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Tyrrellite, a naturally occurring Co–Ni–Cu selenide, has been studied by single-crystal X-ray diffraction. It possesses the normal spinel-type structure, with Cu occupying the tetra­hedral site and (Co+Ni) the octa­hedral site. The average Cu—Se distance of 2.3688 (2) Å is close to that of 2.3703 (8) Å in CuCr2Se4, whereas the average (Co+Ni)—Se distance of 2.3840 (1) Å appears to be slightly shorter than most octa­hedral Co—Se or Ni—Se distances (∼2.40–2.50 Å) in other selenides. The refined structure provides a basis for a redefinition of the ideal chemical formula of tyrrellite, which should be Cu(Co,Ni)2Se4, rather than the previously suggested (Cu,Co,Ni)3Se4.

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S010827010703048X/bc3052sup1.cif
Contains datablocks I, global

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S010827010703048X/bc3052Isup2.hkl
Contains datablock I

Comment top

Selenide materials with the spinel-type structure, AB2Se4, where A and B are tetrahedrally and octahedrally coordinated sites, respectively, have been the subject of numerous studies because of their magnetic and semiconducting properties (see, for example, Juszczyk & Gogolowicz, 1991; Kim et al., 2006; Skrzypek et al., 2006; Noh et al., 2007). Of particular interest is the distribution of various cations between the A and B sites, as such structural variations could significantly alter many physical properties of these materials (see, for example, Hazen & Yang, 1999; Okonska-Kozlowska et al., 2001). Tyrrellite, a cobalt-nickel-copper selenide, was first described by Robinson & Brooker (1952) to have a face-centered cubic lattice (Fm3m) with a = 10.005–10.042 Å and a chemical formula Co3.0Ni2.0Cu3.5Se9.5. However, Machatschki & Stradner (1952) pointed out that the X-ray powder pattern of tyrrellite resembled that of spinel minerals and the calculated intensities, assuming a spinel-type structure, agree well with the probable formula of (Co,Cu,Ni)3Se4. Harris (1970) examined the original tyrrellite material separated by Robinson & Brooker (1952) using a single-crystal X-ray diffractometer and found that all the fragments gave split reflections and were unsuitable for structure determination. No further structural investigation has been reported since then. This study presents the first structure refinement of tyrrellite based on single-crystal X-ray diffraction data and provides a basis for a redefinition of its ideal chemical formula.

Tyrrellite is isostructural with spinel, with Cu and (Co+Ni), respectively, occupying the tetrahedral A and octahedral B sites in the cubic close-packed array of Se atoms (Fig. 1). The preference of Cu for the tetrahedral site has been observed for other spinel-type selenides and sulfides, such as CuCr2Se4 (Okońska-Kozlowska et al., 1993), Cu1 - xCoxCr2Se4 (Okonska-Kozlowska et al., 2001), Cu1 - xNixCr2Se4 and CuCr2 - xNixSe4 (Jendrzejewska, 2000), CuCo2S4 (Williamson & Grimes, 1974), and Cu(Ni0.25Sn0.75)2S4 (Garg et al., 2001). The Cu—Se distance of 2.3688 (2) Å in tyrrellite is comparable with the range of 2.3664–2.3740 Å in spinel-type CuCr2Se4 (Okońska-Kozlowska et al., 1993; Payer et al., 1993; Rodic et al., 1998), whereas the average (Co+Ni)—Se distance of 2.3840 (1) Å appears to be shorter than most Co—Se or Ni—Se distances (~ 2.40—2.50 Å) for six-coordinated Co or Ni in other selenides (see. for example, Furuseth et al., 1969; Kamat Dalal et al., 1971; Foecher & Jeitschko, 2001; Garcia-Garcia et al., 2004).

Unlike oxide spinels, the valence of ions in selenide spinels has been a matter of discussion. For example, three models of electronic structures have been proposed for CuCr2Se4: Cu2+Cr3+2Se2-4 (Goodenough, 1967), Cu+[Cr3+Cr4+]Se2-4 (Lotgering, 1964), and Cu+Cr3+2[Se2-3Se-] (Lotgering & Van Stapele, 1967). Although there is still some disagreement regarding the valence of Cr and Se, experimental results from X-ray photoelectron spectroscopy and neutron diffraction have demonstrated the presence of Cu+, rather than Cu2+, in CuCr2Se4 (Hollander et al., 1974; Yamashita et al., 1979; Payer et al., 1990; Rodic et al., 1998). Since the Cu—Se bond length in tyrrellite agrees very well with that in CuCr2Se4, presumably Cu in tyrrellite is also monovalent. Noteworthy, nevertheless, is the appreciably short (Co+Ni)—Se bond distance in tyrrellite compared with the Cr—Se distances (2.508–2.512 Å) in CuCr2Se4 (Okońska-Kozlowska et al., 1993; Payer et al., 1993; Rodic et al., 1998). If we assume that the chemical bond between Se and the octahedrally coordinated cation is predominately ionic (Juszczyk & Gogolowicz, 1991; Rodic et al., 1998), the calculation of the bond-valence sum using the parameters given by Brese & O'Keeffe (1991) yields a value of 3.77 v.u. for (Co+Ni), suggesting that some Co or/and Ni in tyrrellite might exist in a formal charge greater than 3+.

