Probe size study of apatite irradiation in stem

Abstract : The effect of electron beam irradiation of stoichiometric hydroxyapatite (Ca10(PO4)6(OH)2, HAP) is investigated using electron energy loss spectroscopy (EELS) in the scanning transmission electron microscope (STEM) mode equipped with a LaB6 gun. Initial irradiation at 160 A cm −2 dose rate shows no modification of the low loss spectra. No difference of mass loss for Ca, O and P is observed for two different probe diameters: 4 nm (dose rate = 160 A cm −2) and 24 nm (dose rate = 70 A cm −2). Furthermore no formation of CaO is observed for both experimental conditions. It is proposed that the low values of both electron dose rates and doses (from 350 to 2400 C cm −2) avoid mass loss. At the higher dose rate obtained with a field emission gun (FEG), transformations are observed for the lowloss signal as well as for the Ca, P and O signals. These results might be very useful for the future studies of apatite particles at the nanoscale.
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Étienne F. Brès, José Reyes-Gasga, Christian Rey, Jean Michel. Probe size study of apatite irradiation in stem. European Physical Journal: Applied Physics, EDP Sciences, 2014, vol. 67 (n° 2), pp. 1-6. ⟨10.1051/epjap/2014130104⟩. ⟨hal-01194744⟩



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