Bimetallic nanoparticles of copper and indium by borohydride reduction

This study investigated the preparation of copper–indium bimetallic nanoparticles through the borohydride reduction in an alcohol solution for application in ink-coating and sputtering target materials. Copper, indium metal and copper–indium intermetallic materials were synthesized by reacting CuCl2 and InCl3 with NaBH4 in 2-propanol (IPA) and tetraethylene glycol (TEG) at room temperature. The Cu–In samples contained Cu2In and CuIn phases with particle sizes of 10–100 nm and 30–200 nm in both the IPA and TEG solutions, respectively. The nanoparticulate Cu–In precursor layer was coated onto a soda-lime glass through spin-casting, where the Cu–In intermetallic phases of Cu2In and Cu11In9 were produced through heat treatment in Ar gas and a microstructured CuInSe2 layer was produced in a selenium atmosphere. Cu, In, Cu–In intermetallic nanoparticles and the films were characterized using powder X-ray diffraction, scanning electron microscopy, and energy-dispersive X-ray analyses.