Microstructure and phase evolution in single phase CuInSe{sub 2} particles synthesized using elemental precursors

This paper reports solid-state formation reaction pathways for CuInSe{sub 2} particles synthesized by ultrasonic irradiation of elemental precursors followed by thermal annealing. Effective heat of formation (EHF) model is used to predict the first formed and consecutively formed phases of Cu+Se, In+Se compounds. The XRD patterns showed that CuSe and In{sub 4}Se{sub 3} phases are formed by ultrasonication of Cu+Se and In+Se precursors as predicted by the EHF model. As-sonicated Cu+In+Se precursors are thermally annealed and the CuInSe{sub 2} reaction is investigated based on the crystallographic relation between the binary phases. According to this model, when either CuSe{sub 2} or In{sub 4}Se{sub 3} phases are involved in the CuInSe{sub 2} formation, the reaction is categorized under suppressed reactions due to the missing epitaxial relation. An activated reaction is reported between CuSe and InSe phases due to the epitaxial match. The experimental findings support the crystallographic model by the completion of CuInSe{sub 2} formation reaction at 350 °C annealing temperature, which is after the phase transformation of CuSe{sub 2} to CuSe at 342 °C. - Graphical abstract: Ultrasonically irradiation and thermally annealing of Cu+In+Se mixture result in nanocrystalline CuInSe{sub 2} particles due to the proposed reaction pathways. - Highlights: • Nanocrsytalline CuInSe{sub 2} particles are synthesized from elemental precursors. • Sonochemistry is successfully utilized to prepare binary selenide phases. • Nanocrystalline CuInSe{sub 2} phase started to form with thermal annealing at 250 °C. • Single phase CuInSe{sub 2} is achieved at 350 °C.