Abstract
Sodium potassium copper(II) tetra-[molybdate(VI)], Na0.45K1.55Cu3(MoO4)(4), was synthesized using solid-state reaction route, and its crystal structure (monoclinic P2(1)/c) was solved using single-crystal X-ray diffraction method. Na0.45K1.55Cu3(MoO4)(4) forms 3D framework with elongated cavities occupied by alkali ions. The factor group analysis of Na0.45K1.55Cu3(MoO4)(4) was applied for determination of number and activity of internal and external modes. Infrared and Raman vibrational spectra were investigated, and assignment of observed IR and Raman modes was proposed. The three crystallographically independent Cu2+ cations of Na0.45K1.55Cu3(MoO4)(4) adopt the [4 + 2] CuO6 Jahn-Teller distortion giving rise to an intense d-d transition observed in UV-Vis absorption spectra. The energies of indirect (3.01 eV) and direct (2.17 eV) band gaps were calculated using Kubelka-Munk method combined with the Tauc equation.