Electron density in the sodium vanadium oxide bronze beta-NaxV2O5 at 9 K

The crystal structure and electron density in sodium vanadium oxide bronze, beta -NaxV2O5 [x = 0.282 (3)], have been studied by accurate Mo K alpha X- ray diffraction measurements at 9.6 (3) K. No noticeable difference in the crystal structures at room temperature and 9.6 K has been observed. No supe rstructure reflections, previously found by Kanai, Kagoshima & Nagasawa [(1 982), J. Phys. Soc. Jpn, 51, 697-698], have been detected at low temperatur e. Analysis of the deformation electron density has revealed the presence o f the quasi-two-dimensional sheets of the -V-O-V-O- bonds in the structure. The electron density in the different chemical bonds within each of the th ree crystallographically independent VO6 polyhedra noticeably varies, altho ugh there is no clear evidence that the three crystallographically independ ent V atoms have different valence states.