Abstract
A new double molybdate Na2Co2(MoO4)(3) was synthesized via solid-state reaction and characterized by single-crystal X-ray diffraction (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 = 5.272(2), b = 10.816(3), and c = 18.064(3). 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 x 10(-6) S cm(-1). The bond valence sum map model is used to simulate the cation migration pathways in the anionic framework.