Formation of Pd nanocrystals in titanium-oxide film by rapid thermal annealing of reactively cosputtered TiPdO films

Abstract

In this article, the authors report a novel method for preparation of Pd nanocrystals embedded in TiO2 film; i.e., the TiPdO films are first deposited by reactively cosputtering Ti and Pd targets in a plasma mixture of O2 and Ar, followed by rapid thermal annealing (RTA). The experimental results indicate that the TiPdO film with a high content of Pd is inclined to produce big nanocrystals. Furthermore, the higher the RTA temperature, the bigger the Pd nanocrystals become. In addition, our analyses of the x-ray photoelectron spectroscopy spectra reveal that PdO, PdO2, Ti2O3, and TiO2 coexist in the as-deposited film, and the RTA at 600 °C leads to decomposition of the entire PdO2 and partial PdO, together with the growth of Pd nanocrystals. At the same time, the released oxygen oxidizes fully Ti2O3 into TiO2 during the decomposition. As the RTA temperature is increased up to 900 °C, more and more PdO is decomposed and the Pd nanocrystals become bigger and bigger.