Effects of heat treatment on Na-ion conductivity and conduction pathways of fluorphosphate glass-ceramics

Abstract Fluorphosphate glass-ceramics Na 2 O-NaF-B 2 O 3 -P 2 O 5 -TiO 2 -ZrO 2 (NTBPZ) were prepared by the conventional melt-quenching method following with the reheat treatment. High temperature phases of NaTi 2 (PO 4 ) 3 , Na 2 HPO 4 and Na 2 HPO 4 (H 2 O) 2 nanocrystals were precipitated in the glass-ceramics. The influence of crystallization conditions on structure and ionic conductivity of the glass-ceramics was studied using X-ray diffraction, scanning electron microscope, and Electrochemical impedance spectra (EIS). And the results showed that the Na-ion mobility closely depends on the type and the distribution of the nanocrystal conductors. A room-temperature conductivity as high as 5.52 × 10 − 5 S/cm was achieved for the glass-ceramic crystallized at 600 °C for 20 h. The effects of the heat treatment on Na-ion conduction pathways were also discussed.