New quaternary carbide Mg1.52Li0.24Al0.24C0.86 as a disorder derivative of the family of hexa­gonal close-packed (hcp) structures and the effect of structure modification on the electrochemical behaviour of the electrode

Pavlyuk, V.; Kulawik, D.; Ciesielski, W.; Pavlyuk, N.; Dmytriv, G.

doi:10.1107/S2053229618002851

New quaternary carbide Mg_1.52Li_0.24Al_0.24C_0.86 as a disorder derivative of the family of hexagonal close-packed (hcp) structures and the effect of structure modification on the electrochemical behaviour of the electrode

V. Pavlyuk, D. Kulawik, W. Ciesielski, N. Pavlyuk and G. Dmytriv

Magnesium alloys are the basis for the creation of light and ultra-light alloys. They have attracted attention as potential materials for the accumulation and storage of hydrogen, as well as electrode materials in metal-hydride and magnesium-ion batteries. The search for new metal hydrides has involved magnesium alloys with rare-earth transition metals and doped by p- or s-elements. The synthesis and characterization of a new quaternary carbide, namely dimagnesium lithium aluminium carbide, Mg_1.52Li_0.24Al_0.24C_0.86, belonging to the family of hexagonal close-packed (hcp) structures, are reported. The title compound crystallizes with hexagonal symmetry (space group P $\overline{6}$ m2), where two sites with $\overline{6}$ m2 symmetry and one site with 3m. symmetry are occupied by an Mg/Li statistical mixture (in Wyckoff position 1a), an Mg/Al statistical mixture (in position 1d) and C atoms (2i). The cuboctahedral coordination is typical for Mg/Li and Mg/Al, and the C atom is enclosed in an octahedron. Electronic structure calculations were used for elucidation of the ability of lithium or aluminium to substitute magnesium, and evaluation of the nature of the bonding between atoms. The presence of carbon in the carbide phase improves the corrosion resistance of the Mg_1.52Li_0.24Al_0.24C_0.86 alloy compared to the ternary Mg_1.52Li_0.24Al_0.24 alloy and Mg.

Keywords: intermetallic compound; crystal structure; hexagonal close packing; electronic structure; electrode materials; carbide.

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Supporting information

	Crystallographic Information File (CIF) https://doi.org/10.1107/S2053229618002851/ku3217sup1.cif Contains datablocks I, global
	Structure factor file (CIF format) https://doi.org/10.1107/S2053229618002851/ku3217Isup2.hkl Contains datablock I

CCDC reference: 1824502

Computing details top

Data collection: CrysAlis CCD (Oxford Diffraction, 2008); cell refinement: CrysAlis CCD (Oxford Diffraction, 2008); data reduction: CrysAlis RED (Oxford Diffraction, 2008); program(s) used to solve structure: WinCSD (Akselrud & Grin, 2014); program(s) used to refine structure: SHELXL2014 (Sheldrick, 2015); molecular graphics: DIAMOND (Brandenburg, 2006); software used to prepare material for publication: SHELXL2014 (Sheldrick, 2015).

Dimagnesium lithium aluminium carbide top

Crystal data top

Mg_1.52Li_0.24Al_0.24C_0.86	D_x = 2.002 Mg m⁻³
M_r = 55.42	Mo Kα radiation, λ = 0.71073 Å
Hexagonal, P6m2	Cell parameters from 75 reflections
a = 3.1970 (5) Å	θ = 3.9–29.7°
c = 5.1943 (10) Å	µ = 0.69 mm⁻¹
V = 45.98 (2) Å³	T = 293 K
Z = 1	Plate, metallic grey
F(000) = 27.2	0.04 × 0.02 × 0.01 mm

Data collection top

Oxford Diffraction Xcalibur3 CCD diffractometer	65 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	R_int = 0.028
ω scans	θ_max = 29.7°, θ_min = 3.9°
Absorption correction: analytical (CrysAlis RED; Oxford Diffraction, 2008)	h = −4→4
T_min = 0.985, T_max = 0.992	k = −4→4
1654 measured reflections	l = −7→7
75 independent reflections

Refinement top

Refinement on F²	0 restraints
Least-squares matrix: full	w = 1/[σ²(F_o²) + (0.0125P)² + 0.0327P] where P = (F_o² + 2F_c²)/3
R[F² > 2σ(F²)] = 0.033	(Δ/σ)_max = 0.001
wR(F²) = 0.077	Δρ_max = 0.18 e Å⁻³
S = 1.37	Δρ_min = −0.20 e Å⁻³
75 reflections	Absolute structure: Refined as an inversion twin
9 parameters	Absolute structure parameter: 0 (10)

