UV-visible absorption spectrum determination of optical energy gaps of α and β lithium nitrides

摘要

It is well known that a high pressure can induce α-β phase transformation of lithium nitride (Li _3N). However, this work demonstrated that a reverse phase transformation of Li 3N from β to α could occur when it was subjected to heat-treatment at 500 °C in vacuum. Furthermore, the optical properties of α and β lithium nitrides were evaluated by UV-visible spectra. The optical energy gaps (E _g) of α and β lithium nitrides, which were determined from the derivative UV-visible spectra, are 1.81±0.01 and 2.14±0.01 eV, respectively.