research communications
The 2O7
of KScPaChemistry and Physics of Materials, University of Salzburg, Jakob-Haringerstr. 2A, 5020 Salzburg, Austria
*Correspondence e-mail: guenther.redhammer@sbg.ac.at
Single crystals of KScP2O7, potassium scandium diphosphate, were grown in a borate The title compound crystallizes isotypically with KAlP2O7 in space-group type P21/c, Z = 4. The main building block is an {ScP2O11}9– unit, forming layers parallel to (001). These layers are stacked along [001] via common corners of octahedral and tetrahedral units to span up large heptagonal cavities that host the potassium cations with a of 10. The P—O—P bridging angle increases with increasing size of the octahedrally coordinated MIII cation, as do the K—O distances within a series of KMIIIP2O7 compounds (MIII = Al to Y with ionic radii r = 0.538 to 0.90 Å).
Keywords: KAlP2O7 structure type; pyrophosphate; scandium; isotypism; structure determination; crystal structure.
CCDC reference: 2019936
1. Chemical context
Metal-phosphates with open framework structures raise large interest due to a rich crystal chemistry (Clearfield, 1988) and possible interesting applications, e.g. as non-linear optical materials, solid-state electrolytes, ionic conductors, battery materials or sensors (Hagerman & Poeppelmeier, 1995; Vītiņš et al., 2000). In the context of solid-state electrolytes, we recently investigated the Na-super ionic conducting NaSICON-type compounds Na3Sc2(PO4)3 (NSP) and Ag3Sc2(PO4)3 (ASP) in terms of their structural phase-transition sequences and ionic conductivities (Rettenwander et al., 2018; Ladenstein et al., 2020; Redhammer et al., 2020). To elucidate the role of the alkali metals on symmetry, we intended to synthesize the potassium analogue of NSP with flux-growth techniques. Using a method applied by Sljukic et al. (1967) for the synthesis of large crystals of NaSICON-type KZr2(PO4)3, however, did not yield the intended compound K3Sc2(PO4)3, but the title diphosphate KScP2O7 instead.
Vītiņš et al. (2000) reviewed that for such AIMIIIP2O7 (A = Li, Na, K, Rb, Cs, Tl; M = Al, Ga, Fe, In, Sc, …) compounds six different structure types can be distinguished. They confirm that structure type I, involving compounds with large A site cations, is the largest group, showing P21/c space-group symmetry. KAlP2O7 (Ng & Calvo, 1973) is regarded as the aristo-structure of group I with around 45 different compositions as compiled in the Inorganic Database (ICSD; Zagorac et al., 2019). For K-containing compounds, further materials are KCrP2O7 (Gentil et al., 1997), KGaP2O7 (Genkin & Timofeeva, 1989), KFeP2O7 (Riou et al., 1988; Genkin & Timofeeva, 1989), KVP2O7 (Benhamada et al., 1991), KTiP2O7 (Zatovsky et al., 2000), KMoP2O7 (Leclaire et al., 1989; Chen et al., 1989), KInP2O7 (Zhang et al., 2004), KLuP2O7 (Yuan et al., 2007), KYbP2O7 (Horchani-Naifer & Férid, 2007), KErP2O7 (Chaker et al., 2016) and KYP2O7 (Yuan et al., 2007). Synthesis and lattice parameters of CeIII-doped polycrystalline KScP2O7 as well as the luminescence properties were reported recently by Zhang et al. (2016); however, no atomic coordinates were given.
In this contribution, we present the determination of the 2O7, not reported so far, and compare it with the series of other K-containing diphosphates.
of KScP2. Structural commentary
The title compound crystallizes in P21/c and is isostructural with KAlP2O7 (Ng & Calvo, 1973). It contains one distinct K and Sc atom site, two distinct P atom and seven different oxygen-atom positions, all of them on general position 4 e. The basic building unit is a pyrophosphate group, which is formed by two distinct PO4 tetrahedra (Fig. 1). They share the O4 oxygen atom, and the bridging P1—O4 and P2—O4 bond lengths are distinctly longer [1.6128 (6) and 1.6076 (6) Å, respectively] than the three shorter terminal P—O bonds [ranging between 1.4944 (7) and 1.5207 (6) Å]. These latter distances are those to the oxygen atoms which are shared with the ScO6 octahedra. The tetrahedral O—P—O angles involving the bridging oxygen atom O4 are generally smaller, those involving the terminal oxygen atoms distinctly larger than the ideal O—T—O angle of 109.5°. This – together with the difference in bond lengths between bridging and non-bridging T—O bonds – induces polyhedral distortion (especially for the tetrahedral angle variance, TAV), which is distinctly larger for the P1 tetrahedron. Likewise, the average bond length is slightly larger for the P1O4 tetrahedron than for the P2O4 tetrahedron (Table 1). When comparing average bond lengths and polyhedral distortion parameters of the series of KMIIIP2O7 structures (M = Al to Y), no clear variations with the ionic radius of the M cations can be found from the available data for tetrahedral structure units and distortion parameters, and they remain almost constant. The parameters for KScP2O7 fit well into the data of the other KMIIIP2O7 structures. The tetrahedral bridging angle P1—O4—P2 amounts to 125.80 (5)° and is distinctly larger than that of KAlP2O7 [123.2 (11)°]. On the other hand, here a clear trend of increasing bridging angle with increasing size of the M cation is evident, i.e. the pyrophosphate group is stretched to account for the increase in size of the M cations (Table 1).
