Crystal structures of cristobalite-type and coesite-type PON redetermined on the basis of single-crystal X-ray diffraction data

Bykov, M.; Bykova, E.; Dyadkin, V.; Baumann, D.; Schnick, W.; Dubrovinsky, L.; Dubrovinskaia, N.

doi:10.1107/S205698901501899X

research communications

CRYSTALLOGRAPHIC
COMMUNICATIONS

ISSN: 2056-9890

Volume 71| Part 11| November 2015| Pages 1325-1327

https://doi.org/10.1107/S205698901501899X

Open

access

Crystal structures of cristobalite-type and coesite-type PON redetermined on the basis of single-crystal X-ray diffraction data

Maxim Bykov,^a ^* Elena Bykova,^a Vadim Dyadkin,^b Dominik Baumann,^c Wolfgang Schnick,^c Leonid Dubrovinsky ^a and Natalia Dubrovinskaia ^d

^aBayerisches Geoinstitut, University of Bayreuth, 95440 Bayreuth, Germany, ^bESRF, 38043 Grenoble, France, ^cDepartment of Chemistry, Ludwig Maximilian University, 81377 Munich, Germany, and ^dMaterial Physics and Technology at Extreme Conditions, Laboratory of Crystallography, University of Bayreuth, 95440 Bayreuth, Germany
^*Correspondence e-mail: maxim.bykov@uni-bayreuth.de

Edited by M. Weil, Vienna University of Technology, Austria (Received 10 August 2015; accepted 8 October 2015; online 14 October 2015)

Hitherto, phosphorus oxonitride (PON) could not be obtained in the form of single crystals and only powder diffraction experiments were feasible for structure studies. In the present work we have synthesized two polymorphs of phosphorus oxonitride, cristobalite-type (cri-PON) and coesite-type (coe-PON), in the form of single crystals and reinvestigated their crystal structures by means of in house and synchrotron single-crystal X-ray diffraction. The crystal structures of cri-PON and coe-PON are built from PO₂N₂ tetrahedral units, each with a statistical distribution of oxygen and nitrogen atoms. The crystal structure of the coe-PON phase has the space group C2/c with seven atomic sites in the asymmetric unit [two P and three (N,O) sites on general positions, one (N,O) site on an inversion centre and one (N,O) site on a twofold rotation axis], while the cri-PON phase possesses tetragonal I-42d symmetry with two independent atoms in the asymmetric unit [the P atom on a fourfold inversion axis and the (N,O) site on a twofold rotation axis]. In comparison with previous structure determinations from powder data, all atoms were refined with anisotropic displacement parameters, leading to higher precision in terms of bond lengths and angles.

Keywords: crystal structure; phosphorus oxonitride; silica analogues; redetermination.

CCDC references: 1430221; 1430220

1. Chemical context

The pseudo-binary system P₃N₅/P₂O₅ has been investigated intensively because the properties of related ceramic materials are promising for industrial applications. A mid-member of this system is phosphorus oxonitride (PON), whose chemical stability is essential for its use as an insulator or for fireproofing. This compound has attracted significant attention as a ternary base compound of electrolytes for rechargeable thin-film Li/Li-ion batteries. Phosphorus oxonitride is an isoelectronic analogue of silica (SiO₂) with the charge-balanced substitution P⁵⁺ + N³⁻ = Si⁴⁺ + O²⁻. The crystal structures of the polymorphic forms of SiO₂ and PON are built of tetrahedral SiO₄ and PO₂N₂ units, respectively. At present, five modifications of PON have been identified. Four of them are isostructural to known silica polymorphs, viz. α-quartz- (Léger et al., 1999 ), β-cristobalite- (Léger et al., 2001 ), moganite- (Chateau et al., 1999 ) and coesite-type (Baumann et al., 2015 ). The fifth one, δ-PON, has a structure type different from any of the silica modifications (Baumann et al., 2012 ). A rich variety of polymorphs is a result of the many ways in which the tetrahedra can be linked to form corner-sharing networks. Most of the phases in the P₃N₅/P₂O₅ system are usually obtained either in an amorphous state or in the form of powders consisting of very small crystallites. We succeeded in synthesizing single crystals of pure cristobalite- (cri) and coesite-type (coe) PON of a size suitable for single-crystal X-ray diffraction and report here the results of the structure refinements.

