Erbium nickel disilicide, ErNiSi2

Kończyk, J.; Demchenko, P.; Matvijishyn, R.; Pavlyuk, V.; Marciniak, B.

doi:10.1107/S1600536805040262

Erbium nickel disilicide, ErNiSi₂

J. Konczyk, P. Demchenko, R. Matvijishyn, V. Pavlyuk and B. Marciniak

Single crystals of ErNiSi₂ were synthesized from the corresponding elements by arc melting. The ternary intermetallic compound crystallizes in the orthorhombic space group Cmcm and adopts the CeNiSi₂ structure type [Bodak & Gladyshevskii (1969). Kristallografiya, 14, 990-994], with all four crystallographically unique atoms in special positions of site symmetry m2m.

Read article Similar articles

Supporting information

	Crystallographic Information File (CIF) https://doi.org/10.1107/S1600536805040262/wm6126sup1.cif Contains datablocks global, I
	Structure factor file (CIF format) https://doi.org/10.1107/S1600536805040262/wm6126Isup2.hkl Contains datablock I

checkCIF report

Key indicators

Single-crystal X-ray study
T = 295 K
Mean (i-Si) = 0.001 Å
R factor = 0.025
wR factor = 0.057
Data-to-parameter ratio = 15.6

checkCIF/PLATON results

No syntax errors found



Alert level G
ABSTM02_ALERT_3_G  The ratio of expected to reported Tmax/Tmin(RR) is > 1.50
            Tmin and Tmax reported:      0.002     0.199
            Tmin and Tmax expected:      0.001     0.198
            RR =      1.576
            Please check that your absorption correction is appropriate.

   0 ALERT level A = In general: serious problem
   0 ALERT level B = Potentially serious problem
   0 ALERT level C = Check and explain
   1 ALERT level G = General alerts; check

   0 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
   0 ALERT type 2 Indicator that the structure model may be wrong or deficient
   1 ALERT type 3 Indicator that the structure quality may be low
   0 ALERT type 4 Improvement, methodology, query or suggestion

Comment top

Ternary intermetallics of rare earth metals with the general formula RETX₂ (where RE is a rare earth metal, T is a transition metal and X is a p-block element) crystallize mostly in 23 structure types (Parthé et al., 1993–1994), viz. monoclinic NdRuSi₂, CeCoC₂ and LaCuS₂, orthorhombic CeNiSi₂, YIrGe₂, LuMnGe₂, ZrCrSi₂, CeRhGe₂, TbFeSi₂, LaTmIr₂Ge₄, LuNiSn₂, NdAgAs₂, MgCuAl₂, NdNiGa₂, CeRhSn₂ (Niepmann et al., 1999), ScRhSi₂, ScFeSi₂, CeNiC₂, ScCoC₂ and LuRuB₂, and tetragonal HfCuSi₂, ScCoC₂ and LaRhC₂.

The RETX₂ phases have been the focus of special attention due to their interesting magnetic and electric properties, e.g. the Kondo effect. An accurate determination of the crystal structure for phases of this composition is a basic requirement for the better understanding of their physical properties. The existence of the phase ErNiSi₂ was first reported by Bodak & Gladyshevskii (1969) who, on the basis of X-ray powder diffraction data, established that the crystal structure adopts the orthorhombic CeNiSi₂ structure type. Analogous results were obtained by Gil et al. (1994). In these investigations, any information about structural data (atomic coordinates, displacement parameters) was not presented. Thus, it seemed appropriate to determine completely the crystal structure of ErNiSi₂, and we present these results here.

ErNiSi₂ adopts the CeNiSi₂ structure type (Bodak & Gladyshevskii, 1969). A clinographic projection of the unit-cell contents is shown in Fig. 1. The coordination sphere around Er (site symmetry m2m) consists of 21 atoms, if bonding interactions are considered for distances < 4.0 Å, resulting in an [ErSi₄Ni₄Si₆NiEr₆] polyhedron (Fig. 2a). The coordination polyhedron around the Ni atom (site symmetry m2m) is a monocapped tetragonal antiprism, [NiSi₅Er₄], made up of 4 Er atoms in one basal plane with a capping Si atom, and 4 Si atoms in the second basal plane, if bonding interactions are considered for distances < 3.1 Å (Fig. 2b). The coordination polyhedron around atom Si1 (site symmetry m2m, bonding interactions < 3.1 Å) is a tricapped trigonal prism, [Si1NiSi₂Er₆], with one additional Ni and two Er atoms as capping atoms (Fig. 2c). The coordination polyhedron around atom Si2 (site symmetry m2m, bonding interactions < 3.1 Å) is a distorted cuboctahedron, [Si2Ni₄Si₄Er₄] (Fig. 2d).

