Inversion parameter of the CoGa2O4 spinel determined from single crystal X ray data

inorganic papers

Acta Cryst.(2006). E62, i109–i111 doi:10.1107/S1600536806011044 Nakatsukaet al. _CoGa

2O4

i109

Acta Crystallographica Section E

Structure Reports

Online

ISSN 1600-5368

Inversion parameter of the CoGa

O

spinel

determined from single-crystal X-ray data

Akihiko Nakatsuka,* Yuya Ikeda, Noriaki Nakayama and Tadato Mizota

Department of Advanced Materials Science and Engineering, Faculty of Engineering, Yamaguchi University, Ube, Yamaguchi 755-8611, Japan

Correspondence e-mail: [email protected]

Key indicators

Single-crystal X-ray study T= 296 K

Mean(Co/Ga-O) = 0.002 A˚ Disorder in main residue Rfactor = 0.017 wRfactor = 0.023

Data-to-parameter ratio = 23.9

For details of how these key indicators were automatically derived from the article, see http://journals.iucr.org/e.

Received 21 March 2006 Accepted 27 March 2006

#2006 International Union of Crystallography All rights reserved

Single crystals of cobalt digallium tetraoxide, CoGa2O4, have

been grown by cooling slowly a 1:1 mixture of CoO and Ga2O3

from 1473 K to room temperature under the presence of a PbF2 flux. The compound crystallizes with the cubic spinel

structure (space group Fd3m). The occupancy refinement based on single-crystal X-ray diffraction data shows CoGa2O4

to be a largely normal spinel with an inversion parameter of 0.575 (4), resulting in a structural formula of IV_(Co

0.425

-Ga0.575) VI

[Co0.575Ga1.425]O4, where IV

() and VI[] represent the tetrahedral and the octahedral sites, respectively.

Comment

Typical cation arrangements of spinels,IV(A1xBx) VI

[AxB2x

]-O4, are normal-type (x= 0) and inverse-type (x= 1), where IV_{() and}VI_{[] represent the tetrahedral and the octahedral sites,}

respectively. The inversion parameter (x) depends on the species of constituent cations and temperature of equilibrium; its value approaches2

3, corresponding to a completely random

cation distribution between the two sites, with increasing temperature. In many spinels, the x values observed at ambient conditions are in the range 0 <x<2

3or 2

3<x< 1; the

former case is termed ‘largely normal spinel’ and the latter ‘largely inverse spinel’.

Physical properties of spinels are known to depend largely on their cation distributions (e.g. Gorter, 1950; Schulkes & Blasse, 1963; Blasse, 1966). Moreover, investigations of cation distributions in spinels can provide an insight into the relative stability of cations in tetrahedral and octahedral coordination. From these points of view, the crystal chemistry of spinels has been intensively systematized (Hill et al., 1979; Sickafus & Wills, 1999). However, as to the cation distributions of some spinel compounds, there have been disagreements between different studies. CoGa2O4 is one such example [x = 0.6

(largely normal spinel) at 40 K (Soubeyrouxet al., 1986),x’1 (largely inverse spinel) for the sample synthesized hydro-thermally at 703 K (Christensenet al., 1995),x= 0.72 (largely inverse spinel) for the sample quenched from 1473 K (Porta & Anichini, 1980)]. These disagreements may be because displacement parameters, correlated greatly with occupancies, were not determined in these previous studies, which were performed on the basis of powder diffraction data. We report here the inversion parameter of the CoGa2O4 spinel

deter-mined from a full structure refinement based on single-crystal data, including anisotropic displacement parameters.

The refinement resulted in an inversion parameter of x = 0.575 (4), which shows that CoGa2O4is a largely normal spinel

with a structural formula of IV(Co0.425Ga0.575) VI

-[Co0.575Ga1.425]O4. This result shows that Ga

3+

in the CoGa2O4

site, in contradiction to every effect of cation size (rGa< rCo;

Shannon, 1976), electronegativity (Co= 1.47 < Ga = 2.10;

Sanderson, 1967) and the ligand field of Co2+. Such a peculiar cation distribution was also reported in MgAl2O4 (e.g.

Maekawaet al., 1997; Itoet al., 2000; Nakatsukaet al., 2004), CoAl2O4(Greenwaldet al., 1954; Toriumiet al., 1978; Porta &

Anichini, 1980; O’Neill, 1994; Nakatsukaet al., 2003), FeAl2O4

(Larsson et al., 1994; Harrison et al., 1998) and MnGa2O4

spinels (Garcı´a Casado & Rasines, 1982).

