3.1. Combustion Environment. The co-flow methane-air
inverse diffusion flame at the specified flow rates resulted in a
blue flame approximately 65mm in height without the precursor
solution present. As the precursor solution was introduced
through the central precursor tube, a yellow luminous
flame resulted indicating particle formation (see Figure 2).
To ensure both precursors were delivered to the flame region,
individual precursors (pure TMT and pure IPC) were tested
separately. The pure precursors yielded the distinct luminous
flames to produce respective iron oxide and tin dioxide as
demonstrated by several other studies [21, 22, 26–31]. To
introduce catalytic quantities of iron in the product powders,
2.5 at% IPC was added to TMT in the bubbler and sealed.
The introduction of this precursor solution produced a distinctly
luminous flame compared to the pure TMT system.