi—B8—Al3	103.7 (7)
B8^viii—Al3—Al4	136.1 (4)	Al1—B8—Al3^xi	105.9 (7)
B10—Al3—Al4	50.0 (4)	Al5^xxi—B8—Al3^xi	95.7 (7)
B9^ix—Al3—Al4	119.9 (4)	Al3—B8—Al3^xi	106.6 (6)
B8—Al3—Al1^iii	58.2 (4)	Al1—B8—Al4	78.4 (5)
B8^viii—Al3—Al1^iii	127.3 (4)	Al5^xxi—B8—Al4	167.4 (8)
B10—Al3—Al1^iii	114.6 (4)	Al3—B8—Al4	73.0 (5)
B9^ix—Al3—Al1^iii	47.4 (3)	Al3^xi—B8—Al4	74.1 (3)
Al4—Al3—Al1^iii	92.26 (18)	Al1—B8—Al1^iii	78.3 (5)
B8—Al3—Al4^viii	129.7 (3)	Al5^xxi—B8—Al1^iii	80.5 (3)
B8^viii—Al3—Al4^viii	54.4 (4)	Al3—B8—Al1^iii	71.8 (5)
B10—Al3—Al4^viii	119.8 (5)	Al3^xi—B8—Al1^iii	175.2 (8)
B9^ix—Al3—Al4^viii	48.1 (3)	Al4—B8—Al1^iii	109.3 (7)
Al4—Al3—Al4^viii	165.6 (2)	Al1^xxii—B9—Al4^x	113.8 (6)
Al1^iii—Al3—Al4^viii	83.24 (13)	Al1^xxii—B9—Al6^xxiii	97.5 (6)
B8—Al3—Al6^vi	111.2 (5)	Al4^x—B9—Al6^xxiii	113.3 (6)
B8^viii—Al3—Al6^vi	123.0 (5)	Al1^xxii—B9—Al5^xxiv	104.5 (5)
B10—Al3—Al6^vi	53.5 (4)	Al4^x—B9—Al5^xxiv	119.6 (7)
B9^ix—Al3—Al6^vi	48.6 (4)	Al6^xxiii—B9—Al5^xxiv	105.5 (5)
Al4—Al3—Al6^vi	82.41 (16)	Al1^xxii—B9—Al6^xxv	172.3 (8)
Al1^iii—Al3—Al6^vi	73.34 (17)	Al4^x—B9—Al6^xxv	72.7 (4)
Al4^viii—Al3—Al6^vi	83.18 (15)	Al6^xxiii—B9—Al6^xxv	75.7 (5)
B10—Al4—B9^x	109.3 (5)	Al5^xxiv—B9—Al6^xxv	74.4 (4)
B10—Al4—B8	105.9 (6)	Al1^xxii—B9—Al7^xxv	76.1 (5)
B9^x—Al4—B8	113.7 (6)	Al4^x—B9—Al7^xxv	74.0 (5)
B10—Al4—B11^ii	115.4 (6)	Al6^xxiii—B9—Al7^xxv	172.0 (6)
B9^x—Al4—B11^ii	115.6 (6)	Al5^xxiv—B9—Al7^xxv	72.0 (5)
B8—Al4—B11^ii	96.0 (6)	Al6^xxv—B9—Al7^xxv	110.3 (6)
B10—Al4—Al3	56.1 (4)	Al1^xxii—B9—Al3^xxvi	68.1 (4)
B9^x—Al4—Al3	120.6 (5)	Al4^x—B9—Al3^xxvi	69.7 (3)
B8—Al4—Al3	50.5 (4)	Al6^xxiii—B9—Al3^xxvi	70.5 (4)
B11^ii—Al4—Al3	122.3 (4)	Al5^xxiv—B9—Al3^xxvi	170.5 (7)
B10—Al4—Al2	59.4 (5)	Al6^xxv—B9—Al3^xxvi	112.0 (5)
B9^x—Al4—Al2	121.8 (4)	Al7^xxv—B9—Al3^xxvi	110.6 (5)
B8—Al4—Al2	124.4 (4)	Al4—B10—Al6^ii	80.0 (5)
B11^ii—Al4—Al2	58.0 (3)	Al4—B10—Al3	73.9 (5)
