research communications
High-pressure synthesis and 4As4
of SrGaaLudwig-Maximilians-Universität München, Butenandtstrasse 5-13, D-81377 München, Germany
*Correspondence e-mail: johrendt@lmu.de
Strontium tetragallate(II,III) tetraarsenide, SrGa4As4, was synthesized in a Walker-type multianvil apparatus under high-pressure/high-temperature conditions of 8 GPa and 1573 K. The compound crystallizes in a new structure type (P3221, Z = 3) as a three-dimensional (3D) framework of corner-sharing SrAs8 quadratic antiprisms with strontium situated on a twofold rotation axis (Wyckoff position 3b). This arrangement is surrounded by a 3D framework which can be described as alternately stacked layers of either condensed GaIIIAs4 tetrahedra or honeycomb-like layers built up from distorted ethane-like GaII2As6 units comprising Ga—Ga bonds.
Keywords: crystal structure; strontium; gallium; arsenic; high-pressure synthesis.
1. Chemical context
The ternary systems A–Tr–As (A = Ca, Sr or Ba; Tr = Ga or In) contain numerous compounds with different crystal structures based on TrAs4 tetrahedra which occur isolated (Kauzlarich & Kuromoto, 1991), as dimers, as chains (Stoyko et al., 2015; He et al., 2012), condensed to ethane-like Tr2As6 groups (Mathieu et al., 2008; Goforth et al., 2009; He et al., 2011) or as large supertetrahedral units (Weippert et al., 2019). SrGa4As4 is the first high-pressure compound in this system and contains an unprecedented layer-like framework, thus expanding the structural variety of the A–Tr–As family.
2. Structural commentary
SrGa4As4 crystallizes in the P3221 (No. 154) and constitutes a new structure type. Strontium is coordinated in a quadratic antiprismatic manner by eight As atoms (Fig. 1). The antiprisms are slightly distorted, with their quadratic planes twisted by ∼34° relative to each other instead of 45° for an ideal quadratic antiprism. Sr—As distances range from 3.2665 (4) to 3.4560 (4) Å. The SrAs8 polyhedra are connected through common corners, each As atom shared by two quadratic antiprisms, building up a three-dimensional (3D) framework. A similar structural motif is known for RbAg2SbS4, which crystallizes in the P3121 (Schimek et al., 1996). The surrounding construct in the two crystal structures differs however. SrGa4As4 contains a 3D Ga/As framework that can be subdivided into two types of layers with an AB stacking sequence along the c axis. The first type is built up from corner- and edge-sharing GaAs4 tetrahedra forming sheets with triangular voids (Fig. 2). The tetrahedra are distorted, with angles in the range of 100.790 (19)–127.996 (19)°, and have typical Ga—As distances of 2.4384 (5)–2.5470 (5) Å. The second layer type consists of distorted ethane-like Ga2As6 groups with nearly eclipsed conformations. The Ga2As6 groups are connected via common corners, forming a honeycomb-like sheet (Fig. 3). The Ga1A and Ga1B positions of the Ga–Ga dumbbell are disordered and were treated with split positions having an occupancy of 50% each (Fig. 4). The coordination of each of these Ga sites consists of three As atoms and one Ga atom forming trigonal pyramids, showing torsion angles of 114.5 (1)° for As1vi—Ga1A—Ga1Ai—As1iv and 119.3 (1)° for As2v—Ga1B—Ga1Bi—As2vii (for symmetry codes, see Fig. 4). The Ga—Ga distances range between 2.542 (8) and 2.572 (8) Å and are considered as Ga—Ga bonds, which is consistent with a charge-neutral compound. Ga—As distances between 2.477 (4) and 2.694 (2) Å for Ga1A are near to the covalent radii sum of 2.46 Å (Pauling, 1960). In comparison, the trigonal pyramid around Ga1B is elongated, with Ga—As distances of 2.415 (4)–2.845 (2) Å.
