K2Mn3(AsO4)3: Synthesis, Crystalline Structure and Ionic Conductivity

Brown single crystals of the potassium-manganese arsenate K2Mn3(AsO4)(3) were prepared by solid-state reaction and characterized by X-ray diffraction, infrared spectroscopy and complex impedance measurements. The compound crystallizes in the monoclinic space group C2/c with a = 12.490(1) , b = 13.013(1) , c = 6.888(1) , beta = 114.46(2)A degrees and Z = 4. The crystals belong an alluaudite-like structure characterized by the X(2)X(1)M(1)M(2)(2)(AsO4)(3) formula, in which the X sites are occupied by potassium cations and the M sites contain the manganese atoms. The manganese-arsenate framework is formed by chains of edge-sharing MnO6 octahedra linked together via the AsO4 tetrahedra, yielding two distinct tunnels of potassium cations occupation. Pure solid K2Mn3(AsO4)(3) shows modest ionic conductivity with an activation energy of 0.83 eV in the temperature range from 500 to 700 K. Single crystals of the arsenate K2Mn3(AsO4)(3) were synthesized and characterized by X-ray diffraction, infrared spectroscopy and complex impedance measurements. The compound crystallizes in the monoclinic space group C2/c with an alluaudite-like structure and shows modest ionic conductivity.