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This work presents the crystal structure evolution of a novel ionic conductor Sr11Mo4O23 at high temperature. The formula of this phase can be rewritten as Sr1.750.25SrMoO5.75, highlighting the relationship with double perovskites A2BB′′O6. The crystal network contains oxygen-anion and strontium-cation vacancies. The structure is complex; Sr, Mo and O atoms are distributed in four, two and six distinct Wyckoff sites, respectively. It was refined from neutron powder diffraction data collected at 473, 673, 873 and 1073 K. The thermal evolution of crystallographic parameters supports the known reversible process of removal/uptake of O-atom content in the 673–873 K temperature range. Above 873 K, from difference Fourier maps, it was found that the structure exhibits an oxygen delocalization around one of the Mo sites. This delocalization was understood as a dynamical octahedral tilt of the MoO6 octahedron, yielding an increase in the ionic conductivity at high temperature.

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S160057671502261X/ks5496sup1.cif
Contains datablocks global, Sr11Mo4O23-473K, Sr11Mo4O23-673K, Sr11Mo4O23-873K, Sr11Mo4O23-1073K

rtv

Rietveld powder data file (CIF format) https://doi.org/10.1107/S160057671502261X/ks5496Sr11Mo4O23-473Ksup2.rtv
Contains datablock Sr11Mo4O23-473K

rtv

Rietveld powder data file (CIF format) https://doi.org/10.1107/S160057671502261X/ks5496Sr11Mo4O23-673Ksup3.rtv
Contains datablock Sr11Mo4O23-673K

rtv

Rietveld powder data file (CIF format) https://doi.org/10.1107/S160057671502261X/ks5496Sr11Mo4O23-873Ksup4.rtv
Contains datablock Sr11Mo4O23-873K

rtv

Rietveld powder data file (CIF format) https://doi.org/10.1107/S160057671502261X/ks5496Sr11Mo4O23-1073Ksup5.rtv
Contains datablock Sr11Mo4O23-1073K

CCDC references: 1438983; 1438984; 1438985; 1438986

Computing details top

For all compounds, program(s) used to refine structure: FULLPROF.