The terminal oxygen atoms of the pyrophosphate group share their corners with five neighbouring ScO6 octahedra. Following Leclaire et al. (1989), two phosphate tetrahedra and one octahedron form the basic {ScP2O11}9– units (cf. Fig. 1), which are connected with units of the same kind via corner-sharing to make up a sheet parallel to (001), as depicted in Fig. 2. These layers are stacked along [001] in such a way that a ScO6 octahedron of one layer shares its O3iii and O6i corners (symmetry codes refer to Fig. 1) with one PO4 tetrahedron each of the layer below and above.
Generally, all corners of the octahedron are shared with neighbouring PO4 tetrahedra, whereby all oxygen atoms except O4 directly connect the octahedron with a pyrophosphate P2O7 group, and the O2ii and O5iv oxygen atoms join the octahedron with two PO4 tetrahedra within the above-mentioned layer parallel to (001). Additionally, the O1, O5iv and O7 oxygen atoms (Fig. 1) are also bonded to one KI cation each. The average Sc—O bond length is 2.085 Å while individual bond lengths range between 2.0736 (7) and 2.1122 (6) Å with one shorter bond (Sc—O6i) of 2.0346 (7) Å. A similar behaviour with one significantly shorter M—O bond is also observed in other KMIIIP2O7 compounds and seems to be a more general feature. The Sc—O6i and the Sc—O3iii bonds, which point towards [001] and connect different (001) layers, both are the shortest within the ScO6 octahedron. Assuming that these two bonds are those to the axial oxygen atoms of the octahedron, the appears to be slightly compressed. Also, Ng & Calvo (1973) noted for KAlP2O7 that the axial bonds are considerably shorter that the equatorial ones within the (001) layer and – more generally speaking – this is also found in other KMIIIP2O7 compounds. The ScO6 octahedron in the title compound is only slightly distorted in terms of bond lengths and bond-angle variance (Table 1). It is worth noting that KAlP2O7 shows the most regular octahedral coordination of all KMIIIP2O7 structures compared here, and the distortion increases with increasing size of the octahedral cation as depicted in Fig. 3a. The average <M—O> bond lengths also scale well with the ionic radius of the M site cation and are positively correlated (Fig. 3b).
Large heptagonal cavities are formed in the skeleton of octahedral and tetrahedral units that are made up from four tetrahedrally and two octahedrally coordinated sites within the (001) layer. The stacking of the layers leads to channels running parallel to [001] where the potassium cations are hosted. They are tenfold coordinated with K—O bond lengths ranging between 2.7837 (7) Å and 3.3265 (9) Å, the average K—O bond length being 3.072 Å. As for <M—O>, the average K—O bond length also increases with increasing size of the M site cation, i.e. the channel size increases also.
Using bond-valence energy landscape map (BVEL) calculations, an estimation of possible diffusion pathways of alkali ions in a compound can be facilitated. Using the program SoftBV (Chen & Adams, 2017; Chen et al., 2019) such calculations were performed on KScP2O7 and reveal two energy minima. The lowest lying minimum is indeed occupied by the KI cation, a second one is present at x, y, z = 0.271, 0.317, 0.438 (interstitial i1) and is unoccupied. A one-dimensional diffusion pathway is evident (Fig. 4), involving the i1 position, and is oriented parallel to [001]. An estimated activation energy of ∼0.3 eV would be needed to move a potassium ion from the regular K site to the interstitial i1 site; to move it from i1 to the next K1 site needs ∼1.3 eV. Interestingly, the percolation energy in e.g. FeIII, MoIII and InIII compounds of the KMIIIP2O7 series is distinctly higher with around 1.8 eV as estimated from BVEL maps. Generally, a partial substitution of trivalent cations by divalent ones might be of interest to increase the content of alkaline ions (here KI), which most probably could be found on the interstitial i1 site.
3. Synthesis and crystallization
The title compound was grown during attempts to synthesize NaSICON-type K3Sc2(PO4)3 adopting a growth protocol set up by Sljukic et al. (1967). Sc2O3 and KH2PO4 were mixed in stoichiometric quantities (molar ratio 2:3) and B2O3 was added as a with a sixfold quantity of that of Sc2O3. The complete mixture was transferred to a platinum crucible, covered with a lid, and heated in a chamber furnace to 1473 K, held at this temperature for 24 h and then slowly cooled down to 1073 K at a rate of 3 K h−1. Between 1073 K and room temperature the cooling rate was 50 K h−1. The synthesis batch was immersed in hot water to dissolve the B2O3 and remaining K-phosphates. The residual contained single-phase KScP2O7 as checked by powder X-ray diffraction and showed single crystals of irregular to needle-like form with well-developed faces. The crystals are colorless and highly transparent with sizes up to 140 µm in lengths and ∼80 µm in diameter.
