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The crystal structure and ionic conductivity properties of a novel microcrystalline Sr11Mo4O23 ceramic material are presented. This material has been prepared by thermal treatment up to 1473 K, in air, of previously decomposed citrate precursors. The complex crystal structure was refined from combined X-ray powder diffraction and neutron powder diffraction data. The formula of this phase can be rewritten as Sr1.750.25SrMoO5.75, highlighting the relationship with double perovskites A2BB′′O6. At room temperature, the crystal structure is tetragonal in space group I41/a, with a = 11.6107 (6) Å, c = 16.422 (1) Å and V = 2213.8 (2) Å3. The crystal network contains O anion and Sr cation vacancies. The structure is complex, with Sr, Mo and O atoms distributed over four, two and six distinct Wyckoff sites, respectively. Only one of the Sr sites (SrO6) corresponds to the octahedral network; one of the two MoO6 types of octahedra is axially distorted. The three other Sr positions occupy the A site with higher coordination. There is an occupational deficit of O atoms of 22 (4)%. This defective framework material presents an interesting ionic mobility, enhanced above 773 K owing to a further reduction in the oxygen content.

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S1600576714013491/pd5046sup1.cif
Contains datablocks global, I

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S1600576714013491/pd5046Isup2.hkl
Contains datablock I

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S1600576714013491/pd5046Isup3.hkl
Contains datablock I

CCDC reference: 1007689

Computing details top

Program(s) used to refine structure: FULLPROF.

(I) top
Crystal data top
Mr = 1715.64c = 16.4219 (13) Å
Tetragonal, I41/aV = 2213.8 (2) Å3
Hall symbol: -I 4adConstant Wavelength Neutron Diffraction radiation
a = 11.6107 (6) ÅT = 295 K
Data collection top
Radiation source: nuclear reactor2θmin = 4.119°, 2θmax = 164.769°, 2θstep = 0.050°
Refinement top
Rp = 3.0893214 data points
Rwp = 3.96959 parameters
Rexp = 2.0620 restraints
RBragg = 4.805
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/UeqOcc. (<1)
Sr10.000000.250000.125000.031 (6)*
Sr20.500000.250000.6112 (13)0.044 (6)*
Sr30.2191 (11)0.9791 (15)0.8712 (11)0.021 (3)*
Sr40.2164 (9)0.2367 (12)0.5263 (7)0.018 (2)*
Mo10.000000.000000.000000.011 (2)*
Mo20.000000.000000.500000.0127 (19)*
O10.8716 (12)0.1369 (11)0.2591 (10)0.006 (3)*
O20.6358 (16)0.1329 (19)0.2419 (16)0.030 (5)*
O30.2754 (11)0.2559 (15)0.3648 (8)0.003 (2)*
O40.8365 (14)0.1719 (14)0.6563 (11)0.008 (4)*0.79 (4)
O50.867 (2)0.088 (2)0.500 (2)0.087 (10)*
O60.313 (2)0.170 (3)0.6621 (18)0.076 (10)*
Geometric parameters (Å, º) top
Sr1—O12.97 (2)Sr3—O62.48 (3)
Sr1—O23.02 (2)Sr4—O12.59 (2)
Sr1—O32.61 (1)Sr4—O22.42 (2)
Sr2—O12.60 (2)Sr4—O32.75 (2)
Sr2—O22.68 (3)Sr4—O42.62 (2)
Sr2—O33.20 (2)Sr4—O42.46 (2)
Sr2—O53.33 (3)Sr4—O52.29 (3)
Sr2—O62.50 (3)Sr4—O62.61 (3)
Sr3—O12.74 (2)Sr4—O63.18 (3)
Sr3—O12.85 (2)Mo1—O11.93 (1)
Sr3—O22.82 (3)Mo1—O21.90 (2)
Sr3—O22.76 (3)Mo1—O31.91 (1)
Sr3—O32.73 (2)Mo2—O42.05 (2)
Sr3—O32.49 (2)Mo2—O51.85 (2)
Sr3—O42.66 (2)Mo2—O61.87 (3)
Sr3—O52.64 (3)
O1—Mo1—O292 (1)O1—Mo2—O296 (2)
O1—Mo1—O391 (1)O1—Mo2—O3100 (2)
O2—Mo1—O394 (1)O2—Mo2—O3101 (2)
 

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