2. Structural commentary

The structure of cri-PON (Fig. 1a) can be derived from that of β-cristobalite by tilting each PO₂N₂ tetrahedron about the $[\overline{4}]$ axes alternately clockwise and anticlockwise. This leads to the lowering of symmetry from Fd $[\overline{3}]$ m to I $[\overline{4}]$ 2d, however, the topology remains the same. The length of the P—(O,N) bond in cri-PON is 1.5796 (10) Å, which is in a good agreement with the average of expected P—N (1.626 Å) and P—O (1.537 Å) distances (Huminicki & Hawthorne, 2002 ). All P—(O,N) distances within the PO₂N₂ units are equal, but there is a noticeable (O,N)—P—(O,N) angle variation between 107.86 (2) and 112.73 (5)° due to the compression of the tetrahedra along the c-axis direction.

Figure 1
Crystal structures of cri-PON (a) and coe-PON (b) shown in polyhedral representation. Displacement parameters are drawn at the 50% probability level. Mixed (N,O) sites are shown in red; P atoms are shown in brown.

The structure of coe-PON (Fig. 1b) is isotypic with coesite (SiO₂) (Angel et al., 2003 ). The framework of coe-PON is constructed of four-member rings comprised of corner-sharing PO₂N₂ tetrahedra. These rings are linked in such a manner that crankshaft-like chains are formed. The average P—(O,N) distance in coe-PON (1.572 Å) is slightly shorter than that of 1.581 Å reported by Baumann et al. (2015) likely due to the difference in temperatures at which the experiments were conducted. The tetrahedra are irregularly distorted, with P—(O,N) distances varying between 1.5530 (9) and 1.588 (3) Å, and (O,N)—P—(O,N) angles between 106.79 (19) and 112.0 (2)°.

In comparison with the refinements from powder diffraction data (Léger et al., 2001; Baumann et al., 2015), single-crystal diffraction data revealed a detailed electron density map, which allowed us in addition to a substitutional O-N disorder, to detect a possible positional disorder (for details see Refinement section), which may affect physical properties of coe-PON.

3. Synthesis and crystallisation

Cristobalite-type PON was synthesized from phosphoric triamide by a two-step condensation process. POCl₃ (99%, Sigma Aldrich) was reacted with liquid NH₃ (5.0, Air Liquide) to yield a mixture of PO(NH₂)₃ and NH₄Cl, which was subsequently heated to 893 K for 5 h in a stream of dry ammonia. The amorphous reaction product was crystallized at 1023 K for 7 d in an evacuated fused silica ampoule, yielding pure cristobalite-type PON. Coesite-type PON was obtained by high-pressure/high-temperature reaction of cri-PON in a modified Walker-type multi-anvil apparatus. The starting material was tightly packed in a h-BN capsule, which was centered in a MgO:Cr octahedron (Ceramic Substrates & Components, Isle of Wight, UK) with an edge length of 10 mm. The latter was subsequently compressed between eight truncated tungsten carbide cubes (5 mm truncation edge length, Hawedia, Marklkofen, Germany) using a 1000 t hydraulic press (Voggenreiter, Mainleus, Germany). The sample was compressed to 15.5 GPa, the temperature raised to 1573 K within 15 min and held constant for 60 min. The sample was cooled by turning off the heating, decompressed and mechanically isolated.

4. Refinement

Crystal data, data collection and structure refinement details are summarized in Table 1. Structure refinements of both coe-PON and cri-PON were performed using occupancies of oxygen and nitrogen atoms fixed to 0.5 for each site. As a result of the very similar scattering powers of N and O atoms, an attempt to refine the occupancies resulted in unreliable values with large standard uncertainties. The cri-PON crystal was twinned by inversion with an equal amount of the two twin domains. The refinement of the coe-PON structure revealed a residual electron density peak of 1.41 e⁻·Å⁻³ at a distance 1.22 Å from atom P2 and 1.50, 1.65 and 1.65 Å from atoms O1, O2 and O5, respectively. This density may be explained by a static disorder of the P2 atom between two positions. The disorder is, however, too weak to give additional reliable residual density peaks for the assignments of oxygen and nitrogen atoms.