Al3—Al4—Al2	99.75 (18)	Al6^ii—B10—Al3	112.2 (8)
B10—Al4—Al3^xi	125.1 (5)	Al4—B10—Al6^vi	107.5 (6)
B9^x—Al4—Al3^xi	62.3 (4)	Al6^ii—B10—Al6^vi	171.6 (8)
B8—Al4—Al3^xi	51.5 (4)	Al3—B10—Al6^vi	74.2 (3)
B11^ii—Al4—Al3^xi	116.2 (3)	Al4—B10—Al2	72.5 (5)
Al3—Al4—Al3^xi	81.00 (16)	Al6^ii—B10—Al2	109.2 (6)
Al2—Al4—Al3^xi	173.7 (2)	Al3—B10—Al2	119.8 (6)
B10—Al4—Al6^ii	50.8 (3)	Al6^vi—B10—Al2	70.4 (5)
B9^x—Al4—Al6^ii	58.5 (4)	Al4—B10—Al5^xv	179.4 (7)
B8—Al4—Al6^ii	127.0 (5)	Al6^ii—B10—Al5^xv	100.3 (6)
B11^ii—Al4—Al6^ii	136.2 (4)	Al3—B10—Al5^xv	105.5 (6)
Al3—Al4—Al6^ii	86.39 (17)	Al6^vi—B10—Al5^xv	72.2 (5)
Al2—Al4—Al6^ii	87.11 (17)	Al2—B10—Al5^xv	107.9 (7)
Al3^xi—Al4—Al6^ii	99.23 (17)	Al4—B10—Al2^vi	107.0 (6)
B10—Al4—Al1	127.7 (3)	Al6^ii—B10—Al2^vi	70.7 (4)
B9^x—Al4—Al1	122.3 (4)	Al3—B10—Al2^vi	177.2 (7)
B8—Al4—Al1	47.1 (4)	Al6^vi—B10—Al2^vi	103.0 (7)
B11^ii—Al4—Al1	49.5 (4)	Al2—B10—Al2^vi	58.4 (4)
Al3—Al4—Al1	88.52 (14)	Al5^xv—B10—Al2^vi	73.6 (5)
Al2—Al4—Al1	96.67 (18)	B7^xvii—B11—Al7^xvii	0.0 (4)
Al3^xi—Al4—Al1	77.03 (16)	B7^xvii—B11—Al1^xvii	126.6 (6)
Al6^ii—Al4—Al1	174.1 (2)	Al7^xvii—B11—Al1^xvii	126.6 (6)
B10—Al4—Al7^ii	125.0 (4)	B7^xvii—B11—Al7^xx	73.8 (5)
B9^x—Al4—Al7^ii	58.2 (4)	Al7^xvii—B11—Al7^xx	73.8 (5)
B8—Al4—Al7^ii	128.6 (5)	Al1^xvii—B11—Al7^xx	79.5 (5)
B11^ii—Al4—Al7^ii	58.6 (4)	B7^xvii—B11—Al5^xxvii	81.8 (4)
Al3—Al4—Al7^ii	178.4 (2)	Al7^xvii—B11—Al5^xxvii	81.8 (4)
Al2—Al4—Al7^ii	81.86 (17)	Al1^xvii—B11—Al5^xxvii	79.2 (6)
Al3^xi—Al4—Al7^ii	97.40 (18)	Al7^xx—B11—Al5^xxvii	127.4 (6)
Al6^ii—Al4—Al7^ii	93.67 (16)	B7^xvii—B11—Al4^xvii	157.8 (9)
Al1—Al4—Al7^ii	91.34 (17)	Al7^xvii—B11—Al4^xvii	157.8 (9)
B8^xii—Al5—B9^xiii	126.1 (6)	Al1^xvii—B11—Al4^xvii	74.1 (5)
B8^xii—Al5—B11^xiv	102.5 (6)	Al7^xx—B11—Al4^xvii	106.5 (5)
B9^xiii—Al5—B11^xiv	100.5 (6)	Al5^xxvii—B11—Al4^xvii	112.8 (6)
B8^xii—Al5—B10^xv	111.7 (6)	B7^xvii—B11—Al2^xvii	101.9 (6)
