Optimization of High Conducting Na3Zr2Si2PO12 Phase by new Phosphate Salt for Solid Electrolyte

A composition of NASICON (Na3Zr2Si2PO12) was synthesized by the solid-state reaction method using a new compound Na(2)HPO(4)2H(2)O. The X-ray diffraction patterns of all samples exhibit monoclinic Na3Zr2Si2PO12 as a major phase with a very small amount of monoclinic-ZrO2. The maximum relative density (97 %) and maximum conductivity is obtained in the samples sintered at 1200 degrees C (N3) which is slightly higher than beta-Al2O3. The activation energy is similar to 0.20 eV for the N3 sample which is lower than for beta-Al2O3. The dilatometeric study and Arrhenius plots confirmed a phase transition of NASICON from monoclinic to rhombohedral. The micro-structural study of the samples done by scanning electron microscopy (SEM) indicated a significant influence of the processing conditions on the microstructures. Raman spectroscopy demonstrated that the sample N3 exhibits minor structural changes compared to other samples.