Charge-doped nickel oxide, Y_1.90Ca_0.10BaNiO₅

The crystal structure of orthorhombic yttrium calcium barium nickel pentaoxide, Y_1.90Ca_0.10BaNiO₅, a charge-doped quasi-one-dimensional nickel oxide, has been determined from X-ray single-crystal data at room temperature. Ca²⁺ ions replace at random the Y³⁺ ions within the Immm crystal structure of the undoped compound, Y₂BaNiO₅.

Key indicators

• Single-crystal X-ray study
• T = 293 K
• Mean [sigma](Ni-O) = 0.001 Å
• Disorder in main residue
• R factor = 0.016
• wR factor = 0.042
• Data-to-parameter ratio = 18.6

checkCIF results

No syntax errors found

ADDSYM reports no extra symmetry


 Alert Level C:



PLAT_301  Alert C Main Residue Disorder ........................      24.00 Perc.

PLAT_302  Alert C Anion/Solvent Disorder .......................       2.00 Perc.


 0 Alert Level A = Potentially serious problem

 0 Alert Level B = Potential problem

 2 Alert Level C = Please check

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S1. Comment

The crystal structure of the divalent nickel oxide Y₂BaNiO₅ was first determined from single-crystal diffraction data by Müller-Buschbaum & Schlüter (1990), Amador et al. (1990) and Buttrey et al. (1990). It has an orthorhombic crystal structure that contains infinite linear chains of flattened NiO₆ octahedra sharing corners along the crystallographic a direction. The magnetic properties of this charge-transfer insulator are those of an antiferromagnetic chain compound with a Haldane spin gap (Darriet & Regnault, 1993). Hole doping in Y₂BaNiO₅, which is achieved by substituting Ca²⁺ for Y³⁺, has attracted considerable attention in recent years, arising from quite interesting electronic and physical properties and possible connections to high-temperature superconductivity (Di Tusa et al., 1994; Janod et al., 2001). X-ray and neutron-powder diffraction data for Y_{2 - x}Ca_xBaNiO₅ have been analysed using the Rietveld method (Massarotti et al., 1999) but, as far as we know, no single-crystal structure determination has been published so far.

In this work, we have analyzed a single-crystal of Y_{2 - x}Ca_xBaNiO₅, prepared by a flux method. The refinement of the single-crystal data confirms that Ca²⁺ ions replace at random the Y³⁺ ions within the Immm crystal structure of the undoped compound without any sign of superstructure, in agreement with the results of a previous electron diffraction study (Xu et al., 2001). The refinement of the Ca,Y occupancy factors leads to the composition x = 0.10 (1), in agreement with the value determined from our energy-dispersive X-ray elemental analysis, x = 0.11 (2). Atomic parameters (positions, ADP's and occupation ratio) are obtained here with s.u.'s much smaller than those reported from powder data (Massarotti et al., 1999). Moreover, the z coordinate of the Y/Ca site is very close to those reported for the undoped compound by Müller-Buschbaum & Schlüter (1990) and Amador et al. (1990), but significantly different from that obtained by Buttrey et al. (1990). Our study seems to highlight the unreliability of the refinement of Buttrey et al. (1990) concerning not only the lattice parameters, as already suggested by these authors, but also the z coordinate of the Y site.

We thus confirm that substitution of Y³⁺ by Ca²⁺ does not induce significant structural modification around the Y site. On the other hand, the Ni—O1 and Ni—O2 distances are found to decrease upon doping in spite of a bigger ionic radius for Ca²⁺, as suggested earlier (Massarotti et al., 1999). The shortening of both axial Ni—O1 and equatorial Ni—O2 distances is due to the effects of hole doping on the electronic structure close to the Fermi level (Lannuzel et al., 2001).

