TY  - JOUR
A1  - Fortes, AD
JF  - Acta Crystallographica Section E
SN  - 2056-9890
UR  - http://dx.doi.org/10.1107/S2056989015008774
N1  - This is an open-access article distributed under the terms of the Creative Commons Attribution (CC-BY) Licence, which permits unrestricted use, distribution, and reproduction in any medium, provided the original authors and source are cited.
IS  - Pt 6
SP  - 592
VL  - 71
KW  - neutron powder diffraction
KW  -  sodium molybdate
KW  -  sodium tungstate
ID  - discovery1468469
N2  - Time-of-flight neutron powder diffraction data have been collected from Na2MoO4 and Na2WO4 to a resolution of sin?(?)/? = 1.25?Å(-1), which is substanti-ally better than the previous analyses using Mo K? X-rays, providing roughly triple the number of measured reflections with respect to the previous studies [Okada et al. (1974 ?). Acta Cryst. B30, 1872-1873; Bramnik & Ehrenberg (2004 ?). Z. Anorg. Allg. Chem. 630, 1336-1341]. The unit-cell parameters are in excellent agreement with literature data [Swanson et al. (1962 ?). NBS Monograph No. 25, sect. 1, pp. 46-47] and the structural parameters for the molybdate agree very well with those of Bramnik & Ehrenberg (2004 ?). However, the tungstate structure refinement of Okada et al. (1974 ?) stands apart as being conspicuously inaccurate, giving significantly longer W-O distances, 1.819?(8)?Å, and shorter Na-O distances, 2.378?(8)?Å, than are reported here or in other simple tungstates. As such, this work represents an order-of-magnitude improvement in precision for sodium molybdate and an equally substantial improvement in both accuracy and precision for sodium tungstate. Both compounds adopt the spinel structure type. The Na(+) ions have site symmetry .-3m and are in octa-hedral coordination while the transition metal atoms have site symmetry -43m and are in tetra-hedral coordination.
EP  - 596
AV  - public
Y1  - 2015/06/01/
TI  - Crystal structures of spinel-type Na2MoO4 and Na2WO4 revisited using neutron powder diffraction
ER  -