title: Calcium Phosphate Phase Identification Using XPS and Time-of-Flight Cluster SIMS.
abstract: Reproducible time-of-flight cluster static secondary ion mass spectra (ToF-SSIMS) were obtained for various standard calcium phosphate (CP) powders, which allowed for phase identification. X-ray diffraction was not able to detect signals from microscopic amounts of CP (∼15 mmol m(-)(2)). The phases studied were α-tricalcium phosphate [α-Ca(3)(PO(4))(2)], β-tricalcium phosphate [β-Ca(3)(PO(4))(2)], amorphous calcium phosphate [Ca(3)(PO(4))(2)·xH(2)O], octacalcium phosphate [Ca(8)H(2)(PO(4))(6)·H(2)O], brushite (CaHPO(4)·2H(2)O), and hydroxyapatite [Ca(10)(PO(4))(6)(OH)(2)]. The SIMS spectra were obtained via bombardment with (CsI)Cs(+) projectiles. X-ray photoelectron spectroscopy (XPS) core levels of the P 2p, Ca 2p, and O 1s orbitals and the relative O 1s loss intensity were examined. The PO(3)(-)/PO(2)(-) ratios from ToF-SSIMS spectra in conjunction with XPS of the CP powders showed much promise in differentiating between these phases at microscopic CP coverages on the metal oxide surface.
authors.affiliation: Department of Chemistry, Texas A&M University, P.O. Box 30012, College Station, Texas 77842-3012.
authors.forename: C C
authors.initials: CC
authors.lastname: Chusuei
authors.forename: D W
authors.initials: DW
authors.lastname: Goodman
authors.forename: M J
authors.initials: MJ
authors.lastname: Van Stipdonk
authors.forename: D R
authors.initials: DR
authors.lastname: Justes
authors.forename: E A
authors.initials: EA
authors.lastname: Schweikert