Displacement ellipsoids and selected interatomic distances of the title compound are given in Fig. 1 and Table 1, respectively.

Experimental

Single crystals of the CoGa2O4spinel were grown using a PbF2flux.

Special grade reagents (99.99%) of CoO and Ga2O3were used as

starting materials and mixed together with the PbF2flux in the molar

ratio CoO:Ga2O3:PbF2= 1:1:9. This mixture was placed in a 30 cm3

platinum crucible and heated slowly to 1473 K. The melt of the mixture was then cooled at rates of 5 K h1from 1473 to 973 K and of 10 K h1_{from 973 to 573 K. Subsequently, the heating was turned off}

and the samples were removed from the furnace at room tempera-ture.

Crystal data

CoGa2O4

Mr= 262.37

Cubic,Fd3m a= 8.3281 (3) A˚

V= 577.61 (4) A˚3

Z= 8

Dx= 6.034 Mg m

3

MoKradiation

Cell parameters from 38 reflections

= 20.0–24.7

= 24.01 mm1

T= 296 K Prism, dark blue 0.130.110.09 mm

Data collection

Rigaku AFC-7Rdiffractometer !–2scans

Absorption correction: scan (Northet al., 1968)

Tmin= 0.060,Tmax= 0.115

613 measured reflections 248 independent reflections 215 reflections withF> 3(F)

Rint= 0.023

max= 60.0

h= 0!20

k= 0!20

l= 0!20

3 standard reflections every 100 reflections intensity decay: 1.0%

Refinement

Refinement onF R[F> 3(F)] = 0.017

wR(F) = 0.023

S= 1.72 215 reflections 9 parameters

w= 1/2

(F) (/)max< 0.0001

max= 0.84 e A˚ 3

min=0.43 e A˚ 3

Extinction correction: isotropic Type I (Becker & Coppens, 1974a,b)

Extinction coefficient: 3.06 (6)

104

Table 1

Selected interatomic distances (A˚ ).

Co1/Ga1—O 1.9245 (16) Co2/Ga2—Oi

2.0144 (16) O Oii 3.143 (3)

O Oiii

2.746 (3) O Oiv

2.9478 (16)

Symmetry codes: (i)xþ1;yþ1 4;zþ

1 4; (ii)xþ

1 4;y;zþ

1

4; (iii)xþ 3 4;yþ

3 4;z;

(iv)x1 4;yþ

1 4;zþ

1 2.

The occupancies of the cations at the tetrahedral and the octa-hedral sites were constrained on the basis of the structural formula

IV

(Co1xGax) VI

[CoxGa2x]O4; consequently, the variable occupancy

parameter was only the Ga3+_{occupancy at the tetrahedral site,i.e.the}

inversion parameter (x).

Data collection: WinAFC (Rigaku Corporation, 1999); cell refinement: WinAFC; data reduction: RADY (Sasaki, 1987); program(s) used to solve structure:TEXSAN(Molecular Structure Corporation, 1999); program(s) used to refine structure: RADY; molecular graphics:ATOMS(Dowty, 2000); software used to prepare material for publication:TEXSAN.

This work was partly supported by a Grant-in-Aid for Scientific Research (No. 15740317) from the Ministry of Education, Culture, Sports, Science and Technology of the Japanese Government.

References

Becker, P. J. & Coppens, P. (1974a).Acta Cryst.A30, 129–147. Becker, P. J. & Coppens, P. (1974b).Acta Cryst.A30, 148–153. Blasse, G. (1966).J. Phys. Chem. Solids,27, 383–389.

Christensen, A., Norby, P. & Hanson, J. C. (1995).Powder Diffr.10, 185–188. Dowty, E. (2000).ATOMS for Windows. Version 5.1. Shape Software, 521

Hidden Valley Road, Kingsport, TN 37663, USA.

Garcı´a Casado, P. & Rasines, I. (1982).Z. Kristallogr.160, 33–37. Gorter, E. W. (1950).Nature(London),165, 798–800.

Greenwald, S., Pickart, S. J. & Grannis, F. H. (1954).J. Chem. Phys.22, 1597– 1600.

Harrison, R. J., Redfern, S. A. T. & O’Neill, H. S. C. (1998).Am. Mineral.83, 1092–1099.