3. Synthesis and crystallization
The starting material SrAs was synthesized by heating stoichiometric amounts of Sr (Sigma–Aldrich, 99.95%) and As (Alfa Aesar, 99.99999+%) in alumina crucibles, sealed in silica ampules under an atmosphere of purified argon for 20 h at 1223 K. The title compound was obtained via high-pressure synthesis using a modified Walker-type multianvil set-up driven by a 1000 t hydraulic press (Voggenreiter, Mainleus, Germany). A Cr2O3-substituted (6%) MgO octahedron (Ceramic Substrates & Components, Isle of Wight, UK) with an edge length of 18 mm, housing a ZrO2 sleeve with graphite sleeves (Schunk, Heuchelheim, Germany) for heating and a h-BN crucible (Henze, Kempten, Germany), was compressed with tungsten carbide cubes (Hawedia, Marklkofen, Germany) with an edge length of 11 mm. The starting materials SrAs (73.4 mg, 0.452 mmol), Ga (66.5 mg, 0.953 mmol, Alfa Aesar, 99.999%) and As (60.1 mg, 0.802 mmol) were mixed in a glove-box (H2O, O2 <1 ppm) and filled into the octahedron assembly. The reaction was carried out at 8 GPa and 1573 K, with a dwell time of 3 h. The temperature was increased and decreased over a period of 1 h. The assembly was opened in a glove-box, revealing crystals with a metallic luster.
The composition of SrGa4As4 was verified by EDX measurements using a a Carl Zeiss EVO-MA 10 instrument with a Bruker Nano EDX detector. The experimental values [Sr 12 (1) at%, Ga 44 (2) at% and As 45 (1) at%] are in excellent agreement with the expected values (Sr 11.1 at%, Ga 44.4 at% and As 44.4 at%) within the typical error of the method, and confirm the composition obtained from single-crystal X-ray diffraction data.
4. Refinement
Crystal data, data collection and structure . The Ga1A and Ga1B positions were introduced as half-occupied split positions since one fully occupied position with a prolate ellipsoid caused residual densities in the order of 2.2 e Å−3. Upon exclusion of the Ga1A/Ga1B positions, the contour difference map in PLATON (Spek, 2009) shows two clearly separated maxima justifying this approach. Structural data were standardized with STRUCTURE-TIDY (Gelato & Parthé, 1987).
details are summarized in Table 1Supporting information