4. Refinement
Crystal data, data collection and structure .
details are summarized in Table 2
|
Supporting information
CCDC reference: 2019936
https://doi.org/10.1107/S2056989020010427/wm5578sup1.cif
contains datablocks global, I. DOI:Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S2056989020010427/wm5578Isup2.hkl
Data collection: APEX2 (Bruker, 2012); cell
SAINT (Bruker, 2012); data reduction: SAINT (Bruker, 2012); program(s) used to solve structure: SIR2014 (Burla et al., 2005); program(s) used to refine structure: SHELXL2014/7 (Sheldrick, 2015); molecular graphics: DIAMOND (Brandenburg, 2006), ORTEP for Windows (Farrugia, 2012); software used to prepare material for publication: WinGX publication routines (Farrugia, 2012).KScP2O7 | F(000) = 504 |
Mr = 258 | Dx = 2.752 Mg m−3 |
Monoclinic, P21/c | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: -P 2ybc | Cell parameters from 20981 reflections |
a = 7.4634 (1) Å | θ = 2.9–36.5° |
b = 10.3902 (1) Å | µ = 2.35 mm−1 |
c = 8.3747 (1) Å | T = 293 K |
β = 106.49° | Prismatic, colorless |
V = 622.72 (1) Å3 | 0.16 × 0.09 × 0.08 mm |
Z = 4 |
Bruker SMART APEX CCD diffractometer | 2850 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.021 |
rotation, ω–scans at 4 different φ positions | θmax = 36.5°, θmin = 2.9° |
Absorption correction: multi-scan (SADABS; Krause et al., 2015) | h = −12→12 |
Tmin = 0.38, Tmax = 0.52 | k = −17→17 |
20981 measured reflections | l = −13→13 |
2985 independent reflections |
Refinement on F2 | Primary atom site location: structure-invariant direct methods |
Least-squares matrix: full | Secondary atom site location: structure-invariant direct methods |
R[F2 > 2σ(F2)] = 0.018 | w = 1/[σ2(Fo2) + (0.0257P)2 + 0.274P] where P = (Fo2 + 2Fc2)/3 |
wR(F2) = 0.049 | (Δ/σ)max = 0.001 |
S = 1.05 | Δρmax = 0.79 e Å−3 |
2985 reflections | Δρmin = −0.66 e Å−3 |
101 parameters | Extinction correction: SHELXL2014/7 (Sheldrick 2015), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4 |
0 restraints | Extinction coefficient: 0.0429 (15) |
0 constraints |
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 | ||
K1 | 0.82123 (3) | 0.67829 (3) | 0.94124 (3) | 0.02342 (6) | |
Sc1 | 0.76534 (2) | 0.09952 (2) | 0.74255 (2) | 0.00607 (4) | |
P1 | 0.55749 (3) | 0.36164 (2) | 0.80923 (2) | 0.00673 (5) | |
P2 | 0.86703 (3) | 0.40292 (2) | 0.67637 (3) | 0.00681 (5) | |
O1 | 0.54575 (9) | 0.22058 (6) | 0.76034 (9) | 0.01132 (11) | |
O2 | 0.36433 (9) | 0.42041 (6) | 0.76741 (9) | 0.01313 (11) | |
O3 | 0.67337 (11) | 0.38889 (7) | 0.98492 (9) | 0.01712 (13) | |
O4 | 0.66159 (9) | 0.43502 (6) | 0.69104 (8) | 0.01167 (11) | |
O5 | 0.99440 (9) | 0.50481 (6) | 0.77947 (8) | 0.01003 (10) | |
O6 | 0.85616 (11) | 0.40831 (7) | 0.49554 (8) | 0.01632 (13) | |
O7 | 0.92157 (9) | 0.27011 (6) | 0.75056 (8) | 0.01088 (10) |
U11 | U22 | U33 | U12 | U13 | U23 | |
K1 | 0.02013 (10) | 0.02973 (12) | 0.01843 (10) | 0.00408 (8) | 0.00226 (7) | −0.00089 (8) |