The interatomic distances (Table 1) are in good agreement with the sums of the atomic radii (Emsley, 1991). The shortest distance with the highest deviation (93% of the sum of the atomic radii) is observed between Ni and Si atoms, with an Ni—Si distance of 2.255 (3) Å.

Experimental top

The single-crystal used in this work was extracted from an alloy with nominal composition Er₂₃Ni₂₇Si₅₀, which was prepared by arc melting of the initial components (purity better than 99.9%) in an electric arc furnace with a water-cooled copper bottom (Ti-getter) under an argon atmosphere, and annealwed at 870 K. A preliminary crystal investigation was performed using Laue and rotation methods (RKV-86 and RGNS-2 chambers, Mo Kα radiation).

Computing details top

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 (Sheldrick, 1997).

Figures top

	Fig. 1. A clinographic projection of the ErNiSi₂ unit-cell contents, with displacement ellipsoids drawn at the 95% probability level.
	Fig. 2. The coordination polyhedra around (a) the Er atom, (b) the Ni atom, and (c) and (d) the Si atoms. Er atoms are blue, Ni atoms are green and Si atoms are red.

Erbium nickel disilicide top

Crystal data top

ErNiSi₂	F(000) = 496
M_r = 282.15	D_x = 7.327 Mg m⁻³
Orthorhombic, Cmcm	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -C 2c 2	Cell parameters from 1017 reflections
a = 3.9423 (9) Å	θ = 4.9–32.7°
b = 16.502 (3) Å	µ = 40.49 mm⁻¹
c = 3.9319 (9) Å	T = 295 K
V = 255.79 (9) Å³	Plate, metallic light grey
Z = 4	0.21 × 0.19 × 0.04 mm

Data collection top

Oxford Diffraction Xcalibur3 CCD area-detector diffractometer	281 independent reflections
Radiation source: fine-focus sealed tube	280 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.039
ω scans	θ_max = 32.7°, θ_min = 4.9°
Absorption correction: analytical CrysAlis RED (Oxford Diffraction, 2005)	h = −5→4
T_min = 0.002, T_max = 0.199	k = −24→23
1025 measured reflections	l = −5→5

Refinement top

Refinement on F²	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F² > 2σ(F²)] = 0.025	w = 1/[σ²(F_o²) + (0.023P)² + 5.5174P] where P = (F_o² + 2F_c²)/3
wR(F²) = 0.057	(Δ/σ)_max < 0.001
S = 1.33	Δρ_max = 4.29 e Å⁻³
281 reflections	Δρ_min = −2.85 e Å⁻³
18 parameters	Extinction correction: SHELXL97 (Sheldrick, 1997), Fc^*=kFc[1+0.001xFc²λ³/sin(2θ)]^-1/4
0 restraints	Extinction coefficient: 0.0048 (7)

Crystal data top

ErNiSi₂	V = 255.79 (9) Å³
M_r = 282.15	Z = 4
Orthorhombic, Cmcm	Mo Kα radiation
a = 3.9423 (9) Å	µ = 40.49 mm⁻¹
b = 16.502 (3) Å	T = 295 K
c = 3.9319 (9) Å	0.21 × 0.19 × 0.04 mm

Data collection top

Oxford Diffraction Xcalibur3 CCD area-detector diffractometer	281 independent reflections
Absorption correction: analytical CrysAlis RED (Oxford Diffraction, 2005)	280 reflections with I > 2σ(I)
T_min = 0.002, T_max = 0.199	R_int = 0.039
1025 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.025	18 parameters
wR(F²) = 0.057	0 restraints
S = 1.33	Δρ_max = 4.29 e Å⁻³
281 reflections	Δρ_min = −2.85 e Å⁻³

