Synthesis and Crystal Structure of Silver Nesosilicate, Ag 4 SiO 4

The new silver silicate Ag 4 SiO 4 has been obtained by solid state reactions starting from stoichiometric amounts of the binary oxides at elevated temperatures and oxygen pressures. Ag 4 SiO 4 crystallizes in space group P 4 2 / n (No. 86) with a = 7.3169(3), c = 4.9595(4) Å, V = 265.52(3) Å 3 , Z = 2; the structure refinement was based on 343 independent reflections and resulted in R 1 = 2.70 %, wR 2 = 5.85 %. The crystal structure consists of isolated SiO 4 tetrahedra which are linked by Ag cations. The Ag atoms are almost linearly coordinated by two oxygen atoms. The AgO 2 dumbbells form chains, and every two of these chains are wound around each other forming double helices running along [001]. This arrangement of Ag and O atoms corresponds to a section of the Ag 2 O structure. Ag 4 SiO 4 is photosensitive and decomposes within a few weeks into silver, SiO 2 and oxygen.