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Chain-length-identification strategy in zinc polyphosphate glasses by means of XPS and ToF-SIMS

Crobu, Maura ; Rossi, Antonella ; Mangolini, Filippo ; Spencer, Nicholas

In: Analytical and Bioanalytical Chemistry, 2012, vol. 403, no. 5, p. 1415-1432

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    Title
    • Chain-length-identification strategy in zinc polyphosphate glasses by means of XPS and ToF-SIMS
    Author
    • Crobu, Maura. Laboratory for Surface Science and Technology, Department of Materials, ETH Zurich, Wolfgang-Pauli-Strasse 10, 8093, Zurich, Switzerland
    • Rossi, Antonella. Laboratory for Surface Science and Technology, Department of Materials, ETH Zurich, Wolfgang-Pauli-Strasse 10, 8093, Zurich, Switzerland
    • Mangolini, Filippo. Laboratory for Surface Science and Technology, Department of Materials, ETH Zurich, Wolfgang-Pauli-Strasse 10, 8093, Zurich, Switzerland
    • Spencer, Nicholas. Laboratory for Surface Science and Technology, Department of Materials, ETH Zurich, Wolfgang-Pauli-Strasse 10, 8093, Zurich, Switzerland
    Document Type
    • Postprint
    Language
    • English
    Published in
    • Analytical and Bioanalytical Chemistry, 2012, vol. 403, no. 5, p. 1415-1432. Springer-Verlag
    Other Version
    OAI-PMH Identifier
    • oai:doc.rero.ch:312030
    Summary
    The surface chemistry of amorphous zinc polyphosphates of different compositions (ranging from zinc metaphosphate to zinc orthophosphate) has been investigated by means of X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary-ion mass spectroscopy (ToF-SIMS). The identification of the chain length of zinc polyphosphates by XPS was on the basis of the integrated intensity ratio of the bridging (P-O-P) and nonbridging (P = O and P-O-M) oxygen peaks used for fitting the oxygen 1s signal, the shift of the P 2p3/2 signal towards lower binding energies and the modified Auger parameter towards higher values as the zinc content increases. The discrimination of the polyphosphate chain lengths was also achieved by ToF-SIMS, by comparing the intensities of selected characteristic phosphate fragments. Both techniques appear to be suitable for the investigation of polyphosphate glasses in applications such as tribology, where there is a need to identify the chain length present in the outermost monolayer of the film. Fourier-transform infrared (FT-IR) spectroscopy was used to characterize the bulk compounds. The FT-IR studies showed that long-chain structures linked through P-O-P bonds predominate in the metaphosphate composition, while when the zinc content is increased, the chains become shorter, ultimately being replaced by PO4 monomers in the orthophosphate composition. Figure