S2. Experimental

Single crystals of Y_1.90Ca_0.10BaNiO₅ were prepared using a self-flux method, as described by Yokoo et al. (1995). We first synthetized a ceramic sample of the parent compound Y₂BaNiO₅ by solid-state reaction from a mixture of NiO, Y₂O₃ and BaCO₃ in air. We then added this polycrystalline sample to a mixture of CaCO₃, NiO and BaCO₃, in a mole ratio of CaCO₃:NiO:BaCO₃:Y₂O₃ = 1.62:45:45:10. This mixture was then heated at 1723 K for 2 h in a Pt crucible, and slowly cooled (2 K h^-1) to room temperature.

Computing details

Data collection: CAD-4-PC Software (Enraf-Nonius, 1992); cell refinement: CAD-4-PC Software; data reduction: JANA2000 (Petrícek & Dusek, 2000); program(s) used to refine structure: JANA2000; molecular graphics: DIAMOND (Brandenburg, 1999); software used to prepare material for publication: JANA2000.

Figures

	Fig. 1. A view of the unit cell of Y1.90Ca0.10BaNiO5. Displacement ellipsoids are drawn here at the 97% probability level. Ni—O bonds of the central NiO6 octahedra and unit-cell edges are shown.
	Fig. 2. Schematic view of the crystallographic structure of Y1.90Ca0.10BaNiO5 highlighting the existence of linear chains of vertex-sharing NiO6 octahedra.

(I)

Crystal data

Y1.90Ca0.10BaNiO5	Dx = 6.097 Mg m^−3
Mr = 449	Mo Kα radiation, λ = 0.71069 Å
Orthorhombic, Immm	Cell parameters from 25 reflections
a = 3.7527 (5) Å	θ = 7.4–15.0°
b = 5.7581 (9) Å	µ = 34.10 mm^−1
c = 11.313 (2) Å	T = 293 K
V = 244.46 (6) Å^3	Thick needle, black
Z = 2	0.16 × 0.02 × 0.02 mm
F(000) = 400

Data collection

CAD-4 diffractometer	Rint = 0.035
ω scans	θmax = 38.0°, θmin = 3.6°
Absorption correction: gaussian (JANA2000; Petrícek & Dusek, 2000)	h = −6→6
Tmin = 0.420, Tmax = 0.511	k = −9→9
2650 measured reflections	l = −19→19
409 independent reflections	3 standard reflections every 60 min
387 reflections with I > 2σ(I)	intensity decay: 0.8%

Refinement

Refinement on F^2	Weighting scheme based on measured s.u.'s w = 1/[σ^2(I) + 0.001024I^2]
R[F^2 > 2σ(F^2)] = 0.016	(Δ/σ)max = 0.003
wR(F^2) = 0.042	Δρmax = 1.07 e Å^−3
S = 1.00	Δρmin = −1.64 e Å^−3
409 reflections	Extinction correction: B-C type 1 Lorentzian isotropic
22 parameters	Extinction coefficient: 0.45 (2)

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

	x	y	z	Uiso*/Ueq	Occ. (<1)
Y	0.5	0	0.20285 (2)	0.00457 (7)	0.951 (4)
Ca	0.5	0	0.20285	0.00457	0.049
Ba	0.5	0.5	0	0.00822 (6)
Ni	0	0	0	0.00560 (11)
O1	0.5	0	0	0.0094 (7)
O2	0	0.2400 (2)	0.14833 (12)	0.0081 (3)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Y	0.00578 (14)	0.00403 (13)	0.00390 (12)	0	0	0
Ca	0.00578	0.00403	0.00390	0	0	0
Ba	0.01105 (12)	0.00640 (11)	0.00722 (11)	0	0	0
Ni	0.0039 (2)	0.0071 (2)	0.00575 (18)	0	0	0
O1	0.0076 (12)	0.0161 (14)	0.0044 (10)	0	0	0
O2	0.0096 (6)	0.0066 (6)	0.0080 (6)	0	0	−0.0018 (4)

Geometric parameters (Å, º)

