Modelling the size of red-colouring copper nanoclusters in archaeological glass beads

Archaeometrical analyses of glass cakes and vitreous mosaic tesserae from Messina (Sicily, Italy)

“…Ancient red opaque glass has been widely studied and discussed in the literature [33][34][35][36][37][38][39][40][41]12]. In all these studies, copper was found to be responsible for the color of the samples, either as metallic copper or cuprous oxide.…”

One-step synthesis and properties of monolithic photoluminescent ruby colored cuprous oxide antimony oxide glass nanocomposites

“…The origin of a red color in case of Cu-ruby glasses has been attributed either to the presence of both copper clusters and cuprous oxide or solely to copper nanoparticles [5][6][7][8]. Initially, it was suggested that the origin of color in Cu rubies was due to precipitation of fine metallic Cu [1,20].…”

“…or metal nanoclusters (like Cu, Au, Ag) have a very interesting history [1][2][3][4]. Both the copper-and gold-ruby glasses, in particular, have captured sustained interest of mankind since the Roman times due to their distinctive red color and their fabrication and investigation of the origin of red color still continue to be an interesting branch of glass research [5][6][7][8][9]. Although Au and Cu rubies had initially received significant importance for their applications as decorative items and red filter glasses, but with the introduction of selenium based ruby glasses [10], their commercial importance as filter glass started to diminish gradually.…”

Study of an archeological opaque red glass bead from China by XRD, XRF, and XANES

“…The color mechanism of metallic copper is due to the plasmon oscillations of the free electrons and is known as a plasma‐resonance band . On the other hand, Cu 2 O is a semiconductor, and its band gap energy is 2.17 eV, which is considered to be the origin of the red color of Cu 2 O . In the sample, the form of copper is dominated by metal copper; thus, the optical absorption mechanism of the sample is more similar to that of metal copper.…”