Synthesis and conduction properties of Na + superionic conductors of sodium samarium silicophosphates
Abstract Phosphorus induced Na 5 SmSi 4 O 12 -type sodium superionic conductors were prepared by sol-gel processes with metal alkoxides. The formation region of Na 5 SmSi 4 O 12 -type materials was different from that of glass-ceramics. The ionic conductivities of the sol-gel-derived samples were equal to those of the glass-ceramics in the order of 10 −2 –10 −1 S/cm at 300 °C. The sample with the Na 3.75 Sm 0.75 Si 3 O 9 composition sintered at 1000 °C for 12 h showed the highest ionic conductivity of 4.82 × 10 − 2 S/cm at 300 °C. The grain sizes of the specimens were 3–6 μm and the grain growth was promoted as sintering time increased.