Special details top

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 (Å²) top

	x	y	z	U_iso*/U_eq
Er	0.0000	0.10553 (2)	0.2500	0.00534 (19)
Ni	0.0000	0.32389 (7)	0.2500	0.0063 (3)
Si1	0.0000	0.46055 (16)	0.2500	0.0062 (4)
Si2	0.0000	0.74973 (16)	0.2500	0.0060 (5)

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
Er	0.0039 (2)	0.0069 (2)	0.0052 (2)	0.000	0.000	0.000
Ni	0.0057 (5)	0.0064 (5)	0.0069 (5)	0.000	0.000	0.000
Si1	0.0066 (10)	0.0068 (10)	0.0052 (11)	0.000	0.000	0.000
Si2	0.0054 (10)	0.0050 (8)	0.0075 (12)	0.000	0.000	0.000

Geometric parameters (Å, º) top

Er—Si1ⁱ	2.9899 (10)	Ni—Erⁱ	3.0178 (6)
Er—Si1ⁱⁱ	2.9899 (10)	Ni—Er^iv	3.0178 (6)
Er—Si1ⁱⁱⁱ	2.9899 (10)	Ni—Erⁱⁱⁱ	3.0178 (6)
Er—Si1^iv	2.9899 (10)	Si1—Si1^vii	2.358 (3)
Er—Niⁱⁱ	3.0178 (6)	Si1—Si1^viii	2.358 (3)
Er—Niⁱ	3.0178 (6)	Si1—Erⁱ	2.9899 (10)
Er—Ni^iv	3.0178 (6)	Si1—Erⁱⁱ	2.9899 (10)
Er—Niⁱⁱⁱ	3.0178 (6)	Si1—Er^iv	2.9899 (10)
Er—Si2^v	3.090 (2)	Si1—Erⁱⁱⁱ	2.9899 (10)
Er—Si2^vi	3.090 (2)	Si1—Er^xiii	3.100 (2)
Er—Si2^vii	3.094 (2)	Si1—Er^xiv	3.100 (2)
Er—Si2^viii	3.094 (2)	Si2—Ni^viii	2.3110 (15)
Er—Si1^vi	3.100 (2)	Si2—Ni^vii	2.3110 (15)
Er—Si1^v	3.100 (2)	Si2—Ni^xiii	2.3202 (15)
Er—Er^ix	3.9319 (9)	Si2—Ni^xiv	2.3202 (15)
Er—Er^x	3.9319 (9)	Si2—Si2^xv	2.7840 (5)
Er—Er^xi	3.9423 (9)	Si2—Si2^xvi	2.7840 (5)
Er—Er^xii	3.9423 (9)	Si2—Si2^xvii	2.7840 (5)
Ni—Si1	2.255 (3)	Si2—Si2^xviii	2.7840 (5)
Ni—Si2^viii	2.3110 (15)	Si2—Er^xiv	3.090 (2)
Ni—Si2^vii	2.3110 (15)	Si2—Er^xiii	3.090 (2)
Ni—Si2^vi	2.3202 (15)	Si2—Er^vii	3.094 (2)
Ni—Si2^v	2.3202 (15)	Si2—Er^viii	3.094 (2)
Ni—Erⁱⁱ	3.0178 (6)

