MODULATED PHASES OF NTP AND NFP SUPERIONIC CONDUCTORS

摘要

NTP and NFP crystals are superlonic conductors with Na ion conductivity. The basts of their crystal structure is made up of [Ti2(PO4)4O2] and [Fe2(PO4)4(O,F)2] redicals for NTP respectively NFP with Na atoms between the radicals. The relatively weak bonding between the radicals seems to be the main reason for the existence of several modulated phases in the temperature range from 293K to 800K. In this paper, some specific features and structural differences of similar NTP and NFP modulated phases are discussed, their symmetries in 3D and 4D spaces are compared.