Lu-atom-ordered oxonitridoaluminosilicate Ba0.9Ce0.1LuAl0.2Si3.8N6.9O0.1

Simura, R.; Yamane, H.

doi:10.1107/S2056989020013158

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Volume 76| Part 11| November 2020| Pages 1708-1711

https://doi.org/10.1107/S2056989020013158

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Lu-atom-ordered oxonitridoaluminosilicate Ba_0.9Ce_0.1LuAl_0.2Si_3.8N_6.9O_0.1

Rayko Simura ^a ^* and Hisanori Yamane ^a

^aInstitute of Multidisciplinary Research for Advanced Materials, Tohoku, University, 2-1-1 Katahira, Aoba-ku, Sendai, 980-8577, Japan
^*Correspondence e-mail: ray@tohoku.ac.jp

Edited by P. Roussel, ENSCL, France (Received 14 September 2020; accepted 29 September 2020; online 6 October 2020)

A single crystal of Ba_0.9Ce_0.1LuAl_0.2Si_3.8N_6.9O_0.1 (barium cerium lutetium aluminosilicate nitride oxide) was obtained by heating a mixed powder of Ba₃N₂, Si₃N₄, Al, Lu₂O₃, and CeO₂ at 2173 K for 1 h under N₂ gas at 0.85 MPa. X-ray single-crystal structure analysis revealed that the title oxynitride is hexagonal (lattice constants: a = 6.0378 (5) Å, c = 9.8133 (9) Å; space group: P6₃mc) and isostructural with BaYbSi₄N₇. (Ba,Ce) and Lu atoms occupy twelvefold and sixfold coordination sites, respectively.

Keywords: BaLuSi₄N₇, crystal structure; oxynitride.

CCDC reference: 2034534

1. Chemical context

Huppertz & Schnick (1997b ) determined the hexagonal crystal structures of two isotypic nitrides, SrYbSi₄N₇ [a = 5.9880 (3) Å, c = 9.7499 (9) Å] and BaYbSi₄N₇ [a = 6.0307 (2) Å, c = 9.8198 (4) Å] with space group P6₃mc (Z = 2), by single-crystal X-ray diffraction (XRD). In the crystal structure of BaYbSi₄N₇, the Ba, Yb, and Si atoms are coordinated by twelve, six, and four N atoms of an anticuboctahedron, octahedron, and a tetrahedron, respectively. A three-dimensional framework of SiN₄ tetrahedra is formed by sharing vertex N atoms, and the interspaces of the framework are occupied by Ba and Yb atoms. N atoms at the N1 and N2 sites bond to two Si atoms, and N atoms at the N3 site are surrounded by four Si atoms. Such a high coordination number for the N3 site is characteristic of the crystal structures of SrYbSi₄N₇ and BaYbSi₄N₇ (Huppertz & Schnick, 1997b).

Other nitrides having the same structure type have been synthesized by substitution of Ca and/or other rare-earth (R) atoms for Sr, Ba, and Yb atoms. The crystal structure of SrYSi₄N₇ (a = 6.0160 (1) Å, c = 9.7894 (1) Å) was clarified by powder X-ray diffraction (pXRD) (Li, Fang, et al., 2004 ). Some nitrides doped with Eu²⁺, such as Ba_0.99Eu_0.01YSi₄N₇ [a = 6.0275 (6) Å, c = 9.880 (1) Å], Sr_0.99Eu_0.01YSi₄N₇ [a = 6.0269 (7) Å, c = 9.878 (1)] , and Ca_0.99Eu_0.01YSi₄N₇ [a = 5.9866 (5) Å, c = 9.800 (1) Å] (Li, Fang, et al., 2004; Porob et al., 2012 ), have also been reported. Oxynitrides SrR(Si,Al)₄(N,O)₇ and BaR(Si,Al)₄(N,O)₇ (R = Ho, Er, Tm, Yb; Lieb et al., 2007 ), in which the Si and N atoms are partly replaced by Al and O atoms, have also been synthesized. The crystal structures of the aforementioned compounds were found to be isotypic with SrYbSi₄N₇ and BaYbSi₄N₇. The alkaline-earth (A) atoms of Ca, Sr, or Ba are ordered at the anticuboctahedral (a) site of twelvefold coordination of N or O atoms, and the R atoms are located at the octahedral (o) site of sixfold coordination of N or O atoms. However, the crystal structures of BaLuSi₄N₇ [a = 6.02185 (2) Å, c = 9.81219 (7) Å] and SrLuSi₄N₇ [a = 6.02113 (2) Å, c = 9.80105 (7) Å] were analyzed by the Rietveld method for pXRD patterns using a disordered model in which both Ba/Sr and Lu atoms were statistically located at the a and o sites with the same occupancy of 0.5 (Park et al., 2012 ).

