Composition study of CoPt bimetallic nanocrystals of 2 nm

The synthesis of bimetallic alloy nanocrystals with a well-controlled relative composition is a real challenge and requires chemical analysis techniques with high accuracy. A new chemical route has been used to synthesize cobalt-platinum nanocrystals of 2-nm diameter in a wide range of relative stoichiometry. A study of the elemental composition of the nanoalloy was carried out by X-ray fluorescence (XRF) spectroscopy and energy-dispersive X-ray analysis. We have developed a set-up for XRF analysis using a silicon wafer as a support to determine the elemental composition with only a small amount of sample. The calibration step and the measurement capabilities are described. In a composition range of 25-75% cobalt, the results of both analytical methods are discussed and compared in detail.