Copper Nanoclusters Formation In Glass

Introducing metallic nanoclusters into glass has been used for fabricating optical devices, information storage, optical waveguide, etc., due to its unique performances in optics, electricity, and magnetism. Such materials also provide a good carrier to investigate the metallic nanoclusters formation mechanism. Most studies focused on the formation of silver or gold nanoclusters in glass; however, the behavior of copper in glass is not clearly understood yet.Recently, photo-irradiation induced metallic nanoclusters in glass is a rapidly developing technology, and Au or Ag nanoclusters have been formed. But it is difficult to form Cu nanoclusters because of the complicacy of Cu electron configuration. It is the key issue to improve the activation of Cu⁺ in glass. After adjustment of the glass network former and modifiers, activable Cu⁺ in glass could be obtained. Y-Glass with basic component of 72%SiO₂-8%CaO-20%Na₂O (wt) has been selected in this study. After adding more 1.0 % SnO, 1.2 % Cu₂O and 1.0% carbon in above Y-Glass, a colorless and transparent glass with more activable Cu⁺ and less Cu²⁺ was obtained. The sample could form copper nanoclusters only after heat treatment at the critical temperature of 480℃.Higher heat-treated temperature and longer heating time, bigger size of formed nanoclusters. After UV-light irradiation for 1h, the critical temperature of forming copper nanoclsuters decreased about 20℃compared to the un-irradiated sample.Additive of about 0.08 %CeO₂ improved the UV-light induced copper nanoclusters formation. On the other hand, increase of Cu₂O content, higher intensity of UV-light and longer irradiation time also promoted the formation of copper nanoclusters. The glass after UV-light irradiation could form nanoclusters more rapidly than those without irradiation at the same treatment temperature. The Cu⁺ in glass is a electron trapper. When the Cu⁺ -doped glass was subjected to UV-light,reduction of copper atoms was induced. After heat treatment, copper atoms diffused and aggregated to form nanoclusters in glass. The copper nanoclusters formed in the glass by UV- irradiation induced are long-term stable at room temperature.