During our materials survey of novel Ce-doped phosphors in the Ba–Lu–Si–N system, small numbers of needle-like single crystals of 10 μm in diameter and 60 μm in length (at maximum) were grown at the contact surface between the BN crucible and an aggregate of fine particles consisting of amorphous and crystalline materials. The powder XRD pattern of the crystalline materials were indexed by the similar lattice constants as that of the needle-like crystals. Electron-probe microanalysis (EPMA) performed at 12 points on one of the needle-like single crystals gave a composition of Ce:Ba:Lu:Si:Al:N:O = 0.8 (2):7.6 (5):7.6 (6):29.6 (20):1.6 (4):49 (3):4(1) in weight percent (total mass was normalized to 100 mass%). The lower precision of the N and O contents was due to the lower energy of the characteristic X-rays of these light elements. The molar ratio obtained from the composition was Ce:Ba:Lu:Si:Al:N:O = 0.1 (3):0.99 (7):0.99 (8):3.9 (3):0.21 (5):6.4 (4):0.5 (2) (total sum 13), and the composition of the single crystal was regarded to be Ce_0.1Ba_0.9Lu_1.0Si_3.8Al_0.2N_6.9O_0.1 by assuming Ce atoms situated at the a site with Ba atoms. The XRD spots from the crystal were indexed with hexagonal lattice constants of a = 6.0378 (5) Å and c = 9.8133 (9) Å (Table 1), which were approximately the same as those reported for BaLuSi₄N₇ (Park et al., 2012) within differences of 0.1 and 0.2%, respectively. Initially, a structure refinement of Ce_0.1Ba_0.9Lu_1.0Si_3.8Al_0.2N_6.9O_0.1 was carried out with a disordered model of (Ce_0.1Ba_0.4Lu_0.5)(Ba_0.5Lu_0.5)Al_0.05Si_0.95)₄(N_0.99O_0.01)₇, in which the Ce, Ba, and Lu atoms were at the a site with a ratio of 0.1:0.4:0.5 and Ba and Lu atoms were at the o site with a 0.5:0.5 ratio, in accordance with the structure model of BaLuSi₄N₇ (Park et al., 2012). The R value of refinement was 4.2%, and residual electron densities of 5.52 and −3.46 e Å⁻³ were observed at 0.89 and 1.67 Å, respectively, from the a site and the N/O site (Table 2). Refinement using the ordered model of (Ce_0.1Ba_0.9)(Lu)(Al_0.05Si_0.95)₄(N_0.99O_0.01)₇, in which the Ba and Ce atoms are at the a site with a ratio of 0.9:0.1 and Lu atoms fully occupy the o site, yielded an R value of 2.2% with residual electron densities of 1.70 and −1.40 e Å⁻³ (Table1). As a consequence, the Ba and Lu atoms in Ba_0.9Ce_0.1LuAl_0.2Si_3.8N_6.9O_0.1 were clarified to be ordered at the a and o sites, respectively (Fig. 1).

Table 1
Experimental details

Crystal data
Chemical formula	Ba_0.9Ce_0.1LuAl_0.2Si_3.8N_6.9O_0.1
M_r	1045.99
Crystal system, space group	Hexagonal, P6₃mc
Temperature (K)	301
a, c (Å)	6.0378 (5), 9.8133 (9)
V (Å³)	309.82 (6)
Z	1
Radiation type	Mo Kα
μ (mm⁻¹)	22.95
Crystal size (μm)	0.13 × 0.07 × 0.02

Data collection
Diffractometer	Bruker D8 QUEST
Absorption correction	Multi-scan (SADABS; Bruker, 2018 )
T_min, T_max	0.37, 0.68
No. of measured, independent and observed [I > 2σ(I)] reflections	2818, 395, 381
R_int	0.059
(sin θ/λ)_max (Å⁻¹)	0.713

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.022, 0.055, 1.04
No. of reflections	395
No. of parameters	33
No. of restraints	1
Δρ_max, Δρ_min (e Å⁻³)	1.70, −1.40
Absolute structure	Refined as an inversion twin
Absolute structure parameter	0.10 (3)
Computer programs: Instrument Service (Bruker, 2018), APEX3 (Bruker, 2018), SAINT (Bruker, 2018), SHELXT2014/5 (Sheldrick, 2015a ), SHELXL2014/7 (Sheldrick, 2015b ), VESTA (Momma & Izumi, 2011 ), pubCIF (Westrip, 2010 ).

Table 2
Disordered model (Ce_0.1Ba_0.4Lu_0.5)(Ba_0.5Lu_0.5) (Al_0.05Si_0.95)₄ (N_0.99O_0.01)₇

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.042, 0.115, 1.32
No. of reflections	395
No. of parameters	39
No. of restraints	1
Δρ_max, Δρ_min (e Å⁻³)	5.52, −3.46
Absolute structure	Refined as an inversion twin
Absolute structure parameter	0.12 (9)

Figure 1
(a) Arrangement of cation-centered N/O atoms and (b) the crystal structure illustrated with cation-centered N/O-coordinated polyhedra for Ba_0.90Ce_0.10LuSi_3.80Al_0.20N_6.90O_0.10. Symmetry codes: (i) x, y, z; (ii) x − 1, y, z; (iii) x, y + 1, z; (iv) −y, x − y, z); (v) −y, x − y − 1, z; (vi) −x, −y, z + $[{1\over 2}]$ ); (vii) −y + 1, x − y, z); (viii) −x + y + 1, −x + 1, z; (ix) y, −x + y, z + $[{1\over 2}]$ ; (x) x − y + 1, x, z + $[{1\over 2}]$ ; (xi) −x + 1, −y + 1, z + $[{1\over 2}]$ ; (xii) y, −x + y + 1, z + $[{1\over 2}]$ ; (xiii) x − y, x, z + $[{1\over 2}]$ ; (xiv) −x + y + 1, −x + 2, z; (xv) −y + 1, x − y + 1, z.

2. Structural commentary

The interatomic distances of Ba/Ce—N/O for Ba_0.9Ce_0.1LuAl_0.2Si_3.8N_6.9O_0.1 are 2.975 (10) Å × 3, 3.0236 (5) Å × 4, 3.0236 (5) Å × 2, and 3.052 (10) Å × 3, which are comparable with the Ba/Lu—N distances for the a site of BaLuSi₄N₇ (2.975 Å × 3, 3.0372 Å × 3, 3.038 Å × 3, 3.0783 Å × 3) reported by Park et al. (2012). Lu—N/O distances in the title compound are 2.271 (10) Å × 3 and 2.312 (9) Å × 3, which are 0.139 Å shorter than the Ba/Lu—N distances (2.414 Å × 3, 2.451 Å × 3) for the o site of BaLuSi₄N₇.