Hill, R. J., Craig, J. R. & Gibbs, G. V. (1979).Phys. Chem. Miner.4, 317–339. Ito, T., Yoshiasa, A., Yamanaka, T., Nakatsuka, A. & Maekawa, H. (2000).Z.

Anorg. Allg. Chem.626, 42–49.

Larsson, L., O’Neill, H. S. C. & Annersten, H. (1994).Eur. J. Mineral.6, 39–51. Maekawa, H., Kato, S., Kawamura, K. & Yokokawa, T. (1997).Am. Mineral.

82, 1125–1132.

Molecular Structure Corporation (1999).TEXSAN. Version 1.10. MSC, The Woodlands, Texas, USA.

Nakatsuka, A., Ikeda, Y., Yamasaki, Y., Nakayama, N. & Mizota, T. (2003).

Solid State Commun.128, 85–90.

Nakatsuka, A., Ueno, H., Nakayama, N., Mizota, T. & Maekawa, H. (2004).

Phys. Chem. Miner.31, 278–287.

North, A. C. T., Phillips, D. C. & Mathews, F. S. (1968).Acta Cryst.A24, 351– 359.

O’Neill, H. S. C. (1994).Eur. J. Mineral.6, 603–609.

Porta, P. & Anichini, A. (1980).J. Chem. Soc. Faraday Trans. 1,76, 2448–2456. Rigaku Corporation (1999). WinAFC. Version 1.03. Rigaku Corporation,

Tokyo, Japan.

inorganic papers

i110

2O4 Acta Cryst.(2006). E62, i109–i111

Figure 1

The crystal structure of the CoGa2O4spinel with displacement ellipsoids

Sanderson, R. T. (1967). Inorganic Chemistry. New York: Van Nostrand-Reinhold.

Sasaki, S. (1987).RADY.National Laboratory for High Energy Physics, Japan. Schulkes, J. A. & Blasse, G. (1963).J. Phys. Chem. Solids,24, 1651–1655. Shannon, R. D. (1976).Acta Cryst.A32, 751–767.

Sickafus, K. E. & Wills, J. M. (1999).J. Am. Ceram. Soc.82, 3279–3292. Soubeyroux, J. L., Fiorani, D. & Agostinelli, E. (1986).J. Magn. Magn. Mater.

54–57, 83–84.

Toriumi, K., Ozima, M., Akaogi, M. & Saito, Y. (1978).Acta Cryst.B34, 1093– 1096.

inorganic papers

Acta Cryst.(2006). E62, i109–i111 Nakatsukaet al. _CoGa

supporting information

sup-1 Acta Cryst. (2006). E62, i109–i111

supporting information

Acta Cryst. (2006). E62, i109–i111 [https://doi.org/10.1107/S1600536806011044]

Inversion parameter of the CoGa

O

spinel determined from single-crystal X-ray

data

Akihiko Nakatsuka, Yuya Ikeda, Noriaki Nakayama and Tadato Mizota

cobalt digallium tetraoxide

Crystal data

CoGa2O4

Mr = 262.37

Cubic, Fd3m

Hall symbol: -F 4vw 2vw 3

a = 8.3281 (3) Å

V = 577.61 (4) Å3

Z = 8

F(000) = 968

Dx = 6.034 Mg m−3

Mo Kα radiation, λ = 0.71069 Å

Cell parameters from 38 reflections

θ = 20.0–24.7°

µ = 24.01 mm−1

T = 296 K

Prism, dark blue 0.13 × 0.11 × 0.09 mm

Data collection

Rigaku AFC-7R diffractometer

ω–2θ scans

Absorption correction: ψ scan

(North et al., 1968)

Tmin = 0.060, Tmax = 0.115 613 measured reflections 248 independent reflections

215 reflections with F > 3σ(F)

Rint = 0.023

θmax = 60.0°

h = 0→20

k = 0→20

l = 0→20

3 standard reflections every 100 reflections intensity decay: 1.0%

Refinement

Refinement on F

R[F2 _{> 2σ(F}2_{)] = 0.017}

wR(F2_{) = 0.023}

S = 1.72

215 reflections 9 parameters

w = 1/σ2_(F)

(Δ/σ)max = 0.00008

Δρmax = 0.84 e Å−3 Δρmin = −0.43 e Å−3

Extinction correction: isotropic Type I (Becker & Coppens, 1974a,b)

Extinction coefficient: 3.06 (6)×10-4

Special details

Refinement. Refinement using reflections with F > 3.0 σ(F). The weighted R-factor (wR), goodness of fit (S) and R -factor (gt) are based on F, with F set to zero for negative F. The threshold expression of F > 3.0 σ(F) is used only for calculating R-factor (gt).

