*2.4. Scanning Electron Microscopy*

Scanning electron microscopy was performed on a FEI Quanta 400 field emission, environmental SEM (ESEM) under high vacuum conditions. The samples were examined in a number of configurations. All samples were coated with around 200 Å of carbon. Samples examined in sections were first cut using sheet metal cutters, mounted in conducting bakerlite ground, and then polished. Grinding started with SiC papers (320 through to 2400 SiC), followed by polishing on diamond (8, 3, 1, 0.25 μm) under a non-aqueous medium. Secondary electron and backscattered electron imaging were performed using beam energies of 10 kV, and probe currents of approximately 140–145 pA. Some additional imaging was performed at higher energies to obtain information on subsurface particles, as described in the Results section. Quantmaps were generated using standardless approaches; however, the quantmaps were only used to separate the overlapping signals of the Ti K-series lines from the Ba L-series lines by curve fitting rather than for quantitative analysis.