Si1ⁱ—Er—Si1ⁱⁱ	137.22 (9)	Si2^vii—Er—Er^xii	90.0
Si1ⁱ—Er—Si1ⁱⁱⁱ	82.22 (4)	Si2^viii—Er—Er^xii	90.0
Si1ⁱⁱ—Er—Si1ⁱⁱⁱ	82.49 (4)	Si1^vi—Er—Er^xii	129.49 (3)
Si1ⁱ—Er—Si1^iv	82.49 (4)	Si1^v—Er—Er^xii	50.51 (3)
Si1ⁱⁱ—Er—Si1^iv	82.22 (4)	Er^ix—Er—Er^xii	90.0
Si1ⁱⁱⁱ—Er—Si1^iv	137.22 (9)	Er^x—Er—Er^xii	90.0
Si1ⁱ—Er—Niⁱⁱ	178.69 (5)	Er^xi—Er—Er^xii	180.00 (2)
Si1ⁱⁱ—Er—Niⁱⁱ	44.09 (6)	Si1—Ni—Si2^viii	121.71 (6)
Si1ⁱⁱⁱ—Er—Niⁱⁱ	98.22 (3)	Si1—Ni—Si2^vii	121.71 (6)
Si1^iv—Er—Niⁱⁱ	97.96 (3)	Si2^viii—Ni—Si2^vii	116.57 (12)
Si1ⁱ—Er—Niⁱ	44.09 (6)	Si1—Ni—Si2^vi	121.83 (6)
Si1ⁱⁱ—Er—Niⁱ	178.69 (5)	Si2^viii—Ni—Si2^vi	73.90 (2)
Si1ⁱⁱⁱ—Er—Niⁱ	97.96 (3)	Si2^vii—Ni—Si2^vi	73.90 (2)
Si1^iv—Er—Niⁱ	98.22 (3)	Si1—Ni—Si2^v	121.83 (6)
Niⁱⁱ—Er—Niⁱ	134.59 (4)	Si2^viii—Ni—Si2^v	73.90 (2)
Si1ⁱ—Er—Ni^iv	98.22 (3)	Si2^vii—Ni—Si2^v	73.90 (2)
Si1ⁱⁱ—Er—Ni^iv	97.96 (3)	Si2^vi—Ni—Si2^v	116.33 (12)
Si1ⁱⁱⁱ—Er—Ni^iv	178.69 (5)	Si1—Ni—Erⁱⁱ	67.30 (2)
Si1^iv—Er—Ni^iv	44.09 (6)	Si2^viii—Ni—Erⁱⁱ	139.207 (12)
Niⁱⁱ—Er—Ni^iv	81.30 (2)	Si2^vii—Ni—Erⁱⁱ	69.43 (4)
Niⁱ—Er—Ni^iv	81.56 (2)	Si2^vi—Ni—Erⁱⁱ	139.332 (12)
Si1ⁱ—Er—Niⁱⁱⁱ	97.96 (3)	Si2^v—Ni—Erⁱⁱ	69.43 (4)
Si1ⁱⁱ—Er—Niⁱⁱⁱ	98.22 (3)	Si1—Ni—Erⁱ	67.30 (2)
Si1ⁱⁱⁱ—Er—Niⁱⁱⁱ	44.09 (6)	Si2^viii—Ni—Erⁱ	69.43 (4)
Si1^iv—Er—Niⁱⁱⁱ	178.69 (5)	Si2^vii—Ni—Erⁱ	139.207 (12)
Niⁱⁱ—Er—Niⁱⁱⁱ	81.56 (2)	Si2^vi—Ni—Erⁱ	69.43 (4)
Niⁱ—Er—Niⁱⁱⁱ	81.30 (2)	Si2^v—Ni—Erⁱ	139.332 (12)
Ni^iv—Er—Niⁱⁱⁱ	134.59 (4)	Erⁱⁱ—Ni—Erⁱ	134.59 (4)
Si1ⁱ—Er—Si2^v	134.54 (4)	Si1—Ni—Er^iv	67.30 (2)
Si1ⁱⁱ—Er—Si2^v	81.97 (5)	Si2^viii—Ni—Er^iv	69.43 (4)
Si1ⁱⁱⁱ—Er—Si2^v	134.54 (4)	Si2^vii—Ni—Er^iv	139.207 (12)
Si1^iv—Er—Si2^v	81.97 (5)	Si2^vi—Ni—Er^iv	139.332 (12)
Niⁱⁱ—Er—Si2^v	44.45 (2)	Si2^v—Ni—Er^iv	69.43 (4)
Niⁱ—Er—Si2^v	96.86 (3)	Erⁱⁱ—Ni—Er^iv	81.30 (2)
Ni^iv—Er—Si2^v	44.45 (2)	Erⁱ—Ni—Er^iv	81.56 (2)
Niⁱⁱⁱ—Er—Si2^v	96.86 (3)	Si1—Ni—Erⁱⁱⁱ	67.30 (2)
Si1ⁱ—Er—Si2^vi	81.97 (5)	Si2^viii—Ni—Erⁱⁱⁱ	139.207 (12)
Si1ⁱⁱ—Er—Si2^vi	134.54 (4)	Si2^vii—Ni—Erⁱⁱⁱ	69.43 (4)
Si1ⁱⁱⁱ—Er—Si2^vi	81.97 (5)	Si2^vi—Ni—Erⁱⁱⁱ	69.43 (4)
