Oriented Au-Cu nanoalloy particle incorporated SiO(2) films using a new layer by layer deposition technique

Oriented Au-Cu nanoalloys have been generated in SiO(2) films using a new two-layer (TL) coating approach. Two successive overlapping coating layers were deposited on silica glass substrate using Au- and Cu-incorporated inorganic-organic hybrid silica sols. The concentrations of the Au and Cu (3 equivalent mol% metal-97% SiO(2) in each case) in the respective layers and their individual coating thicknesses were kept similar for the generation of Au-Cu alloys of an approximate atomic ratio 1 : 1. The UV-visible and X-ray diffraction (XRD) spectra of the TL films show the formation of nanoalloys with a gradual increase of Cu content with increasing heat-treatment temperature up to 750 degrees C in 10% H(2)-90% Ar. The XRD patterns reveal that the Au and Cu gradually formed Au-Cu nanoalloys of different ratios with a orientation. Estimation shows that the final nanoalloy composition reaches Au(0.58)Cu(0.42). The transmission electron microscope (TEM) image obtained from an Au(0.58)Cu(0.42) nanoalloy containing film shows the presence of mainly oriented plate-like circular nanoalloys of diameter 9-14 nm. XRD and TEM confirm that the alloy formation took place mainly through the diffusion and gradual dissolution of Cu atoms onto the planes of Au and intermediate Au-Cu nanoalloy crystals