Data collection: SAINT (Bruker, 2016); cell
APEX3 (Bruker, 2016); data reduction: APEX3 (Bruker, 2016); program(s) used to solve structure: SUPERFLIP (Palatinus & Chapuis, 2007) and EDMA (Palatinus et al., 2012); program(s) used to refine structure: SHELXL (Sheldrick, 2015); molecular graphics: DIAMOND (Brandenburg, 2014); software used to prepare material for publication: PLATON (Spek, 2009).SrGa4As4 | Dx = 5.711 Mg m−3 |
Mr = 666.18 | Mo Kα radiation, λ = 0.71073 Å |
Trigonal, P3221 | Cell parameters from 9912 reflections |
a = 6.3615 (1) Å | θ = 3.7–30.4° |
c = 16.5792 (2) Å | µ = 37.42 mm−1 |
V = 581.05 (2) Å3 | T = 293 K |
Z = 3 | Block, black |
F(000) = 882 | 0.10 × 0.05 × 0.05 mm |
Bruker APEXII D8 Quest CCD diffractometer | 928 independent reflections |
Radiation source: Iµ S | 918 reflections with I > 2σ(I) |
Goebel Mirror monochromator | Rint = 0.034 |
combined φ and ω scans | θmax = 27.9°, θmin = 3.7° |
Absorption correction: multi-scan (SADABS; Bruker, 2016) | h = −8→8 |
Tmin = 0.446, Tmax = 0.746 | k = −8→8 |
14966 measured reflections | l = −21→21 |
Refinement on F2 | Primary atom site location: iterative |
Least-squares matrix: full | Secondary atom site location: difference Fourier map |
R[F2 > 2σ(F2)] = 0.012 | w = 1/[σ2(Fo2) + (0.0102P)2 + 0.3943P] where P = (Fo2 + 2Fc2)/3 |
wR(F2) = 0.025 | (Δ/σ)max < 0.001 |
S = 1.17 | Δρmax = 0.51 e Å−3 |
928 reflections | Δρmin = −0.69 e Å−3 |
52 parameters | Absolute structure: Flack x determined using 340 quotients [(I+)-(I-)]/[(I+)+(I-)] (Parsons et al., 2013) |
0 restraints | Absolute structure parameter: −0.024 (11) |
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. |
x | y | z | Uiso*/Ueq | Occ. (<1) | |
Sr1 | 0.52374 (8) | 0.000000 | 0.166667 | 0.01264 (11) | |
Ga1A | 0.8090 (7) | 0.9427 (8) | 0.8779 (2) | 0.0120 (4) | 0.5 |
Ga1B | 0.8516 (7) | 0.9303 (8) | 0.8920 (2) | 0.0175 (5) | 0.5 |
Ga2 | 0.27470 (8) | 0.54448 (7) | 0.00800 (2) | 0.00988 (9) | |
As1 | 0.50915 (7) | 0.49019 (6) | 0.11634 (2) | 0.00817 (8) | |
As2 | 0.86593 (6) | 0.17439 (6) | 0.00577 (2) | 0.00838 (8) |
U11 | U22 | U33 | U12 | U13 | U23 | |
Sr1 | 0.01406 (18) | 0.0121 (2) | 0.0111 (2) | 0.00605 (12) | 0.00104 (9) | 0.00209 (17) |