The Al/Si1—N/O distances are 1.701 (9) Å × 3 and 1.85 (2) Å, and the Al/Si2—N/O distances are 1.738 (9) Å, 1.743 (6) Å × 2, and 1.954 (7) Å. These distances are consistent with those of Si—N (1.705 Å × 3, 1.887 Å and 1.724 Å, 1.721 Å × 2, 1.962 Å) for BaYbSi₄N₇ (Huppertz & Schnick, 1997b) but 0.07–0.2 Å longer than those of Si1–N (1.478 Å × 3, 1.776 Å) and Si2—N (1.671, 1.673, 1.889, 1.937 Å) reported for BaLuSi₄N₇ by Park et al. (2012), although the lattice constants of Ba_0.9Ce_0.1LuAl_0.2Si_3.8N_6.9O_0.1 and BaLuSi₄N₇ are similar, as previously mentioned. The average distances of Al/Si2—N/O and Si2—O of 1.792 and 1.782 Å, respectively, are slightly longer than those of Al/Si1—N/O (1.741 Å) and Si1—N (1.750 Å). The ^IVSi⁴⁺—^IVN³⁻ and ^IVAl³⁺—^IVN³⁻ distances calculated with the effective ionic radius for nitrides (^IVSi⁴⁺ = 0.29, ^IVAl³⁺ = 0.41 Å, ^IVN³⁻ = 1.46 Å; Baur, 1987 ) are 1.75 and 1.87 Å, respectively, which are similar to the Si—N and Al/Si—N/O distances of BaYbSi₄N₇ and Ba_0.9Ce_0.1LuAl_0.2Si_3.8N_6.9O_0.1. The bond-valence sum (BVS) (Brown & Altermatt, 1985 ) for the Lu site of Ba_0.9Ce_0.1LuAl_0.2Si_3.8N_6.9O_0.1 was calculated to be 3.07 with a bond-valence parameter of Lu—N (r₀ = 2.046, b = 0.37) reported by Brese & O'Keeffe (1991 ), in good agreement with the valence of Lu³⁺. The BVS with a parameter of Ba—N [r₀ = 2.47; Brese and O'Keeffe (1991)] is 2.73, which is greater than the valence of Ba²⁺. The BVSs of Al/Si1 and Al/Si2 with the parameter of Si–N (r₀ = 1.77, b = 0.37) are 4.39 and 3.87, respectively.

3. Database survey

The Inorganic Crystal Structure Database (ICSD) includes some records of BaYbSi₄N₇-type nitrides and oxynitrides that include alkaline-earth and rare-earth elements: BaYbSi₄N₇ and SrYbSi₄N₇ by Huppertz & Schnick (1997b) and SrYSi₄N₇ by Li, Fang et al. (2004). EuYbSi₄N₇ and EuYSi₄N₇ (Huppertz & Schnick, 1997a ; Li, Fang et al., 2004) are isostructural with BaYbSi₄N₇ but do not include an alkaline-earth metal element.

Oxynitrides in which Si and N atoms were partly replaced with Al and O atoms, respectively, have also been reported: BaYb(Si,Al)₄(O,N)₇ (Vinograd et al., 2007 ), BaEr(Si,Al)₄(O,N)₇, BaHo(Si,Al)₄(O,N)₇, BaTm(Si,Al)₄(O,N)₇, BaYb(Si,Al)₄(O,N)₇, SrEr(Si,Al)₄(O,N)₇, SrHo(Si,Al)₄(O,N)₇, SrTm(Si,Al)₄(O,N)₇, SrYb(Si,Al)₄(O,N)₇, EuEr(Si,Al)₄(O,N)₇, EuHo(Si,Al)₄(O,N)₇, EuTm(Si,Al)₄(O,N)₇, and EuYb(Si,Al)₄(O,N)₇ (Lieb et al., 2007).

First-principles calculations of the electronic structures of SrYSi₄N₇ and BaYSi₄N₇ have been reported (Fang et al., 2003 ). Moreover, numerous researchers have investigated the luminescence of oxynitrides and nitrides doped with Ce and Eu, including Ce³⁺-BaYSi₄N₇, Eu²⁺-BaYSi₄N₇ (Li, deWith et al., 2004 ), Ce³⁺-SrYSi₄N₇, Eu²⁺-SrYSi₄N₇ (Li, Fang et al., 2004), Eu²⁺-(Ca,Sr, or Ba)YSi₄N₇, Eu²⁺-(Ca,Sr, or Ba)Y(Si,Al)₄(N,O)₇ (Kurushima et al., 2010 ), Eu²⁺-(Ca, Sr, or Ba)(Sc, Y, or La)Si₄N₇ (Horikawa et al., 2012 ), Eu²⁺-(Ca,Sr, or Ba)Y(Y, La, or Lu)Si₄N₇ (Park et al., 2012), and Eu²⁺-SrScSi₄(N,O)₇ (Porob et al., 2012).

