La3Si6N11

Hisanori Yamane; Toshiki Nagura; Tomohiro Miyazaki

doi:10.1107/S1600536814009234

. 2014 May 3;70(Pt 6):i23–i24. doi: 10.1107/S1600536814009234

La₃Si₆N₁₁

Hisanori Yamane ^a,^*, Toshiki Nagura ^a, Tomohiro Miyazaki ^a

PMCID: PMC4051113 PMID: 24940184

Abstract

Colorless transparent single crystals of trilanthanum hexasilicon undecanitrogen, La₃Si₆N₁₁, were prepared at 0.85 MPa of N₂ and 2273 K. The title compound is isotypic with Sm₃Si₆N₁₁. Silicon-centered nitrogen tetrahedra form a three-dimensional network structure by sharing their corners. Layers of one type of SiN₄ tetrahedra and slabs composed of the two different La³⁺ cations and the other type of SiN₄ tetrahedra are alternately stacked along the c axis of the tetragonal unit cell. The site symmetries of the two La³⁺ cations are are ..m and 4.., respectively.

Related literature

For the lattice parameters of La₃Si₆N₁₁, see: Woike & Jeitschko (1995 ▶). For isotypic Ce₃Si₆N₁₁, Pr₃Si₆N₁₁, Nd₃Si₆N₁₁, Sm₃Si₆N₁₁ and La₃Si₅AlON₁₀, see: Gaudé et al. (1983 ▶); Woike & Jeitschko (1995 ▶); Schlieper & Schnick (1995 ▶, 1996 ▶); Lauterbach & Schnick (2000 ▶). Recently, La₃Si₆N₁₁ has received attention as a host crystal of phosphors by Ce³⁺ doping; for La₃Si₆N₁₁:Ce, (La,Ca)₃Si₆N₁₁:Ce, see: Seto et al. (2009 ▶); Suehiro et al. (2011 ▶); George et al. (2013 ▶). For the ionic radii of La³⁺ and Sm³⁺ cations in nitrides, see: Baur (1987 ▶). For the Madelung energies of La₃Si₆N₁₁, LaN and Si₃N₄, see: Hoppe (1966 ▶, 1970 ▶), Klemm & Winkelmann (1956 ▶) and Boulay et al. (2004 ▶), respectively.

Experimental

Crystal data

La₃Si₆N₁₁
M _r = 739.38
Tetragonal,
a = 10.1988 (4) Å
c = 4.84153 (19) Å
V = 503.60 (3) Å³
Z = 2
Mo Kα radiation
μ = 13.22 mm⁻¹
T = 293 K
0.15 × 0.14 × 0.03 mm

Data collection

Rigaku R-AXIS RAPID II diffractometer
Absorption correction: numerical (NUMABS; Higashi, 1999 ▶) T _min = 0.219, T _max = 0.726
4700 measured reflections
624 independent reflections
599 reflections with I > 2σ(I)
R _int = 0.039

Refinement

R[F ² > 2σ(F ²)] = 0.017
wR(F ²) = 0.030
S = 1.20
624 reflections
39 parameters
1 restraint
Δρ_max = 0.83 e Å⁻³
Δρ_min = −0.90 e Å⁻³
Absolute structure: Flack (1983 ▶), 275 Friedel pairs
Absolute structure parameter: 0.05 (3)

Data collection: PROCESS-AUTO (Rigaku/MSC, 2005 ▶); cell refinement: PROCESS-AUTO; data reduction: PROCESS-AUTO; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: VESTA (Momma & Izumi, 2008 ▶); software used to prepare material for publication: SHELXL97.

Supplementary Material

Crystal structure: contains datablock(s) I. DOI: 10.1107/S1600536814009234/ru2057sup1.cif

e-70-00i23-sup1.cif^{(21.6KB, cif)}

Structure factors: contains datablock(s) I. DOI: 10.1107/S1600536814009234/ru2057Isup2.hkl

e-70-00i23-Isup2.hkl^{(31.3KB, hkl)}

CCDC reference: 999175

Additional supporting information: crystallographic information; 3D view; checkCIF report

Table 1. Selected bond lengths (Å).

La1—N1ⁱ	2.551 (3)
La1—N1ⁱⁱ	2.551 (3)
La1—N4	2.6227 (7)
La1—N2ⁱⁱⁱ	2.674 (3)
La1—N2^iv	2.674 (3)
La1—N2^v	2.853 (3)
La1—N2^vi	2.853 (3)
La1—N3^vii	2.864 (5)
La2—N2	2.644 (3)
La2—N2^viii	2.644 (3)
La2—N2^ix	2.644 (3)
La2—N2^x	2.644 (3)
La2—N1^xi	2.649 (3)
La2—N1^xii	2.649 (3)
La2—N1^xiii	2.649 (3)
La2—N1^xiv	2.649 (3)
Si1—N1^x	1.724 (3)
Si1—N2	1.729 (4)
Si1—N1	1.743 (3)
Si1—N3^xv	1.776 (3)
Si2—N4^xvi	1.6868 (14)
Si2—N2^xvii	1.725 (4)
Si2—N2^xvi	1.725 (4)
Si2—N3^xiv	1.764 (5)

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Symmetry codes: (i) Inline graphic ; (ii) ; (iii) ; (iv) ; (v) ; (vi) ; (vii) ; (viii) ; (ix) ; (x) ; (xi) ; (xii) ; (xiii) ; (xiv) ; (xv) ; (xvi) ; (xvii) .