Sc1 | 0.00647 (6) | 0.00539 (6) | 0.00639 (6) | 0.00013 (4) | 0.00190 (4) | −0.00015 (4) |
P1 | 0.00662 (8) | 0.00633 (8) | 0.00731 (8) | 0.00074 (6) | 0.00208 (6) | −0.00046 (6) |
P2 | 0.00755 (8) | 0.00703 (8) | 0.00616 (8) | −0.00186 (6) | 0.00246 (6) | −0.00017 (5) |
O1 | 0.0091 (2) | 0.0070 (2) | 0.0185 (3) | 0.00026 (18) | 0.0050 (2) | −0.00208 (19) |
O2 | 0.0086 (2) | 0.0100 (2) | 0.0214 (3) | 0.00284 (19) | 0.0052 (2) | −0.0002 (2) |
O3 | 0.0209 (3) | 0.0207 (3) | 0.0073 (3) | 0.0010 (3) | −0.0001 (2) | −0.0025 (2) |
O4 | 0.0086 (2) | 0.0124 (2) | 0.0150 (3) | 0.00151 (19) | 0.0050 (2) | 0.0054 (2) |
O5 | 0.0103 (2) | 0.0097 (2) | 0.0107 (2) | −0.00398 (18) | 0.00393 (19) | −0.00307 (18) |
O6 | 0.0199 (3) | 0.0229 (3) | 0.0069 (2) | −0.0082 (2) | 0.0049 (2) | −0.0016 (2) |
O7 | 0.0098 (2) | 0.0069 (2) | 0.0159 (3) | −0.00059 (18) | 0.0035 (2) | 0.00091 (19) |
K1—O5 | 2.7837 (7) | P1—O3 | 1.5068 (7) |
K1—O7i | 2.7966 (7) | P1—O2 | 1.5123 (7) |
K1—O1ii | 2.8141 (7) | P1—O1 | 1.5176 (6) |
K1—O7iii | 2.9876 (7) | P1—O4 | 1.6128 (6) |
K1—O5i | 3.0259 (7) | P1—K1vii | 3.5569 (3) |
K1—O2ii | 3.1505 (7) | P2—O6 | 1.4944 (7) |
K1—O3 | 3.2592 (8) | P2—O5 | 1.5178 (6) |
K1—O4 | 3.2835 (7) | P2—O7 | 1.5207 (6) |
K1—O2iv | 3.2927 (7) | P2—O4 | 1.6076 (6) |
K1—O6iii | 3.3265 (9) | P2—K1i | 3.4856 (3) |
K1—P2i | 3.4856 (3) | P2—K1viii | 3.6237 (3) |
K1—P1ii | 3.5570 (3) | O1—K1vii | 2.8141 (7) |
Sc1—O6v | 2.0346 (7) | O2—Sc1ii | 2.0883 (6) |
Sc1—O3vi | 2.0736 (7) | O2—K1vii | 3.1505 (7) |
Sc1—O2vii | 2.0884 (6) | O2—K1iv | 3.2927 (7) |
Sc1—O5viii | 2.0989 (6) | O3—Sc1v | 2.0736 (7) |
Sc1—O1 | 2.1045 (6) | O5—Sc1iii | 2.0990 (6) |
Sc1—O7 | 2.1122 (6) | O5—K1i | 3.0259 (7) |
Sc1—K1viii | 3.9059 (3) | O6—Sc1vi | 2.0346 (7) |
Sc1—K1vi | 3.9333 (3) | O6—K1viii | 3.3265 (9) |
Sc1—K1i | 4.1501 (3) | O7—K1i | 2.7966 (7) |
Sc1—K1vii | 4.2870 (3) | O7—K1viii | 2.9875 (7) |
O5—K1—O7i | 106.35 (2) | O2vii—Sc1—K1vi | 56.82 (2) |
O5—K1—O1ii | 108.45 (2) | O5viii—Sc1—K1vi | 49.513 (18) |
O7i—K1—O1ii | 145.07 (2) | O1—Sc1—K1vi | 135.284 (19) |
O5—K1—O7iii | 59.145 (18) | O7—Sc1—K1vi | 118.557 (19) |
O7i—K1—O7iii | 93.300 (18) | K1viii—Sc1—K1vi | 70.210 (7) |
O1ii—K1—O7iii | 106.983 (19) | O6v—Sc1—K1i | 52.43 (2) |
O5—K1—O5i | 78.29 (2) | O3vi—Sc1—K1i | 126.74 (2) |
O7i—K1—O5i | 50.565 (17) | O2vii—Sc1—K1i | 140.66 (2) |
O1ii—K1—O5i | 135.51 (2) | O5viii—Sc1—K1i | 79.508 (19) |
O7iii—K1—O5i | 113.314 (18) | O1—Sc1—K1i | 94.313 (18) |
O5—K1—O2ii | 116.03 (2) | O7—Sc1—K1i | 37.741 (18) |
O7i—K1—O2ii | 115.93 (2) | K1viii—Sc1—K1i | 66.889 (5) |
O1ii—K1—O2ii | 48.919 (17) | K1vi—Sc1—K1i | 128.501 (4) |
O7iii—K1—O2ii | 72.254 (18) | O6v—Sc1—K1vii | 112.70 (2) |
O5i—K1—O2ii | 164.277 (19) | O3vi—Sc1—K1vii | 67.21 (2) |
O5—K1—O3 | 71.10 (2) | O2vii—Sc1—K1vii | 75.012 (19) |
O7i—K1—O3 | 103.820 (19) | O5viii—Sc1—K1vii | 150.317 (19) |
O1ii—K1—O3 | 84.749 (19) | O1—Sc1—K1vii | 34.402 (18) |
O7iii—K1—O3 | 130.140 (19) | O7—Sc1—K1vii | 110.455 (18) |
O5i—K1—O3 | 55.064 (17) | K1viii—Sc1—K1vii | 131.220 (7) |