Ga1A | 0.0136 (10) | 0.0079 (6) | 0.0131 (10) | 0.0044 (6) | 0.0032 (6) | 0.0001 (6) |
Ga1B | 0.0184 (13) | 0.0080 (7) | 0.0206 (13) | 0.0025 (7) | 0.0107 (9) | −0.0018 (8) |
Ga2 | 0.0105 (2) | 0.00988 (18) | 0.01119 (18) | 0.00654 (16) | −0.00233 (16) | −0.00109 (14) |
As1 | 0.00767 (16) | 0.00801 (17) | 0.00862 (16) | 0.00376 (14) | −0.00032 (13) | 0.00041 (12) |
As2 | 0.00712 (16) | 0.00890 (17) | 0.00970 (17) | 0.00444 (14) | 0.00033 (13) | 0.00055 (13) |
Sr1—As2 | 3.2665 (4) | Ga1A—As1xii | 2.477 (4) |
Sr1—As2i | 3.2666 (4) | Ga1A—As2xiii | 2.503 (4) |
Sr1—As1i | 3.2739 (4) | Ga1A—Ga1Bxiv | 2.5444 (13) |
Sr1—As1 | 3.2739 (4) | Ga1A—Ga1Axiv | 2.572 (8) |
Sr1—As1ii | 3.3048 (4) | Ga1A—As1xv | 2.694 (2) |
Sr1—As1iii | 3.3048 (4) | Ga1B—As2xiii | 2.415 (4) |
Sr1—Ga1Biv | 3.312 (4) | Ga1B—As1xii | 2.515 (4) |
Sr1—Ga1Bv | 3.312 (4) | Ga1B—Ga1Bxiv | 2.542 (8) |
Sr1—Ga1Avi | 3.346 (4) | Ga1B—As2xvi | 2.845 (2) |
Sr1—Ga1Avii | 3.346 (4) | Ga2—As2viii | 2.4384 (5) |
Sr1—Ga2viii | 3.3505 (4) | Ga2—As1 | 2.4668 (5) |
Sr1—Ga2ix | 3.3506 (4) | Ga2—As2xvii | 2.4868 (5) |
Sr1—As2x | 3.4560 (4) | Ga2—As1viii | 2.5470 (5) |
Sr1—As2xi | 3.4560 (4) | Ga2—Ga2viii | 2.9844 (8) |
As2—Sr1—As2i | 120.45 (2) | Ga1Axiv—Ga1B—As2xvi | 89.08 (12) |
As2—Sr1—As1i | 134.533 (8) | As2xiii—Ga1B—Sr1xviii | 142.90 (10) |
As2i—Sr1—As1i | 78.453 (9) | As1xii—Ga1B—Sr1xviii | 67.51 (9) |
As2—Sr1—As1 | 78.453 (9) | Ga1Bxiv—Ga1B—Sr1xviii | 67.43 (7) |
As2i—Sr1—As1 | 134.533 (8) | Ga1Axiv—Ga1B—Sr1xviii | 72.45 (15) |
As1i—Sr1—As1 | 119.39 (2) | As2xvi—Ga1B—Sr1xviii | 63.55 (6) |
As2—Sr1—As1ii | 79.285 (11) | As2xiii—Ga1B—Sr1xv | 67.96 (9) |
As2i—Sr1—As1ii | 74.128 (11) | As1xii—Ga1B—Sr1xv | 137.34 (9) |
As1i—Sr1—As1ii | 66.217 (5) | Ga1Bxiv—Ga1B—Sr1xv | 68.95 (7) |
As1—Sr1—As1ii | 150.471 (11) | Ga1Axiv—Ga1B—Sr1xv | 64.32 (16) |
As2—Sr1—As1iii | 74.128 (11) | As2xvi—Ga1B—Sr1xv | 119.38 (13) |
As2i—Sr1—As1iii | 79.284 (11) | Sr1xviii—Ga1B—Sr1xv | 136.38 (13) |
As1i—Sr1—As1iii | 150.470 (11) | As2xiii—Ga1B—Sr1xix | 100.06 (10) |
As1—Sr1—As1iii | 66.217 (5) | As1xii—Ga1B—Sr1xix | 39.58 (5) |
As1ii—Sr1—As1iii | 124.89 (2) | Ga1Bxiv—Ga1B—Sr1xix | 118.30 (16) |
As2—Sr1—Ga1Biv | 51.25 (5) | Ga1Axiv—Ga1B—Sr1xix | 125.48 (7) |
