Later on, several new sites (A2, A3, or mid-A, etc., where A = Li or Na) were introduced by modifying the framework. Detailed site environments are here. The A1 is situated between two TiO 6 octahedra along the crystallographic c-axis, while A2 connects two A1 sites. The A1 is surrounded by oxygen octahedra (A 1 O 6 ) and exhibits a coordination number of six, while eight oxygens irregularly coordinate A2 . Structural modifications of the framework involve partial replacement of P with Si, resulting in the generation of an additional site known as mid-A (36f). These mid-A sites form a circular arrangement parallel to the ab-plane and are surrounded by each A1 site. The presence of such three-dimensional distributed sites facilitates the formation of a 3D migration path for Na ions. The composition Na 1+x Zr 2 Si x P 3-x O 12 (NZPO) with x = 2.0 exhibits the highest ionic conductivity, as shown in Fig. (c) . Consequently, theoretical studies, particularly those involving MD simulations, had been dedicated to comprehending the dynamics of ionic motion within NASICONs and elucidating the factors responsible for high ionic conductivity at this specific composition .