O2ii—K1—O3 | 133.582 (19) | K1vi—Sc1—K1vii | 101.144 (6) |
O5—K1—O4 | 47.582 (17) | K1i—Sc1—K1vii | 128.415 (5) |
O7i—K1—O4 | 140.014 (19) | O3—P1—O2 | 113.29 (4) |
O1ii—K1—O4 | 67.811 (18) | O3—P1—O1 | 114.72 (4) |
O7iii—K1—O4 | 94.293 (17) | O2—P1—O1 | 110.44 (4) |
O5i—K1—O4 | 90.703 (17) | O3—P1—O4 | 105.51 (4) |
O2ii—K1—O4 | 103.768 (18) | O2—P1—O4 | 105.11 (4) |
O3—K1—O4 | 44.629 (17) | O1—P1—O4 | 106.97 (4) |
O5—K1—O2iv | 120.669 (19) | O3—P1—K1vii | 144.71 (3) |
O7i—K1—O2iv | 72.463 (19) | O2—P1—K1vii | 62.23 (3) |
O1ii—K1—O2iv | 87.172 (19) | O1—P1—K1vii | 49.33 (3) |
O7iii—K1—O2iv | 165.347 (19) | O4—P1—K1vii | 109.38 (3) |
O5i—K1—O2iv | 54.972 (17) | O3—P1—K1 | 56.74 (3) |
O2ii—K1—O2iv | 116.65 (2) | O2—P1—K1 | 95.62 (3) |
O3—K1—O2iv | 53.305 (18) | O1—P1—K1 | 153.20 (3) |
O4—K1—O2iv | 94.610 (18) | O4—P1—K1 | 58.24 (3) |
O5—K1—O6iii | 97.331 (19) | K1vii—P1—K1 | 152.503 (8) |
O7i—K1—O6iii | 55.891 (18) | O6—P2—O5 | 113.29 (4) |
O1ii—K1—O6iii | 121.365 (19) | O6—P2—O7 | 112.29 (4) |
O7iii—K1—O6iii | 46.342 (17) | O5—P2—O7 | 110.41 (4) |
O5i—K1—O6iii | 100.309 (18) | O6—P2—O4 | 106.93 (4) |
O2ii—K1—O6iii | 72.478 (18) | O5—P2—O4 | 105.59 (4) |
O3—K1—O6iii | 153.88 (2) | O7—P2—O4 | 107.91 (3) |
O4—K1—O6iii | 140.332 (18) | O6—P2—K1i | 140.37 (3) |
O2iv—K1—O6iii | 122.924 (18) | O5—P2—K1i | 59.96 (3) |
O5—K1—P2i | 90.537 (15) | O7—P2—K1i | 51.21 (3) |
O7i—K1—P2i | 25.078 (13) | O4—P2—K1i | 112.48 (3) |
O1ii—K1—P2i | 150.579 (16) | O6—P2—K1viii | 66.61 (3) |
O7iii—K1—P2i | 102.011 (14) | O5—P2—K1viii | 104.90 (3) |
O5i—K1—P2i | 25.736 (12) | O7—P2—K1viii | 53.74 (3) |
O2ii—K1—P2i | 140.943 (16) | O4—P2—K1viii | 148.68 (3) |
O3—K1—P2i | 80.358 (14) | K1i—P2—K1viii | 77.363 (6) |
O4—K1—P2i | 115.250 (14) | O6—P2—K1 | 126.27 (3) |
O2iv—K1—P2i | 63.593 (13) | O5—P2—K1 | 42.96 (2) |
O6iii—K1—P2i | 76.323 (13) | O7—P2—K1 | 121.13 (3) |
O5—K1—P1ii | 117.439 (16) | O4—P2—K1 | 62.66 (3) |
O7i—K1—P1ii | 131.596 (16) | K1i—P2—K1 | 77.719 (8) |
O1ii—K1—P1ii | 24.144 (13) | K1viii—P2—K1 | 146.911 (7) |
O7iii—K1—P1ii | 92.076 (14) | P1—O1—Sc1 | 127.58 (4) |
O5i—K1—P1ii | 154.610 (15) | P1—O1—K1vii | 106.53 (3) |
O2ii—K1—P1ii | 25.133 (12) | Sc1—O1—K1vii | 120.60 (3) |
O3—K1—P1ii | 108.821 (15) | P1—O2—Sc1ii | 140.31 (4) |
O4—K1—P1ii | 87.268 (13) | P1—O2—K1vii | 92.64 (3) |
O2iv—K1—P1ii | 99.950 (13) | Sc1ii—O2—K1vii | 124.31 (3) |
O6iii—K1—P1ii | 97.304 (14) | P1—O2—K1iv | 106.05 (3) |
P2i—K1—P1ii | 151.985 (9) | Sc1ii—O2—K1iv | 91.12 (2) |
O6v—Sc1—O3vi | 178.96 (3) | K1vii—O2—K1iv | 87.202 (17) |
O6v—Sc1—O2vii | 91.12 (3) | P1—O3—Sc1v | 162.86 (5) |
O3vi—Sc1—O2vii | 89.85 (3) | P1—O3—K1 | 100.52 (4) |
O6v—Sc1—O5viii | 91.86 (3) | Sc1v—O3—K1 | 92.33 (3) |
O3vi—Sc1—O5viii | 88.54 (3) | P2—O4—P1 | 125.80 (4) |
O2vii—Sc1—O5viii | 88.65 (3) | P2—O4—K1 | 91.56 (3) |
O6v—Sc1—O1 | 89.20 (3) | P1—O4—K1 | 97.07 (3) |
O3vi—Sc1—O1 | 90.26 (3) | P2—O5—Sc1iii | 133.60 (4) |
O2vii—Sc1—O1 | 100.03 (3) | P2—O5—K1 | 115.23 (3) |
