Crystallochemistry and properties of compounds with rhombohedral frameworks of the [[Msub(2)(EOsub(4))sub(3)]sup(p-)]sub(3infinity) type and of the solid solutions on their basis

Results of investigations into compounds and solid solutions with rhombohedral frameworks of ([Msub(2)(EhOsub(4))sub(3)] sup(p-))sub(3) infinity type (M-tri- or tetravalent cation, Eh-P, Si, Ge) are generalized. Conditions for existence of phases close by structure and properties to sodium-zirconium silicophosphate of approximate composition Na3Zr2Si2PO12 (NASICON) are analyzed, and effect of different substitutions in the framework on structural and electrophysical characteristics of these phases is stated. Impossibility of existing single-phase rhombohedral Na3Zr2Si2PO12 and Na3M2(PO4)3 (M-Lusub(x)-Er, In, Y) is substantiated. Highest values of conductivity are attained for compounds with rhombohedral frameworks of ([Msub(2)(POsub(4))sub(3)]sup(p-))sub(3) infinite type at dimensions of hexagonal rings between cavities close to maximum possible for the given structural type and at population of these framework cavities by Na+ cations by approximately 3/4