Solid-State NMR Studies of Lithium Phosphorus Oxynitride Films Prepared by Nitrogen Ion Beam-Assisted Deposition

Abstract

The chemical stability of phosphate glasses can be improved through the incorporation of nitrogen into the structure. In nitrided amorphous thin films (LiPON), the exceptional stability and enhanced conductivity make them particularly attractive for microbattery applications. Reported here are and solid-state nuclear magnetic resonance (NMR) studies of LiPON thin films fabricated by an ion beam-assisted deposition (IBAD) process. Variable temperature measurements of the resonance yield an activation energy of about 0.2 eV, which is smaller than values obtained from ionic conductivities. spectra provide direct evidence for at least three phosphate environments: two resonances associated with and structures and a third anomalous peak assigned to a nitrided tetrahedral phosphate structural unit of charge −3. Additional evidence exists for other nitrided phosphate structures of charge −2. spectra show evidence for type units and molecular with relative intensities that vary with the nitrogen ion beam gun voltage. No peak associated with trigonal units is observed. Additional evidence for molecular is provided by Fourier transform infrared measurements. A structural model of the phosphorus oxynitride host is presented. © 2005 The Electrochemical Society. All rights reserved.