4. Synthesis and crystallization

Powdered Si₃N₄ (Ube Industries Ltd., UBE-SN-E10, 95+%), Ba₃N₂ (Materion Corp., ∼20 mesh 99.7%), Al (Rare Metallic, ∼200 mesh, 99.9%), Lu₂O₃ (Nippon Yttrium Co. Ltd., 99.999%), CeO₂ (Shin-Etsu Chemical Co. Ltd., 99.99%) were weighed out in an Si:Ba:Lu:Al:Ce molar ratio of 3.25:1:1:0.25:0.04 in an Ar-filled glove box (MBRAUN; [O₂] and [H₂O] < 1 ppm). The weighed powders were mixed in an agate mortar, and a disk-shaped pellet with a diameter of 10 mm was formed with a die in an Ar gas-filled glove box. The pellet was placed in a BN crucible (Showa Denko, K. K., 99.5%) with an 18 mm inner diameter and 20 mm height, and a BN lid was placed on it. The BN crucible was heated to 1200°C for 1 h under vacuum using a carbon furnace (VESTA, Shimadzu Industrial Systems Co., Ltd.), and the temperature was maintained at 1200 °C for 1 h. N₂ gas (Taiyo Nippon Sanso Corp., 99.9995+%) was introduced into the furnace to a pressure of 0.85 MPa, and the furnace was then heated to 1900°C for 25 min. After the temperature and the N₂ gas pressure were maintained for 1 h, the sample was cooled to 1200°C for 25 min. The heater power was then cut off. After the furnace reached room temperature, the crucible was removed from the furnace. The chemical composition of the single crystal was analyzed by EPMA (JEOL JXA-8200).

5. Refinement

Crystal data and the data collection details are summarized in Table 1, and the structural refinement details are reported in Table 2. Ordered and disordered models were investigated, and the best result was obtained using an ordered model in which the Ce/Ba mixed site and Lu site are located at the a site and o site, respectively. Because the R and S values were not affected by refinement with ordered models of Al and Si atoms and N and O atoms, the occupancies of the Al/Si and N/O sites were fixed at 0.05/0.95 and 0.99/0.01, respectively. Final refinement was carried out with anisotropic displacement parameters.

Supporting information

CCDC reference: 2034534

Crystal structure: contains datablock I. DOI: https://doi.org/10.1107/S2056989020013158/ru2072sup1.cif

Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S2056989020013158/ru2072Isup2.hkl

checkCIF report

Computing details top

Data collection: Instrument Service (Bruker, 2018); cell refinement: APEX3 (Bruker, 2018); data reduction: SAINT (Bruker, 2018); program(s) used to solve structure: SHELXT2014/5 (Sheldrick, 2015a); program(s) used to refine structure: SHELXL2014/7 (Sheldrick, 2015b); molecular graphics: VESTA (Momma & Izumi, 2011); software used to prepare material for publication: pubCIF (Westrip, 2010).

Barium cerium lutetium aluminosilicate nitride oxide top

Crystal data top

Ba_0.9Ce_0.1LuAl_0.2Si_3.8N_6.9O_0.1	D_x = 5.606 Mg m⁻³
M_r = 1045.99	Mo Kα radiation, λ = 0.71073 Å
Hexagonal, P6₃mc	Cell parameters from 127 reflections
a = 6.0378 (5) Å	θ = 4.2–30.8°
c = 9.8133 (9) Å	µ = 22.95 mm⁻¹
V = 309.82 (6) Å³	T = 301 K
Z = 1	Block, colorless
F(000) = 464	0.13 × 0.07 × 0.02 mm

Data collection top

Bruker D8 QUEST diffractometer	381 reflections with I > 2σ(I)
Detector resolution: 7.3910 pixels mm^-1	R_int = 0.059
ω and σcans	θ_max = 30.5°, θ_min = 3.9°
Absorption correction: multi-scan (SADABS; Bruker, 2018)	h = −7→8
T_min = 0.37, T_max = 0.68	k = −8→8
2818 measured reflections	l = −14→14
395 independent reflections

Refinement top

Refinement on F²	w = 1/[σ²(F_o²) + (0.0313P)² + 0.7267P] where P = (F_o² + 2F_c²)/3
Least-squares matrix: full	(Δ/σ)_max < 0.001
R[F² > 2σ(F²)] = 0.022	Δρ_max = 1.70 e Å⁻³
wR(F²) = 0.055	Δρ_min = −1.40 e Å⁻³
S = 1.04	Extinction correction: SHELXL-2014/7 (Sheldrick 2015b), Fc^*=kFc[1+0.001xFc²λ³/sin(2θ)]^-1/4
395 reflections	Extinction coefficient: 0.0052 (16)
33 parameters	Absolute structure: Refined as an inversion twin.
1 restraint	Absolute structure parameter: 0.10 (3)

Special details top

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. Refined as a two-component inversion twin

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

	x	y	z	U_iso*/U_eq	Occ. (<1)
Lu1	0.3333	0.6667	0.07616 (4)	0.0074 (2)
Ba2	0.3333	0.6667	0.44902 (10)	0.0099 (3)	0.9
Ce2	0.3333	0.6667	0.44902 (10)	0.0099 (3)	0.1
Si1	0.8275 (2)	0.1725 (2)	0.2646 (5)	0.0084 (5)	0.95
Al1	0.8275 (2)	0.1725 (2)	0.2646 (5)	0.0084 (5)	0.05
Si2	0.0000	0.0000	0.0006 (7)	0.0071 (9)	0.95
Al2	0.0000	0.0000	0.0006 (7)	0.0071 (9)	0.05
N1	0.5097 (8)	0.4903 (8)	0.2112 (11)	0.0087 (14)	0.9857
O1	0.5097 (8)	0.4903 (8)	0.2112 (11)	0.0087 (14)	0.0143
N2	0.8474 (8)	0.1526 (8)	0.4404 (9)	0.0123 (19)	0.9857
O2	0.8474 (8)	0.1526 (8)	0.4404 (9)	0.0123 (19)	0.0143
N3	0.0000	0.0000	0.1880 (18)	0.016 (3)	0.9857
O3	0.0000	0.0000	0.1880 (18)	0.016 (3)	0.0143