Si1^iv—Er—Si2^vi	134.54 (4)	Si2^v—Ni—Erⁱⁱⁱ	139.332 (12)
Niⁱⁱ—Er—Si2^vi	96.86 (3)	Erⁱⁱ—Ni—Erⁱⁱⁱ	81.56 (2)
Niⁱ—Er—Si2^vi	44.45 (2)	Erⁱ—Ni—Erⁱⁱⁱ	81.30 (2)
Ni^iv—Er—Si2^vi	96.86 (3)	Er^iv—Ni—Erⁱⁱⁱ	134.59 (4)
Niⁱⁱⁱ—Er—Si2^vi	44.45 (2)	Ni—Si1—Si1^vii	123.51 (11)
Si2^v—Er—Si2^vi	79.27 (6)	Ni—Si1—Si1^viii	123.51 (11)
Si1ⁱ—Er—Si2^vii	134.38 (4)	Si1^vii—Si1—Si1^viii	113.0 (2)
Si1ⁱⁱ—Er—Si2^vii	82.17 (5)	Ni—Si1—Erⁱ	68.61 (5)
Si1ⁱⁱⁱ—Er—Si2^vii	82.17 (5)	Si1^vii—Si1—Erⁱ	138.56 (3)
Si1^iv—Er—Si2^vii	134.38 (4)	Si1^viii—Si1—Erⁱ	69.71 (4)
Niⁱⁱ—Er—Si2^vii	44.60 (2)	Ni—Si1—Erⁱⁱ	68.61 (5)
Niⁱ—Er—Si2^vii	96.66 (3)	Si1^vii—Si1—Erⁱⁱ	69.71 (4)
Ni^iv—Er—Si2^vii	96.66 (3)	Si1^viii—Si1—Erⁱⁱ	138.56 (3)
Niⁱⁱⁱ—Er—Si2^vii	44.60 (2)	Erⁱ—Si1—Erⁱⁱ	137.22 (9)
Si2^v—Er—Si2^vii	53.516 (10)	Ni—Si1—Er^iv	68.61 (5)
Si2^vi—Er—Si2^vii	53.516 (10)	Si1^vii—Si1—Er^iv	138.56 (3)
Si1ⁱ—Er—Si2^viii	82.17 (5)	Si1^viii—Si1—Er^iv	69.71 (4)
Si1ⁱⁱ—Er—Si2^viii	134.38 (4)	Erⁱ—Si1—Er^iv	82.49 (4)
Si1ⁱⁱⁱ—Er—Si2^viii	134.38 (4)	Erⁱⁱ—Si1—Er^iv	82.22 (4)
Si1^iv—Er—Si2^viii	82.17 (5)	Ni—Si1—Erⁱⁱⁱ	68.61 (5)
Niⁱⁱ—Er—Si2^viii	96.66 (3)	Si1^vii—Si1—Erⁱⁱⁱ	69.71 (4)
Niⁱ—Er—Si2^viii	44.60 (2)	Si1^viii—Si1—Erⁱⁱⁱ	138.56 (3)
Ni^iv—Er—Si2^viii	44.60 (2)	Erⁱ—Si1—Erⁱⁱⁱ	82.22 (4)
Niⁱⁱⁱ—Er—Si2^viii	96.66 (3)	Erⁱⁱ—Si1—Erⁱⁱⁱ	82.49 (4)
Si2^v—Er—Si2^viii	53.516 (10)	Er^iv—Si1—Erⁱⁱⁱ	137.22 (9)
Si2^vi—Er—Si2^viii	53.516 (10)	Ni—Si1—Er^xiii	140.51 (3)
Si2^vii—Er—Si2^viii	78.91 (6)	Si1^vii—Si1—Er^xiii	64.78 (9)
Si1ⁱ—Er—Si1^vi	45.52 (5)	Si1^viii—Si1—Er^xiii	64.78 (9)
Si1ⁱⁱ—Er—Si1^vi	97.92 (2)	Erⁱ—Si1—Er^xiii	134.48 (5)
Si1ⁱⁱⁱ—Er—Si1^vi	45.52 (5)	Erⁱⁱ—Si1—Er^xiii	82.08 (2)
Si1^iv—Er—Si1^vi	97.92 (2)	Er^iv—Si1—Er^xiii	82.08 (2)
Niⁱⁱ—Er—Si1^vi	135.50 (2)	Erⁱⁱⁱ—Si1—Er^xiii	134.48 (5)
Niⁱ—Er—Si1^vi	83.25 (3)	Ni—Si1—Er^xiv	140.51 (3)
Ni^iv—Er—Si1^vi	135.50 (2)	Si1^vii—Si1—Er^xiv	64.78 (9)
Niⁱⁱⁱ—Er—Si1^vi	83.25 (3)	Si1^viii—Si1—Er^xiv	64.78 (9)
Si2^v—Er—Si1^vi	179.85 (4)	Erⁱ—Si1—Er^xiv	82.08 (2)
