research papers
Single-crystal X-ray diffraction data [synchrotron radiation; λ = 1.2682 (4) Å] are used to solve and refine the crystal structure of heptacalcium hexatantalum heptazirconium hexatriacontaoxide, Ca7Zr7Ta6O36. The structure adopts space group Fddd with cell dimensions a = 36.394 (1), b = 7.3674 (5), c = 31.006 (2) Å. The structure was solved by direct methods. Refinement using 1299 unique reflections leads to final values of R = 0.031 and wR = 0.034. The refined metal-atom ordering scheme is far from fully ordered and reminiscent of the A/B metal-atom ordering characteristic of the pyrochlore structure type. Bond-valence sums are calculated to confirm the plausibility of the crystal chemistry of Ca7Zr7Ta6O36.
Supporting information
Crystallographic Information File (CIF) | |
Structure factor file (SHELXL table format) |
Computing details top
Data collection: Tsukuba BL-14A software; cell refinement: Tsukuba BL-14A software; data reduction: xtal_DIFDAT_ADDREF_SORTRF; program(s) used to solve structure: xtal_GENTAN and SHELX97; program(s) used to refine structure: xtal_CRYLSQ and RAELS95; molecular graphics: CrystalMaker; software used to prepare material for publication: xtal_BONDLA_CIFIO.
calcium zirconium tantalum oxide top
Crystal data top
Ca7O36Ta6Zr7 | F(000) = 13752 |
Mr = 2580.78 | Dx = 6.186 Mg m−3 |
Orthorhombic, Fddd | Xray radiation, λ = 1.2682 (4) Å |
Hall symbol: -F 2uv 2vw | Cell parameters from 24 reflections |
a = 36.394 (1) Å | θ = 16.5–24° |
b = 7.3674 (5) Å | µ = 42.71 mm−1 |
c = 31.006 (2) Å | T = 293 K |
V = 8313.2 (12) Å3 | Square_prism, white |
Z = 12 | 0.02 × 0.01 × 0.01 mm |
Data collection top
Tsukuba_BL14A diffractometer | Rint = 0.039 |
Radiation source: synchrotron | θmax = 50.1°, θmin = 3.1° |
Si(111)_double_crystal monochromator | h = −44→43 |
θ/2θ scans | k = −8→8 |
0.123370+05 measured reflections | l = −34→37 |
1928 independent reflections | 9 standard reflections every 200/100 reflections |
1299 reflections with I > 2σ(I) | intensity decay: none |
Refinement top
Refinement on F | 0 restraints |
Least-squares matrix: full | 0 constraints |
R[F2 > 2σ(F2)] = 0.031 | |
wR(F2) = 0.038 | (Δ/σ)max = 0.021 |
S = 1.38 | Δρmax = 1.41 e Å−3 |
1299 reflections | Δρmin = −2.08 e Å−3 |
195 parameters |