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
Lu1	0.0075 (3)	0.0075 (3)	0.0072 (4)	0.00374 (13)	0.000	0.000
Ba2	0.0098 (4)	0.0098 (4)	0.0101 (6)	0.00489 (18)	0.000	0.000
Ce2	0.0098 (4)	0.0098 (4)	0.0101 (6)	0.00489 (18)	0.000	0.000
Si1	0.0076 (8)	0.0076 (8)	0.0097 (10)	0.0035 (9)	−0.0002 (6)	0.0002 (6)
Al1	0.0076 (8)	0.0076 (8)	0.0097 (10)	0.0035 (9)	−0.0002 (6)	0.0002 (6)
Si2	0.0061 (10)	0.0061 (10)	0.009 (3)	0.0031 (5)	0.000	0.000
Al2	0.0061 (10)	0.0061 (10)	0.009 (3)	0.0031 (5)	0.000	0.000
N1	0.007 (2)	0.007 (2)	0.010 (3)	0.002 (2)	0.0010 (16)	−0.0010 (16)
O1	0.007 (2)	0.007 (2)	0.010 (3)	0.002 (2)	0.0010 (16)	−0.0010 (16)
N2	0.015 (3)	0.015 (3)	0.011 (5)	0.011 (4)	0.0010 (14)	−0.0010 (14)
O2	0.015 (3)	0.015 (3)	0.011 (5)	0.011 (4)	0.0010 (14)	−0.0010 (14)
N3	0.018 (5)	0.018 (5)	0.013 (8)	0.009 (3)	0.000	0.000
O3	0.018 (5)	0.018 (5)	0.013 (8)	0.009 (3)	0.000	0.000

Geometric parameters (Å, º) top

Lu1—O1ⁱ	2.271 (10)	Si1—Ba2^ix	3.521 (2)
Lu1—N1ⁱ	2.271 (10)	Si1—Ba2^x	3.521 (2)
Lu1—O1ⁱⁱ	2.271 (10)	Si2—O2^xi	1.701 (9)
Lu1—N1ⁱⁱ	2.271 (10)	Si2—N2^xi	1.701 (9)
Lu1—N1	2.271 (10)	Si2—O2^iv	1.701 (9)
Lu1—O2ⁱⁱⁱ	2.312 (9)	Si2—N2^iv	1.701 (9)
Lu1—N2ⁱⁱⁱ	2.312 (9)	Si2—O2^xii	1.701 (9)
Lu1—O2^iv	2.312 (9)	Si2—N2^xii	1.701 (9)
Lu1—N2^iv	2.312 (9)	Si2—N3	1.839 (19)
Lu1—O2^v	2.312 (9)	Si2—Ba2^xiii	3.5225 (11)
Lu1—N2^v	2.312 (9)	Si2—Ba2^xiv	3.5225 (11)
Ba2—N1	2.975 (10)	Si2—Ba2^v	3.5226 (11)
Ba2—O1ⁱⁱ	2.975 (10)	N1—Al1^vii	1.743 (6)
Ba2—N1ⁱⁱ	2.975 (10)	N1—Si1^vii	1.743 (6)
Ba2—O1ⁱ	2.975 (10)	N1—Al1^vi	1.743 (6)
Ba2—N1ⁱ	2.975 (10)	N1—Si1^vi	1.743 (6)
Ba2—O2^vi	3.0236 (5)	N1—Ba2^xiv	3.052 (10)
Ba2—N2^vi	3.0236 (5)	N2—Al2^xv	1.701 (9)
Ba2—O2^vii	3.0236 (5)	N2—Si2^xv	1.701 (9)
Ba2—N2^vii	3.0236 (5)	N2—Lu1^xv	2.313 (9)
Ba2—O2^viii	3.0237 (6)	N2—Ba2^ix	3.0237 (6)
Ba2—N2^viii	3.0237 (6)	N2—Ce2^ix	3.0237 (6)
Si1—N2	1.738 (9)	N2—Ce2^x	3.0237 (6)
Si1—O1^vi	1.743 (6)	N2—Ba2^x	3.0237 (6)
Si1—N1^vi	1.743 (6)	N3—Al1^vi	1.954 (7)
Si1—O1^vii	1.743 (6)	N3—Si1^vi	1.954 (7)
Si1—N1^vii	1.743 (6)	N3—Al1^xvi	1.954 (7)
Si1—O3^ix	1.954 (7)	N3—Si1^xvi	1.954 (7)
Si1—N3^ix	1.954 (7)	N3—Si1^viii	1.954 (7)
Si1—Al1^vii	2.914 (4)	N3—Al1^viii	1.954 (7)
Si1—Al1^vi	2.914 (4)

