“…For sodium-free single crystals, very high conductivities (2.7 Â 10 À3 and 0.18 S cm À1 at 25 and 300 C, respectively) and E a ¼ 23 kJ mol À1 were reported [203], but no data are available for ceramics. Two topologically different framework types with the general formula Li x M 2 T 3 O 12 [1, 2, 6, 10-13, [204][205][206][207][208][209][210][211][212] are based on lanterns of two MO 6 octahedra corner-linked with three TO 4 tetrahedra (Figure 7.21, I). One of these frameworks (R), typified by LiTi 2 (PO 4 ) 3 , is of the NASICON type (see Figure 7.15), with the lanterns in parallel orientation; in another framework (P), typified by Li 3 M 2 (PO 4 ) (M ¼ Sc, Cr, Fe), the lanterns are inclined alternatively in opposite directions (Figure 7.21, II).…”