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
x | y | z | Uiso*/Ueq | Occ. (<1) | |
Ta1 | 0.01975 (2) | 0.37500 | 0.87500 | 0.0045 (4) | 0.62 |
Zr1 | 0.01975 (2) | 0.37500 | 0.87500 | 0.0045 (4) | 0.38 |
Ta2 | 0.02395 (2) | 0.37500 | 0.37500 | 0.0039 (4) | 0.85 |
Zr2 | 0.02395 (2) | 0.37500 | 0.37500 | 0.0039 (4) | 0.15 |
Ta3 | 0.074378 (18) | 0.12299 (8) | 0.458627 (14) | 0.0039 (3) | 0.80 |
Zr3 | 0.074378 (18) | 0.12299 (8) | 0.458627 (14) | 0.0039 (3) | 0.20 |
Ta4 | 0.12253 (2) | 0.36635 (8) | 0.202284 (18) | 0.0065 (3) | 0.45 |
Zr4 | 0.12253 (2) | 0.36635 (8) | 0.202284 (18) | 0.0065 (3) | 0.55 |
Ta5 | 0.06757 (3) | 0.12500 | 0.12500 | 0.0113 (5) | 0.23 |
Zr5 | 0.06757 (3) | 0.12500 | 0.12500 | 0.0113 (5) | 0.77 |
Ta6 | 0.03224 (2) | 0.37420 (16) | 0.03484 (2) | 0.0069 (4) | 0.13 |
Zr6 | 0.03224 (2) | 0.37420 (16) | 0.03484 (2) | 0.0069 (4) | 0.87 |
Ca7 | 0.07788 (5) | 0.1453 (3) | 0.29208 (6) | 0.0228 (10) | 0.81 |
Zr7 | 0.07788 (5) | 0.1453 (3) | 0.29208 (6) | 0.0228 (10) | 0.19 |
Ca8 | 0.02322 (5) | 0.8705 (4) | 0.03899 (5) | 0.0086 (8) | 0.92 |
Zr8 | 0.02322 (5) | 0.8705 (4) | 0.03899 (5) | 0.0086 (8) | 0.08 |
Ca9 | 0.11849 (7) | 0.37500 | 0.87500 | 0.0230 (12) | 0.78 |
Zr9 | 0.11849 (7) | 0.37500 | 0.87500 | 0.0230 (12) | 0.22 |
Ca10 | 0.07446 (7) | 0.62500 | 0.12500 | 0.0047 (11) | |
Zr10 | 0.07446 (7) | 0.62500 | 0.12500 | 0.0047 (11) | 0.0 |
O1 | 0.12500 | 0.62500 | 0.0725 (2) | 0.006 (4) | |
O2 | 0.01909 (16) | 0.5821 (8) | 0.0803 (2) | 0.008 (3) | |
O3 | 0.02361 (15) | 0.1223 (10) | −0.1005 (2) | 0.013 (3) | |
O4 | 0.03071 (17) | 0.1449 (11) | −0.0002 (2) | 0.011 (3) | |
O5 | 0.08503 (17) | 0.4303 (8) | 0.0020 (2) | 0.009 (3) | |
O6 | 0.0761 (2) | 0.9129 (9) | 0.0834 (2) | 0.017 (4) | |
O7 | 0.08621 (18) | 0.8215 (8) | −0.0001 (2) | 0.011 (3) | |
O8 | 0.02478 (14) | 0.6069 (11) | −0.0139 (2) | 0.009 (3) | |
O9 | 0.06362 (18) | 0.4293 (8) | −0.0840 (2) | 0.012 (3) | |
O10 | 0.12500 | 0.12500 | 0.0155 (3) | 0.018 (5) | |
O11 | 0.01802 (18) | 0.1812 (9) | 0.0855 (2) | 0.014 (4) | |
O12 | 0.12500 | 0.62500 | −0.0665 (3) | 0.016 (4) | |
O13 | 0.0794 (2) | 0.3315 (9) | 0.0800 (2) | 0.019 (4) | |
O14 | 0.0627 (2) | 0.8242 (9) | −0.0820 (2) | 0.018 (4) | |
O15 | 0.12500 | 0.12500 | −0.0847 (3) | 0.030 (6) | |
O16 | 0.12500 | 0.12500 | 0.0989 (5) | 0.070 (10) |
