Crystal structure of BaV13O18

Single crystals of BaV13O18 (V+2.62) containing a small amount of Cr (about 7% of vanadium sites) were prepared by heating a mixture of BaCO3, V2O5, V , and Cr powders at 1973 K for 40 h in flowing Ar. Crystal structure analys is using single-crystal data (Rigaku AFC7R, 4037 reflections) showed that t he BaV13O18 has a rhombohedral unit cell with a(h) = 12.621(5) Angstrom, C- h = 7.020(5) Angstrom, v = 968.4(9) Angstrom (3), Z = 3, D-cal = 5.595 g.cm (-3) and space group R-3 (R-1 = 1.96%, wR(2) = 3.60%, S = 1.095), In the st ructure, Be and O formed a cubic close-packed arrangement and every V was c oordinated by six O, BaV13O18 has three kinds of vanadium environments: one almost regular octahedral site and two distorted octahedral sites. VO6 oct ahedra share their corners and edges, (C) 2001 Academic Press.