Si2^vi—Er—Si1^vi	100.88 (5)	Erⁱⁱ—Si1—Er^xiv	134.48 (5)
Si2^vii—Er—Si1^vi	126.58 (3)	Er^iv—Si1—Er^xiv	134.48 (5)
Si2^viii—Er—Si1^vi	126.58 (3)	Erⁱⁱⁱ—Si1—Er^xiv	82.08 (2)
Si1ⁱ—Er—Si1^v	97.92 (2)	Er^xiii—Si1—Er^xiv	78.97 (6)
Si1ⁱⁱ—Er—Si1^v	45.52 (5)	Ni^viii—Si2—Ni^vii	116.57 (12)
Si1ⁱⁱⁱ—Er—Si1^v	97.92 (2)	Ni^viii—Si2—Ni^xiii	106.10 (2)
Si1^iv—Er—Si1^v	45.52 (5)	Ni^vii—Si2—Ni^xiii	106.10 (2)
Niⁱⁱ—Er—Si1^v	83.25 (3)	Ni^viii—Si2—Ni^xiv	106.10 (2)
Niⁱ—Er—Si1^v	135.50 (2)	Ni^vii—Si2—Ni^xiv	106.10 (2)
Ni^iv—Er—Si1^v	83.25 (3)	Ni^xiii—Si2—Ni^xiv	116.33 (12)
Niⁱⁱⁱ—Er—Si1^v	135.50 (2)	Ni^viii—Si2—Si2^xv	127.04 (10)
Si2^v—Er—Si1^v	100.88 (5)	Ni^vii—Si2—Si2^xv	53.20 (5)
Si2^vi—Er—Si1^v	179.85 (4)	Ni^xiii—Si2—Si2^xv	52.90 (5)
Si2^vii—Er—Si1^v	126.58 (3)	Ni^xiv—Si2—Si2^xv	126.86 (10)
Si2^viii—Er—Si1^v	126.58 (3)	Ni^viii—Si2—Si2^xvi	53.20 (5)
Si1^vi—Er—Si1^v	78.97 (6)	Ni^vii—Si2—Si2^xvi	127.04 (10)
Si1ⁱ—Er—Er^ix	48.888 (18)	Ni^xiii—Si2—Si2^xvi	126.86 (10)
Si1ⁱⁱ—Er—Er^ix	131.112 (18)	Ni^xiv—Si2—Si2^xvi	52.90 (5)
Si1ⁱⁱⁱ—Er—Er^ix	131.112 (18)	Si2^xv—Si2—Si2^xvi	179.6 (2)
Si1^iv—Er—Er^ix	48.888 (18)	Ni^viii—Si2—Si2^xvii	127.04 (10)
Niⁱⁱ—Er—Er^ix	130.652 (11)	Ni^vii—Si2—Si2^xvii	53.20 (5)
Niⁱ—Er—Er^ix	49.348 (11)	Ni^xiii—Si2—Si2^xvii	126.86 (10)
Ni^iv—Er—Er^ix	49.348 (11)	Ni^xiv—Si2—Si2^xvii	52.90 (5)
Niⁱⁱⁱ—Er—Er^ix	130.652 (11)	Si2^xv—Si2—Si2^xvii	90.151 (19)
Si2^v—Er—Er^ix	90.0	Si2^xvi—Si2—Si2^xvii	89.848 (19)
Si2^vi—Er—Er^ix	90.0	Ni^viii—Si2—Si2^xviii	53.20 (5)
Si2^vii—Er—Er^ix	129.46 (3)	Ni^vii—Si2—Si2^xviii	127.04 (10)
Si2^viii—Er—Er^ix	50.54 (3)	Ni^xiii—Si2—Si2^xviii	52.90 (5)
Si1^vi—Er—Er^ix	90.0	Ni^xiv—Si2—Si2^xviii	126.86 (10)
Si1^v—Er—Er^ix	90.0	Si2^xv—Si2—Si2^xviii	89.848 (19)
Si1ⁱ—Er—Er^x	131.112 (18)	Si2^xvi—Si2—Si2^xviii	90.151 (19)
Si1ⁱⁱ—Er—Er^x	48.888 (18)	Si2^xvii—Si2—Si2^xviii	179.6 (2)
Si1ⁱⁱⁱ—Er—Er^x	48.888 (18)	Ni^viii—Si2—Er^xiv	66.12 (5)
Si1^iv—Er—Er^x	131.112 (18)	Ni^vii—Si2—Er^xiv	66.12 (5)
Niⁱⁱ—Er—Er^x	49.348 (11)	Ni^xiii—Si2—Er^xiv	161.47 (9)
