Rietveld Analysis and Raman Spectroscopic Investigations on α‐Y2Si2O7

Polycrystalline material of α‐Y2Si2O7has been obtained from the thermal decomposition of a precursor prepared by a sol‐gel process and subsequently characterized by X‐ray powder diffraction and Raman spectroscopy. The structure belongs to the so‐called B‐type of rare earth element disilicates and was refined using the Rietveld method. α‐Y2Si2O7is triclinic with a = 6.58620(3), b = 6.62895(4), c = 12.02723(7) Å, α = 94.4706(4)°, β = 89.0681(4)°, γ = 88.2347(4)°, V = 523.166(5) Å3, space groupP 1 , Z = 4 and Dx= 4.39 g/cm3. The structure (Rwp= 4.7 %, RB= 2.9 %) is built from triple tetrahedral [Si3O10]‐groups and isolated [SiO4]‐units, i.e. from a structural point of view it belongs to the group of mixed anion silicates. The silicate anions are located in layers parallel to (11 1). Linkage between the anionic groups is provided by Y cations having six and eight oxygen neighbours. The corresponding coordination polyhedra can be approximately described as distorted octahedra as well as bicapped trigonal prisms, respectively.