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 2-component inversion twin

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

	x	y	z	U_iso*/U_eq	Occ. (<1)
Mg1	0.3333	0.6667	0.5000	0.0545 (18)	0.76 (4)
Al	0.3333	0.6667	0.5000	0.0545 (18)	0.24 (4)
Mg2	0.0000	0.0000	0.0000	0.0429 (16)	0.76 (8)
Li	0.0000	0.0000	0.0000	0.0429 (16)	0.24 (8)
C	0.6667	0.3333	0.243 (5)	0.041 (3)	0.430 (11)

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
Mg1	0.053 (2)	0.053 (2)	0.057 (3)	0.0267 (12)	0.000	0.000
Al	0.053 (2)	0.053 (2)	0.057 (3)	0.0267 (12)	0.000	0.000
Mg2	0.043 (2)	0.043 (2)	0.043 (3)	0.0214 (12)	0.000	0.000
Li	0.043 (2)	0.043 (2)	0.043 (3)	0.0214 (12)	0.000	0.000
C	0.039 (4)	0.039 (4)	0.045 (6)	0.0196 (18)	0.000	0.000

Geometric parameters (Å, º) top

Mg1—Cⁱ	2.277 (14)	Mg2—Cⁱⁱⁱ	2.237 (13)
Mg1—C	2.277 (14)	Mg2—Mg1^xii	3.1862 (4)
Mg1—Cⁱⁱ	2.277 (14)	Mg2—Al^xii	3.1862 (4)
Mg1—Cⁱⁱⁱ	2.277 (14)	Mg2—Mg1^xiii	3.1862 (4)
Mg1—C^iv	2.277 (14)	Mg2—Mg1^x	3.1862 (4)
Mg1—C^v	2.277 (14)	Mg2—Al^x	3.1862 (4)
Mg1—Mg2	3.1862 (4)	Mg2—Al^xiii	3.1862 (4)
Mg1—Li^vi	3.1862 (4)	C—Li^xiv	2.237 (13)
Mg1—Mg2^vi	3.1862 (4)	C—Mg2^xiv	2.237 (13)
Mg1—Li^vii	3.1862 (4)	C—Li^xv	2.237 (13)
Mg1—Li^v	3.1862 (4)	C—Mg2^xv	2.237 (13)
Mg2—C^viii	2.237 (13)	C—Mg1^xiv	2.277 (14)
Mg2—C^ix	2.237 (13)	C—Al^xiv	2.277 (14)
Mg2—C^x	2.237 (13)	C—Mg1^xvi	2.277 (14)
Mg2—C	2.237 (13)	C—Al^xvi	2.277 (14)
Mg2—C^xi	2.237 (13)

