Ilmenite-type Na₂(Fe_2/3Te_4/3)O₆

Na₂(Fe_2/3Te_4/3)O₆ (Z = 3) or Na₃(FeTe₂)O₉ (Z = 2), tris­odium iron(III) ditellurium(VI) nona­oxide, adopts the ilmenite (FeTiO₃, Z = 6) structure type with the Ti site (site symmetry 3.) replaced by Na and the Fe site (site symmetry 3.) replaced by a mixed-occupied (Fe^III,Te^VI) site in a Fe:Te ratio of 1:2. Whereas the [(Fe,Te)O₆] octa­hedron is only slightly distorted, the [NaO₆] octa­hedron shows much stronger distortions, as revealed by a larger spread of the bond lengths and some distortion parameters.

Key indicators

Structure: I

• Single-crystal X-ray study
• T = 300 K
• Mean [sigma]() = 0.000 Å
• Disorder in main residue
• R factor = 0.027
• wR factor = 0.066
• Data-to-parameter ratio = 26.7

checkCIF/PLATON results

No syntax errors found



Alert level C
CRYSC01_ALERT_1_C The word below has not been recognised as a standard
            identifier.
            yellowish
CRYSC01_ALERT_1_C No recognised colour has been given for crystal colour.
PLAT041_ALERT_1_C Calc. and Reported SumFormula    Strings  Differ     Please Check
              Calc: Fe0.67 Na2 O6 Te1.33
              Rep.: Fe0.6666 Na2 O6 Te1.3333

Alert level G
PLAT004_ALERT_5_G Polymeric Structure Found with Maximum Dimension          2 Info
PLAT045_ALERT_1_G Calculated and Reported Z Differ by a Factor ...      0.667 Check
PLAT069_ALERT_1_G Atom Label Without Numerical Part ..............         Te Do !
PLAT069_ALERT_1_G Atom Label Without Numerical Part ..............         Fe Do !
PLAT069_ALERT_1_G Atom Label Without Numerical Part ..............         Na Do !
PLAT069_ALERT_1_G Atom Label Without Numerical Part ..............          O Do !
PLAT168_ALERT_4_G The CIF-Embedded .res File Contains EXYZ Records          1 Report
PLAT171_ALERT_4_G The CIF-Embedded .res File Contains EADP Records          1 Report
PLAT300_ALERT_4_G Atom Site Occupancy of Te         Constrained at     0.6667 Check
PLAT300_ALERT_4_G Atom Site Occupancy of Fe         Constrained at     0.3333 Check
PLAT301_ALERT_3_G Main Residue  Disorder ..............(Resd    1)        50% Note
PLAT811_ALERT_5_G No ADDSYM Analysis: Too Many Excluded Atoms ....          ! Info
PLAT870_ALERT_4_G ALERTS Related to Twinning Effects Suppressed ..          ! Info
PLAT883_ALERT_1_G No Info/Value for _atom_sites_solution_primary .     Please Do !
PLAT910_ALERT_3_G Missing # of FCF Reflection(s) Below Theta(Min).          1 Note
                0  0  3,
PLAT912_ALERT_4_G Missing # of FCF Reflections Above STh/L=  0.600          1 Note
PLAT933_ALERT_2_G Number of HKL-OMIT Records in Embedded .res File          1 Note
                0  0  3,
PLAT955_ALERT_1_G Reported (CIF) and Actual (FCF) Lmax Differ by .          1 Units
PLAT969_ALERT_5_G The 'Henn et al.' R-Factor-gap value ...........       3.36 Note
              Predicted wR2: Based on SigI   2  1.96 or SHELX Weight  6.50       

   0 ALERT level A = Most likely a serious problem - resolve or explain
   0 ALERT level B = A potentially serious problem, consider carefully
   3 ALERT level C = Check. Ensure it is not caused by an omission or oversight
  19 ALERT level G = General information/check it is not something unexpected

  10 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
   1 ALERT type 2 Indicator that the structure model may be wrong or deficient
   2 ALERT type 3 Indicator that the structure quality may be low
   6 ALERT type 4 Improvement, methodology, query or suggestion
   3 ALERT type 5 Informative message, check

---

Computing details

Trisodium iron(III) ditellurium(VI) nonaoxide

Crystal data

Na2Fe0.6666Te1.3333O6	Dx = 4.604 Mg m^−3
Mr = 349.33	Mo Kα radiation, λ = 0.71073 Å
Trigonal, R3:H	Cell parameters from 3735 reflections
a = 5.2598 (8) Å	θ = 3.9–31.3°
c = 15.778 (3) Å	µ = 9.76 mm^−1
V = 378.02 (14) Å^3	T = 300 K
Z = 3	Plate, yellowish
F(000) = 470	0.05 × 0.04 × 0.01 mm

