The Stereochemical Effect of 6s2Lone-Pair Electrons: The Crystal Structure of a New Lead Bismuth Oxyphosphate Pb4BiO4PO4

The crystal structure of Ga-rich plumbogummite from Tsumeb, Namibia

“…We note that in the structure of Ga-rich plumbogummite, refinement of Pb at the origin (0, 0, 0) dramatically increased the R factor, indicating that the Pb atom is displaced off the origin. Giuseppetti andTadini (1980, 1987) reported the Pb atom on the origin in the structures of osarizawaite and corkite; however, the Pb atom had large thermal ellipsoids, which indicate stereochemical activity of the 6s 2 lone pair. Here, we report off-centring to the [x, 0, 0] position for the Pb, consistent with other refinements.…”

The crystal structure of a bimuth–transition metal phosphate Bi6TiP2O16

“…The discovery of the oxygen ion conductor Bi 4 V 2 O 11 [1] has given rise to a large crystal chemical literature describing structures and properties of compounds resulting from the substitution of other cations for Bi and V [2][3][4][5][6][7][8][9][10][11]. The articulations of the polyhedra are not only influenced by the 6 s 2 lone-pair electrons of the group IVB and VB metals but also by vacancies, mixed valence states and domain variations of the chemical composition within single crystals that usually manifest themselves as disorder, twinning or superstructures.…”

Crystal Structure of Pb5Bi18P4O42: A Fluorite-Related Superstructure

“…Three somewhat less regular tetrahedra are present around P(2). The "rst is formed by O(12)}O(15)}2O (18), the second by O(15)}O(20)}2O (19), and the third by O(12)}O(14)}2O (13), Fig. 1.…”