Cⁱ—Mg1—C	71.7 (10)	C^viii—Mg2—Mg1^xiii	91.0 (5)
Cⁱ—Mg1—Cⁱⁱ	89.2 (7)	C^ix—Mg2—Mg1^xiii	45.6 (4)
C—Mg1—Cⁱⁱ	132.2 (3)	C^x—Mg2—Mg1^xiii	159.8 (5)
Cⁱ—Mg1—Cⁱⁱⁱ	132.2 (3)	C—Mg2—Mg1^xiii	102.8 (4)
C—Mg1—Cⁱⁱⁱ	89.2 (7)	C^xi—Mg2—Mg1^xiii	45.6 (4)
Cⁱⁱ—Mg1—Cⁱⁱⁱ	132.2 (3)	Cⁱⁱⁱ—Mg2—Mg1^xiii	102.8 (4)
Cⁱ—Mg1—C^iv	89.2 (7)	Mg1^xii—Mg2—Mg1^xiii	60.224 (10)
C—Mg1—C^iv	132.2 (3)	Al^xii—Mg2—Mg1^xiii	60.2
Cⁱⁱ—Mg1—C^iv	89.2 (7)	C^viii—Mg2—Mg1^x	102.8 (4)
Cⁱⁱⁱ—Mg1—C^iv	71.7 (10)	C^ix—Mg2—Mg1^x	159.8 (5)
Cⁱ—Mg1—C^v	132.2 (3)	C^x—Mg2—Mg1^x	45.6 (4)
C—Mg1—C^v	89.2 (7)	C—Mg2—Mg1^x	91.0 (5)
Cⁱⁱ—Mg1—C^v	71.7 (10)	C^xi—Mg2—Mg1^x	102.8 (4)
Cⁱⁱⁱ—Mg1—C^v	89.2 (7)	Cⁱⁱⁱ—Mg2—Mg1^x	45.6 (4)
C^iv—Mg1—C^v	132.2 (3)	Mg1^xii—Mg2—Mg1^x	109.198 (14)
Cⁱ—Mg1—Mg2	104.0 (4)	Al^xii—Mg2—Mg1^x	109.2
C—Mg1—Mg2	44.6 (3)	Mg1^xiii—Mg2—Mg1^x	146.327 (6)
Cⁱⁱ—Mg1—Mg2	161.3 (5)	C^viii—Mg2—Al^x	102.8 (4)
Cⁱⁱⁱ—Mg1—Mg2	44.6 (3)	C^ix—Mg2—Al^x	159.8 (5)
C^iv—Mg1—Mg2	104.0 (4)	C^x—Mg2—Al^x	45.6 (4)
C^v—Mg1—Mg2	89.5 (5)	C—Mg2—Al^x	91.0 (5)
Cⁱ—Mg1—Li^vi	44.6 (3)	C^xi—Mg2—Al^x	102.8 (4)
C—Mg1—Li^vi	104.0 (4)	Cⁱⁱⁱ—Mg2—Al^x	45.6 (4)
Cⁱⁱ—Mg1—Li^vi	44.6 (3)	Mg1^xii—Mg2—Al^x	109.198 (14)
Cⁱⁱⁱ—Mg1—Li^vi	161.3 (5)	Al^xii—Mg2—Al^x	109.198 (14)
C^iv—Mg1—Li^vi	89.5 (5)	Mg1^xiii—Mg2—Al^x	146.327 (6)
C^v—Mg1—Li^vi	104.0 (4)	Mg1^x—Mg2—Al^x	0.0
Mg2—Mg1—Li^vi	146.3	C^viii—Mg2—Al^xiii	91.0 (5)
Cⁱ—Mg1—Mg2^vi	44.6 (3)	C^ix—Mg2—Al^xiii	45.6 (4)
C—Mg1—Mg2^vi	104.0 (4)	C^x—Mg2—Al^xiii	159.8 (5)
Cⁱⁱ—Mg1—Mg2^vi	44.6 (3)	C—Mg2—Al^xiii	102.8 (4)
Cⁱⁱⁱ—Mg1—Mg2^vi	161.3 (5)	C^xi—Mg2—Al^xiii	45.6 (4)
C^iv—Mg1—Mg2^vi	89.5 (5)	Cⁱⁱⁱ—Mg2—Al^xiii	102.8 (4)
C^v—Mg1—Mg2^vi	104.0 (4)	Mg1^xii—Mg2—Al^xiii	60.224 (10)
Mg2—Mg1—Mg2^vi	146.326 (6)	Al^xii—Mg2—Al^xiii	60.224 (10)
Li^vi—Mg1—Mg2^vi	0.0	Mg1^xiii—Mg2—Al^xiii	0.0
Cⁱ—Mg1—Li^vii	89.5 (5)	Mg1^x—Mg2—Al^xiii	146.327 (6)
C—Mg1—Li^vii	161.3 (5)	Al^x—Mg2—Al^xiii	146.327 (6)
Cⁱⁱ—Mg1—Li^vii	44.6 (3)	Li^xiv—C—Mg2^xiv	0.0
Cⁱⁱⁱ—Mg1—Li^vii	104.0 (4)	Li^xiv—C—Mg2	91.2
C^iv—Mg1—Li^vii	44.6 (3)	Mg2^xiv—C—Mg2	91.2 (7)
C^v—Mg1—Li^vii	104.0 (4)	Li^xiv—C—Li^xv	91.2 (7)
Mg2—Mg1—Li^vii	146.3	Mg2^xiv—C—Li^xv	91.2 (7)
Li^vi—Mg1—Li^vii	60.224 (11)	Mg2—C—Li^xv	91.2
Mg2^vi—Mg1—Li^vii	60.224 (11)	Li^xiv—C—Mg2^xv	91.2
Cⁱ—Mg1—Li^v	161.3 (5)	Mg2^xiv—C—Mg2^xv	91.2 (7)
C—Mg1—Li^v	89.5 (5)	Mg2—C—Mg2^xv	91.2 (7)
Cⁱⁱ—Mg1—Li^v	104.0 (4)	Li^xv—C—Mg2^xv	0.0