As2i—Sr1—Ga1Biv | 73.07 (5) | As2xvi—Ga1B—Sr1xix | 138.21 (12) |
As1i—Sr1—Ga1Biv | 109.71 (7) | Sr1xviii—Ga1B—Sr1xix | 101.86 (10) |
As1—Sr1—Ga1Biv | 126.49 (6) | Sr1xv—Ga1B—Sr1xix | 98.42 (5) |
As1ii—Sr1—Ga1Biv | 44.67 (7) | As2xiii—Ga1B—Sr1xiii | 30.22 (6) |
As1iii—Sr1—Ga1Biv | 81.77 (7) | As1xii—Ga1B—Sr1xiii | 86.93 (10) |
As2—Sr1—Ga1Bv | 73.07 (5) | Ga1Bxiv—Ga1B—Sr1xiii | 155.24 (14) |
As2i—Sr1—Ga1Bv | 51.25 (5) | Ga1Axiv—Ga1B—Sr1xiii | 146.47 (15) |
As1i—Sr1—Ga1Bv | 126.49 (6) | As2xvi—Ga1B—Sr1xiii | 80.65 (8) |
As1—Sr1—Ga1Bv | 109.71 (7) | Sr1xviii—Ga1B—Sr1xiii | 128.07 (9) |
As1ii—Sr1—Ga1Bv | 81.77 (7) | Sr1xv—Ga1B—Sr1xiii | 93.16 (8) |
As1iii—Sr1—Ga1Bv | 44.67 (7) | Sr1xix—Ga1B—Sr1xiii | 80.08 (6) |
Ga1Biv—Sr1—Ga1Bv | 45.14 (14) | As2viii—Ga2—As1 | 127.996 (19) |
As2—Sr1—Ga1Avi | 111.75 (6) | As2viii—Ga2—As2xvii | 101.790 (19) |
As2i—Sr1—Ga1Avi | 123.12 (5) | As1—Ga2—As2xvii | 107.308 (18) |
As1i—Sr1—Ga1Avi | 48.02 (5) | As2viii—Ga2—As1viii | 112.107 (18) |
As1—Sr1—Ga1Avi | 74.76 (5) | As1—Ga2—As1viii | 100.790 (19) |
As1ii—Sr1—Ga1Avi | 95.97 (6) | As2xvii—Ga2—As1viii | 104.987 (18) |
As1iii—Sr1—Ga1Avi | 138.60 (6) | As2viii—Ga2—Ga2viii | 160.190 (16) |
Ga1Biv—Sr1—Ga1Avi | 135.24 (5) | As1—Ga2—Ga2viii | 54.718 (14) |
Ga1Bv—Sr1—Ga1Avi | 174.30 (10) | As2xvii—Ga2—Ga2viii | 94.821 (13) |
As2—Sr1—Ga1Avii | 123.12 (5) | As1viii—Ga2—Ga2viii | 52.245 (14) |
As2i—Sr1—Ga1Avii | 111.75 (6) | As2viii—Ga2—Sr1xx | 66.554 (14) |
As1i—Sr1—Ga1Avii | 74.76 (5) | As1—Ga2—Sr1xx | 164.526 (19) |
As1—Sr1—Ga1Avii | 48.02 (5) | As2xvii—Ga2—Sr1xx | 70.850 (14) |
As1ii—Sr1—Ga1Avii | 138.60 (6) | As1viii—Ga2—Sr1xx | 65.805 (12) |
As1iii—Sr1—Ga1Avii | 95.97 (7) | Ga2viii—Ga2—Sr1xx | 109.825 (18) |
Ga1Biv—Sr1—Ga1Avii | 174.30 (10) | As2viii—Ga2—Sr1xxi | 65.922 (13) |
Ga1Bv—Sr1—Ga1Avii | 135.23 (5) | As1—Ga2—Sr1xxi | 62.098 (13) |
Ga1Avi—Sr1—Ga1Avii | 45.20 (14) | As2xvii—Ga2—Sr1xxi | 126.697 (18) |
As2—Sr1—Ga2viii | 43.223 (9) | As1viii—Ga2—Sr1xxi | 128.043 (18) |
As2i—Sr1—Ga2viii | 161.548 (17) | Ga2viii—Ga2—Sr1xxi | 112.066 (16) |
As1i—Sr1—Ga2viii | 118.760 (14) | Sr1xx—Ga2—Sr1xxi | 131.844 (12) |
As1—Sr1—Ga2viii | 45.205 (10) | As2viii—Ga2—Sr1xvii | 94.008 (14) |
