Chiolite-like Ca5Te3O14: An X-ray and neutron diffraction study

The crystal structure of Ca5Te3O14 at room temperature was studied by the Rietveld method using combined X-ray and neutron powder diffraction data. The compound crystallizes in the space group Cmca with the lattice parameters a=10.4268(2) Å, b=10.3908(2) Å and c=10.4702(2) Å. The structure of Ca5Te3O14 is chiolite-like and consists of a framework of corner-linked TeO6 octahedral layers in which a linear TeO2 group of every fourth octahedron is substituted by a Ca atom. This type of structure was previously observed in BaSr4U3O14. The relationship between the chiolite-like structure and the fluorite structure is discussed.

The structure of Ca5Te3O14 around z=0(a) and 0.25(b), respectively. The dimension of the unit cell is drawn in full line and that of the sub-cell in dashed line. In (b) the relatively too long Ca2–O1 and Ca3–O1 bond distances are also shown in dashed line.Figure optionsDownload as PowerPoint slide