Acknowledgments

We are grateful to Dr Kyota Ueda and Mr Satoshi Shimooka (Mitsubishi Chemical Group, Science and Technology Research Center, Inc.) for their help with the sample preparation. This work was supported in part by a Grant-in-Aid for Scientific Resarch (C) (No. 25420701, 2013) from the Ministry of Education, Culture, Sports and Technology (MEXT), Japan.

supplementary crystallographic information

1. Comment

Woike and Jeitschko (1995) measured the tetragonal unit cell parameters of La₃Si₆N₁₁ by X-ray powder diffraction and showed that Ln₃Si₆N₁₁, Ln = Sr, as well as Ce, Pr, Nd, is isostructural with Sm₃Si₆N₁₁ firstly reported by Gaudé et al. (1983). The crystal structure of Sm₃Si₆N₁₁ was analyzed by single crystal X-ray diffraction with the noncentrosymmetric space group P4bm (Woike & Jeitschko, 1995). The crystal structures of isotypic compounds, Ce₃Si₆N₁₁, Pr₃Si₆N₁₁ and La₃Si₅AlON₁₀ (Schlieper & Schnick, 1995, 1996; Lauterbach & Schinick, 2000), have also been studied, while there is no report on the structure parameters of La₃Si₆N₁₁. Recently, La₃Si₆N₁₁ has received attention as host crystals of phosphors by Ce³⁺ doping (Seto et al., 2009; Suehiro et al., 2011; George et al., 2013).

The cell parameters and volume determined by single crystal X-ray diffraction are close to those (a = 10.189 (1) Å, c = 4.837 (2) Å, V = 502.2 (2) Å³) reported in the previous study (Woike & Jeitschko, 1995). Fig. 1 shows the coordination environments of the Si1, Si2, La1 and La2 atoms. Si1 atoms are at general positions 8d and Si2 at special position 4c. Si1—N and Si2—N bond lengths are in the ranges of 1.724 (3)–1.776 (3) Å, and 1.6868 (14)–1.764 (5) Å, respectively. These ranges are comparable with those (1.709–1.775 Å and 1.675–1.753 Å) reported for Sm₃Si₆N₁₁ (Woike & Jeitschko, 1995).

La1 atoms at 4c site with site symmetry (..m) and La2 atom at 2a site with (4..) are surrounded by 8 N atoms. La1—N distances of 2.551 (3)–2.864 (5) Å and La2—N distances of 2.644 (3) Å and 2.649 (3) Å are longer than the distances of Sm1—N (2.417–2.866 Å ) and Sm2—N (2.557 Å and 2.571 Å) in Sm₃Si₆N₁₁, which is in accordance with the difference between the effective ionic radii of La (1.25 Å) and Sm (1.15 Å) atoms in nitrides (Baur, 1987).

The site potentials calculated with the structure parameters using VESTA program (Momma & Izumi 2008) are -27.3 V (La1³⁺), 28.5 V (La2³⁺), -51.9 V (Si1⁴⁺), -51.6 V (Si2⁴⁺) and 36.6–39.4 V (N^3- sites). The value of the Madelung energy for La₃Si₆N₁₁ (MAPLE, MAdelung Part of Lattice Energy, Hoppe 1966, 1970) is -132,000 kJ/mol, which are almost identical to the value of -131,300 kJ/mol (difference Δ = 0.5%) of the Madelung energies: LaN (-8,240 kJ/mol, Klemm & Winkelman, 1956) and Si₃N₄ (-53,300 kJ/mol, Boulay et al., 2004) with the formula 3LaN + 2Si₃N₄→ La₃Si₆N₁₁.

2. Experimental

Starting powders of LaN (0.6205 g, Koujundo Chemical Laboratory Co., Ltd.) and Si₃N₄ (0.3795 g, SN—E10, Ube Industries, Ltd.) were weighed and mixed in an aluminum mortar with a pestle in an Ar gas-filled glove box (O₂ and H₂O < 1 ppm). A sintered BN crucible (UHS-FL, inside diameter 18 mm; depth 18 mm, Showa Denko K. K., 99.5%) was loaded with the powder mixture and heated at 0.9 MPa of N₂ (99.9995%) and 1800°C for 2 h with a gas pressure carbon furnace (VESTA, Shimadzu Mectem, Inc.). The obtained product was powdered with the mortar and pestle and heated at 0.85 MPa of N₂ and 2000°C for 4 h. Colorless transparent single crystals (size less than 0.15 mm) were obtained in the product.

3. Refinement

Because the principal mean square atomic displacement for the N2 site was not positive definite, isotropic displacement parameters were refined for all nitrogen sites. The highest peak in the difference electron density map was 1.11 Å from La2 while the deepest hole was 0.79 Å from the same atom.