Maximum Na + conductivity of 1.66 × 10 -3 S cm -1 is achieved with a Si/P ratio of 6:94, closely matching reported experimental conductivity values . Aliovalent substitution is a commonly employed strategy for enhancing ionic conductivity, as demonstrated by Maus et al. . Their work resulted in remarkable Na + ion conductivity, reaching 41 mS cm -1 in the case of Na 2.9 Sb 0.9 W 0.1 S 4 . It is noteworthy that while pristine Na 3 SbS 4 crystallizes in a tetragonal structure, the aliovalent-substituted Na 2.9 Sb 0.9 W 0.1 S 4 adopts a cubic phase at RT, as indicated by its X-ray diffractogram.