Atomic displacement parameters (Å2) top
U11 | U22 | U33 | U12 | U13 | U23 | |
Ta1 | 0.0042 (4) | 0.0057 (4) | 0.0037 (4) | 0.00000 | 0.00000 | 0.0001 (5) |
Zr1 | 0.0042 (4) | 0.0057 (4) | 0.0037 (4) | 0.00000 | 0.00000 | 0.0001 (5) |
Ta2 | 0.0042 (4) | 0.0039 (4) | 0.0038 (3) | 0.00000 | 0.00000 | 0.0004 (5) |
Zr2 | 0.0042 (4) | 0.0039 (4) | 0.0038 (3) | 0.00000 | 0.00000 | 0.0004 (5) |
Ta3 | 0.0038 (3) | 0.0049 (3) | 0.0030 (3) | −0.0009 (3) | 0.00001 (17) | 0.0003 (4) |
Zr3 | 0.0038 (3) | 0.0049 (3) | 0.0030 (3) | −0.0009 (3) | 0.00001 (17) | 0.0003 (4) |
Ta4 | 0.0031 (3) | 0.0084 (3) | 0.0082 (3) | −0.0004 (4) | −0.0005 (2) | 0.0044 (2) |
Zr4 | 0.0031 (3) | 0.0084 (3) | 0.0082 (3) | −0.0004 (4) | −0.0005 (2) | 0.0044 (2) |
Ta5 | 0.0069 (5) | 0.0031 (5) | 0.0237 (5) | 0.00000 | 0.00000 | −0.0005 (6) |
Zr5 | 0.0069 (5) | 0.0031 (5) | 0.0237 (5) | 0.00000 | 0.00000 | −0.0005 (6) |
Ta6 | 0.0074 (4) | 0.0062 (4) | 0.0072 (3) | −0.0013 (4) | 0.0013 (3) | −0.0017 (4) |
Zr6 | 0.0074 (4) | 0.0062 (4) | 0.0072 (3) | −0.0013 (4) | 0.0013 (3) | −0.0017 (4) |
Ca7 | 0.0136 (10) | 0.0324 (11) | 0.0222 (9) | 0.0024 (9) | −0.0145 (6) | −0.0103 (11) |
Zr7 | 0.0136 (10) | 0.0324 (11) | 0.0222 (9) | 0.0024 (9) | −0.0145 (6) | −0.0103 (11) |
Ca8 | 0.0080 (9) | 0.0084 (8) | 0.0094 (8) | 0.0002 (7) | −0.0022 (6) | 0.0031 (10) |
Zr8 | 0.0080 (9) | 0.0084 (8) | 0.0094 (8) | 0.0002 (7) | −0.0022 (6) | 0.0031 (10) |
Ca9 | 0.0388 (16) | 0.0103 (10) | 0.0200 (12) | 0.00000 | 0.00000 | 0.0099 (9) |
Zr9 | 0.0388 (16) | 0.0103 (10) | 0.0200 (12) | 0.00000 | 0.00000 | 0.0099 (9) |
Ca10 | 0.0031 (10) | 0.0079 (12) | 0.0031 (10) | 0.00000 | 0.00000 | 0.0011 (14) |
Zr10 | 0.0031 (10) | 0.0079 (12) | 0.0031 (10) | 0.00000 | 0.00000 | 0.0011 (14) |
O1 | 0.006 (4) | 0.003 (4) | 0.011 (4) | 0.004 (4) | 0.00000 | 0.00000 |
O2 | 0.009 (3) | 0.005 (4) | 0.009 (3) | 0.001 (2) | 0.001 (2) | −0.003 (2) |
O3 | 0.016 (3) | 0.009 (3) | 0.014 (3) | 0.003 (3) | 0.001 (2) | −0.007 (3) |
O4 | 0.014 (3) | 0.008 (3) | 0.012 (3) | −0.002 (3) | −0.005 (3) | 0.001 (3) |
O5 | 0.008 (3) | 0.012 (4) | 0.008 (3) | −0.000 (2) | 0.000 (3) | 0.007 (2) |
O6 | 0.039 (4) | 0.009 (4) | 0.004 (3) | 0.011 (3) | 0.004 (3) | 0.002 (3) |
O7 | 0.017 (3) | 0.009 (4) | 0.006 (3) | −0.004 (3) | −0.002 (3) | −0.004 (2) |
