The NaCdVO₄–Cd₃V₂O₈ and CdO–V₂O₅ sections of the ternary system Na₂O–CdO–V₂O₅ have been studied and the crystal structures of Cd₃V₂O₈ and Cd₁₈V₈O₃₈ compounds were determined from single-crystal X-ray diffraction data. Cd₃V₂O₈ crystallizes with the maricite-type structure in space group <i>Pnma</i>, <i>a</i>=9.8133(10) Å, <i>b</i>=6.9882(10) Å, <i>c</i>=5.3251(10) Å and <i>Z</i>=4, whereas Cd₁₈V₈O₃₈ crystallizes in space group <i>P</i>1 with a new-type structure, <i>a</i>=8.5761(14), <i>b</i>=8.607(3), <i>c</i>=12.896(2) Å, <i>α</i>=95.64(1), <i>β</i>=102.45(1), <i>γ</i>=108.42(1)° and <i>Z</i>=1. The Cd₃V₂O₈ structure is made up of Cd1O₄ infinite chains of edge-sharing Cd1O₆ octahedra which are parallel to the <i>b</i> direction. The Cd1O₄ chains are linked together by VO₄ tetrahedra and strongly distorted Cd2O₄ tetrahedra. The structure of Cd₁₈V₈O₃₈ is based on an ordered three-dimensional framework of cadmium and vanadium polyhedra that share corners. The distorted CdO₆ octahedra, CdO₅ trigonal bipyramids and CdO₅ square pyramids share corners, edges or faces.< Leer menos