To aid in discussion, the plasma jet can be divided
into two regions w13x: (i) the core or hot region which
is at very high temperatures ()2000 8C) and (ii) the
periphery or cold region which is at lower temperatures
(-2000 8C). Due to the vast differences in the temperature
histories experienced by the precursor droplets
along the two regions, it was found that the deposits
from the precursor injected into the hot region of the
plasma jet are crystalline 7-YSZ, whilst those from the
precursor droplets riding along the cold region of the
plasma jet are amorphous and contain significant amount
of water w14x. In order to elucidate the difference in
deposition mechanisms of precursor droplets injected
into these two regions of plasma jet, two different
substrate arrangements were employed in the stationary
plasma-torch experiments.