Modified solid-state metathesis route to ternary lithium silicon nitrides : Li2SiN2

Abstract Ternary nitride Li 2 SiN 2 , a promising fast ionic conductor, has been successfully synthesized by using SiO 2 , SiO or Si and Li 3 N as precursors via a simple modified solid-state metathesis (exchange) route. All the reflections of Li 2 SiN 2 before 50° in 2 θ can be well indexed on the basis of a primitive tetragonal cell with a lattice parameter of a  = 9.902(1) A and c  = 15.012(5) A. It has been found that X-ray-pure phase of Li 2 SiN 2 can be definitely obtained by three kinds of silicon sources and the formation of lithia or Li 14.10 Si 6 is likely to be serving as the driving force. By varying the ratio of Li 3 N to silicon sources, only Li 2 SiN 2 can be approached. Ionic conductivity measurements showed a conductivity of 1.26 × 10 − 3  S cm − 1 at 730 K. This study provides a low-cost and facile pathway to Li 2 SiN 2 without the assistance of any addition.