O5viii—Sc1—O1 | 171.24 (3) | Sc1iii—O5—K1 | 105.40 (2) |
O6v—Sc1—O7 | 89.01 (3) | P2—O5—K1i | 94.31 (3) |
O3vi—Sc1—O7 | 90.06 (3) | Sc1iii—O5—K1i | 98.65 (2) |
O2vii—Sc1—O7 | 173.98 (3) | K1—O5—K1i | 101.71 (2) |
O5viii—Sc1—O7 | 85.32 (2) | P2—O6—Sc1vi | 163.73 (5) |
O1—Sc1—O7 | 86.00 (2) | P2—O6—K1viii | 89.04 (3) |
O6v—Sc1—K1viii | 110.60 (2) | Sc1vi—O6—K1viii | 98.58 (3) |
O3vi—Sc1—K1viii | 69.08 (2) | P2—O7—Sc1 | 131.85 (4) |
O2vii—Sc1—K1viii | 125.45 (2) | P2—O7—K1i | 103.71 (3) |
O5viii—Sc1—K1viii | 43.401 (17) | Sc1—O7—K1i | 114.72 (3) |
O1—Sc1—K1viii | 128.378 (19) | P2—O7—K1viii | 102.03 (3) |
O7—Sc1—K1viii | 49.150 (18) | Sc1—O7—K1viii | 98.52 (2) |
O6v—Sc1—K1vi | 125.03 (2) | K1i—O7—K1viii | 100.37 (2) |
O3vi—Sc1—K1vi | 55.89 (2) |
Symmetry codes: (i) −x+2, −y+1, −z+2; (ii) −x+1, y+1/2, −z+3/2; (iii) −x+2, y+1/2, −z+3/2; (iv) −x+1, −y+1, −z+2; (v) x, −y+1/2, z+1/2; (vi) x, −y+1/2, z−1/2; (vii) −x+1, y−1/2, −z+3/2; (viii) −x+2, y−1/2, −z+3/2. |
Vol. = polyhedral volume, DI = distortion index, ECoN = effective coordination number, OQE = octahedral quadratic elongation, OAV = octahedral angle variance, TQE = tetrahedral quadratic elongation, TAV = tetrahedral angle variance. All calculations were performed using VESTA (Momma & Izumi 2011; for the mathematical meaning see the VESTA Handbook); ionic radii were taken from Shannon (1976). |
M | Al | Cr | Ga | Fea | Feb | V | Ti | Mo | Sc | In | Lu | Yb | Er | Y |
ionic radius (Å) | 0.536 | 0.615 | 0.62 | 0.645 | 0.645 | 0.64 | 0.67 | 0.69 | 0.745 | 0.8 | 0.861 | 0.868 | 0.89 | 0.9 |
<K—O> (Å) | 2.949 | 2.975 | 2.982 | 3.017 | 2.993 | 2.998 | 3.029 | 3.029 | 3.072 | 3.056 | 3.118 | 3.130 | 3.119 | 3.150 |
Vol. (Å3) | 44.03 | 45.21 | 45.23 | 50.08 | 45.73 | 46.03 | 47.21 | 47.63 | 49.40 | 48.45 | 52.04 | 52.11 | 52.09 | 53.25 |
DI | 0.0442 | 0.0519 | 0.0484 | 0.0484 | 0.0535 | 0.0560 | 0.0596 | 0.0636 | 0.0620 | 0.0641 | 0.0695 | 0.0735 | 0.0813 | 0.0774 |
ECoN | 8.84 | 8.38 | 8.54 | 8.58 | 8.29 | 8.22 | 7.89 | 7.51 | 7.66 | 7.29 | 7.09 | 6.63 | 6.80 | 6.40 |
<M—O> (Å) | 1.889 | 1.973 | 1.964 | 2.021 | 1.991 | 2.000 | 2.036 | 2.091 | 2.085 | 2.124 | 2.199 | 2.207 | 2.301 | 2.266 |
Vol. (Å3) | 8.95 | 10.20 | 10.06 | 10.97 | 10.46 | 10.63 | 11.19 | 12.10 | 12.02 | 12.68 | 14.05 | 14.19 | 15.86 | 15.38 |
DI | 0.0102 | 0.0091 | 0.0076 | 0.0313 | 0.0106 | 0.0154 | 0.0220 | 0.0086 | 0.0100 | 0.0073 | 0.0139 | 0.0116 | 0.0266 | 0.0074 |
OQE | 1.0025 | 1.0031 | 1.0033 | 1.0032 | 1.0036 | 1.0036 | 1.0048 | 1.0045 | 1.0040 | 1.0047 | 1.0068 | 1.0070 | 1.0170 | 1.0060 |
OAV (°2) | 7.97 | 10.31 | 11.42 | 6.47 | 11.79 | 10.66 | 12.98 | 15.40 | 13.52 | 16.38 | 22.62 | 23.79 | 54.07 | 20.97 |
ECoN | 5.96 | 5.97 | 5.98 | 5.73 | 5.96 | 5.92 | 5.85 | 5.97 | 5.96 | 5.99 | 5.95 | 5.95 | 5.75 | 5.98 |
<P1—O> (Å) | 1.536 | 1.542 | 1.540 | 1.537 | 1.537 | 1.540 | 1.540 | 1.536 | 1.537 | 1.538 | 1.545 | 1.531 | 1.494 | 1.518 |
Vol. (Å3) | 1.85 | 1.87 | 1.86 | 1.85 | 1.85 | 1.86 | 1.87 | 1.85 | 1.86 | 1.85 | 1.87 | 1.83 | 1.68 | 1.78 |