Table 1
Experimental details

	cri-PON	coe-PON
Crystal data
Chemical formula	PON	PON
M_r	60.98	60.98
Crystal system, space group	Tetragonal, I $[\overline{4}]$ 2d	Monoclinic, C2/c
Temperature (K)	293	100
a, b, c (Å)	4.6135 (2), 4.6135 (2), 6.9991 (5)	6.9464 (6), 12.0340 (4), 6.9463 (5)
α, β, γ (°)	90, 90, 90	90, 119.914 (10), 90
V (Å³)	148.97 (2)	503.30 (7)
Z	4	16
Radiation type	Mo Kα	Synchrotron, λ = 0.69428 Å
μ (mm⁻¹)	1.24	1.35
Crystal size (mm)	0.02 × 0.02 × 0.02	0.02 × 0.02 × 0.02

Data collection
Diffractometer	Bruker SMART APEX CCD	PILATUS@SNBL
Absorption correction	Multi-scan (CrysAlis PRO; Agilent, 2014 )	Multi-scan (CrysAlis PRO; Agilent, 2014)
T_min, T_max	0.791, 1.000	0.949, 1.000
No. of measured, independent and observed [I > 2σ(I)] reflections	445, 92, 92	2415, 535, 469
R_int	0.016	0.038
(sin θ/λ)_max (Å⁻¹)	0.666	0.640

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.016, 0.043, 1.45	0.037, 0.102, 1.05
No. of reflections	92	535
No. of parameters	8	57
Δρ_max, Δρ_min (e Å⁻³)	0.21, −0.28	1.41, −0.54
Absolute structure	Refined as a perfect inversion twin.	–
Absolute structure parameter	0.5	–
Computer programs: CrysAlis PRO (Agilent, 2014), SHELXS (Sheldrick, 2008 ), SHELXL2014/7 (Sheldrick, 2015 ), DIAMOND (Brandenburg, 2006 ) and publCIF (Westrip, 2010 ).

Supporting information

CCDC references: 1430221; 1430220

Crystal structure: contains datablocks coe-PON, New_Global_Publ_Block, cri-PON. DOI: https://doi.org/10.1107/S205698901501899X/wm5203sup1.cif

Structure factors: contains datablock cri-PON. DOI: https://doi.org/10.1107/S205698901501899X/wm5203cri-PONsup2.hkl

Structure factors: contains datablock coe-PON. DOI: https://doi.org/10.1107/S205698901501899X/wm5203coe-PONsup3.hkl

checkCIF report

Computing details top

For both compounds, data collection: CrysAlis PRO (Agilent, 2014); cell refinement: CrysAlis PRO (Agilent, 2014); data reduction: CrysAlis PRO (Agilent, 2014); program(s) used to solve structure: SHELXS (Sheldrick, 2008); program(s) used to refine structure: SHELXL2014/7 (Sheldrick, 2015); molecular graphics: DIAMOND (Brandenburg, 2006); software used to prepare material for publication: publCIF (Westrip, 2010).

(cri-PON) Phosphorus oxonitride top

Crystal data top

NOP	D_x = 2.719 Mg m⁻³
M_r = 60.98	Mo Kα radiation, λ = 0.71069 Å
Tetragonal, I42d	Cell parameters from 431 reflections
a = 4.6135 (2) Å	θ = 5.3–28.2°
c = 6.9991 (5) Å	µ = 1.24 mm⁻¹
V = 148.97 (2) Å³	T = 293 K
Z = 4	Prism, colourless
F(000) = 120	0.02 × 0.02 × 0.02 mm

Data collection top

Three-circle diffractometer	92 independent reflections
Radiation source: rotating-anode X-ray tube, Rigaku Rotor Flex FR-D	92 reflections with I > 2σ(I)
Detector resolution: 16.6 pixels mm^-1	R_int = 0.016
ω scans	θ_max = 28.3°, θ_min = 5.3°
Absorption correction: multi-scan (CrysAlis PRO; Agilent, 2014)	h = −5→5
T_min = 0.791, T_max = 1.000	k = −5→6
445 measured reflections	l = −5→9

Refinement top

Refinement on F²	0 restraints
Least-squares matrix: full	w = 1/[σ²(F_o²) + (0.0229P)² + 0.0508P] where P = (F_o² + 2F_c²)/3
R[F² > 2σ(F²)] = 0.016	(Δ/σ)_max < 0.001
wR(F²) = 0.043	Δρ_max = 0.21 e Å⁻³
S = 1.45	Δρ_min = −0.28 e Å⁻³
92 reflections	Absolute structure: Refined as a perfect inversion twin.
8 parameters	Absolute structure parameter: 0.5

Special details top

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

Refinement. Refined as a 2-component perfect inversion twin.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å²) top

	x	y	z	U_iso*/U_eq	Occ. (<1)
P	0.5000	0.5000	0.0000	0.0106 (3)
N	0.3630 (5)	0.2500	0.1250	0.0155 (5)	0.5
O	0.3630 (5)	0.2500	0.1250	0.0155 (5)	0.5