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

x y z Uiso*/Ueq Occ. (<1)

supporting information

sup-2 Acta Cryst. (2006). E62, i109–i111

Ga1 0.1250 0.1250 0.1250 0.00373 0.575 (4)

Co2 0.5000 0.5000 0.5000 0.00353 (1) 0.288

Ga2 0.5000 0.5000 0.5000 0.00353 0.712

O 0.25842 (19) 0.25842 0.25842 0.00760 (4)

Atomic displacement parameters (Å2₎

U11 _U22 _U33 _U12 _U13 _U23

Co1 0.00373 (12) 0.00373 0.00373 0.00000 0.00000 0.00000

Ga1 0.00373 0.00373 0.00373 0.00000 0.00000 0.00000

Co2 0.00353 (9) 0.00353 0.00353 −0.00040 (7) −0.00040 −0.00040

Ga2 0.00353 0.00353 0.00353 −0.00040 −0.00040 −0.00040

O 0.0076 (3) 0.0076 0.0076 0.0002 (4) 0.0002 0.0002

Geometric parameters (Å, º)

Co1/Ga1—O 1.9245 (16) Co2/Ga2—Oix _{2.0144 (16)}

Co1/Ga1—Oi _{1.9245 (16) O—O}ii _{3.143 (3)}

Co1/Ga1—Oii _{1.9245 (16) O—O}iii _{3.143 (3)}

Co1/Ga1—Oiii _{1.9245 (16) O—O}ix _{2.746 (3)}

Co2/Ga2—Oiv _{2.0144 (16) O—O}viii _{2.746 (3)}

Co2/Ga2—Ov _{2.0144 (16) O—O}x _{2.9478 (16)}

Co2/Ga2—Ovi _{2.0144 (16) O—O}xi _{2.9478 (16)}

Co2/Ga2—Ovii _{2.0144 (16) O—O}xii _{2.9478 (16)}

Co2/Ga2—Oviii _{2.0144 (16) O—O}xiii _{2.9478 (16)}

O—Co1/Ga1—Oi _{109.47 (10) O}viii_{—Co2/Ga2—O}iv _{94.06 (9)}

O—Co1/Ga1—Oii _{109.47 (10) O}vii_{—Co2/Ga2—O}vi _{94.06 (7)}

O—Co1/Ga1—Oiii _{109.47 (10) O}vii_{—Co2/Ga2—O}v _{94.06 (9)}

Oii_{—Co1/Ga1—O}i _{109.47 (10) O}vii_{—Co2/Ga2—O}iv _180.00

Oiii_{—Co1/Ga1—O}i _{109.47 (10) O}vi_{—Co2/Ga2—O}v _{85.94 (7)}

Oiii_{—Co1/Ga1—O}ii _{109.47 (10) O}vi_{—Co2/Ga2—O}iv _{85.94 (7)}

Oix_{—Co2/Ga2—O}viii _{85.94 (7) O}v_{—Co2/Ga2—O}iv _{85.94 (7)}

Oix_{—Co2/Ga2—O}vii _{85.94 (7) Co1/Ga1—O—Co/Ga2}xiv _{122.44 (8)}

Oix_{—Co2/Ga2—O}vi _{179.97 Co1/Ga1—O—Co/Ga2}xv _{122.44 (8)}

Oix_{—Co2/Ga2—O}v _{94.06 (7) Co1/Ga1—O—Co/Ga2}xvi _{122.44 (8)}

Oix_{—Co2/Ga2—O}iv _{94.06 (7) Co2/Ga2}xiv_{—O—Co/Ga2}xv _{93.92 (7)}

Oviii_{—Co2/Ga2—O}vii _{85.94 (7) Co2/Ga2}xiv_{—O—Co/Ga2}xvi _{93.92 (7)}

Oviii_{—Co2/Ga2—O}vi _{94.06 (7) Co2/Ga2}xv_{—O—Co/Ga2}xvi _{93.92 (7)}

Oviii_{—Co2/Ga2—O}v _179.97

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