(Sr11Mo4O23-473K) top
Crystal data top
Mo4O23.12Sr11V = 2229.74 (17) Å3
Mr = 1717.17Z = 4
Tetragonal, I41/aConstant Wavelength Neutron Diffraction radiation
Hall symbol: -I 4adT = 473 K
a = 11.6416 (4) Åyellow
c = 16.4524 (9) Å
Data collection top
D2B Institut Laue Langevin
diffractometer
2θmin = 0.103°, 2θmax = 159.797°, 2θstep = 0.050°
Radiation source: nuclear reactor
Refinement top
Rp = 3.185χ2 = 12.834
Rwp = 4.3733199 data points
Rexp = 1.22155 parameters
RBragg = 8.5680 restraints
Crystal data top
Mo4O23.12Sr11V = 2229.74 (17) Å3
Mr = 1717.17Z = 4
Tetragonal, I41/aConstant Wavelength Neutron Diffraction radiation
a = 11.6416 (4) ÅT = 473 K
c = 16.4524 (9) Å
Data collection top
D2B Institut Laue Langevin
diffractometer
2θmin = 0.103°, 2θmax = 159.797°, 2θstep = 0.050°
Refinement top
Rp = 3.185χ2 = 12.834
Rwp = 4.3733199 data points
Rexp = 1.22155 parameters
RBragg = 8.5680 restraints
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/UeqOcc. (<1)
Sr10.000000.250000.125000.045 (5)*
Sr20.500000.250000.6013 (16)0.060 (6)*
Sr30.2242 (12)0.9764 (14)0.8771 (10)0.033 (2)*
Sr40.2117 (11)0.2377 (13)0.5293 (10)0.051 (3)*
Mo10.000000.000000.000000.0094 (15)*
Mo20.000000.000000.500000.045 (3)*
O10.1149 (12)0.1202 (10)0.0065 (9)0.032 (4)*
O20.1244 (10)0.1150 (13)0.0075 (12)0.031 (4)*
O30.0035 (10)0.0204 (15)0.1165 (8)0.023 (3)*
O40.08400 (13)0.0803 (10)0.5946 (9)0.021 (4)*0.78 (2)
O50.1203 (11)0.0832 (10)0.4934 (9)0.046 (4)*
O60.0947 (12)0.0624 (14)0.5702 (10)0.056 (4)*
Geometric parameters (Å, º) top
Mo1—O11.939 (13)Mo2—O42.062 (15)
Mo1—O21.976 (14)Mo2—O51.706 (13)
Mo1—O31.932 (14)Mo2—O61.754 (16)
O1—Mo1—O290.8 (3)O4—Mo2—O585.2 (3)
O1—Mo1—O391.1 (3)O4—Mo2—O689.4 (3)
O2—Mo1—O392.1 (7)O5—Mo2—O6108.8 (4)
(Sr11Mo4O23-673K) top
Crystal data top
Mo4O23.16Sr11V = 2245.16 (17) Å3
Mr = 1718.77Z = 4
Tetragonal, I41/aConstant Wavelength Neutron Diffraction radiation
Hall symbol: -I 4adT = 673 K
a = 11.6696 (4) Åyellow
c = 16.4869 (9) Å
Data collection top
D2B Institut Laue Langevin
diffractometer
2θmin = 0.058°, 2θmax = 159.842°, 2θstep = 0.050°
Radiation source: nuclear reactor
Refinement top
Rp = 2.886χ2 = 9.848
Rwp = 3.8943199 data points
Rexp = 1.24155 parameters
RBragg = 7.0760 restraints
Crystal data top
Mo4O23.16Sr11V = 2245.16 (17) Å3
Mr = 1718.77Z = 4
Tetragonal, I41/aConstant Wavelength Neutron Diffraction radiation
a = 11.6696 (4) ÅT = 673 K
c = 16.4869 (9) Å
Data collection top
D2B Institut Laue Langevin
diffractometer
2θmin = 0.058°, 2θmax = 159.842°, 2θstep = 0.050°
Refinement top
Rp = 2.886χ2 = 9.848
Rwp = 3.8943199 data points
Rexp = 1.24155 parameters
RBragg = 7.0760 restraints
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/UeqOcc. (<1)
Sr10.000000.250000.125000.054 (7)*
Sr20.500000.250000.6026 (14)0.091 (7)*
Sr30.2345 (10)0.9722 (10)0.8805 (8)0.039 (3)*
Sr40.2201 (10)0.2330 (12)0.5338 (8)0.064 (3)*
Mo10.000000.000000.000000.030 (2)*
Mo20.000000.000000.500000.030 (2)*
O10.1209 (14)0.11140 (12)0.0014 (8)0.031 (3)*
O20.1125 (12)0.1169 (17)0.0085 (10)0.038 (5)*
O30.0038 (9)0.0224 (14)0.1177 (7)0.028 (3)*
O40.0802 (17)0.0889 (13)0.5930 (11)0.041 (4)*0.79 (2)
O50.1239 (14)0.0896 (15)0.4940 (11)0.077 (7)*
O60.092 (2)0.0762 (3)0.5650 (14)0.122 (9)*
Geometric parameters (Å, º) top
Mo1—O11.919 (16)Mo2—O42.074 (18)
Mo1—O21.898 (18)Mo2—O51.787 (17)
Mo1—O31.959 (12)Mo2—O61.76 (3)
O1—Mo1—O291.2 (3)O4—Mo2—O588.2 (4)
O1—Mo1—O393.5 (3)O4—Mo2—O694.5 (4)
O2—Mo1—O392.2 (3)O5—Mo2—O6103.4 (4)
(Sr11Mo4O23-873K) top
Crystal data top
Mo4O21.84Sr11V = 2269.09 (14) Å3
Mr = 1697.01Z = 4
