Abstract
A new sodium-potassium cobalt diphosphate, K0.86Na1.14CoP2O7, is synthesized by solid state reaction method and characterized by X-ray diffraction (XRD) and impedance spectroscopy. The resulting structural model is supports by bond-valence-sum analysis (BVS) and charge distribution validations (CHARDIT) tools. The mixed pyrophosphate crystallizes in the tetragonal system, space group P4(2)/mnm with a=7.808(3) angstrom, c=10.757(3) angstrom. The structure is described as a 2D anionic framework with alkali cations sandwiched between layers. As mechanical grinder, ball-milling was used in order to reduce average particle size of the prepared powder. The optimal sintering temperature of the ceramic is 560 degrees C, leading to a relative density of 83%. Their microstructure is characterized by scanning electron microscopy (SEM). The conductivity measurements of the obtained ceramic are studied over a temperature range from 360 degrees C to 480 degrees C. It shows that K0.86Na1.14CoP2O7 material is a low ionic conductor with a conductivity of sigma=8.26x10(-7) S.cm(-1) at 390 degrees C and an activation energy of 1.34 eV. The bond valence site energy (BVSE) model is used to identify the conduction pathways for the monovalent cations, allowing a better correlation between the electrical and the structural data.