Data collection

Stoe Stadivari diffractometer	383 reflections with I > 2σ(I)
Radiation source: Axo_Mo	Rint = 0.043
rotation method, ω scans	θmax = 31.3°, θmin = 4.7°
Absorption correction: multi-scan (LANA; Koziskova et al., 2016)	h = −4→7
Tmin = 0.519, Tmax = 0.596	k = −7→5
3266 measured reflections	l = −22→23
454 independent reflections

Refinement

Refinement on F^2	17 parameters
Least-squares matrix: full	0 restraints
R[F^2 > 2σ(F^2)] = 0.027	w = 1/[σ^2(Fo^2) + (0.0446P)^2] where P = (Fo^2 + 2Fc^2)/3
wR(F^2) = 0.066	(Δ/σ)max < 0.001
S = 1.03	Δρmax = 1.64 e Å^−3
454 reflections	Δρmin = −1.30 e Å^−3

Special details

Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes.

Refinement. Refined as a 2-component inversion twin.

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

	x	y	z	Uiso*/Ueq	Occ. (<1)
Te	0.000000	0.000000	0.16114 (4)	0.0138 (2)	0.6667
Fe	0.000000	0.000000	0.16114 (4)	0.0138 (2)	0.3333
Na	0.000000	0.000000	0.3619 (2)	0.0215 (6)
O	0.3411 (6)	0.0563 (7)	0.0969 (2)	0.0181 (6)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Te	0.0101 (2)	0.0101 (2)	0.0212 (3)	0.00503 (11)	0.000	0.000
Fe	0.0101 (2)	0.0101 (2)	0.0212 (3)	0.00503 (11)	0.000	0.000
Na	0.0183 (9)	0.0183 (9)	0.0278 (15)	0.0091 (4)	0.000	0.000
O	0.0126 (14)	0.0156 (13)	0.0260 (15)	0.0068 (11)	0.0020 (11)	−0.0026 (12)

Geometric parameters (Å, º)

Te—O	1.951 (3)	Na—O^vi	2.297 (3)
Te—O^i	1.951 (3)	Na—O^vii	2.297 (3)
Te—O^ii	1.951 (3)	Na—O^viii	2.297 (3)
Te—O^iii	1.993 (3)	Na—O^iii	2.545 (4)
Te—O^iv	1.993 (3)	Na—O^iv	2.545 (4)
Te—O^v	1.993 (3)	Na—O^v	2.545 (4)
O—Te—O^i	95.42 (13)	O^vi—Na—O^iii	98.45 (11)
O—Te—O^ii	95.42 (13)	O^vii—Na—O^iii	91.78 (15)
O^i—Te—O^ii	95.42 (13)	O^viii—Na—O^iii	156.33 (16)
O—Te—O^iii	98.82 (19)	O^vi—Na—O^iv	91.78 (15)
O^i—Te—O^iii	79.08 (15)	O^vii—Na—O^iv	156.34 (16)
O^ii—Te—O^iii	165.14 (16)	O^viii—Na—O^iv	98.45 (11)
O—Te—O^iv	79.08 (15)	O^iii—Na—O^iv	65.98 (14)
O^i—Te—O^iv	165.15 (16)	O^vi—Na—O^v	156.34 (16)
O^ii—Te—O^iv	98.82 (19)	O^vii—Na—O^v	98.45 (11)
O^iii—Te—O^iv	88.08 (14)	O^viii—Na—O^v	91.77 (15)
O—Te—O^v	165.14 (16)	O^iii—Na—O^v	65.98 (14)
O^i—Te—O^v	98.82 (19)	O^iv—Na—O^v	65.98 (14)
O^ii—Te—O^v	79.08 (15)	Te—O—Te^iv	100.92 (15)
O^iii—Te—O^v	88.08 (14)	Te—O—Na^ix	120.25 (14)
O^iv—Te—O^v	88.08 (14)	Te^iv—O—Na^ix	123.88 (14)
O^vi—Na—O^vii	99.80 (15)	Te—O—Na^iv	142.72 (16)
O^vi—Na—O^viii	99.80 (15)	Te^iv—O—Na^iv	87.65 (11)
O^vii—Na—O^viii	99.80 (15)	Na^ix—O—Na^iv	81.55 (11)

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