O1ⁱ—Lu1—N1ⁱ	0.0	N1^vi—Si1—Al1^vi	88.8 (2)
O1ⁱ—Lu1—O1ⁱⁱ	89.4 (3)	O1^vii—Si1—Al1^vi	33.3 (3)
N1ⁱ—Lu1—O1ⁱⁱ	89.4 (3)	N1^vii—Si1—Al1^vi	33.3 (3)
O1ⁱ—Lu1—N1ⁱⁱ	89.4	O3^ix—Si1—Al1^vi	143.1 (3)
N1ⁱ—Lu1—N1ⁱⁱ	89.4 (3)	N3^ix—Si1—Al1^vi	143.1 (3)
O1ⁱⁱ—Lu1—N1ⁱⁱ	0.0	Al1^vii—Si1—Al1^vi	60.0
O1ⁱ—Lu1—N1	89.4	N2—Si1—Ba2^ix	59.17 (6)
N1ⁱ—Lu1—N1	89.4 (3)	O1^vi—Si1—Ba2^ix	57.6 (3)
O1ⁱⁱ—Lu1—N1	89.4	N1^vi—Si1—Ba2^ix	57.6 (3)
N1ⁱⁱ—Lu1—N1	89.4 (3)	O1^vii—Si1—Ba2^ix	149.6 (3)
O1ⁱ—Lu1—O2ⁱⁱⁱ	90.2 (2)	N1^vii—Si1—Ba2^ix	149.6 (3)
N1ⁱ—Lu1—O2ⁱⁱⁱ	90.2 (2)	O3^ix—Si1—Ba2^ix	100.5 (2)
O1ⁱⁱ—Lu1—O2ⁱⁱⁱ	90.2 (2)	N3^ix—Si1—Ba2^ix	100.5 (2)
N1ⁱⁱ—Lu1—O2ⁱⁱⁱ	90.2 (2)	Al1^vii—Si1—Ba2^ix	65.56 (4)
N1—Lu1—O2ⁱⁱⁱ	179.5 (3)	Al1^vi—Si1—Ba2^ix	116.34 (4)
O1ⁱ—Lu1—N2ⁱⁱⁱ	90.2 (2)	N2—Si1—Ba2^x	59.17 (6)
N1ⁱ—Lu1—N2ⁱⁱⁱ	90.2 (2)	O1^vi—Si1—Ba2^x	149.6 (3)
O1ⁱⁱ—Lu1—N2ⁱⁱⁱ	90.2 (2)	N1^vi—Si1—Ba2^x	149.6 (3)
N1ⁱⁱ—Lu1—N2ⁱⁱⁱ	90.2 (2)	O1^vii—Si1—Ba2^x	57.6 (3)
N1—Lu1—N2ⁱⁱⁱ	179.5 (3)	N1^vii—Si1—Ba2^x	57.6 (3)
O2ⁱⁱⁱ—Lu1—N2ⁱⁱⁱ	0.0	O3^ix—Si1—Ba2^x	100.5 (2)
O1ⁱ—Lu1—O2^iv	179.5 (3)	N3^ix—Si1—Ba2^x	100.5 (2)
N1ⁱ—Lu1—O2^iv	179.5 (3)	Al1^vii—Si1—Ba2^x	116.34 (4)
O1ⁱⁱ—Lu1—O2^iv	90.2 (2)	Al1^vi—Si1—Ba2^x	65.56 (4)
N1ⁱⁱ—Lu1—O2^iv	90.2 (2)	Ba2^ix—Si1—Ba2^x	118.08 (12)
N1—Lu1—O2^iv	90.2 (2)	O2^xi—Si2—N2^xi	0.0
O2ⁱⁱⁱ—Lu1—O2^iv	90.1 (3)	O2^xi—Si2—O2^iv	108.6 (4)
N2ⁱⁱⁱ—Lu1—O2^iv	90.1 (3)	N2^xi—Si2—O2^iv	108.6 (4)
O1ⁱ—Lu1—N2^iv	179.5 (3)	O2^xi—Si2—N2^iv	108.6
N1ⁱ—Lu1—N2^iv	179.5 (3)	N2^xi—Si2—N2^iv	108.6 (4)
O1ⁱⁱ—Lu1—N2^iv	90.2 (2)	O2^iv—Si2—N2^iv	0.0
N1ⁱⁱ—Lu1—N2^iv	90.2 (2)	O2^xi—Si2—O2^xii	108.6 (4)
N1—Lu1—N2^iv	90.2 (2)	N2^xi—Si2—O2^xii	108.6 (4)
O2ⁱⁱⁱ—Lu1—N2^iv	90.1	O2^iv—Si2—O2^xii	108.6 (4)
N2ⁱⁱⁱ—Lu1—N2^iv	90.1 (3)	N2^iv—Si2—O2^xii	108.6 (4)
O2^iv—Lu1—N2^iv	0.0	O2^xi—Si2—N2^xii	108.6
O1ⁱ—Lu1—O2^v	90.2 (2)	N2^xi—Si2—N2^xii	108.6 (4)
N1ⁱ—Lu1—O2^v	90.2 (2)	O2^iv—Si2—N2^xii	108.6
O1ⁱⁱ—Lu1—O2^v	179.5 (3)	N2^iv—Si2—N2^xii	108.6 (4)
N1ⁱⁱ—Lu1—O2^v	179.5 (3)	O2^xii—Si2—N2^xii	0.0
N1—Lu1—O2^v	90.2 (2)	O2^xi—Si2—N3	110.3 (3)
O2ⁱⁱⁱ—Lu1—O2^v	90.1 (3)	N2^xi—Si2—N3	110.3 (3)
N2ⁱⁱⁱ—Lu1—O2^v	90.1 (3)	O2^iv—Si2—N3	110.3 (3)
O2^iv—Lu1—O2^v	90.1 (3)	N2^iv—Si2—N3	110.3 (3)
N2^iv—Lu1—O2^v	90.1 (3)	O2^xii—Si2—N3	110.3 (3)
O1ⁱ—Lu1—N2^v	90.2 (2)	N2^xii—Si2—N3	110.3 (3)
N1ⁱ—Lu1—N2^v	90.2 (2)	O2^xi—Si2—Ba2^xiii	59.07 (3)
O1ⁱⁱ—Lu1—N2^v	179.5 (3)	N2^xi—Si2—Ba2^xiii	59.07 (3)
N1ⁱⁱ—Lu1—N2^v	179.5 (3)	O2^iv—Si2—Ba2^xiii	151.4 (4)
N1—Lu1—N2^v	90.2 (2)	N2^iv—Si2—Ba2^xiii	151.4 (4)
O2ⁱⁱⁱ—Lu1—N2^v	90.1	O2^xii—Si2—Ba2^xiii	59.07 (3)
N2ⁱⁱⁱ—Lu1—N2^v	90.1 (3)	N2^xii—Si2—Ba2^xiii	59.07 (3)
O2^iv—Lu1—N2^v	90.1	N3—Si2—Ba2^xiii	98.27 (11)
N2^iv—Lu1—N2^v	90.1 (3)	O2^xi—Si2—Ba2^xiv	151.4 (4)
