Flux synthesis and structural and spectroscopic characterization of a cobalt europium trisilicate

A trisilicate with a new structure type, CoEu₂Si ₃O₁₀, was obtained from molybdate-carbonate mixtures in Pt crucibles by using a high-temperature flux-growth method. The structural characterization of CoEu₂Si₃O₁₀ was done by evaluation of single-crystal X-ray diffraction data collected at three different temperatures (105, 293, and 370 K). The light violet crystals are monoclinic, space group P2₁/n with a = 6.5620(13), b = 6.7207(13), c = 16.986(3) Å, β = 90.06(3)°, V = 749.1(3) ų, and R(F) = 2.49 %, at room temperature. The new crystal structure type features layers parallel to (001) containing Si₃O₁₀ groups and Co ₂O₁₀ dimers. The Si-Si-Si angle of the Si ₃O₁₀ unit is 115.7°. Raman spectroscopy and a study of the photoluminescence properties of the Eu³⁺ ions in CoEu ₂Si₃O₁₀ were undertaken. A new structure type containing layers parallel to (001) built up from Si₃O₁₀ groups and Co₂O₁₀ dimers was determined to be the trisilicate CoEu₂Si₃O₁₀. Light violet monoclinic crystals were obtained by using a high-temperature flux-growth method.