ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

Vibrational and optical studies of Na_0.45K_1.55Cu₃(MoO₄)₄

Wassim Dridi, Riadh Marzouki, Majed M. Alghamdi, Mahmoud A. Sayed, Miroslaw Maczka, Mohamed Faouzi Zid, and Maciej Ptak

Laboratory of Materials, Crystal Chemistry and Applied Thermodynamics, LR15ES01, Faculty of Sciences of Tunis, University of Tunis El Manar, Tunis, Tunisia

E-mail: wassimdridi35@yahoo.fr

Received: 28 October 2019  Accepted: 28 March 2020

Abstract:

Sodium potassium copper(II) tetra-[molybdate(VI)], Na_0.45K_1.55Cu₃(MoO₄)₄, was synthesized using solid-state reaction route, and its crystal structure (monoclinic P2₁/c) was solved using single-crystal X-ray diffraction method. Na_0.45K_1.55Cu₃(MoO₄)₄ forms 3D framework with elongated cavities occupied by alkali ions. The factor group analysis of Na_0.45K_1.55Cu₃(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 Na_0.45K_1.55Cu₃(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.

Keywords: Molybdate; Phonon properties; Raman spectra; IR spectra; Band gap

Full paper is available at www.springerlink.com.

DOI: 10.1007/s11696-020-01144-y

Chemical Papers 74 (9) 3127–3133 (2020)