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
P	0.0112 (4)	0.0112 (4)	0.0094 (4)	0.000	0.000	0.000
N	0.0151 (11)	0.0149 (12)	0.0165 (9)	0.000	0.000	0.0065 (10)
O	0.0151 (11)	0.0149 (12)	0.0165 (9)	0.000	0.000	0.0065 (10)

Geometric parameters (Å, º) top

P—Oⁱ	1.5796 (10)	P—Oⁱⁱⁱ	1.5796 (10)
P—Nⁱ	1.5796 (10)	P—Nⁱⁱⁱ	1.5796 (10)
P—Oⁱⁱ	1.5796 (10)	P—N	1.5796 (10)
P—Nⁱⁱ	1.5796 (10)	N—P^iv	1.5796 (10)

Oⁱ—P—Nⁱ	0.0	Nⁱ—P—Nⁱⁱⁱ	107.86 (2)
Oⁱ—P—Oⁱⁱ	107.86 (2)	Oⁱⁱ—P—Nⁱⁱⁱ	112.7
Nⁱ—P—Oⁱⁱ	107.86 (2)	Nⁱⁱ—P—Nⁱⁱⁱ	112.73 (5)
Oⁱ—P—Nⁱⁱ	107.9	Oⁱⁱⁱ—P—Nⁱⁱⁱ	0.0
Nⁱ—P—Nⁱⁱ	107.86 (2)	Oⁱ—P—N	112.7
Oⁱⁱ—P—Nⁱⁱ	0.0	Nⁱ—P—N	112.73 (5)
Oⁱ—P—Oⁱⁱⁱ	107.86 (2)	Oⁱⁱ—P—N	107.9
Nⁱ—P—Oⁱⁱⁱ	107.86 (2)	Nⁱⁱ—P—N	107.86 (2)
Oⁱⁱ—P—Oⁱⁱⁱ	112.73 (5)	Oⁱⁱⁱ—P—N	107.9
Nⁱⁱ—P—Oⁱⁱⁱ	112.73 (5)	Nⁱⁱⁱ—P—N	107.86 (2)
Oⁱ—P—Nⁱⁱⁱ	107.9	P—N—P^iv	132.83 (16)

Symmetry codes: (i) −x+1, −y+1, z; (ii) y, −x+1, −z; (iii) −y+1, x, −z; (iv) x, −y+1/2, −z+1/4.

(coe-PON) Phosphorus oxonitride top

Crystal data top

NOP	F(000) = 480
M_r = 60.98	D_x = 3.219 Mg m⁻³
Monoclinic, C2/c	Synchrotron radiation, λ = 0.69428 Å
a = 6.9464 (6) Å	Cell parameters from 1202 reflections
b = 12.0340 (4) Å	θ = 3.3–26.3°
c = 6.9463 (5) Å	µ = 1.35 mm⁻¹
β = 119.914 (10)°	T = 100 K
V = 503.30 (7) Å³	Prism, colourless
Z = 16	0.02 × 0.02 × 0.02 mm

Data collection top

PILATUS@SNBL diffractometer	535 independent reflections
Radiation source: Beamline BM1A, SNBL ESRF, Grenoble, France	469 reflections with I > 2σ(I)
Detector resolution: 5.8 pixels mm^-1	R_int = 0.038
φ scans	θ_max = 26.4°, θ_min = 3.3°
Absorption correction: multi-scan (CrysAlis PRO; Agilent, 2014)	h = −8→8
T_min = 0.949, T_max = 1.000	k = −15→15
2415 measured reflections	l = −8→8

Refinement top

Refinement on F²	57 parameters
Least-squares matrix: full	0 restraints
R[F² > 2σ(F²)] = 0.037	w = 1/[σ²(F_o²) + (0.054P)² + 4.3556P] where P = (F_o² + 2F_c²)/3
wR(F²) = 0.102	(Δ/σ)_max < 0.001
S = 1.05	Δρ_max = 1.41 e Å⁻³
535 reflections	Δρ_min = −0.54 e Å⁻³