B9^xiii—Al5—B10^xv	106.7 (5)	Al7^xvii—B11—Al2^xvii	101.9 (6)
B11^xiv—Al5—B10^xv	107.3 (4)	Al1^xvii—B11—Al2^xvii	121.7 (7)
B8^xii—Al5—Al7^xvi	127.4 (5)	Al7^xx—B11—Al2^xvii	151.9 (8)
B9^xiii—Al5—Al7^xvi	58.0 (4)	Al5^xxvii—B11—Al2^xvii	77.9 (4)
B11^xiv—Al5—Al7^xvi	42.5 (4)	Al4^xvii—B11—Al2^xvii	67.0 (3)
B10^xv—Al5—Al7^xvi	115.8 (4)	B7^xvii—B11—Al7	93.3 (7)
B8^xii—Al5—Al6^xvi	136.6 (4)	Al7^xvii—B11—Al7	93.3 (7)
B9^xiii—Al5—Al6^xvi	56.2 (4)	Al1^xvii—B11—Al7	113.5 (5)
B11^xiv—Al5—Al6^xvi	120.2 (4)	Al7^xx—B11—Al7	62.2 (4)
B10^xv—Al5—Al6^xvi	51.0 (3)	Al5^xxvii—B11—Al7	166.5 (7)
Al7^xvi—Al5—Al6^xvi	92.11 (19)	Al4^xvii—B11—Al7	68.6 (3)
B8^xii—Al5—Al1^xvi	54.1 (4)	Al2^xvii—B11—Al7	90.9 (5)
B9^xiii—Al5—Al1^xvi	125.1 (4)	Al2—B12—B2^xvii	112.4 (8)
B11^xiv—Al5—Al1^xvi	48.4 (4)	Al2—B12—Al2^xvii	112.4 (8)
B10^xv—Al5—Al1^xvi	124.1 (3)	B2^xvii—B12—Al2^xvii	0.0 (3)
Al7^xvi—Al5—Al1^xvi	80.49 (17)	Al2—B12—B2^ii	112.4 (8)
Al6^xvi—Al5—Al1^xvi	167.97 (19)	B2^xvii—B12—B2^ii	112.4 (8)
B8^xii—Al5—Al2^xvi	123.9 (5)	Al2^xvii—B12—B2^ii	112.4 (8)
B9^xiii—Al5—Al2^xvi	109.0 (4)	Al2—B12—Al2^ii	112.4 (8)
B11^xiv—Al5—Al2^xvi	53.5 (3)	B2^xvii—B12—Al2^ii	112.4 (8)

Symmetry codes: (i) −x+y−1/3, −x+1/3, z−2/3; (ii) −x+y, −x, z; (iii) −x+2/3, −y+1/3, −z+1/3; (iv) y, −x+y, −z; (v) −x+y+1, −x+1, z; (vi) y, −x+y, −z+1; (vii) x−y, x, −z+1; (viii) −x+y+2/3, −x+1/3, z+1/3; (ix) x−y+1, x, −z+1; (x) −x+1/3, −y+2/3, −z+2/3; (xi) −y+1/3, x−y−1/3, z−1/3; (xii) y+2/3, −x+y+1/3, −z+1/3; (xiii) x−y+4/3, x−1/3, −z+2/3; (xiv) x+1, y, z; (xv) −x+1, −y, −z+1; (xvi) −y+1, x−y, z; (xvii) −y, x−y, z; (xviii) −y+1, x−y+1, z; (xix) y−2/3, −x+y−1/3, −z+2/3; (xx) x−y, x, −z; (xxi) x−y−1/3, x−2/3, −z+1/3; (xxii) −y+1/3, x−y+2/3, z+2/3; (xxiii) −x+y, −x+1, z; (xxiv) y+1/3, −x+y+5/3, −z+2/3; (xxv) x−y+1/3, x+2/3, −z+2/3; (xxvi) y, −x+y+1, −z+1; (xxvii) x−1, y, z.