As1ii—Sr1—Ga2viii | 105.550 (10) | As1—Ga2—Sr1xvii | 87.434 (14) |
As1iii—Sr1—Ga2viii | 86.374 (9) | As2xvii—Ga2—Sr1xvii | 33.956 (10) |
Ga1Biv—Sr1—Ga2viii | 93.55 (5) | As1viii—Ga2—Sr1xvii | 137.041 (15) |
Ga1Bv—Sr1—Ga2viii | 110.30 (5) | Ga2viii—Ga2—Sr1xvii | 105.802 (10) |
Ga1Avi—Sr1—Ga2viii | 75.33 (5) | Sr1xx—Ga2—Sr1xvii | 97.358 (11) |
Ga1Avii—Sr1—Ga2viii | 81.05 (6) | Sr1xxi—Ga2—Sr1xvii | 93.202 (9) |
As2—Sr1—Ga2ix | 161.548 (17) | As2viii—Ga2—Sr1 | 154.513 (14) |
As2i—Sr1—Ga2ix | 43.223 (9) | As1—Ga2—Sr1 | 29.480 (10) |
As1i—Sr1—Ga2ix | 45.205 (10) | As2xvii—Ga2—Sr1 | 84.221 (13) |
As1—Sr1—Ga2ix | 118.759 (14) | As1viii—Ga2—Sr1 | 89.655 (14) |
As1ii—Sr1—Ga2ix | 86.374 (9) | Ga2viii—Ga2—Sr1 | 37.413 (11) |
As1iii—Sr1—Ga2ix | 105.549 (10) | Sr1xx—Ga2—Sr1 | 137.673 (13) |
Ga1Biv—Sr1—Ga2ix | 110.30 (5) | Sr1xxi—Ga2—Sr1 | 90.483 (9) |
Ga1Bv—Sr1—Ga2ix | 93.55 (5) | Sr1xvii—Ga2—Sr1 | 77.087 (5) |
Ga1Avi—Sr1—Ga2ix | 81.05 (6) | As2viii—Ga2—Sr1xxii | 123.013 (14) |
Ga1Avii—Sr1—Ga2ix | 75.33 (5) | As1—Ga2—Sr1xxii | 78.871 (13) |
Ga2viii—Sr1—Ga2ix | 154.42 (2) | As2xvii—Ga2—Sr1xxii | 117.500 (15) |
As2—Sr1—As2x | 69.230 (6) | As1viii—Ga2—Sr1xxii | 22.713 (10) |
As2i—Sr1—As2x | 150.543 (8) | Ga2viii—Ga2—Sr1xxii | 37.772 (10) |
As1i—Sr1—As2x | 76.839 (11) | Sr1xx—Ga2—Sr1xxii | 88.357 (8) |
As1—Sr1—As2x | 72.738 (10) | Sr1xxi—Ga2—Sr1xxii | 111.288 (14) |
As1ii—Sr1—As2x | 81.367 (9) | Sr1xvii—Ga2—Sr1xxii | 141.184 (8) |
As1iii—Sr1—As2x | 129.115 (8) | Sr1—Ga2—Sr1xxii | 73.220 (6) |
Ga1Biv—Sr1—As2x | 100.60 (6) | Ga2—As1—Ga1Axii | 114.64 (6) |
Ga1Bv—Sr1—As2x | 140.87 (6) | Ga2—As1—Ga1Bxii | 105.91 (6) |
Ga1Avi—Sr1—As2x | 43.14 (7) | Ga1Axii—As1—Ga1Bxii | 9.02 (9) |
Ga1Avii—Sr1—As2x | 76.71 (7) | Ga2—As1—Ga2viii | 73.038 (18) |
Ga2viii—Sr1—As2x | 42.823 (9) | Ga1Axii—As1—Ga2viii | 96.32 (10) |
Ga2ix—Sr1—As2x | 120.222 (14) | Ga1Bxii—As1—Ga2viii | 96.14 (9) |
As2—Sr1—As2xi | 150.543 (8) | Ga2—As1—Ga1Avii | 98.03 (9) |
As2i—Sr1—As2xi | 69.230 (6) | Ga1Axii—As1—Ga1Avii | 141.90 (4) |
As1i—Sr1—As2xi | 72.738 (10) | Ga1Bxii—As1—Ga1Avii | 147.27 (17) |
As1—Sr1—As2xi | 76.839 (11) | Ga2viii—As1—Ga1Avii | 112.22 (9) |
As1ii—Sr1—As2xi | 129.114 (8) | Ga2—As1—Sr1 | 128.755 (16) |
