Hydrothermally deposited thin films with vertically oriented columnar growth.
A novel growth mode for hydrothermal films of lead zirconium titanate (PZT) has been discovered. Previously reported hydrothermal PZT films have had a loosely-packed cubic morphology, and indeed that is the most common growth mode. However, under special growth conditions, with much more dilute reagent concentrations than previously reported, substantially vertically oriented, long rod-like grains may be grown. Metal-organic reagents such as lead acetate trihydrate, zirconium propoxide, and titanium isopropoxide were used along with potassium hydroxide mineralizer. The hydrothermal process involves simultaneous deposition and etching, and it is believed that the amorphous metal-organic components deposit, and are converted to inorganic oxides insoluble in the alkaline solution. Metal and metal-coated substrates with appropriate seed layers, such as lead titanate (PT) and PZT were used. The hydrothermal process does not require high deposition temperatures, for example 160 degrees C reactor temperature was used in these experiments. The unique vertical rod-like films may be useful in electrical devices such as capacitors.
Solberg, S. E.; Rodkin, A.; Xu, B.; Littau, K. Hydrothermally deposited thin films with vertically oriented columnar growth. Materials Research Society Conference Proceedings, Symposium C : Ferroelectric Thin Films XII; 2003 December 1-5; Boston, MA. Warrendale, PA: MRS; 2003; 784: 281-286.