Niⁱ—Er—Er^x	130.652 (11)	Ni^xiv—Si2—Er^xiv	82.20 (4)
Ni^iv—Er—Er^x	130.652 (11)	Si2^xv—Si2—Er^xiv	117.01 (11)
Niⁱⁱⁱ—Er—Er^x	49.348 (11)	Si2^xvi—Si2—Er^xiv	63.31 (7)
Si2^v—Er—Er^x	90.0	Si2^xvii—Si2—Er^xiv	63.31 (7)
Si2^vi—Er—Er^x	90.0	Si2^xviii—Si2—Er^xiv	117.01 (11)
Si2^vii—Er—Er^x	50.54 (3)	Ni^viii—Si2—Er^xiii	66.12 (5)
Si2^viii—Er—Er^x	129.46 (3)	Ni^vii—Si2—Er^xiii	66.12 (5)
Si1^vi—Er—Er^x	90.0	Ni^xiii—Si2—Er^xiii	82.20 (4)
Si1^v—Er—Er^x	90.0	Ni^xiv—Si2—Er^xiii	161.47 (9)
Er^ix—Er—Er^x	180.000 (10)	Si2^xv—Si2—Er^xiii	63.31 (7)
Si1ⁱ—Er—Er^xi	48.756 (18)	Si2^xvi—Si2—Er^xiii	117.01 (11)
Si1ⁱⁱ—Er—Er^xi	131.244 (18)	Si2^xvii—Si2—Er^xiii	117.01 (11)
Si1ⁱⁱⁱ—Er—Er^xi	48.756 (18)	Si2^xviii—Si2—Er^xiii	63.31 (7)
Si1^iv—Er—Er^xi	131.244 (18)	Er^xiv—Si2—Er^xiii	79.27 (6)
Niⁱⁱ—Er—Er^xi	130.782 (11)	Ni^viii—Si2—Er^vii	161.17 (9)
Niⁱ—Er—Er^xi	49.218 (11)	Ni^vii—Si2—Er^vii	82.26 (4)
Ni^iv—Er—Er^xi	130.782 (11)	Ni^xiii—Si2—Er^vii	65.97 (5)
Niⁱⁱⁱ—Er—Er^xi	49.218 (11)	Ni^xiv—Si2—Er^vii	65.97 (5)
Si2^v—Er—Er^xi	129.64 (3)	Si2^xv—Si2—Er^vii	63.18 (7)
Si2^vi—Er—Er^xi	50.36 (3)	Si2^xvi—Si2—Er^vii	116.51 (11)
Si2^vii—Er—Er^xi	90.0	Si2^xvii—Si2—Er^vii	63.18 (7)
Si2^viii—Er—Er^xi	90.0	Si2^xviii—Si2—Er^vii	116.51 (11)
Si1^vi—Er—Er^xi	50.51 (3)	Er^xiv—Si2—Er^vii	126.484 (10)
Si1^v—Er—Er^xi	129.49 (3)	Er^xiii—Si2—Er^vii	126.484 (10)
Er^ix—Er—Er^xi	90.0	Ni^viii—Si2—Er^viii	82.26 (4)
Er^x—Er—Er^xi	90.0	Ni^vii—Si2—Er^viii	161.17 (9)
Si1ⁱ—Er—Er^xii	131.244 (18)	Ni^xiii—Si2—Er^viii	65.97 (5)
Si1ⁱⁱ—Er—Er^xii	48.756 (18)	Ni^xiv—Si2—Er^viii	65.97 (5)
Si1ⁱⁱⁱ—Er—Er^xii	131.244 (18)	Si2^xv—Si2—Er^viii	116.51 (11)
Si1^iv—Er—Er^xii	48.756 (18)	Si2^xvi—Si2—Er^viii	63.18 (7)
Niⁱⁱ—Er—Er^xii	49.218 (11)	Si2^xvii—Si2—Er^viii	116.51 (11)
Niⁱ—Er—Er^xii	130.782 (11)	Si2^xviii—Si2—Er^viii	63.18 (7)
Ni^iv—Er—Er^xii	49.218 (11)	Er^xiv—Si2—Er^viii	126.484 (10)
Niⁱⁱⁱ—Er—Er^xii	130.782 (11)	Er^xiii—Si2—Er^viii	126.484 (10)
Si2^v—Er—Er^xii	50.36 (3)	Er^vii—Si2—Er^viii	78.91 (6)
Si2^vi—Er—Er^xii	129.64 (3)

