Erbium dinickel disilicide, ErNi₂Si₂

Erbium dinickel disilicide, ErNi₂Si₂, crystallizes in the tetra­gonal ThCr₂Si₂ structure type, which is an ordered superstucture of the BaAl₄ type. The coordination numbers are 22 for Er (2a site), 12 for Ni (4d site), and 9 for Si (4e site).

Key indicators

• Single-crystal X-ray study
• T = 295 K
• Mean [sigma](i-Si)= 0.004 Å
• R factor = 0.014
• wR factor = 0.036
• Data-to-parameter ratio = 10.9

checkCIF/PLATON results

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Computing details

Data collection: CrysAlis CCD (Oxford Diffraction, 2004); cell refinement: CrysAlis CCD; data reduction: CrysAlis RED (Oxford Diffraction, 2005); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: DIAMOND (Brandenburg, 1999); software used to prepare material for publication: SHELXL97.

Erbium dinickel disilicon

Crystal data

ErNi2Si2	Dx = 7.629 Mg m^−3
Mr = 340.86	Mo Kα radiation, λ = 0.71073 Å
Tetragonal, I4/mmm	Cell parameters from 584 reflections
Hall symbol: -I 4 2	θ = 4.2–30.1°
a = 3.9431 (9) Å	µ = 41.06 mm^−1
c = 9.543 (2) Å	T = 295 K
V = 148.37 (6) Å^3	Needle, metallic light grey
Z = 2	0.17 × 0.05 × 0.02 mm
F(000) = 304

Data collection

Oxford Xcalibur3 CCD area-detector diffractometer	87 independent reflections
Radiation source: fine-focus sealed tube	87 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.029
ω scans	θmax = 30.1°, θmin = 4.3°
Absorption correction: analytical (CrysAlis RED; Oxford Diffraction, 2005)	h = −4→5
Tmin = 0.094, Tmax = 0.432	k = −5→3
603 measured reflections	l = −13→12

Refinement

Refinement on F^2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.014	w = 1/[σ^2(Fo^2) + (0.0158P)^2 + 2.224P] where P = (Fo^2 + 2Fc^2)/3
wR(F^2) = 0.037	(Δ/σ)max < 0.001
S = 1.26	Δρmax = 0.63 e Å^−3
87 reflections	Δρmin = −1.35 e Å^−3
8 parameters	Extinction correction: SHELXL97 (Sheldrick, 1997)
0 restraints	Extinction coefficient: 0.0042 (10)

Special details

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. Refinement of F² against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F², conventional R-factors R are based on F, with F set to zero for negative F². The threshold expression of F² > σ(F²) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F² are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger.

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

	x	y	z	Uiso*/Ueq
Er	0.0000	0.0000	0.0000	0.00408 (19)
Ni	0.0000	0.5000	0.2500	0.0063 (3)
Si	0.0000	0.0000	0.3745 (3)	0.0056 (5)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Er	0.0034 (2)	0.0034 (2)	0.0055 (3)	0.000	0.000	0.000
Ni	0.0059 (4)	0.0059 (4)	0.0070 (5)	0.000	0.000	0.000
Si	0.0050 (7)	0.0050 (7)	0.0068 (10)	0.000	0.000	0.000

Geometric parameters (Å, º)

