NASICON sodium (Na) super ionic conductor structures exhibit great structural stability and high ionic conductivity -especially for sodium ions. They belong to the family of superionic conductors, which are materials that display exceptionally high ionic conductivity at or near room temperature. Furthermore, they are classified as a polyanionic compounds, meaning they contain anions with multiple negative charges, such as the characteristic, tetrahedral anionic units XO 4 or their derivatives. The NASICON structure contains two distinct positions for monovalent ions usually called Na1 and Na2 sites. In contrast, multivalent ions like magnesium or calcium typically only occupy the Na1-position within the NASICON framework because of their higher charge. This leads to a lower occupation of crystal sites with the Na2 site becoming energetically much more unfavorable for bivalent ions, except for some sulfur structures in which Na2 positions can also be occupied as they are also energetically favorable. The missing occupation of the Na2 sites leads to a higher structural rigidity of the crystal structure which reduces structural changes upon intercalation/de-intercalation. Furthermore, this also leads to a different energetic shape of the diffusion path, as there is no intermediate stable state at Na2, and to a less facile migration caused by the increased electrostatic interactions with the framework. In times of energy crisis and more demand for electrical storage both in homes and vehicles, the design of new battery systems which do not rely on lithium and, more importantly, on the fast depleting cobalt are in high demand. An obvious choice for higher capacity, especially when the size of the battery is important, are multivalent charge carriers. A promising candidate here is calcium as it additionally does not form dendrites and is very abundant in the earths crust. Furthermore, all-solid batteries have drawn a lot of attention in recent times and the NASICON structure is a popular choice as an solid electrolyte which has been tested intensively with different transition metals, dopants as well as partial or full exchange of charge carriers. It can also be utilized as a electrode material under the constraint of electronic conductibility. However, batteries based on multivalent charge carriers are plagued by a lower ion mobility in solid battery materials due to their larger electrostatic interaction with the host lattice. This work explores potential differences in ion mobility within NASICON phases where sodium is fully substituted by calcium. NASICON materials offer a wide range of transition metal options, and we focus on comparing the zirconium-based phase with the titanium-based phase because of their shared group in the periodic table, meaning they contribute the same number of electrons to redox reactions. However, their different atomic sizes may influence ion mobility, particularly with respect to the so-called bottleneck size. This work aims to investigate how these size differences impact the overall ion mobility within the system.