Synthesis, structural and spectroscopic properties of acentric triple molybdate Cs2NaBi(MoO4)3

Abstract New ternary molybdate Cs 2 NaBi(MoO 4 ) 3 is synthesized in the system Na 2 MoO 4 –Cs 2 MoO 4 –Bi 2 (MoO 4 ) 3 . The structure of Cs 2 NaBi(MoO 4 ) 3 of a new type is determined in noncentrosymmetric space group R 3 c , a =10.6435(2), c =40.9524(7) A, V =4017.71(13) A 3 , Z =12 in anisotropic approximation for all atoms taking into account racemic twinning. The structure is completely ordered, Mo atoms are tetrahedrally coordinated, Bi(1) and Bi(2) atoms are in octahedra, and Na(1) and Na(2) atoms have a distorted trigonal prismatic coordination. The Cs(1) and Cs(2) atoms are in the framework cavities with coordination numbers 12 and 10, respectively. No phase transitions were found in Cs 2 NaBi(MoO 4 ) 3 up to the melting point at 826 K. The compound shows an SHG signal, I 2w / I 2w (SiO 2 )=5 estimated by the powder method. The vibrational properties are evaluated by Raman spectroscopy, and 26 narrow lines are measured.