Er—Si^i	3.0344 (11)	Ni—Ni^xi	2.7882 (6)
Er—Si^ii	3.0344 (11)	Ni—Ni^v	2.7882 (6)
Er—Si^iii	3.0344 (11)	Ni—Ni^xii	2.7882 (6)
Er—Si^iv	3.0344 (11)	Ni—Ni^i	2.7882 (6)
Er—Si^v	3.0344 (11)	Ni—Er^xiii	3.0950 (5)
Er—Si^vi	3.0344 (11)	Ni—Er^x	3.0950 (5)
Er—Si^vii	3.0344 (11)	Ni—Er^xiv	3.0950 (5)
Er—Si^viii	3.0344 (11)	Si—Ni^v	2.3020 (13)
Er—Ni	3.0950 (5)	Si—Ni^xv	2.3020 (13)
Er—Ni^ix	3.0950 (5)	Si—Ni^i	2.3020 (13)
Er—Ni^ii	3.0950 (5)	Si—Si^xvi	2.395 (5)
Er—Ni^i	3.0950 (5)	Si—Er^xiii	3.0344 (11)
Ni—Si^v	2.3020 (13)	Si—Er^xvii	3.0344 (11)
Ni—Si^x	2.3020 (13)	Si—Er^xiv	3.0344 (11)
Ni—Si^i	2.3020 (13)	Si—Er^xviii	3.0344 (11)
Ni—Si	2.3020 (13)
Si^i—Er—Si^ii	180.00 (9)	Si—Ni—Ni^xii	127.27 (2)
Si^i—Er—Si^iii	133.52 (9)	Ni^xi—Ni—Ni^xii	90.0
Si^ii—Er—Si^iii	46.48 (9)	Ni^v—Ni—Ni^xii	90.0
Si^i—Er—Si^iv	46.48 (9)	Si^v—Ni—Ni^i	127.27 (2)
Si^ii—Er—Si^iv	133.52 (9)	Si^x—Ni—Ni^i	127.27 (2)
Si^iii—Er—Si^iv	180.0	Si^i—Ni—Ni^i	52.73 (2)
Si^i—Er—Si^v	81.04 (3)	Si—Ni—Ni^i	52.73 (2)
Si^ii—Er—Si^v	98.96 (3)	Ni^xi—Ni—Ni^i	90.0
Si^iii—Er—Si^v	81.04 (3)	Ni^v—Ni—Ni^i	90.0
Si^iv—Er—Si^v	98.96 (3)	Ni^xii—Ni—Ni^i	180.0
Si^i—Er—Si^vi	81.04 (3)	Si^v—Ni—Er	66.55 (4)
Si^ii—Er—Si^vi	98.96 (3)	Si^x—Ni—Er	160.65 (5)
Si^iii—Er—Si^vi	81.04 (3)	Si^i—Ni—Er	66.55 (4)
Si^iv—Er—Si^vi	98.96 (3)	Si—Ni—Er	81.51 (6)
Si^v—Er—Si^vi	133.52 (9)	Ni^xi—Ni—Er	116.772 (6)
Si^i—Er—Si^vii	98.96 (3)	Ni^v—Ni—Er	63.228 (6)
Si^ii—Er—Si^vii	81.04 (3)	Ni^xii—Ni—Er	116.772 (6)
Si^iii—Er—Si^vii	98.96 (3)	Ni^i—Ni—Er	63.228 (6)
Si^iv—Er—Si^vii	81.04 (3)	Si^v—Ni—Er^xiii	160.65 (5)
Si^v—Er—Si^vii	46.48 (9)	Si^x—Ni—Er^xiii	66.55 (4)
Si^vi—Er—Si^vii	180.0	Si^i—Ni—Er^xiii	81.51 (6)
Si^i—Er—Si^viii	98.96 (3)	Si—Ni—Er^xiii	66.55 (4)
Si^ii—Er—Si^viii	81.04 (3)	Ni^xi—Ni—Er^xiii	63.228 (6)
Si^iii—Er—Si^viii	98.96 (3)	Ni^v—Ni—Er^xiii	116.772 (6)
Si^iv—Er—Si^viii	81.04 (3)	Ni^xii—Ni—Er^xiii	116.772 (6)
Si^v—Er—Si^viii	180.0	Ni^i—Ni—Er^xiii	63.228 (6)
Si^vi—Er—Si^viii	46.48 (9)	Er—Ni—Er^xiii	126.456 (12)
Si^vii—Er—Si^viii	133.52 (9)	Si^v—Ni—Er^x	66.55 (4)
Si^i—Er—Ni	44.11 (3)	Si^x—Ni—Er^x	81.51 (6)
Si^ii—Er—Ni	135.89 (3)	Si^i—Ni—Er^x	66.55 (4)
Si^iii—Er—Ni	96.30 (4)	Si—Ni—Er^x	160.65 (5)
Si^iv—Er—Ni	83.70 (4)	Ni^xi—Ni—Er^x	63.228 (6)
Si^v—Er—Ni	44.11 (3)	Ni^v—Ni—Er^x	116.772 (6)
Si^vi—Er—Ni	96.30 (4)	Ni^xii—Ni—Er^x	63.228 (6)
Si^vii—Er—Ni	83.70 (4)	Ni^i—Ni—Er^x	116.772 (6)
Si^viii—Er—Ni	135.89 (3)	Er—Ni—Er^x	79.140 (19)
Si^i—Er—Ni^ix	135.89 (3)	Er^xiii—Ni—Er^x	126.456 (12)
Si^ii—Er—Ni^ix	44.11 (3)	Si^v—Ni—Er^xiv	81.51 (6)
Si^iii—Er—Ni^ix	83.70 (4)	Si^x—Ni—Er^xiv	66.55 (4)
Si^iv—Er—Ni^ix	96.30 (4)	Si^i—Ni—Er^xiv	160.65 (5)
Si^v—Er—Ni^ix	135.89 (3)	Si—Ni—Er^xiv	66.55 (4)