Y—O1	2.2949 (2)	Ba—O2^viii	2.9287 (12)
Y—O2	2.4107 (10)	Ba—O2^ix	2.9287 (12)
Y—O2^i	2.4107 (10)	Ba—O2^x	2.9287 (12)
Y—O2^ii	2.2528 (15)	Ba—O2^xi	2.9287 (12)
Y—O2^iii	2.2528 (15)	Ba—O2^xii	2.9287 (12)
Y—O2^iv	2.4107 (10)	Ni—O1^xiii	1.8764 (3)
Y—O2^v	2.4107 (10)	Ni—O1	1.8764 (3)
Ba—O1	2.8791 (5)	Ni—O2	2.1740 (15)
Ba—O1^vi	2.8791 (5)	Ni—O2^xiv	2.1740 (15)
Ba—O2	2.9287 (12)	Ni—O2^ix	2.1740 (15)
Ba—O2^i	2.9287 (12)	Ni—O2^iv	2.1740 (15)
Ba—O2^vii	2.9287 (12)
O1—Y—O2	75.18 (3)	O2^i—Ba—O2^xi	110.08 (3)
O1—Y—O2^i	75.18 (3)	O2^i—Ba—O2^xii	61.47 (4)
O1—Y—O2^ii	138.36 (3)	O2^vii—Ba—O2	100.31 (2)
O1—Y—O2^iii	138.36 (3)	O2^vii—Ba—O2^i	180
O1—Y—O2^iv	75.18 (3)	O2^vii—Ba—O2^viii	79.69 (2)
O1—Y—O2^v	75.18 (3)	O2^vii—Ba—O2^ix	61.47 (4)
O2—Y—O2^i	102.22 (4)	O2^vii—Ba—O2^x	110.08 (3)
O2—Y—O2^ii	79.06 (4)	O2^vii—Ba—O2^xi	69.92 (3)
O2—Y—O2^iii	124.90 (3)	O2^vii—Ba—O2^xii	118.53 (4)
O2—Y—O2^iv	69.97 (4)	O2^viii—Ba—O2	180
O2—Y—O2^v	150.35 (4)	O2^viii—Ba—O2^i	100.31 (2)
O2^i—Y—O2	102.22 (4)	O2^viii—Ba—O2^vii	79.69 (2)
O2^i—Y—O2^ii	79.06 (4)	O2^viii—Ba—O2^ix	110.08 (3)
O2^i—Y—O2^iii	124.90 (3)	O2^viii—Ba—O2^x	61.47 (4)
O2^i—Y—O2^iv	150.35 (4)	O2^viii—Ba—O2^xi	118.53 (4)
O2^i—Y—O2^v	69.97 (4)	O2^viii—Ba—O2^xii	69.92 (3)
O2^ii—Y—O2	79.06 (4)	O2^ix—Ba—O2	69.92 (3)
O2^ii—Y—O2^i	79.06 (4)	O2^ix—Ba—O2^i	118.53 (4)
O2^ii—Y—O2^iii	83.28 (5)	O2^ix—Ba—O2^vii	61.47 (4)
O2^ii—Y—O2^iv	124.90 (3)	O2^ix—Ba—O2^viii	110.08 (3)
O2^ii—Y—O2^v	124.90 (3)	O2^ix—Ba—O2^x	79.69 (2)
O2^iii—Y—O2	124.90 (3)	O2^ix—Ba—O2^xi	100.31 (2)
O2^iii—Y—O2^i	124.90 (3)	O2^ix—Ba—O2^xii	180
O2^iii—Y—O2^ii	83.28 (5)	O2^x—Ba—O2	118.53 (4)
O2^iii—Y—O2^iv	79.06 (4)	O2^x—Ba—O2^i	69.92 (3)
O2^iii—Y—O2^v	79.06 (4)	O2^x—Ba—O2^vii	110.08 (3)
O2^iv—Y—O2	69.97 (4)	O2^x—Ba—O2^viii	61.47 (4)
O2^iv—Y—O2^i	150.35 (4)	O2^x—Ba—O2^ix	79.69 (2)
