title: Crystal chemistry of mimetite, Pb10(AsO4)6Cl1.48O0.26, and finnemanite, Pb10(AsO3)6Cl2.
abstract: The crystal chemistries of synthetic mimetite, Pb(10)(As(5+)O(4))(6)(Cl(2 - x)O(x/2)), a neutral apatite, and finnemanite, Pb(10)(As(3+)O(3))(6)Cl(2), a reduced apatite, were characterized using a combination of X-ray powder diffraction, neutron diffraction, transmission electron microscopy and X-ray photoelectron spectroscopy. Both phases conform to hexagonal P6(3)/m symmetry; however, the temperature-driven transformation of clinomimetite to mimetite described earlier was not confirmed. The average mimetite structure is best described through the introduction of partially occupied oxygen sites. A better understanding of the mixed arsenic speciation in apatites can guide the formulation of waste form ceramics and improve models of long-term durability after landfill disposal.
authors.affiliation: School of Materials Science and Engineering, Nanyang Technological University, Block N4.1, 50 Nanyang Avenue, Singapore 639798. tbaikie@ntu.edu.sg
authors.forename: Tom
authors.initials: T
authors.lastname: Baikie
authors.forename: Cristiano
authors.initials: C
authors.lastname: Ferraris
authors.forename: Wim T
authors.initials: WT
authors.lastname: Klooster
authors.forename: S
authors.initials: S
authors.lastname: Madhavi
authors.forename: Stevin S
authors.initials: SS
authors.lastname: Pramana
authors.forename: Allan
authors.initials: A
authors.lastname: Pring
authors.forename: G
authors.initials: G
authors.lastname: Schmidt
authors.forename: T J
authors.initials: TJ
authors.lastname: White
mesh_terms: D018360:Crystallography, X-Ray; D007854:Lead / Q000737:chemistry*; D015394:Molecular Structure; D013057:Spectrum Analysis / Q000379:methods; D013696:Temperature
chemical_list: D007854:Lead