Si^vi—Er—Ni^ix	83.70 (4)	Ni^xi—Ni—Er^xiv	116.772 (6)
Si^vii—Er—Ni^ix	96.30 (4)	Ni^v—Ni—Er^xiv	63.228 (6)
Si^viii—Er—Ni^ix	44.11 (3)	Ni^xii—Ni—Er^xiv	63.228 (6)
Ni—Er—Ni^ix	180.0	Ni^i—Ni—Er^xiv	116.772 (6)
Si^i—Er—Ni^ii	135.89 (3)	Er—Ni—Er^xiv	126.456 (12)
Si^ii—Er—Ni^ii	44.11 (3)	Er^xiii—Ni—Er^xiv	79.140 (19)
Si^iii—Er—Ni^ii	83.70 (4)	Er^x—Ni—Er^xiv	126.456 (12)
Si^iv—Er—Ni^ii	96.30 (4)	Ni^v—Si—Ni^xv	74.54 (5)
Si^v—Er—Ni^ii	83.70 (4)	Ni^v—Si—Ni^i	117.84 (11)
Si^vi—Er—Ni^ii	135.89 (3)	Ni^xv—Si—Ni^i	74.54 (5)
Si^vii—Er—Ni^ii	44.11 (3)	Ni^v—Si—Ni	74.54 (5)
Si^viii—Er—Ni^ii	96.30 (4)	Ni^xv—Si—Ni	117.84 (11)
Ni—Er—Ni^ii	126.456 (12)	Ni^i—Si—Ni	74.54 (5)
Ni^ix—Er—Ni^ii	53.544 (12)	Ni^v—Si—Si^xvi	121.08 (5)
Si^i—Er—Ni^i	44.11 (3)	Ni^xv—Si—Si^xvi	121.08 (5)
Si^ii—Er—Ni^i	135.89 (3)	Ni^i—Si—Si^xvi	121.08 (5)
Si^iii—Er—Ni^i	96.30 (4)	Ni—Si—Si^xvi	121.08 (5)
Si^iv—Er—Ni^i	83.70 (4)	Ni^v—Si—Er^xiii	139.478 (16)
Si^v—Er—Ni^i	96.30 (4)	Ni^xv—Si—Er^xiii	139.478 (16)
Si^vi—Er—Ni^i	44.11 (3)	Ni^i—Si—Er^xiii	69.344 (13)
Si^vii—Er—Ni^i	135.89 (3)	Ni—Si—Er^xiii	69.344 (13)
Si^viii—Er—Ni^i	83.70 (4)	Si^xvi—Si—Er^xiii	66.76 (4)
Ni—Er—Ni^i	53.544 (12)	Ni^v—Si—Er^xvii	69.344 (13)
Ni^ix—Er—Ni^i	126.456 (12)	Ni^xv—Si—Er^xvii	69.344 (13)
Ni^ii—Er—Ni^i	180.0	Ni^i—Si—Er^xvii	139.478 (16)
Si^v—Ni—Si^x	105.46 (5)	Ni—Si—Er^xvii	139.478 (16)
Si^v—Ni—Si^i	117.84 (11)	Si^xvi—Si—Er^xvii	66.76 (4)
Si^x—Ni—Si^i	105.46 (5)	Er^xiii—Si—Er^xvii	133.52 (9)
Si^v—Ni—Si	105.46 (5)	Ni^v—Si—Er^xiv	69.344 (13)
Si^x—Ni—Si	117.84 (11)	Ni^xv—Si—Er^xiv	139.478 (16)
Si^i—Ni—Si	105.46 (5)	Ni^i—Si—Er^xiv	139.478 (16)
Si^v—Ni—Ni^xi	127.27 (2)	Ni—Si—Er^xiv	69.344 (13)
Si^x—Ni—Ni^xi	52.73 (2)	Si^xvi—Si—Er^xiv	66.76 (4)
Si^i—Ni—Ni^xi	52.73 (2)	Er^xiii—Si—Er^xiv	81.04 (3)
Si—Ni—Ni^xi	127.27 (2)	Er^xvii—Si—Er^xiv	81.04 (3)
Si^v—Ni—Ni^v	52.73 (2)	Ni^v—Si—Er^xviii	139.478 (16)
Si^x—Ni—Ni^v	127.27 (2)	Ni^xv—Si—Er^xviii	69.344 (13)
Si^i—Ni—Ni^v	127.27 (2)	Ni^i—Si—Er^xviii	69.344 (13)
Si—Ni—Ni^v	52.73 (2)	Ni—Si—Er^xviii	139.478 (16)
Ni^xi—Ni—Ni^v	180.0	Si^xvi—Si—Er^xviii	66.76 (4)
Si^v—Ni—Ni^xii	52.73 (2)	Er^xiii—Si—Er^xviii	81.04 (3)
Si^x—Ni—Ni^xii	52.73 (2)	Er^xvii—Si—Er^xviii	81.04 (3)
Si^i—Ni—Ni^xii	127.27 (2)	Er^xiv—Si—Er^xviii	133.52 (9)

Symmetry codes: (i) −x+1/2, −y+1/2, −z+1/2; (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+1/2; (vi) −x+1/2, −y−1/2, −z+1/2; (vii) x−1/2, y+1/2, z−1/2; (viii) x+1/2, y−1/2, z−1/2; (ix) −x, −y, −z; (x) x, y+1, z; (xi) −x+1/2, −y+3/2, −z+1/2; (xii) −x−1/2, −y+3/2, −z+1/2; (xiii) x+1/2, y+1/2, z+1/2; (xiv) x−1/2, y+1/2, z+1/2; (xv) x, y−1, z; (xvi) −x, −y, −z+1; (xvii) x−1/2, y−1/2, z+1/2; (xviii) x+1/2, y−1/2, z+1/2.