Related literature top

For related literature, see: Brese & O'Keeffe (1991); Foecher & Jeitschko (2001); Furuseth et al. (1969); Garcia-Garcia, Larsson, Noren & Withers (2004); Garg et al. (2001); Goodenough (1967); Harris (1970); Hazen & Yang (1999); Hollander et al. (1974); Jendrzejewska (2000); Juszczyk & Gogolowicz (1991); Kamat Dalal, Keer & Biswas (1971); Kim et al. (2006); Lotgering (1964); Lotgering & Van Stapele (1967); Machatschki & Stradner (1952); Noh et al. (2007); Okońska-Kozlowska, Kopyczok, Lutz & Stingl (1993); Okonska-Kozlowska, Malicka, Waskowska, Heimann & Mydlarz (2001); Payer et al. (1990, 1993); Robinson & Brooker (1952); Rodic et al. (1998); Skrzypek et al. (2006); Williamson & Grimes (1974); Yamashita et al. (1979).

Experimental top

The tyrrellite specimen used in this study is from the type locality Eagle Claims, Beaverlodge Lake area, Saskatchewan, Canada, and is in the collection of the RRUFF project (deposition No. R060481; https://rruff.info). The specimen was described by Robinson & Brooker (1952) and Harris (1970). The average chemical composition (15 point analyses), Cu0.99(Co0.69Ni0.31)2Se4, was determined with a CAMECA SX50 electron microprobe.

Refinement top

The A site was assumed to be fully occupied by Cu during the refinement. The Co:Ni ratio in the B site was allowed to vary and yielded occupancies of 0.68 (6) for Co and 0.32 (6) for Ni.

Computing details top

Data collection: APEX2 (Bruker, 2003); cell refinement: SAINT (Bruker, 2005); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: Please provide missing information; software used to prepare material for publication: SHELXTL (Bruker, 1997).

