Synthesis, sintering, electrical properties, and sodium migration pathways of new lyonsite Na 2 Co 2 (MoO 4 )3

Authors : Rawia NASRI, Riadh MARZOUKI, Samuel GEORGES, Saïd OBBADE, Mohamed Faouzi ZID

Pages : 1251-1264

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Publication Date : 0000-00-00

Article Type : Research Paper

Abstract :  A new double molybdate Na 2 2 Co 2 2 insert ignore into journalissuearticles values(MoO 4 ); 3 4);3 was synthesized via solid-state reaction and characterized by single-crystal X-ray diffraction insert ignore into journalissuearticles values(XRD);. This compound is a new member of the lyonsite structure type. It crystallized in the orthorhombic system, space group Pnma with cell parameters a a = 5.272insert ignore into journalissuearticles values(2); Å, b b = 10.816insert ignore into journalissuearticles values(3); Å, and c c = 18.064insert ignore into journalissuearticles values(3); Å. The structure can be described as a three-dimensional framework with hexagonal tunnels in which the Na + + cations lie. The obtained structural model is supported by charge distribution analysis and bond valence sum validation tools. Fourier-transform infrared spectroscopy and scanning electron microscopy analyses were carried out. Ball milling was used to reduce the particle size of the synthesized powder. Dense ceramics with a relative density of 78% were obtained by sintering at 853 K. The conductivity of the title compound was studied for different relative densities. The ionic conductivity at 723 K with an activation energy of 1.2 eV was 3.24 × × 10 − 6 −6 S cm − 1 −1 . The bond valence sum map model is used to simulate the cation migration pathways in the anionic framework.
Keywords : Solid state reaction, lyonsite, sintering, electrical properties