O2^v—Lu1—N2^v	0.0	N2^xi—Si2—Ba2^xiv	151.4 (4)
N1—Ba2—O1ⁱⁱ	65.0	O2^iv—Si2—Ba2^xiv	59.07 (3)
N1—Ba2—N1ⁱⁱ	65.0 (3)	N2^iv—Si2—Ba2^xiv	59.07 (3)
O1ⁱⁱ—Ba2—N1ⁱⁱ	0.0	O2^xii—Si2—Ba2^xiv	59.07 (3)
N1—Ba2—O1ⁱ	65.0	N2^xii—Si2—Ba2^xiv	59.07 (3)
O1ⁱⁱ—Ba2—O1ⁱ	65.0 (3)	N3—Si2—Ba2^xiv	98.27 (11)
N1ⁱⁱ—Ba2—O1ⁱ	65.0 (3)	Ba2^xiii—Si2—Ba2^xiv	117.97 (6)
N1—Ba2—N1ⁱ	65.0 (3)	O2^xi—Si2—Ba2^v	59.07 (3)
O1ⁱⁱ—Ba2—N1ⁱ	65.0	N2^xi—Si2—Ba2^v	59.07 (3)
N1ⁱⁱ—Ba2—N1ⁱ	65.0 (3)	O2^iv—Si2—Ba2^v	59.07 (3)
O1ⁱ—Ba2—N1ⁱ	0.0	N2^iv—Si2—Ba2^v	59.07 (3)
N1—Ba2—O2^vi	57.1 (2)	O2^xii—Si2—Ba2^v	151.4 (4)
O1ⁱⁱ—Ba2—O2^vi	87.01 (17)	N2^xii—Si2—Ba2^v	151.4 (4)
N1ⁱⁱ—Ba2—O2^vi	87.01 (17)	N3—Si2—Ba2^v	98.27 (11)
O1ⁱ—Ba2—O2^vi	122.0 (3)	Ba2^xiii—Si2—Ba2^v	117.97 (6)
N1ⁱ—Ba2—O2^vi	122.0 (3)	Ba2^xiv—Si2—Ba2^v	117.97 (6)
N1—Ba2—N2^vi	57.1 (2)	Al1^vii—N1—Si1^vii	0.0
O1ⁱⁱ—Ba2—N2^vi	87.01 (17)	Al1^vii—N1—Al1^vi	113.4 (6)
N1ⁱⁱ—Ba2—N2^vi	87.01 (17)	Si1^vii—N1—Al1^vi	113.4 (6)
O1ⁱ—Ba2—N2^vi	122.0 (3)	Al1^vii—N1—Si1^vi	113.4
N1ⁱ—Ba2—N2^vi	122.0 (3)	Si1^vii—N1—Si1^vi	113.4 (6)
O2^vi—Ba2—N2^vi	0.0	Al1^vi—N1—Si1^vi	0.0
N1—Ba2—O2^vii	57.1 (2)	Al1^vii—N1—Lu1	123.3 (3)
O1ⁱⁱ—Ba2—O2^vii	122.0 (3)	Si1^vii—N1—Lu1	123.3 (3)
N1ⁱⁱ—Ba2—O2^vii	122.0 (3)	Al1^vi—N1—Lu1	123.3 (3)
O1ⁱ—Ba2—O2^vii	87.01 (17)	Si1^vi—N1—Lu1	123.3 (3)
N1ⁱ—Ba2—O2^vii	87.01 (17)	Al1^vii—N1—Ba2	92.8 (4)
O2^vi—Ba2—O2^vii	65.6 (3)	Si1^vii—N1—Ba2	92.8 (4)
N2^vi—Ba2—O2^vii	65.6 (3)	Al1^vi—N1—Ba2	92.8 (4)
N1—Ba2—N2^vii	57.1 (2)	Si1^vi—N1—Ba2	92.8 (4)
O1ⁱⁱ—Ba2—N2^vii	122.0 (3)	Lu1—N1—Ba2	87.4 (2)
N1ⁱⁱ—Ba2—N2^vii	122.0 (3)	Al1^vii—N1—Ba2^xiv	90.4 (3)
O1ⁱ—Ba2—N2^vii	87.01 (17)	Si1^vii—N1—Ba2^xiv	90.4 (3)
N1ⁱ—Ba2—N2^vii	87.01 (17)	Al1^vi—N1—Ba2^xiv	90.4 (3)
O2^vi—Ba2—N2^vii	65.6	Si1^vi—N1—Ba2^xiv	90.4 (3)
N2^vi—Ba2—N2^vii	65.6 (3)	Lu1—N1—Ba2^xiv	86.8 (3)
O2^vii—Ba2—N2^vii	0.0	Ba2—N1—Ba2^xiv	174.2 (4)
N1—Ba2—O2^viii	87.01 (17)	Al2^xv—N2—Si2^xv	0.0
O1ⁱⁱ—Ba2—O2^viii	57.1 (2)	Al2^xv—N2—Si1	117.2 (5)
N1ⁱⁱ—Ba2—O2^viii	57.1 (2)	Si2^xv—N2—Si1	117.2 (5)
O1ⁱ—Ba2—O2^viii	122.0 (3)	Al2^xv—N2—Lu1^xv	124.5 (5)
N1ⁱ—Ba2—O2^viii	122.0 (3)	Si2^xv—N2—Lu1^xv	124.5 (5)
O2^vi—Ba2—O2^viii	54.4 (3)	Si1—N2—Lu1^xv	118.3 (4)
N2^vi—Ba2—O2^viii	54.4 (3)	Al2^xv—N2—Ba2^ix	92.07 (17)
O2^vii—Ba2—O2^viii	119.924 (18)	Si2^xv—N2—Ba2^ix	92.07 (17)
N2^vii—Ba2—O2^viii	119.924 (18)	Si1—N2—Ba2^ix	91.25 (18)
N1—Ba2—N2^viii	87.01 (17)	Lu1^xv—N2—Ba2^ix	86.80 (17)
O1ⁱⁱ—Ba2—N2^viii	57.1 (2)	Al2^xv—N2—Ce2^ix	92.07 (17)
N1ⁱⁱ—Ba2—N2^viii	57.1 (2)	Si2^xv—N2—Ce2^ix	92.07 (17)
O1ⁱ—Ba2—N2^viii	122.0 (3)	Si1—N2—Ce2^ix	91.25 (18)
N1ⁱ—Ba2—N2^viii	122.0 (3)	Lu1^xv—N2—Ce2^ix	86.80 (17)
O2^vi—Ba2—N2^viii	54.4	Ba2^ix—N2—Ce2^ix	0.0
N2^vi—Ba2—N2^viii	54.4 (3)	Al2^xv—N2—Ce2^x	92.07 (17)
