Conductivity and structural investigations in lacunary Pb6Ca2Li2(PO4)(6) apatite

摘要

Prismatic crystals of Pb6Li2Ca2(PO4)(6) were obtained by solid-state reaction. They were characterized by IR spectroscopy and chemical analyses. The structure as determined by X-ray diffraction study on single crystal revealed that the compound is isostructural to the hexagonal phase Pb8Na2(PO4)(6). Crystal data for Pb6Li2Ca2(PO4)(6): space group P63/m (No. 176), a = b = 9.6790(15) Angstrom, c = 7.1130(7), Z = 1, R = 0.039. In the compound, lithium was found to preferentially occupy the site (1) and the structure is stabilized by interactions between electron lone pairs of lead (II) ions. Electrical conductivity measured in a wide range of temperature is governed by a hopping mechanism of Li ions in tunnels. (C) 2002 Elsevier Science (USA). [References: 40]