As1iii—Sr1—As2xi | 81.366 (9) | Ga1Axii—As1—Sr1 | 102.71 (6) |
Ga1Biv—Sr1—As2xi | 140.87 (6) | Ga1Bxii—As1—Sr1 | 111.12 (6) |
Ga1Bv—Sr1—As2xi | 100.60 (6) | Ga2viii—As1—Sr1 | 68.989 (12) |
Ga1Avi—Sr1—As2xi | 76.71 (7) | Ga1Avii—As1—Sr1 | 67.39 (9) |
Ga1Avii—Sr1—As2xi | 43.14 (7) | Ga2—As1—Sr1xxi | 76.628 (13) |
Ga2viii—Sr1—As2xi | 120.222 (14) | Ga1Axii—As1—Sr1xxi | 73.33 (8) |
Ga2ix—Sr1—As2xi | 42.823 (9) | Ga1Bxii—As1—Sr1xxi | 67.82 (8) |
As2x—Sr1—As2xi | 117.382 (19) | Ga2viii—As1—Sr1xxi | 139.977 (16) |
As1xii—Ga1A—As2xiii | 114.84 (16) | Ga1Avii—As1—Sr1xxi | 97.23 (9) |
As1xii—Ga1A—Ga1Bxiv | 119.2 (2) | Sr1—As1—Sr1xxi | 150.472 (11) |
As2xiii—Ga1A—Ga1Bxiv | 121.43 (16) | Ga2—As1—Sr1xvii | 65.908 (13) |
As1xii—Ga1A—Ga1Axiv | 127.04 (14) | Ga1Axii—As1—Sr1xvii | 161.16 (10) |
As2xiii—Ga1A—Ga1Axiv | 112.61 (17) | Ga1Bxii—As1—Sr1xvii | 156.82 (8) |
Ga1Bxiv—Ga1A—Ga1Axiv | 8.82 (9) | Ga2viii—As1—Sr1xvii | 101.547 (13) |
As1xii—Ga1A—As1xv | 87.94 (10) | Ga1Avii—As1—Sr1xvii | 32.12 (9) |
As2xiii—Ga1A—As1xv | 107.20 (13) | Sr1—As1—Sr1xvii | 89.333 (9) |
Ga1Bxiv—Ga1A—As1xv | 95.81 (13) | Sr1xxi—As1—Sr1xvii | 89.018 (12) |
Ga1Axiv—Ga1A—As1xv | 99.49 (15) | Ga1Bxxiii—As2—Ga2viii | 109.16 (6) |
As1xii—Ga1A—Sr1xv | 151.81 (10) | Ga1Bxxiii—As2—Ga2xxiv | 107.80 (10) |
As2xiii—Ga1A—Sr1xv | 70.77 (10) | Ga2viii—As2—Ga2xxiv | 111.741 (17) |
Ga1Bxiv—Ga1A—Sr1xv | 72.42 (16) | Ga1Bxxiii—As2—Ga1Axxiii | 8.97 (10) |
Ga1Axiv—Ga1A—Sr1xv | 67.40 (7) | Ga2viii—As2—Ga1Axxiii | 100.47 (6) |
As1xv—Ga1A—Sr1xv | 64.59 (7) | Ga2xxiv—As2—Ga1Axxiii | 110.18 (10) |
As1xii—Ga1A—Sr1xviii | 64.22 (9) | Ga1Bxxiii—As2—Ga1Biv | 88.49 (12) |
As2xiii—Ga1A—Sr1xviii | 128.43 (8) | Ga2viii—As2—Ga1Biv | 133.38 (9) |
Ga1Bxiv—Ga1A—Sr1xviii | 63.92 (16) | Ga2xxiv—As2—Ga1Biv | 102.40 (9) |
Ga1Axiv—Ga1A—Sr1xviii | 68.55 (7) | Ga1Axxiii—As2—Ga1Biv | 96.31 (10) |
As1xv—Ga1A—Sr1xviii | 123.83 (13) | Ga1Bxxiii—As2—Sr1 | 127.93 (10) |
Sr1xv—Ga1A—Sr1xviii | 135.95 (13) | Ga2viii—As2—Sr1 | 70.223 (14) |
As1xii—Ga1A—Sr1xix | 44.97 (5) | Ga2xxiv—As2—Sr1 | 120.879 (15) |
As2xiii—Ga1A—Sr1xix | 105.82 (11) | Ga1Axxiii—As2—Sr1 | 128.03 (10) |
Ga1Bxiv—Ga1A—Sr1xix | 127.80 (7) | Ga1Biv—As2—Sr1 | 65.20 (9) |
Ga1Axiv—Ga1A—Sr1xix | 135.48 (17) | Ga1Bxxiii—As2—Sr1xxii | 71.67 (8) |