Cⁱⁱⁱ—Mg1—Li^v	44.6 (3)	Li^xiv—C—Mg1^xiv	89.79 (2)
C^iv—Mg1—Li^v	104.0 (4)	Mg2^xiv—C—Mg1^xiv	89.79 (2)
C^v—Mg1—Li^v	44.6 (3)	Mg2—C—Mg1^xiv	178.5 (10)
Mg2—Mg1—Li^v	60.2	Li^xv—C—Mg1^xiv	89.79 (2)
Li^vi—Mg1—Li^v	146.326 (6)	Mg2^xv—C—Mg1^xiv	89.79 (2)
Mg2^vi—Mg1—Li^v	146.326 (6)	Li^xiv—C—Al^xiv	89.79 (2)
Li^vii—Mg1—Li^v	109.197 (13)	Mg2^xiv—C—Al^xiv	89.79 (2)
C^viii—Mg2—C^ix	91.2 (7)	Mg2—C—Al^xiv	178.5 (10)
C^viii—Mg2—C^x	68.8 (10)	Li^xv—C—Al^xiv	89.79 (2)
C^ix—Mg2—C^x	131.3 (3)	Mg2^xv—C—Al^xiv	89.79 (2)
C^viii—Mg2—C	131.3 (3)	Mg1^xiv—C—Al^xiv	0.0
C^ix—Mg2—C	68.8 (10)	Li^xiv—C—Mg1	178.5 (10)
C^x—Mg2—C	91.2 (7)	Mg2^xiv—C—Mg1	178.5 (10)
C^viii—Mg2—C^xi	91.2 (7)	Mg2—C—Mg1	89.79 (2)
C^ix—Mg2—C^xi	91.2 (7)	Li^xv—C—Mg1	89.79 (2)
C^x—Mg2—C^xi	131.3 (3)	Mg2^xv—C—Mg1	89.79 (2)
C—Mg2—C^xi	131.3 (3)	Mg1^xiv—C—Mg1	89.2 (7)
C^viii—Mg2—Cⁱⁱⁱ	131.3 (3)	Al^xiv—C—Mg1	89.2
C^ix—Mg2—Cⁱⁱⁱ	131.3 (3)	Li^xiv—C—Mg1^xvi	89.79 (2)
C^x—Mg2—Cⁱⁱⁱ	91.2 (7)	Mg2^xiv—C—Mg1^xvi	89.79 (2)
C—Mg2—Cⁱⁱⁱ	91.2 (7)	Mg2—C—Mg1^xvi	89.79 (2)
C^xi—Mg2—Cⁱⁱⁱ	68.8 (10)	Li^xv—C—Mg1^xvi	178.5 (10)
C^viii—Mg2—Mg1^xii	45.6 (4)	Mg2^xv—C—Mg1^xvi	178.5 (10)
C^ix—Mg2—Mg1^xii	91.0 (5)	Mg1^xiv—C—Mg1^xvi	89.2 (7)
C^x—Mg2—Mg1^xii	102.8 (4)	Al^xiv—C—Mg1^xvi	89.2
C—Mg2—Mg1^xii	159.8 (5)	Mg1—C—Mg1^xvi	89.2 (7)
C^xi—Mg2—Mg1^xii	45.6 (4)	Li^xiv—C—Al^xvi	89.79 (2)
Cⁱⁱⁱ—Mg2—Mg1^xii	102.8 (4)	Mg2^xiv—C—Al^xvi	89.79 (2)
C^viii—Mg2—Al^xii	45.6 (4)	Mg2—C—Al^xvi	89.79 (2)
C^ix—Mg2—Al^xii	91.0 (5)	Li^xv—C—Al^xvi	178.5 (10)
C^x—Mg2—Al^xii	102.8 (4)	Mg2^xv—C—Al^xvi	178.5 (10)
C—Mg2—Al^xii	159.8 (5)	Mg1^xiv—C—Al^xvi	89.2 (7)
C^xi—Mg2—Al^xii	45.6 (4)	Al^xiv—C—Al^xvi	89.2 (7)
Cⁱⁱⁱ—Mg2—Al^xii	102.8 (4)	Mg1—C—Al^xvi	89.2
Mg1^xii—Mg2—Al^xii	0.0	Mg1^xvi—C—Al^xvi	0.0

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

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New quaternary carbide Mg1.52Li0.24Al0.24C0.86 as a disorder derivative of the family of hexa­gonal close-packed (hcp) structures and the effect of structure modification on the electrochemical behaviour of the electrode

Supporting information

New quaternary carbide Mg_1.52Li_0.24Al_0.24C_0.86 as a disorder derivative of the family of hexagonal close-packed (hcp) structures and the effect of structure modification on the electrochemical behaviour of the electrode