Tetragonal, I41/aConstant Wavelength Neutron Diffraction radiation
Hall symbol: -I 4adT = 873 K
a = 11.7075 (3) Åyellow
c = 16.5548 (8) Å
Data collection top
D2B Institut Laue Langevin
diffractometer
2θmin = 0.078°, 2θmax = 159.822°, 2θstep = 0.050°
Radiation source: nuclear reactor
Refinement top
Rp = 2.831χ2 = 8.528
Rwp = 3.9373199 data points
Rexp = 1.34872 parameters
RBragg = 11.10824 restraints
Crystal data top
Mo4O21.84Sr11V = 2269.09 (14) Å3
Mr = 1697.01Z = 4
Tetragonal, I41/aConstant Wavelength Neutron Diffraction radiation
a = 11.7075 (3) ÅT = 873 K
c = 16.5548 (8) Å
Data collection top
D2B Institut Laue Langevin
diffractometer
2θmin = 0.078°, 2θmax = 159.822°, 2θstep = 0.050°
Refinement top
Rp = 2.831χ2 = 8.528
Rwp = 3.9373199 data points
Rexp = 1.34872 parameters
RBragg = 11.10824 restraints
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/UeqOcc. (<1)
Sr10.000000.250000.125000.074 (7)*
Sr20.500000.250000.602 (2)0.057 (7)*
Sr30.2263 (17)0.980 (2)0.8731 (11)0.055 (4)*
Sr40.2089 (15)0.246 (3)0.5270 (14)0.070 (2)*
Mo10.000000.000000.000000.0272 (17)*
Mo20.000000.000000.500000.0340 (19)*
O10.877 (2)0.1465 (16)0.2531 (13)0.049 (4)*
O20.6434 (12)0.1262 (15)0.2464 (11)0.031 (3)*
O30.2631 (19)0.243 (2)0.3666 (16)0.055 (4)*
O4a0.0857 (14)0.055 (2)0.4116 (17)0.03800*0.30 (2)
O4b0.0869 (17)0.094 (2)0.425 (3)0.03800*0.13 (2)
O4c0.000 (2)0.072 (2)0.4003 (16)0.03800*0.30 (1)
O5a0.132 (3)0.094 (3)0.490 (3)0.03800*0.30 (2)
O5b0.137 (3)0.087 (3)0.485 (3)0.03800*0.30 (2)
O5c0.163 (2)0.005 (4)0.477 (3)0.03800*0.30 (2)
O5d0.000 (2)0.170 (2)0.500 (2)0.03800*0.18 (2)
O6a0.0869 (17)0.061 (2)0.4124 (18)0.03800*0.30 (2)
O6b0.0857 (14)0.083 (2)0.409 (2)0.03800*0.22 (2)
O6c0.000 (2)0.1479 (19)0.435 (2)0.03800*0.13 (1)
(Sr11Mo4O23-1073K) top
Crystal data top
Mo4O21.92Sr11V = 2291.72 (14) Å3
Mr = 1698.29Z = 4
Tetragonal, I41/aConstant Wavelength Neutron Diffraction radiation
Hall symbol: -I 4adT = 1073 K
a = 11.7466 (3) Åyellow
c = 16.6088 (8) Å
Data collection top
D2B Institut Laue Langevin
diffractometer
2θmin = 0.071°, 2θmax = 159.829°, 2θstep = 0.050°
Radiation source: nuclear reactor
Refinement top
Rp = 2.602χ2 = 7.028
Rwp = 3.6633199 data points
Rexp = 1.38272 parameters
RBragg = 10.72124 restraints
Crystal data top
Mo4O21.92Sr11V = 2291.72 (14) Å3
Mr = 1698.29Z = 4
Tetragonal, I41/aConstant Wavelength Neutron Diffraction radiation
a = 11.7466 (3) ÅT = 1073 K
c = 16.6088 (8) Å
Data collection top
D2B Institut Laue Langevin
diffractometer
2θmin = 0.071°, 2θmax = 159.829°, 2θstep = 0.050°
Refinement top
Rp = 2.602χ2 = 7.028
Rwp = 3.6633199 data points
Rexp = 1.38272 parameters
RBragg = 10.72124 restraints
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/UeqOcc. (<1)
Sr10.000000.250000.125000.081 (7)*
Sr20.500000.250000.6004 (17)0.057 (6)*
Sr30.2274 (19)0.976 (2)0.8743 (13)0.062 (4)*
Sr40.2069 (18)0.246 (3)0.5281 (16)0.084 (3)*
Mo10.000000.000000.000000.0313 (17)*
Mo20.000000.000000.500000.0363 (18)*
O10.875 (2)0.1450 (15)0.2515 (16)0.056 (5)*
O20.6416 (12)0.1271 (16)0.2468 (12)0.042 (3)*
O30.259 (2)0.2418 (19)0.3656 (14)0.059 (4)*
O4a0.0837 (13)0.047 (2)0.4109 (15)0.03800*0.30 (2)
O4b0.0847 (18)0.101 (2)0.429 (3)0.03800*0.14 (2)
O4c0.0000 (18)0.0759 (18)0.4030 (15)0.03800*0.30 (2)
O5a0.131 (3)0.093 (3)0.488 (3)0.03800*0.30 (2)
O5b0.142 (2)0.080 (3)0.490 (3)0.03800*0.30 (2)
O5c0.162 (2)0.000 (5)0.477 (3)0.03800*0.30 (2)
O5d0.000 (2)0.170 (2)0.500 (2)0.03800*0.15 (1)
O6a0.0847 (18)0.060 (2)0.4125 (19)0.03800*0.30 (1)
O6b0.0837 (13)0.081 (2)0.407 (2)0.03800*0.24 (2)
O6c0.000 (2)0.142 (2)0.4280 (15)0.03800*0.15 (1)

