Crystal structure of europium tungstate

Abstract

The structure of europium tungstate, Eu2(WO4)8, has been determined by single-crystal X-ray diffraction data. The crystals are monoclinic, space group, C2/c, with a = 7.676 _+ 0.003, b = 11.463 +_ 0-003, c = 11.396 _+ 0.005/~, fl = 109.63 + 0-04 °, Z = 4, dz = 7.37 g.cm -3 . The atomic arrangement may be described as a scheelite superlattice with ordered vacancies in the cation positions, but atoms are displaced by considerable distances from the scheelite locations. Each W atom has four oxygen neighbors at average distances of 1.74 or 1.78 A. Some ~7 atoms have a fifth neighbor at 2.19 A. Each Eu atom has eight oxygen neighbors at an average distance of 2.43 A. Introduction