The solid solution Ba5.78Pb1.22F12Cl2

摘要

The title compound, hexa-barium lead(II) dodeca-fluoride dichloride, is a solid solution in the system Pb 7 F 12 Cl 2 –Ba 7 F 12 Cl 2 and crystallizes isotypically with the ordered modification of the parent compounds in the space group P -6. The coordination polyhedra of the three different metal sites are distorted tricapped trigonal prisms with F 7 Cl 2 coordination sets for two of these sites (Wyckoff positions 3 k and 3 j , each with site symmetry m ..), and the remaining site being exclusively coordinated by fluoride ions (1 a , -6..). By sharing faces, a three-dimensional structure is accomplished. The three metal sites have remarkably different occupancies by the two types of metal ions. Whereas the site on the 3 k position shows only a minor incorporation of Pb 2+ [occupancy ratio Ba:Pb = 0.93?(4):0.07?(4)], the 3 j site shows the highest amount of incorporated Pb 2+ [Ba:Pb = 0.71?(5):29?(5)]. The occupancy ratio with respect to the 1 a site is Ba:Pb = 0.86?(5):0.14?(5).