Experimental details

(Sr11Mo4O23-473K)(Sr11Mo4O23-673K)(Sr11Mo4O23-873K)(Sr11Mo4O23-1073K)
Crystal data
Chemical formulaMo4O23.12Sr11Mo4O23.16Sr11Mo4O21.84Sr11Mo4O21.92Sr11
Mr1717.171718.771697.011698.29
Crystal system, space groupTetragonal, I41/aTetragonal, I41/aTetragonal, I41/aTetragonal, I41/a
Temperature (K)4736738731073
a, c (Å)11.6416 (4), 16.4524 (9)11.6696 (4), 16.4869 (9)11.7075 (3), 16.5548 (8)11.7466 (3), 16.6088 (8)
V3)2229.74 (17)2245.16 (17)2269.09 (14)2291.72 (14)
Z4444
Radiation typeConstant Wavelength Neutron DiffractionConstant Wavelength Neutron DiffractionConstant Wavelength Neutron DiffractionConstant Wavelength Neutron Diffraction
Specimen shape, size (mm)?, ? × ? × ??, ? × ? × ??, ? × ? × ??, ? × ? × ?
Data collection
DiffractometerD2B Institut Laue LangevinD2B Institut Laue LangevinD2B Institut Laue LangevinD2B Institut Laue Langevin
Specimen mounting????
Data collection mode????
Scan method????
2θ values (°)2θmin = 0.103 2θmax = 159.797 2θstep = 0.0502θmin = 0.058 2θmax = 159.842 2θstep = 0.0502θmin = 0.078 2θmax = 159.822 2θstep = 0.0502θmin = 0.071 2θmax = 159.829 2θstep = 0.050
Refinement
R factors and goodness of fitRp = 3.185, Rwp = 4.373, Rexp = 1.221, RBragg = 8.568, χ2 = 12.834Rp = 2.886, Rwp = 3.894, Rexp = 1.241, RBragg = 7.076, χ2 = 9.848Rp = 2.831, Rwp = 3.937, Rexp = 1.348, RBragg = 11.108, χ2 = 8.528Rp = 2.602, Rwp = 3.663, Rexp = 1.382, RBragg = 10.721, χ2 = 7.028
No. of parameters55557272
No. of restraints002424

Computer programs: FULLPROF.

Selected geometric parameters (Å, º) for (Sr11Mo4O23-473K) top
Mo1—O11.939 (13)Mo2—O42.062 (15)
Mo1—O21.976 (14)Mo2—O51.706 (13)
Mo1—O31.932 (14)Mo2—O61.754 (16)
O1—Mo1—O290.8 (3)O4—Mo2—O585.2 (3)
O1—Mo1—O391.1 (3)O4—Mo2—O689.4 (3)
O2—Mo1—O392.1 (7)O5—Mo2—O6108.8 (4)
Selected geometric parameters (Å, º) for (Sr11Mo4O23-673K) top
Mo1—O11.919 (16)Mo2—O42.074 (18)
Mo1—O21.898 (18)Mo2—O51.787 (17)
Mo1—O31.959 (12)Mo2—O61.76 (3)
O1—Mo1—O291.2 (3)O4—Mo2—O588.2 (4)
O1—Mo1—O393.5 (3)O4—Mo2—O694.5 (4)
O2—Mo1—O392.2 (3)O5—Mo2—O6103.4 (4)
 

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