Moreover, nano-sized WO3-epoxy composites consist of a higher number of WO3 particles/gram when compared to micro-sized WO3-epoxy composites. Therefore, the distribution of the nano-sized WO3 in the resin should also be different from that presented by micro-sized WO3, thus resulting in a more uniform dispersion in the resin. As a consequence, the chances of an X-ray photon with lower energy to interact and be absorbed by WO3 particles may be higher in nano-sized WO3-epoxy composites than in micro-sized WO3-epoxy composites. Fig. 6 shows the back-scattered images of the same loading of WO3 (4 vol%) within nano-sized WO3-epoxy and micro-sized WO3-epoxy composites using the Zeiss Evo 40XVP scanning electron microscope. The WO3 particles were seen to be more closely dispersed in the nano-sized WO3-epoxy composite (Fig. 6a) as compared to its micro-sized counterpart (Fig. 6b). Thus, the probability for the lower energy photons to interact with the WO3 particles and be absorbed is higher for the nano-sized WO3-epoxy composite.