Table 4: The size of primary particles (of the “as-received” powders), as defined by their corresponding Feret’s diameter. Mean diameter (±1 SD) of a minimum of 50–100 particles measured in the SEM images; the SD here represents the broadness of the size distribution.

Sample name Supplier Mean Feret diameter (±1 SD) from SEM images Nanograin CeO2 Umicore Belgium 28.4 ± 10.4 Nanosun ZnO Micronisers, Australia 42.5 ± 3.6 Micron ZnO Sigma Aldrich, UK 891.8 ± 800.0 Z-COTE ZnO BASF, Germany 151.0 ± 55.6 Micron CeO2 Sigma Aldrich, UK 615.3 ± 430.5 Ceria dry CeO2 Antaria, Australia 44.9 ± 14.6