Thermolysis of the NaCu[B₁₀H₁₀]/NaOH·SiO₂ system: encapsulation of in situ formed Cu₃Si into a sodium boron silicate matrix

The paper proposes a fundamentally new approach to the introduction of copper(I) ions into sodium liquid glass NaOH·SiO₂, as well as to the solid-phase synthesis of tricopper silicide Cu₃Si. The possibility of forming a composite based on a sodium boron silicate matrix and tricopper silicide Cu₃Si formed in situ during the thermolysis of the NaCu^I[B₁₀H₁₀]/NaOH·SiO₂ system is shown. The latter has been obtained by a cation metathesis when copper(I) complex {(Et₃NH)Cu^I[B₁₀H₁₀]}_n has been allowed to react with a 30% solution of sodium liquid glass (NaOH·SiO₂). Thermolysis of NaCu^I[B₁₀H₁₀]/NaOH·SiO₂ has been carried out in an argon atmosphere at 900 °C. It is established that this process is accompanied by a redox transformation and leads to the formation of binary copper compound Cu₃Si encapsulated in a sodium boron silicate matrix. The initial system and the annealed product have been identified by a complex of physicochemical methods: TGA, IR spectroscopy, X-ray powder diffraction, and X-ray spectral fluorescence. The morphology of the product has been studied.