Synthesis, structures and luminescence of two new Europium(II) Silicate‐Chlorides, Eu 2 SiO 3 Cl 2 and Eu 5 SiO 4 Cl 6

Eu 2 SiO 3 Cl 2 and Eu 5 SiO 4 Cl 6 were prepared by reaction of EuCl 2 with EuSiO 3 and Eu 2 SiO 4 , respectively, Sr 2 SiO 3 Cl 2 : Eu 2+ from mixtures of SrCO 3 , Eu 2 O 3 , SrCl 2 · 6H 2 O and SiO 2 under reducing conditions. The crystal structures of Eu 2 SiO 3 Cl 2 [a = 1118.7(5), c = 952.6(1) pm, tetragonal, I4/m, Z = 8, R = 3.3, R w = 3.0%] and Eu 5 SiO 4 Cl 6 [a = 900.4(1), b = 1401.7(2), c = 1112.3(2) pm, β = 103.51(1)°, monoclinic, C2/c, Z = 4, R = 3.6, R w = 2.6%] were determined from four‐circle diffractometer data and compared with related compounds. The luminescence properties were investigated at 300 K and at 4.2 K; all compounds show intense bluish‐green photoluminescence. Sr 2 SiO 3 Cl 2 :Eu 2+ shows thermoluminescence.