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

Experimental details

Crystal data
Chemical formula	ErNiSi₂
M_r	282.15
Crystal system, space group	Orthorhombic, Cmcm
Temperature (K)	295
a, b, c (Å)	3.9423 (9), 16.502 (3), 3.9319 (9)
V (Å³)	255.79 (9)
Z	4
Radiation type	Mo Kα
µ (mm⁻¹)	40.49
Crystal size (mm)	0.21 × 0.19 × 0.04

Data collection
Diffractometer	Oxford Diffraction Xcalibur3 CCD area-detector diffractometer
Absorption correction	Analytical CrysAlis RED (Oxford Diffraction, 2005)
T_min, T_max	0.002, 0.199
No. of measured, independent and observed [I > 2σ(I)] reflections	1025, 281, 280
R_int	0.039
(sin θ/λ)_max (Å⁻¹)	0.760

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.025, 0.057, 1.33
No. of reflections	281
No. of parameters	18
Δρ_max, Δρ_min (e Å⁻³)	4.29, −2.85

Computer programs: CrysAlis CCD (Oxford Diffraction, 2004), CrysAlis CCD, CrysAlis RED (Oxford Diffraction, 2005), SHELXS97 (Sheldrick, 1997), SHELXL97 (Sheldrick, 1997), DIAMOND (Brandenburg, 1999).

Selected bond lengths (Å) top

Er—Si1ⁱ	2.9899 (10)	Ni—Si1	2.255 (3)
Er—Niⁱⁱ	3.0178 (6)	Ni—Si2^vii	2.3110 (15)
Er—Si2ⁱⁱⁱ	3.090 (2)	Ni—Si2^iv	2.3202 (15)
Er—Si1^iv	3.100 (2)	Si1—Si1^viii	2.358 (3)
Er—Er^v	3.9319 (9)	Si2—Si2^ix	2.7840 (5)
Er—Er^vi	3.9423 (9)

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

Format		BIBTeX
		EndNote
		RefMan
		Refer
		Medline
		CIF
		SGML
		Text
		Plain Text

Format		BIBTeX
		EndNote
		RefMan
		Refer
		Medline
		CIF
		SGML
		Text
		Plain Text

Search IUCr Journals		doi		Advanced search
Author		volume	page