A new series of tungstoniobium monophosphates with an intersecting tunnel structure closely related to ReO3: ANb(4)WO(9)(PO4)(3) (A = K, Rb, Cs), KLiNb5O9(PO4)(3), and KLi1-x(Nb, W)(5)O-9(PO4)(3)

摘要

A new series of tungstoniobium monophosphates, ANb(4)WO(9) (PO4)(3) (A = K, Rb, Cs), KLiNb,O-5(9)(PO4)(3), and KLi1-x(Nb, W)(5) O-9(PO4)(3), has been synthesized. They all crystallize in the space group Pbam with a approximate to 15.5 Angstrom b approximate to 10.4 Angstrom, c approximate to 10.5 Angstrom. Their original intersecting channel structure involving tunnels running along b and c is described by [M4P2O19](infinity) layers parallel to (001) interconnected through [MPO8](infinity) chains. In fact the MO6 octahedra form a distorted perovskite 3D framework where some octahedra are missing. The study of the transport properties of this phase shows linear behavior for Ln sigma vs T-1/4, characteristic of variable, range-hopping conductivity. (C) 1998 Academic Press. [References: 14]