The yellow oxynitride Li-2.3(O-0.7 N-0.3) was obtained on the surface of Li3N pellets fired at 750 degrees C for 10 h under a flow of nitrogen containing 1-10 ppm oxygen. The lithium ion conductivity of this material was enhanced compared to that of Li2O by at least one order of magnitude over the temperature range from 250 degrees C to 320 degrees C as a result of introducing the nitride anion into its antifluorite-type crystal lattice to form the interstitial Li+ ions. (C) 2015 Elsevier B.V. All rights reserved.