Structure of α-dicalcium silicate hydrate

Ca 2 (SiO 3 OH)(OH), M r =190.26, orthorhombic, P2 1 2 1 2 1 , a=9.487 (4), b=9.179 (4), c=10.666 (7) A, V=928.8 (8) A, Z=8, D x = 2.72 g cm -3 , λ(Mo Kα)=0.71069 A, μ=25.07 cm -1 , F(000)=768, T=293 K, final R=0.054 for 1677 unique non-zero reflections having I>3σ(I). The crystal was hydrothermally synthesized from a mixture of CaO and quartz at 403 K. The structure was redetermined by means of Patterson synthesis and refined by least-squares calculations. Calcium ions are coordinated by six or seven O atoms. Calcium polyhedra are linked together with shared edges to form a waved polyhedral sheet parallel to {001}