Embedding crystalline Cu and Cu2O nanoparticles in silicate glasses through an ion-exchange process followed by gamma irradiation and annealing: an optical absorption spectroscopy assessment

Abstract

Studies focusing on finding methodologies to obtain nanocrystalline structures in the form of nanoparticles have gained significant interest in the last two decades, given their broad possibilities to serve in different technological applications, and those related to glass technology are not an exception. Different routes are utilized to characterize crystalline nanoparticle growth. Hereby, an ion-exchange process followed by gamma ray irradiation and/or annealing treatment was used to effectuate the growth of copper nanoparticles (CuNPs) in glass matrices. Relying on well-established optical absorption spectroscopy, a precise and timely analysis of the changes occurring in the glass matrix, along with the formation of the CuNPs, defining their oxidation state and their sizes was performed. The study revealed that the formation of CuNPs in the glass matrix takes place within an unexpectedly short duration after the ion-exchange process. Irradiating the Cu-exchanged glass with gamma rays at ≈100 kGy increased the CuNPs formation and volume fraction, whereas at higher doses ≈1000 kGy the formed nanoparticles had smaller sizes. Interestingly, combining γ-irradiation with annealing for the Cu-exchanged glasses resulted in either size growth of CuNPs or their partial or total oxidation and their conversion to the more stable and ecofriendly Cu₂O nanoparticles.