O8 | 0.003 (3) | 0.013 (4) | 0.010 (3) | −0.001 (3) | 0.001 (2) | −0.004 (3) |
O9 | 0.010 (3) | 0.013 (4) | 0.011 (3) | −0.006 (3) | −0.001 (3) | −0.002 (3) |
O10 | 0.017 (5) | 0.010 (4) | 0.028 (5) | −0.010 (5) | 0.00000 | 0.00000 |
O11 | 0.012 (3) | 0.019 (4) | 0.011 (3) | −0.004 (3) | 0.005 (3) | 0.002 (3) |
O12 | 0.009 (4) | 0.029 (5) | 0.011 (4) | 0.000 (5) | 0.00000 | 0.00000 |
O13 | 0.031 (4) | 0.019 (4) | 0.007 (3) | −0.016 (3) | 0.009 (3) | −0.006 (3) |
O14 | 0.023 (4) | 0.019 (4) | 0.012 (3) | 0.006 (3) | −0.009 (3) | 0.001 (3) |
O15 | 0.033 (6) | 0.034 (6) | 0.023 (5) | 0.009 (6) | 0.00000 | 0.00000 |
O16 | 0.073 (10) | 0.062 (10) | 0.074 (10) | −0.002 (10) | 0.00000 | 0.00000 |
Bond lengths (Å) top
Ta1—O3i | 2.016 (7) | Zr6—O11 | 2.181 (7) |
Ta1—O9i | 2.080 (6) | Zr6—O13 | 2.238 (7) |
Ta1—O2ii | 2.004 (6) | Zr6—O8xiii | 2.179 (5) |
Ta1—O2iii | 2.004 (6) | Ca7—O3v | 2.683 (6) |
Ta1—O3iv | 2.016 (7) | Ca7—O4v | 2.173 (7) |
Ta1—O9iv | 2.080 (6) | Ca7—O5v | 2.773 (6) |
Zr1—O3i | 2.016 (7) | Ca7—O9v | 2.770 (7) |
Zr1—O9i | 2.080 (6) | Ca7—O10v | 2.481 (7) |
Zr1—O2ii | 2.004 (6) | Ca7—O15v | 2.170 (7) |
Zr1—O2iii | 2.004 (6) | Ca7—O7vi | 2.477 (6) |
Zr1—O3iv | 2.016 (7) | Ca7—O14vi | 2.472 (7) |
Zr1—O9iv | 2.080 (6) | Zr7—O3v | 2.683 (6) |
Ta2—O3v | 1.974 (7) | Zr7—O4v | 2.173 (7) |
Ta2—O14vi | 1.976 (7) | Zr7—O5v | 2.773 (6) |
Ta2—O14vii | 1.976 (7) | Zr7—O9v | 2.770 (7) |
Ta2—O3viii | 1.974 (7) | Zr7—O10v | 2.481 (7) |
Ta2—O11ix | 2.001 (7) | Zr7—O15v | 2.170 (7) |
Ta2—O11x | 2.001 (7) | Zr7—O7vi | 2.477 (6) |
Zr2—O3v | 1.974 (7) | Zr7—O14vi | 2.472 (7) |
Zr2—O14vi | 1.976 (7) | Ca8—O2 | 2.486 (6) |
Zr2—O14vii | 1.976 (7) | Ca8—O6 | 2.387 (7) |
Zr2—O3viii | 1.974 (7) | Ca8—O7 | 2.619 (7) |
Zr2—O11ix | 2.001 (7) | Ca8—O8 | 2.543 (8) |
Zr2—O11x | 2.001 (7) | Ca8—O4xiv | 2.374 (8) |
Ta3—O5vii | 1.994 (6) | Ca8—O11xiv | 2.711 (7) |
Ta3—O7vii | 1.990 (6) | Ca8—O3xiii | 2.558 (6) |
Ta3—O8vii | 1.999 (5) | Ca8—O4xiii | 2.304 (7) |
Ta3—O9vii | 1.984 (6) | Zr8—O2 | 2.486 (6) |
Ta3—O12vii | 2.000 (3) | Zr8—O6 | 2.387 (7) |
Ta3—O14vii | 1.992 (7) | Zr8—O7 | 2.619 (7) |
Zr3—O5vii | 1.994 (6) | Zr8—O8 | 2.543 (8) |
Zr3—O7vii | 1.990 (6) | Zr8—O4xiv | 2.374 (8) |
Zr3—O8vii | 1.999 (5) | Zr8—O11xiv | 2.711 (7) |
Zr3—O9vii | 1.984 (6) | Zr8—O3xiii | 2.558 (6) |
Zr3—O12vii | 2.000 (3) | Zr8—O4xiii | 2.304 (7) |