Special details top

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å²) top

	x	y	z	U_iso*/U_eq	Occ. (<1)
P1	0.28266 (16)	0.09026 (8)	0.04006 (16)	0.0067 (4)
P2	0.31812 (17)	0.35749 (7)	0.42525 (17)	0.0084 (4)
N1	0.2117 (5)	0.4603 (2)	0.4818 (6)	0.0148 (8)	0.5
O1	0.2117 (5)	0.4603 (2)	0.4818 (6)	0.0148 (8)	0.5
N2	0.2500	0.2500	0.5000	0.0116 (10)	0.5
O2	0.2500	0.2500	0.5000	0.0116 (10)	0.5
N3	0.2322 (6)	0.3532 (3)	0.1704 (5)	0.0188 (8)	0.5
O3	0.2322 (6)	0.3532 (3)	0.1704 (5)	0.0188 (8)	0.5
N4	0.5000	0.1336 (3)	0.2500	0.0110 (10)	0.5
O4	0.5000	0.1336 (3)	0.2500	0.0110 (10)	0.5
N5	0.0792 (5)	0.1273 (3)	0.0656 (6)	0.0186 (8)	0.5
O5	0.0792 (5)	0.1273 (3)	0.0656 (6)	0.0186 (8)	0.5

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
P1	0.0054 (7)	0.0057 (6)	0.0070 (7)	0.0003 (3)	0.0016 (5)	0.0013 (3)
P2	0.0075 (7)	0.0071 (6)	0.0095 (7)	0.0000 (4)	0.0035 (5)	0.0011 (4)
N1	0.0191 (18)	0.0047 (15)	0.0250 (19)	0.0010 (12)	0.0142 (16)	−0.0018 (12)
O1	0.0191 (18)	0.0047 (15)	0.0250 (19)	0.0010 (12)	0.0142 (16)	−0.0018 (12)
N2	0.013 (2)	0.006 (2)	0.016 (2)	−0.0007 (16)	0.008 (2)	0.0032 (17)
O2	0.013 (2)	0.006 (2)	0.016 (2)	−0.0007 (16)	0.008 (2)	0.0032 (17)
N3	0.028 (2)	0.0177 (16)	0.0062 (18)	−0.0054 (14)	0.0048 (16)	0.0015 (13)
O3	0.028 (2)	0.0177 (16)	0.0062 (18)	−0.0054 (14)	0.0048 (16)	0.0015 (13)
N4	0.008 (2)	0.009 (2)	0.013 (2)	0.000	0.003 (2)	0.000
O4	0.008 (2)	0.009 (2)	0.013 (2)	0.000	0.003 (2)	0.000
N5	0.0034 (17)	0.0255 (18)	0.0213 (19)	0.0014 (13)	0.0020 (15)	−0.0079 (15)
O5	0.0034 (17)	0.0255 (18)	0.0213 (19)	0.0014 (13)	0.0020 (15)	−0.0079 (15)

Geometric parameters (Å, º) top

P1—O3ⁱ	1.568 (3)	P2—O5ⁱⁱⁱ	1.584 (3)
P1—N3ⁱ	1.568 (3)	P2—N5ⁱⁱⁱ	1.584 (3)
P1—O1ⁱⁱ	1.573 (3)	P2—N1	1.588 (3)
P1—N1ⁱⁱ	1.573 (3)	N1—P1^iv	1.574 (3)
P1—N5	1.574 (3)	N2—P2^v	1.5530 (9)
P1—N4	1.5755 (17)	N3—P1ⁱ	1.568 (3)
P2—N2	1.5530 (9)	N4—P1^vi	1.5755 (17)
P2—N3	1.562 (3)	N5—P2^vii	1.584 (3)

O3ⁱ—P1—N3ⁱ	0.0	N2—P2—N3	110.10 (13)
O3ⁱ—P1—O1ⁱⁱ	109.55 (17)	N2—P2—O5ⁱⁱⁱ	109.69 (13)
N3ⁱ—P1—O1ⁱⁱ	109.55 (17)	N3—P2—O5ⁱⁱⁱ	112.0 (2)
O3ⁱ—P1—N1ⁱⁱ	109.55 (17)	N2—P2—N5ⁱⁱⁱ	109.69 (13)
N3ⁱ—P1—N1ⁱⁱ	109.55 (17)	N3—P2—N5ⁱⁱⁱ	112.0 (2)
O1ⁱⁱ—P1—N1ⁱⁱ	0.0	O5ⁱⁱⁱ—P2—N5ⁱⁱⁱ	0.0
O3ⁱ—P1—N5	109.7 (2)	N2—P2—N1	108.03 (12)
N3ⁱ—P1—N5	109.7 (2)	N3—P2—N1	110.13 (18)
O1ⁱⁱ—P1—N5	111.04 (17)	O5ⁱⁱⁱ—P2—N1	106.79 (19)
N1ⁱⁱ—P1—N5	111.04 (17)	N5ⁱⁱⁱ—P2—N1	106.79 (19)
O3ⁱ—P1—N4	107.83 (16)	P1^iv—N1—P2	135.5 (2)
N3ⁱ—P1—N4	107.83 (16)	P2—N2—P2^v	180.0
O1ⁱⁱ—P1—N4	111.09 (19)	P2—N3—P1ⁱ	148.5 (2)
N1ⁱⁱ—P1—N4	111.09 (19)	P1^vi—N4—P1	141.3 (3)
N5—P1—N4	107.57 (15)	P1—N5—P2^vii	141.3 (2)

