Fig. 8.

XRD crystallite and primary particle diameters of powders made at 2.5 L/min C₂H₂ and HAN = 1–3 cm with the optional shielding tube preventing air entrainment in the non-burning spray (Fig. 1). As the GOF values for bi- and unimodal XRD fit are indistinguishable, homogeneous product powders are obtained at all HAN. The primary particle diameter and the average crystallite size increase with increasing HAN as this reduces heat loss for heating entrained air allowing droplets enough residence time to evaporate and mix with the dispersion O₂ prior to mixing with surrounding air. Insets show TEM images of Bi₂O₃ produced at HAN = 1 (left) and 3 cm (right) consistent with GOF values (below) for unimodal nanoparticles