Synthesis and characterization of Na+ conducting glass-ceramic Na5FeSi4O12 doped with boron, aluminum, and gallium oxides

Abstract

Sodium-ion conductive glass-ceramics of Na5FeSi4O12 were successfully synthesized through the crystallization of glasses with the composition Na5FeSi4O12. The optimum crystallization conditions and the kinetics of the glasses were examined by differential thermal analysis. The characterization of crystallization and conduction properties were performed on thus obtained glass-ceramic Na5FeSi4O12 by a non-isothermal modified Kissinger and complex impedance methods, respectively. The activation energy for crystallization was 279 kJ mol−1 and the sodium-ion conductivity was obtained as 1.33 × 10−3 S cm−1 at 300 °C. To improve the conductivity with a small amount of Si-substitutes, Na5FeSi4O12-isostructural derivatives containing such as B, Al, and Ga were also prepared according to the same crystallization process of glasses with the composition Na5.1FeM0.1Si3.9O12 (M = B, Al, Ga). Without phase separation, the ionic conductivities of glass-ceramics were enhanced up to 1.69 × 10−3 at 300 °C on Na5.1FeB0.1Si3.9O12, whereas decreased down to 1.30 × 10−3 and 1.12 × 10−3 S cm−1 at 300 °C on Na5.1FeAl0.1Si3.9O12, and Na5.1FeGa0.1Si3.9O12, respectively.