O2^vii—Ba2—N2^viii	119.9	Si2^xv—N2—Ce2^x	92.07 (17)
N2^vii—Ba2—N2^viii	119.924 (18)	Si1—N2—Ce2^x	91.25 (18)
O2^viii—Ba2—N2^viii	0.0	Lu1^xv—N2—Ce2^x	86.80 (17)
N2—Si1—O1^vi	111.0 (4)	Ba2^ix—N2—Ce2^x	173.6 (3)
N2—Si1—N1^vi	111.0 (4)	Ce2^ix—N2—Ce2^x	173.6 (3)
O1^vi—Si1—N1^vi	0.0	Al2^xv—N2—Ba2^x	92.07 (17)
N2—Si1—O1^vii	111.0 (4)	Si2^xv—N2—Ba2^x	92.07 (17)
O1^vi—Si1—O1^vii	109.3 (6)	Si1—N2—Ba2^x	91.25 (18)
N1^vi—Si1—O1^vii	109.3 (6)	Lu1^xv—N2—Ba2^x	86.80 (17)
N2—Si1—N1^vii	111.0 (4)	Ba2^ix—N2—Ba2^x	173.6 (3)
O1^vi—Si1—N1^vii	109.3	Ce2^ix—N2—Ba2^x	173.6
N1^vi—Si1—N1^vii	109.3 (6)	Ce2^x—N2—Ba2^x	0.0
O1^vii—Si1—N1^vii	0.0	Si2—N3—Al1^vi	112.6 (5)
N2—Si1—O3^ix	105.7 (6)	Si2—N3—Si1^vi	112.6 (5)
O1^vi—Si1—O3^ix	109.9 (4)	Al1^vi—N3—Si1^vi	0.0
N1^vi—Si1—O3^ix	109.9 (4)	Si2—N3—Al1^xvi	112.6 (5)
O1^vii—Si1—O3^ix	109.9 (4)	Al1^vi—N3—Al1^xvi	106.2 (5)
N1^vii—Si1—O3^ix	109.9 (4)	Si1^vi—N3—Al1^xvi	106.2 (5)
N2—Si1—N3^ix	105.7 (6)	Si2—N3—Si1^xvi	112.6 (5)
O1^vi—Si1—N3^ix	109.9 (4)	Al1^vi—N3—Si1^xvi	106.2
N1^vi—Si1—N3^ix	109.9 (4)	Si1^vi—N3—Si1^xvi	106.2 (5)
O1^vii—Si1—N3^ix	109.9 (4)	Al1^xvi—N3—Si1^xvi	0.0
N1^vii—Si1—N3^ix	109.9 (4)	Si2—N3—Si1^viii	112.6 (5)
O3^ix—Si1—N3^ix	0.0	Al1^vi—N3—Si1^viii	106.2
N2—Si1—Al1^vii	96.0 (2)	Si1^vi—N3—Si1^viii	106.2 (5)
O1^vi—Si1—Al1^vii	33.3 (3)	Al1^xvi—N3—Si1^viii	106.2
N1^vi—Si1—Al1^vii	33.3 (3)	Si1^xvi—N3—Si1^viii	106.2 (5)
O1^vii—Si1—Al1^vii	88.8 (2)	Si2—N3—Al1^viii	112.6 (5)
N1^vii—Si1—Al1^vii	88.8 (2)	Al1^vi—N3—Al1^viii	106.2 (5)
O3^ix—Si1—Al1^vii	143.1 (3)	Si1^vi—N3—Al1^viii	106.2 (5)
N3^ix—Si1—Al1^vii	143.1 (3)	Al1^xvi—N3—Al1^viii	106.2 (5)
N2—Si1—Al1^vi	96.0 (2)	Si1^xvi—N3—Al1^viii	106.2 (5)
O1^vi—Si1—Al1^vi	88.8 (2)	Si1^viii—N3—Al1^viii	0.0 (2)

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

Disordered model (Ce_0.1Ba_0.4Lu_0.5)(Ba_0.5Lu_0.5) (Al_0.05Si_0.95)₄ (N_0.99O_0.01)₇ top

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.042, 0.115, 1.32
No. of reflections	395
No. of parameters	39
No. of restraints	1
Δρ_max, Δρ_min (e Å^-3)	5.52, -3.46
Absolute structure	Refined as an inversion twin
Absolute structure parameter	0.12 (9)

Acknowledgements

We thank Ms Y. Suzuki for preparing the sample and Mr T. Kamaya for the EPMA measurement. This work is supported by the joint research budget between Tohoku University and the Mitsubishi Chemical Corporation (J190002825).

Funding information

Funding for this research was provided by: a joint research with Tohoku University and the Mitsu-bishi Chemical Group, Science and Technology ResearchCenter, Inc. J190002825.

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