O2^iv—Y—O2^ii	124.90 (3)	O2^x—Ba—O2^xi	180
O2^iv—Y—O2^iii	79.06 (4)	O2^x—Ba—O2^xii	100.31 (2)
O2^iv—Y—O2^v	102.22 (4)	O2^xi—Ba—O2	61.47 (4)
O2^v—Y—O2	150.35 (4)	O2^xi—Ba—O2^i	110.08 (3)
O2^v—Y—O2^i	69.97 (4)	O2^xi—Ba—O2^vii	69.92 (3)
O2^v—Y—O2^ii	124.90 (3)	O2^xi—Ba—O2^viii	118.53 (4)
O2^v—Y—O2^iii	79.06 (4)	O2^xi—Ba—O2^ix	100.31 (2)
O2^v—Y—O2^iv	102.22 (4)	O2^xi—Ba—O2^x	180
O1—Ba—O1^vi	180	O2^xi—Ba—O2^xii	79.69 (2)
O1—Ba—O2	59.26 (2)	O2^xii—Ba—O2	110.08 (3)
O1—Ba—O2^i	59.26 (2)	O2^xii—Ba—O2^i	61.47 (4)
O1—Ba—O2^vii	120.74 (2)	O2^xii—Ba—O2^vii	118.53 (4)
O1—Ba—O2^viii	120.74 (2)	O2^xii—Ba—O2^viii	69.92 (3)
O1—Ba—O2^ix	59.26 (2)	O2^xii—Ba—O2^ix	180
O1—Ba—O2^x	59.26 (2)	O2^xii—Ba—O2^x	100.31 (2)
O1—Ba—O2^xi	120.74 (2)	O2^xii—Ba—O2^xi	79.69 (2)
O1—Ba—O2^xii	120.74 (2)	O1^xiii—Ni—O1	180
O1^vi—Ba—O1	180	O1^xiii—Ni—O2	90
O1^vi—Ba—O2	120.74 (2)	O1^xiii—Ni—O2^xiv	90
O1^vi—Ba—O2^i	120.74 (2)	O1^xiii—Ni—O2^ix	90
O1^vi—Ba—O2^vii	59.26 (2)	O1^xiii—Ni—O2^iv	90
O1^vi—Ba—O2^viii	59.26 (2)	O1—Ni—O1^xiii	180
O1^vi—Ba—O2^ix	120.74 (2)	O1—Ni—O2	90
O1^vi—Ba—O2^x	120.74 (2)	O1—Ni—O2^xiv	90
O1^vi—Ba—O2^xi	59.26 (2)	O1—Ni—O2^ix	90
O1^vi—Ba—O2^xii	59.26 (2)	O1—Ni—O2^iv	90
O2—Ba—O2^i	79.69 (2)	O2—Ni—O2^xiv	180
O2—Ba—O2^vii	100.31 (2)	O2—Ni—O2^ix	101.04 (5)
O2—Ba—O2^viii	180	O2—Ni—O2^iv	78.96 (5)
O2—Ba—O2^ix	69.92 (3)	O2^xiv—Ni—O2	180
O2—Ba—O2^x	118.53 (4)	O2^xiv—Ni—O2^ix	78.96 (5)
O2—Ba—O2^xi	61.47 (4)	O2^xiv—Ni—O2^iv	101.04 (5)
O2—Ba—O2^xii	110.08 (3)	O2^ix—Ni—O2	101.04 (5)
O2^i—Ba—O2	79.69 (2)	O2^ix—Ni—O2^xiv	78.96 (5)
O2^i—Ba—O2^vii	180	O2^ix—Ni—O2^iv	180
O2^i—Ba—O2^viii	100.31 (2)	O2^iv—Ni—O2	78.96 (5)
O2^i—Ba—O2^ix	118.53 (4)	O2^iv—Ni—O2^xiv	101.04 (5)
O2^i—Ba—O2^x	69.92 (3)	O2^iv—Ni—O2^ix	180

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