Zr3—O14vii | 1.992 (7) | Ca9—O9i | 2.401 (7) |
Ta4—O10v | 2.041 (5) | Ca9—O12i | 2.596 (6) |
Ta4—O16v | 2.384 (11) | Ca9—O15i | 2.238 (6) |
Ta4—O1vi | 2.057 (3) | Ca9—O14xv | 2.862 (7) |
Ta4—O6vi | 2.031 (7) | Ca9—O9iv | 2.401 (7) |
Ta4—O7vi | 2.039 (6) | Ca9—O12iv | 2.596 (6) |
Ta4—O5xi | 2.148 (6) | Ca9—O15iv | 2.238 (6) |
Ta4—O13xi | 2.032 (7) | Ca9—O14xvi | 2.862 (7) |
Zr4—O10v | 2.041 (5) | Zr9—O9i | 2.401 (7) |
Zr4—O16v | 2.384 (11) | Zr9—O12i | 2.596 (6) |
Zr4—O1vi | 2.057 (3) | Zr9—O15i | 2.238 (6) |
Zr4—O6vi | 2.031 (7) | Zr9—O14xv | 2.862 (7) |
Zr4—O7vi | 2.039 (6) | Zr9—O9iv | 2.401 (7) |
Zr4—O5xi | 2.148 (6) | Zr9—O12iv | 2.596 (6) |
Zr4—O13xi | 2.032 (7) | Zr9—O15iv | 2.238 (6) |
Ta5—O11 | 2.219 (7) | Zr9—O14xvi | 2.862 (7) |
Ta5—O13 | 2.109 (7) | Ca10—O1 | 2.456 (5) |
Ta5—O16 | 2.242 (6) | Ca10—O2 | 2.466 (6) |
Ta5—O6xii | 2.050 (7) | Ca10—O6 | 2.483 (7) |
Ta5—O11v | 2.219 (7) | Ca10—O13 | 2.579 (7) |
Ta5—O13v | 2.109 (7) | Ca10—O1vi | 2.456 (5) |
Ta5—O16v | 2.242 (6) | Ca10—O2vi | 2.466 (6) |
Ta5—O6vi | 2.050 (7) | Ca10—O6vi | 2.483 (7) |
Zr5—O11 | 2.219 (7) | Ca10—O13vi | 2.579 (7) |
Zr5—O13 | 2.109 (7) | Zr10—O1 | 2.456 (5) |
Zr5—O16 | 2.242 (6) | Zr10—O2 | 2.466 (6) |
Zr5—O6xii | 2.050 (7) | Zr10—O6 | 2.483 (7) |
Zr5—O11v | 2.219 (7) | Zr10—O13 | 2.579 (7) |
Zr5—O13v | 2.109 (7) | Zr10—O1vi | 2.456 (5) |
Zr5—O16v | 2.242 (6) | Zr10—O2vi | 2.466 (6) |
Zr5—O6vi | 2.050 (7) | Zr10—O6vi | 2.483 (7) |
Ta6—O2 | 2.136 (6) | Zr10—O13vi | 2.579 (7) |
Ta6—O4 | 2.009 (8) | O5—O8 | 2.597 (9) |
Ta6—O5 | 2.213 (6) | O5—O13 | 2.533 (9) |
Ta6—O8 | 2.302 (7) | O6—O16xiv | 2.416 (8) |
Ta6—O11 | 2.181 (7) | O8—O8xiii | 2.545 (9) |
Ta6—O13 | 2.238 (7) | O10—O16 | 2.584 (18) |
Ta6—O8xiii | 2.179 (5) | O11—O13 | 2.500 (10) |
Zr6—O2 | 2.136 (6) | O11—O11v | 2.585 (9) |
Zr6—O4 | 2.009 (8) | O13—O16 | 2.326 (8) |
Zr6—O5 | 2.213 (6) | O16—O16v | 1.62 (2) |
Zr6—O8 | 2.302 (7) |
Symmetry codes: (i) x, y, z+1; (ii) −x, −y+1, −z+1; (iii) −x, y−1/4, z+3/4; (iv) x, −y+3/4, −z+3/4; (v) x, −y+1/4, −z+1/4; (vi) x, −y+5/4, −z+1/4; (vii) x, y−1/2, z+1/2; (viii) x, y+1/2, z+1/2; (ix) −x, −y+1/2, −z+1/2; (x) −x, y+1/4, z+1/4; (xi) −x+1/4, y, −z+1/4; (xii) x, y−1, z; (xiii) −x, −y+1, −z; (xiv) x, y+1, z; (xv) −x+1/4, −y+5/4, z+1; (xvi) −x+1/4, y−1/2, −z+3/4. |