(Li_0.91Mn_0.09)Mn₂O₄

Lithium manganese oxide crystals with composition (Li_0.91Mn_0.09)Mn₂O₄ were synthesized by a flux method. The crystals have a structure closely related to that of the cubic spinel LiMn₂O₄, but 9% of the lithium ions in the tetrahedral 4a site are substituted by Mn²⁺ ions. This substitution lowers the average Mn oxidation state below 3.5+, resulting in a Jahn-Teller distortion of the MnO₆ octahedron.

Computing details

Data collection: STOE IPDS; cell refinement: Rigaku AFC-6R; data reduction: X-RED and X-SHAPE (Stoe & Cie, 1996); program(s) used to refine structure: DUPALS (Lundgren, 1983); molecular graphics: ORTEPII (Johnson, 1976); software used to prepare material for publication: DISTAN (Lundgren, 1983).

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Crystal data

(Li0.91Mn0.09)Mn2O4	? #Insert any comments here.
Mr = 185.13	Dx = 4.304 Mg m^−3
Tetragonal, I41/amd	Mo Kα1 radiation, λ = 0.71073 Å
Hall symbol: -I 4bd 2	Cell parameters from 25 reflections
a = 5.7502 (9) Å	θ = 19.0–20.0°
c = 8.637 (3) Å	µ = 8.78 mm^−1
V = 285.58 (11) Å^3	T = 293 K
Z = 4	Octahedral, black
F(000) = 476	0.3 × 0.3 × 0.2 mm

Data collection

STOE IPDS diffractometer	103 independent reflections
Radiation source: xray tube	1225 reflections with Inet > −15.0σ(Inet)
Graphite monochromator	Rint = 0.049
ω scan b/P/b	θmax = 28.0°, θmin = 4.3°
Absorption correction: numerical JANA'98 (Petriçek & Dušek, 1997)	h = −7→7
Tmin = 0.182, Tmax = 0.377	k = −7→7
1225 measured reflections	l = −11→11

Refinement

Refinement on F^2	w = 1/[σ^2(F)^2 + 0.01F^2]
Least-squares matrix: full	(Δ/σ)max = 0.1
R[F^2 > 2σ(F^2)] = 0.038	Δρmax = 0.52 e Å^−3
wR(F^2) = 0.083	Δρmin = −0.55 e Å^−3
S = 3.94	Extinction correction: Becker & Coppens (1974), isotropic type 2
1225 reflections	Extinction coefficient: 0.8 (1) x 10^3
14 parameters

Special details

Experimental. ? #Insert any special details here.

Refinement. ? #Insert any special details here.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq	Occ. (<1)
Mn1	0.5000	0.0000	0.0000	0.0103 (2)
O	0.2762 (2)	0.2500	0.01191 (17)	0.0195 (8)
Mn2	0.0000	0.7500	0.1250	0.0190 (8)*	0.093 (3)
Li	0.0000	0.7500	0.1250	0.0190 (8)*	0.907 (3)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Mn1	0.0079 (2)	0.0070 (2)	0.0159 (2)	0.0000	0.0000	−0.00166 (10)
O	0.0125 (8)	0.0125 (9)	0.0336 (9)	0.0000	−0.0028 (7)	0.0000

Geometric parameters (Å, º)

Mn1^i—Mn1	2.9657 (5)	O^i—O	2.670 (3)
Mn1^ii—Mn1	2.8751 (4)	O^v—O	2.574 (3)
Mn1—O	1.9322 (10)	O^vi—O	2.8824 (5)
Mn1—O^iii	2.0619 (16)	Mn2^vii—O	1.9800 (15)
O^iv—O	2.9734 (5)	Li^vii—O	1.9800 (15)
O—Mn1—O^iii	96.17 (6)	Mn1—O—Li	120.16 (5)
O—Mn1—O^viii	180	Mn1^i—O—Mn2^vii	122.48 (7)
O—Mn1—O^v	83.53 (6)	Mn1—O—Li	122.48 (7)
O—Mn1—O^vi	96.47 (6)	O^xi—Mn2—O^xii	110.90 (4)
O—Mn1—O^ix	83.83 (6)	O^xi—Mn2—O^xiii	106.66 (9)
Mn1—O—Mn1^i	95.84 (5)	O^xi—Li—O^xii	110.90 (4)
Mn1—O—Mn1^x	96.14 (6)	O^xi—Li—O^xiii	106.66 (9)
Mn1—O—Mn2^vii	120.16 (5)

Symmetry codes: (i) y+1/4, −x+3/4, −z+1/4; (ii) −x+1, −y−1/2, z; (iii) y+1/4, −x+1/4, z−1/4; (iv) −y+1/4, x−1/4, z+1/4; (v) −x+1, y, z; (vi) x, −y, −z; (vii) x, y−1/2, −z; (viii) −x+1, −y, −z; (ix) −y+3/4, x−1/4, −z+1/4; (x) −x+1, −y+1/2, z; (xi) −y+1/4, x+3/4, z+1/4; (xii) −x, y+1/2, −z; (xiii) y−1/4, −x+3/4, z+1/4.