Microwave-initiated metathesis route to Li 2 SiN 2 Richard B. Kaner, UCLA, DMR-0453121

1. Microwave-initiated metathesis route to Li2SiN2Richard B. Kaner, UCLA,DMR-0453121 Solid-state metathesis reactions can provide an attractive alternative to the traditional synthesis of lithium silicon nitride, a fast-ion conductor and potential component in nitrogen sensors. The method we report in the Journal of Materials Chemistry (16, 1318, 2006) is especially promising since it utilizes an industrial by-product (SiCl4) and can be initiated easily in a conventional microwave oven. This is advantageous when compared to the reaction of Li3N with Si3N4, which is hindered by the high energy input required and the high cost of Si3N4. A metathesis reaction between SiCl4 with Li3N and LiNH2 acting as nitrogen and lithium sources, respectively, produces Li2SiN2 in seconds when initiated in a microwave oven: 6SiCl4 + 8Li3N + 3LiNH2 + 12NH4Cl  6Li2SiN2 + 15LiCl + 11NH3 + 21HCl The product phase (Li2SiN2 versus LiSi2N3) can be controlled by the amount of LiNH2 or Li3N present in the reaction mixture; while the product yield and crystallinity can be controlled by the addition of NH4Cl. The amount of lithium in the mixed nitride can be tuned by varying the amount of LiNH2 in a given reaction mixture.

2. Microwave-initiated metathesis route to Li2SiN2 Richard B. Kaner, UCLA,DMR-0453121 The fast ion conductor Li2SiN2 can now be made in seconds from the reaction of four solids (6SiCl4, 8Li3N, 3LiNH2, 12NH4Cl) initiated by microwaves. In this photograph taken through the door of a conventional microwave oven, the reaction zone and outline of the glass vial are added in white for clarity as reported in the Journal of Materials Chemistry (16, 1318, 2006).