DI | 0.0240 | 0.0241 | 0.0240 | 0.0124 | 0.0237 | 0.0245 | 0.0234 | 0.0256 | 0.0245 | 0.0281 | 0.0329 | 0.0264 | 0.0584 | 0.0326 |
TQE | 1.0049 | 1.0053 | 1.0049 | 1.0042 | 1.0048 | 1.0047 | 1.0037 | 1.0052 | 1.0043 | 1.0059 | 1.0080 | 1.0043 | 1.0179 | 1.0074 |
TAV (°2) | 19.55 | 21.29 | 19.79 | 17.39 | 18.95 | 18.34 | 14.44 | 20.41 | 16.80 | 22.82 | 27.35 | 16.12 | 37.83 | 24.70 |
ECoN | 3.89 | 3.89 | 3.88 | 3.97 | 3.89 | 3.89 | 3.90 | 3.88 | 3.89 | 3.85 | 3.77 | 3.87 | 3.14 | 3.77 |
<P2—O> (Å) | 1.531 | 1.535 | 1.535 | 1.530 | 1.531 | 1.535 | 1.536 | 1.534 | 1.535 | 1.530 | 1.546 | 1.535 | 1.509 | 1.529 |
Vol. (Å3) | 1.83 | 1.85 | 1.85 | 1.84 | 1.84 | 1.85 | 1.85 | 1.85 | 1.85 | 1.83 | 1.88 | 1.85 | 1.72 | 1.83 |
DI | 0.0241 | 0.0242 | 0.0260 | 0.0088 | 0.0241 | 0.0227 | 0.0247 | 0.0231 | 0.0236 | 0.0272 | 0.0470 | 0.0237 | 0.0400 | 0.0351 |
TQE | 1.0034 | 1.0032 | 1.0035 | 1.0011 | 1.0030 | 1.0026 | 1.0027 | 1.0027 | 1.0027 | 1.0034 | 1.0058 | 1.0024 | 1.0206 | 1.0038 |
TAV (°2) | 12.54 | 11.68 | 12.48 | 4.49 | 10.67 | 9.18 | 9.12 | 9.60 | 9.48 | 10.99 | 9.51 | 7.94 | 71.43 | 4.61 |
ECoN | 3.87 | 3.87 | 3.86 | 3.98 | 3.88 | 3.89 | 3.88 | 3.88 | 3.89 | 3.80 | 3.61 | 3.89 | 3.57 | 3.71 |
P1—O4—P2 (°) | 123.18 (11) | 123.68 (10) | 123.8 (2) | n.d. | 124.32 (10) | 124.24 | 125.0 (2) | 124.97 (15) | 125.80 (5) | 125.6 (5) | 123.8 (9) | 127.5 (3) | 123.72 (7) | 127.4 (6) |
Notes: (a )data from Riou et al. (1988); (b) data from Genkin & Timofeeva (1989). |
References
Benhamada, L., Grandin, A., Borel, M. M., Leclaire, A. & Raveau, B. (1991). Acta Cryst. C47, 424–425. CrossRef ICSD CAS Web of Science IUCr Journals Google Scholar
Brandenburg, K. (2006). DIAMOND. Crystal Impact GbR, Bonn, Germany. Google Scholar
Bruker (2012). APEX2 and SAINT. Bruker AXS Inc, Madison, Wisconsin, USA. Google Scholar
Burla, M. C., Caliandro, R., Camalli, M., Carrozzini, B., Cascarano, G. L., De Caro, L., Giacovazzo, C., Polidori, G. & Spagna, R. (2005). J. Appl. Cryst. 38, 381–388. Web of Science CrossRef CAS IUCr Journals Google Scholar
Chaker, M., Horchani-Naifer, K. & Férid, M. (2016). J. Alloys Compd. 688, 104–110. Web of Science CrossRef ICSD CAS Google Scholar
Chen, H. & Adams, S. (2017). IUCrJ, 4, 614–625. Web of Science CrossRef CAS PubMed IUCr Journals Google Scholar
Chen, H., Wong, L. L. & Adams, S. (2019). Acta Cryst. B75, 18–33. Web of Science CrossRef IUCr Journals Google Scholar
Chen, J. J., Wang, C. C. & Lii, K. H. (1989). Acta Cryst. C45, 673–675. CrossRef ICSD CAS Web of Science IUCr Journals Google Scholar
Clearfield, A. (1988). Chem. Rev. 88, 125–148. CrossRef CAS Web of Science Google Scholar
Farrugia, L. J. (2012). J. Appl. Cryst. 45, 849–854. Web of Science CrossRef CAS IUCr Journals Google Scholar
Genkin, E. A. & Timofeeva, V. A. (1989). J. Struct. Chem. 30, 149–151. CrossRef Web of Science Google Scholar
