Abstract
Cadmium stannate powder and polycrystalline thin films were prepared from chelate-based sol gel chemistry and crystallized at different temperatures in preheated tube furnace. The films were further annealed at 680°C in nitrogen for 1h. These powders and films were characterized for their structural evolution. The crystallinity and phase purity of powders and films were particularly sensitive to firing and annealing temperatures, firing ambient, and the level of cadmium in the starting precursor system. Deviations in the Cd content of the powder and film were principally due to metallic cadmium volatilization. The adverse effect of cadmium loss during CTO processing is typically circumvented by providing excess cadmium. The effect of several variables on crystallization behavior of CTO powder and film was investigated to determine the best conditions for preparing monophasic spinel phase as it is known to give the best electro-optical properties. An optimized firing profile for CTO films was developed. A pyrolysis step at 500°C was crucial to the preparation of Cd2SnO4 thin film with good electro-optical properties.
•The deviation from stoichiometry is quantitatively monitored by XPS measurements.•Deviation from stoichiometry is more pronounced at the film surface.•Cadmium level is at highest at around 500°C in agreement with XRD patterns.•Two-step firing profile is indispensable to obtain pure spinel phase.•The film orientation can be changed when Cd:Sn ratio in the sol increases.