As1xv—Ga1A—Sr1xix | 46.51 (6) | Ga2viii—As2—Sr1xxii | 73.974 (13) |
Sr1xv—Ga1A—Sr1xix | 107.02 (6) | Ga2xxiv—As2—Sr1xxii | 66.325 (12) |
Sr1xviii—Ga1A—Sr1xix | 104.00 (10) | Ga1Axxiii—As2—Sr1xxii | 66.09 (8) |
As1xii—Ga1A—Sr1xiii | 85.55 (10) | Ga1Biv—As2—Sr1xxii | 151.44 (9) |
As2xiii—Ga1A—Sr1xiii | 29.68 (6) | Sr1—As2—Sr1xxii | 143.341 (12) |
Ga1Bxiv—Ga1A—Sr1xiii | 149.64 (10) | Ga1Bxxiii—As2—Sr1xxv | 21.56 (6) |
Ga1Axiv—Ga1A—Sr1xiii | 140.99 (16) | Ga2viii—As2—Sr1xxv | 128.411 (14) |
As1xv—Ga1A—Sr1xiii | 102.85 (10) | Ga2xxiv—As2—Sr1xxv | 103.930 (14) |
Sr1xv—Ga1A—Sr1xiii | 94.16 (9) | Ga1Axxiii—As2—Sr1xxv | 30.44 (6) |
Sr1xviii—Ga1A—Sr1xiii | 120.80 (7) | Ga1Biv—As2—Sr1xxv | 68.27 (8) |
Sr1xix—Ga1A—Sr1xiii | 81.80 (6) | Sr1—As2—Sr1xxv | 120.158 (9) |
As2xiii—Ga1B—As1xii | 116.66 (16) | Sr1xxii—As2—Sr1xxv | 88.418 (8) |
As2xiii—Ga1B—Ga1Bxiv | 125.23 (17) | Ga1Bxxiii—As2—Sr1xxvi | 139.37 (9) |
As1xii—Ga1B—Ga1Bxiv | 117.83 (16) | Ga2viii—As2—Sr1xxvi | 97.627 (13) |
As2xiii—Ga1B—Ga1Axiv | 116.7 (2) | Ga2xxiv—As2—Sr1xxvi | 32.041 (11) |
As1xii—Ga1B—Ga1Axiv | 126.56 (18) | Ga1Axxiii—As2—Sr1xxvi | 142.22 (10) |
Ga1Bxiv—Ga1B—Ga1Axiv | 8.90 (9) | Ga1Biv—As2—Sr1xxvi | 94.88 (8) |
As2xiii—Ga1B—As2xvi | 80.20 (9) | Sr1—As2—Sr1xxvi | 89.306 (7) |
As1xii—Ga1B—As2xvi | 102.75 (11) | Sr1xxii—As2—Sr1xxvi | 87.812 (8) |
Ga1Bxiv—Ga1B—As2xvi | 93.10 (15) | Sr1xxv—As2—Sr1xxvi | 130.398 (9) |
Symmetry codes: (i) x−y, −y, −z+1/3; (ii) x, y−1, z; (iii) x−y+1, −y+1, −z+1/3; (iv) y, x−1, −z+1; (v) −x+y+1, −x+1, z−2/3; (vi) y−1, x−1, −z+1; (vii) −x+y, −x+1, z−2/3; (viii) y, x, −z; (ix) −x+y, −x, z+1/3; (x) y, x−1, −z; (xi) −x+y+1, −x+1, z+1/3; (xii) y, x, −z+1; (xiii) x, y+1, z+1; (xiv) −x+2, −x+y+1, −z+5/3; (xv) −y+1, x−y+1, z+2/3; (xvi) y+1, x, −z+1; (xvii) x−1, y, z; (xviii) −y+1, x−y, z+2/3; (xix) −y, x−y, z+2/3; (xx) −y, x−y, z−1/3; (xxi) x, y+1, z; (xxii) −y+1, x−y, z−1/3; (xxiii) x, y−1, z−1; (xxiv) x+1, y, z; (xxv) −y+1, x−y−1, z−1/3; (xxvi) x+1, y+1, z. |
Acknowledgements
We thank Lucien Eisenburger for assistance with the high pressure synthesis. Funding for this research was provided by Deutsche Forschungsgemeinschaft.
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