Synthesis of mixed-phase titania films by low-temperature ultrasonic spray pyrolysis

Fully dense TiO2 films with (1) mixed-phase rutile and anatase and (2) anatase (sole phase) were deposited on fused quartz substrates by ultrasonic spray pyrolysis at nominally 400 degrees C. The presence and absence of insulation around the entrainment pathway traversing 20 cm above the substrate/hot plate were investigated (174 degrees C vs 122 degrees C). The thick films were assessed in terms of mineralogies (qualitative and quantitative), microstructures (topography, thickness and grain size), and visible light transmission (optical and microstructural considerations). With insulation, opaque mixed anatase (similar to 30 vol.%; <50 nm) and rutile (similar to 70 vol.%; similar to 1 mu m) were observed; without insulation, only transparent anatase (<50 nm) was observed. (C) 2010 Elsevier B.V. All rights reserved.