Symmetry codes: (i) −x+1/2, −y+1/2, −z; (ii) −x+1/2, y−1/2, −z+1/2; (iii) x+1/2, −y+1/2, z+1/2; (iv) −x+1/2, y+1/2, −z+1/2; (v) −x+1/2, −y+1/2, −z+1; (vi) −x+1, y, −z+1/2; (vii) x−1/2, −y+1/2, z−1/2.

Acknowledgements

We gratefully acknowledge financial support by the Fonds der Chemischen Industrie (FCI) and the Deutsche Forschungsgemeinschaft (DFG) (priority program SPP1236, project SCHN 377–13). ND thanks the German Research Foundation for financial support through the DFG Heisenberg Program. ND and LD gratefully acknowledge the Federal Ministry of Education and Research (BMBF, Germany) for funding.

References

Agilent (2014). CrysAlis PRO. Agilent Technologies, Yarnton, England. Google Scholar
Angel, R. J., Shaw, C. S. J. & Gibbs, G. V. (2003). Phys. Chem. Miner. 30, 167–176. Web of Science CrossRef CAS Google Scholar
Baumann, D., Niklaus, R. & Schnick, W. (2015). Angew. Chem. Int. Ed. 54, 4388–4391. Web of Science CrossRef CAS Google Scholar
Baumann, D., Sedlmaier, S. J. & Schnick, W. (2012). Angew. Chem. Int. Ed. 51, 4707–4709. Web of Science CrossRef CAS Google Scholar
Brandenburg, K. (2006). DIAMOND. Crystal Impact GbR, Bonn, Germany. Google Scholar
Chateau, C., Haines, J., Léger, J. M., Lesauze, A. & Marchand, R. (1999). Am. Mineral. 84, 207–210. CAS Google Scholar
Huminicki, D. M. C. & Hawthorne, F. C. (2002). Rev. Mineral. Geochem. 48, 123–253. Web of Science CrossRef CAS Google Scholar
Léger, J.-M., Haines, J., de Oliveira, L. S., Chateau, C., Le Sauze, A., Marchand, R. & Hull, S. (1999). J. Phys. Chem. Solids, 60, 145–152. Google Scholar
Léger, J. M., Haines, J., Chateau, C., Bocquillon, G., Schmidt, M. W., Hull, S., Gorelli, F., Lesauze, A. & Marchand, R. (2001). Phys. Chem. Miner. 28, 388–398. Web of Science CrossRef CAS Google Scholar
Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. Web of Science CrossRef CAS IUCr Journals Google Scholar
Sheldrick, G. M. (2015). Acta Cryst. C71, 3–8. Web of Science CrossRef IUCr Journals Google Scholar
Westrip, S. P. (2010). J. Appl. Cryst. 43, 920–925. Web of Science CrossRef CAS IUCr Journals 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.

CRYSTALLOGRAPHIC
COMMUNICATIONS

ISSN: 2056-9890

Volume 71| Part 11| November 2015| Pages 1325-1327

https://doi.org/10.1107/S205698901501899X

Open

access

Format		BIBTeX
		EndNote
		RefMan
		Refer
		Medline
		CIF
		SGML
		Plain Text

Format		BIBTeX
		EndNote
		RefMan
		Refer
		Medline
		CIF
		SGML
		Plain Text

Search IUCr Journals		doi		Advanced search
Author		volume	page

research communications\(\def\hfill{\hskip 5em}\def\hfil{\hskip 3em}\def\eqno#1{\hfil {#1}}\)

Crystal structures of cristobalite-type and coesite-type PON redetermined on the basis of single-crystal X-ray diffraction data

1. Chemical context

2. Structural commentary

3. Synthesis and crystallisation

4. Refinement

Supporting information

Acknowledgements

References

research communications