Gentil, S., Andreica, D., Lujan, M., Rivera, J. P., Kubel, F. & Schmid, H. (1997). Ferroelectrics, 204, 35–44. Web of Science CrossRef ICSD CAS Google Scholar
Hagerman, M. E. & Poeppelmeier, K. R. (1995). Chem. Mater. 7, 602–621. CrossRef CAS Web of Science Google Scholar
Horchani-Naifer, K. & Férid, M. (2007). Acta Cryst. E63, i33–i34. Web of Science CrossRef ICSD IUCr Journals Google Scholar
Krause, L., Herbst-Irmer, R., Sheldrick, G. M. & Stalke, D. (2015). J. Appl. Cryst. 48, 3–10. Web of Science CSD CrossRef ICSD CAS IUCr Journals Google Scholar
Ladenstein, L., Lunghammer, S., Wang, E. Y., Miara, L. J., Wilkening, M. H. R., Redhammer, G. J. & Rettenwander, D. (2020). J. Phys. Energ. 2, 035003. CrossRef Google Scholar
Leclaire, A., Borel, M. M., Grandin, A. & Raveau, B. (1989). J. Solid State Chem. 78, 220–226. CrossRef ICSD CAS Web of Science Google Scholar
Momma, K. & Izumi, F. (2011). J. Appl. Cryst. 44, 1272–1276. Web of Science CrossRef CAS IUCr Journals Google Scholar
Ng, H. N. & Calvo, C. (1973). Can. J. Chem. 51, 2613–2620. CrossRef ICSD CAS Web of Science Google Scholar
Redhammer, G. J., Tippelt, G., Stahl, Q., Benisek, A. & Rettenwander, D. (2020). Acta Cryst. B76, submitted [Co-editor code RM5035]. Google Scholar
Rettenwander, D., Redhammer, G. J., Guin, M., Benisek, A., Krüger, H., Guillon, O., Wilkening, M., Tietz, F. & Fleig, J. (2018). Chem. Mater. 30, 1776–1781. Web of Science CrossRef CAS PubMed Google Scholar
Riou, D., Labbe, P. & Goreaud, M. (1988). Eur. J. Solid State Inorg. Chem. 25, 215–229. CAS Google Scholar
Shannon, R. D. (1976). Acta Cryst. A32, 751–767. CrossRef CAS IUCr Journals Web of Science Google Scholar
Sheldrick, G. M. (2015). Acta Cryst. C71, 3–8. Web of Science CrossRef IUCr Journals Google Scholar
Sljukic, M., Matkovic, B., Prodic, B. & Scavnicar, S. (1967). Croat. Chem. Acta, 39, 145–. CAS Google Scholar
Vītiņš, G., Kaņepe, Z., Vītiņš, A., Ronis, J., Dindūne, A. & Lūsis, A. (2000). J. Solid State Electrochem. 4, 146–152. Web of Science CrossRef ICSD CAS Google Scholar
Yuan, J. L., Zhang, H., Chen, H. H., Yang, X. X., Zhao, J. T. & Gu, M. (2007). J. Solid State Chem. 180, 3381–3387. Web of Science CrossRef ICSD CAS Google Scholar
Zagorac, D., Müller, H., Ruehl, S., Zagorac, J. & Rehme, S. (2019). J. Appl. Cryst. 52, 918–925. Web of Science CrossRef CAS IUCr Journals Google Scholar
Zatovsky, I. V., Slobodyanik, N. S., Kowalski, A. & Slyva, T. Yu. (2000). Dopov. Nats. Akad. Nauk Ukr. pp. 151–155. Google Scholar
Zhang, X. M., Zhang, H. Z., Chen, C., Kim, S. I. & Seo, H. J. (2016). Mater. Lett. 168, 207–209. Web of Science CrossRef CAS Google Scholar
Zhang, Y. C., Cheng, W. D., Wu, D. S., Zhang, H., Chen, D. G., Gong, Y. J. & Kan, Z. G. (2004). Chem. Mater. 16, 4150–4159. Web of Science CrossRef ICSD CAS Google Scholar
This is an open-access article distributed under the terms of the Creative Commons Attribution (CC-BY) Licence, which permits unrestricted use, distribution, and reproduction in any medium, provided the original authors and source are cited.