  In this work, a comprehensive research coupling experiment and computation
has been performed to understand the phase transition of Na3SbS4 and to
synthesize cubic Na3SbS4 (c-Na3SbS4), a high temperature phase of Na3SbS4 that
is difficult to be preserved from high temperature. The formation of c-Na3SbS4
is verified by Rietveld refinement and electrochemical impedance spectroscopy.
Both experiment and theoretical calculation reveal that the ionic conductivity
of c-Na3SbS4 is higher than that of t-Na3SbS4, though the values are in the
same order of magnitude. Both structures allow fast ion transport.