Figures top
[Figure 1] Fig. 1. A polyhedral view of the crystal structure of tyrrellite.
copper cobalt nickel tetraselenide top
Crystal data top
Co1.36CuNi0.64Se4Dx = 6.627 Mg m3
Mr = 497.06Mo Kα radiation, λ = 0.71073 Å
Cubic, Fd3mCell parameters from 1008 reflections
Hall symbol: -F 4vw 2vwθ = 3.5–44.1°
a = 9.9885 (1) ŵ = 40.12 mm1
V = 996.55 (2) Å3T = 293 K
Z = 8Block, black
F(000) = 17570.07 × 0.07 × 0.06 mm
Data collection top
Bruker APEXII CCD area-detector
diffractometer
227 independent reflections
Radiation source: fine-focus sealed tube206 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.030
π and ω scansθmax = 44.8°, θmin = 3.5°
Absorption correction: multi-scan
(SADABS; Sheldrick, 2005)
h = 1819
Tmin = 0.123, Tmax = 0.142k = 1812
2566 measured reflectionsl = 1711
Refinement top
Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.014 w = 1/[σ2(Fo2) + (0.0086P)2 + 2.3104P]
where P = (Fo2 + 2Fc2)/3
wR(F2) = 0.028(Δ/σ)max = 0.001
S = 1.12Δρmax = 0.79 e Å3
227 reflectionsΔρmin = 1.27 e Å3
9 parametersExtinction correction: SHELXL97 (Sheldrick, 1997), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
0 restraintsExtinction coefficient: 0.00182 (6)
Crystal data top
Co1.36CuNi0.64Se4Z = 8
Mr = 497.06Mo Kα radiation
Cubic, Fd3mµ = 40.12 mm1
a = 9.9885 (1) ÅT = 293 K
V = 996.55 (2) Å30.07 × 0.07 × 0.06 mm
Data collection top
Bruker APEXII CCD area-detector
diffractometer
227 independent reflections
Absorption correction: multi-scan
(SADABS; Sheldrick, 2005)
206 reflections with I > 2σ(I)
Tmin = 0.123, Tmax = 0.142Rint = 0.030
2566 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0149 parameters
wR(F2) = 0.0280 restraints
S = 1.12Δρmax = 0.79 e Å3
227 reflectionsΔρmin = 1.27 e Å3
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
xyzUiso*/UeqOcc. (<1)
Cu10.12500.12500.12500.01020 (11)
Co10.50000.00000.00000.00624 (11)0.68 (6)
Ni10.50000.00000.00000.00624 (11)0.32 (6)
Se10.261923 (14)0.011923 (14)0.011923 (14)0.00705 (6)
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Cu10.01020 (11)0.01020 (11)0.01020 (11)0.0000.0000.000
Co10.00624 (11)0.00624 (11)0.00624 (11)0.00031 (6)0.00031 (6)0.00031 (6)
Ni10.00624 (11)0.00624 (11)0.00624 (11)0.00031 (6)0.00031 (6)0.00031 (6)
Se10.00705 (6)0.00705 (6)0.00705 (6)0.00027 (4)0.00027 (4)0.00027 (4)
Geometric parameters (Å, º) top
Cu1—Se1i2.3688 (2)Co1—Se1v2.3840 (1)
Cu1—Se1ii2.3688 (2)Co1—Se12.3840 (1)
Cu1—Se1iii2.3688 (2)Co1—Se1vi2.3840 (1)
Cu1—Se12.3688 (2)Co1—Se1vii2.3840 (1)
Co1—Se1iv2.3840 (1)Co1—Se1viii2.3840 (1)
Se1i—Cu1—Se1ii109.5Se1—Co1—Se1viii180.0
Se1i—Cu1—Se1iii109.5Se1vi—Co1—Se1viii84.137 (7)
Se1ii—Cu1—Se1iii109.5Se1vii—Co1—Se1viii84.137 (7)
Se1i—Cu1—Se1109.5Cu1—Se1—Ni1iv121.213 (5)
Se1ii—Cu1—Se1109.5Cu1—Se1—Ni1v121.213 (5)
Se1iii—Cu1—Se1109.5Ni1iv—Se1—Ni1v95.576 (7)
Se1iv—Co1—Se1v84.137 (7)Cu1—Se1—Co1iv121.213 (5)
Se1iv—Co1—Se184.137 (7)Ni1iv—Se1—Co1iv0.0
Se1v—Co1—Se184.137 (7)Ni1v—Se1—Co1iv95.576 (7)
Se1iv—Co1—Se1vi180.0Cu1—Se1—Co1v121.213 (5)
Se1v—Co1—Se1vi95.863 (7)Ni1iv—Se1—Co1v95.576 (7)
Se1—Co1—Se1vi95.863 (7)Ni1v—Se1—Co1v0.0
Se1iv—Co1—Se1vii95.863 (7)Co1iv—Se1—Co1v95.576 (7)
Se1v—Co1—Se1vii180.0Cu1—Se1—Co1121.213 (5)
Se1—Co1—Se1vii95.863 (7)Ni1iv—Se1—Co195.576 (7)
Se1vi—Co1—Se1vii84.137 (7)Ni1v—Se1—Co195.576 (7)
Se1iv—Co1—Se1viii95.863 (7)Co1iv—Se1—Co195.576 (7)
Se1v—Co1—Se1viii95.863 (7)Co1v—Se1—Co195.576 (7)
Symmetry codes: (i) x+1/4, y, z+1/4; (ii) x+1/4, y+1/4, z; (iii) x, y+1/4, z+1/4; (iv) x+3/4, y, z1/4; (v) x+3/4, y1/4, z; (vi) x+1/4, y, z+1/4; (vii) x+1/4, y+1/4, z; (viii) x+1, y, z.

Experimental details

Crystal data
Chemical formulaCo1.36CuNi0.64Se4
Mr497.06
Crystal system, space groupCubic, Fd3m
Temperature (K)293
a (Å)9.9885 (1)
V3)996.55 (2)
Z8
Radiation typeMo Kα
µ (mm1)40.12
Crystal size (mm)0.07 × 0.07 × 0.06
Data collection
DiffractometerBruker APEXII CCD area-detector
diffractometer
Absorption correctionMulti-scan
(SADABS; Sheldrick, 2005)
Tmin, Tmax0.123, 0.142
No. of measured, independent and
observed [I > 2σ(I)] reflections
2566, 227, 206
Rint0.030
(sin θ/λ)max1)0.991
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.014, 0.028, 1.12
No. of reflections227
No. of parameters9
Δρmax, Δρmin (e Å3)0.79, 1.27

Computer programs: APEX2 (Bruker, 2003), SAINT (Bruker, 2005), SAINT, SHELXS97 (Sheldrick, 1997), SHELXL97 (Sheldrick, 1997), Please provide missing information, SHELXTL (Bruker, 1997).

 

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