Despite the attractive features of NASICON LATP, it is not clear whether the high conductivity of Li 1+x Ti 2−x Al x (PO 4) 3 composition is intrinsic to the structure or the formation of secondary phases that favors sintering and eliminate grain-boundary resistance is the cause of high conductivity [5], [6]. Towards this end, lithium-ion conduction of mixed-metal NASICON-phases of the formula, LiM v M iii (PO 4) 3 , where M V = Nb, Ta; M iii = Al, Cr, Fe were examined to obtained a NASICON phase possessing intrinsic conducting properties similar to LiTi 2 (PO 4) 3 but without Ti iv [6]. The planetary mono mill is a technique that uses a high energy ball mill for synthesizing solid electrolyte materials to achieve phase homogeneity of the final product. However, the use of this milling machine is a well-known technique and has attracted the interest of