title: Crystal chemical characteristics of ellestadite-type apatite: implications for toxic metal immobilization.
abstract: The ellestadite apatites Ca10[(SiO4)x(PO4)6-2x(SO4)x]Cl2 were studied by powder X-ray and neutron diffraction to establish baseline crystallographic data. These synthetic materials, unlike mineral specimens that are well equilibrated, show no Si/P/S ordering and conform to P63/m symmetry. Phosphate-rich ellestadites where 0 ≤ x ≤ 1 show chemical stability towards Toxicity Characterization Leaching Procedure (TCLP) testing and are potential immobilization matrices for mixed toxic metal wastes.
authors.affiliation: School of Materials Science & Engineering, Nanyang Technological University, 50 Nanyang Avenue, 639798, Singapore. YNFANG@ntu.edu.sg tjwhite@ntu.edu.sg.
authors.forename: Y N
authors.initials: YN
authors.lastname: Fang
authors.forename: Clemens
authors.initials: C
authors.lastname: Ritter
authors.forename: T J
authors.initials: TJ
authors.lastname: White
mesh_terms: D001031:Apatites / Q000737:chemistry*; D002713:Chlorine / Q000737:chemistry; D006256:Hazardous Waste; D019216:Metals, Heavy / Q000737:chemistry; D046529:Microscopy, Electron, Transmission; D033363:Neutron Diffraction; D010758:Phosphorus / Q000737:chemistry; D033362:Powder Diffraction; D012825:Silicon / Q000737:chemistry; D012995:Solubility; D017550:Spectroscopy, Fourier Transform Infrared; D013455:Sulfur / Q000737:chemistry; D018505:Waste Management; D014961:X-Ray Diffraction
chemical_list: D001031:Apatites; D006256:Hazardous Waste; D019216:Metals, Heavy; D010758:Phosphorus; D002713:Chlorine; D013455:Sulfur; D012825:Silicon