The local atomic order and the valence state of Cu in Cu-implanted soda-lime glasses

The local atomic order and the valence states of Cu ions ion-implanted into soda-lime glasses have been studied by X-ray absorption spectroscopy. The use of X-ray fluorescent yield and the total electron yield collection modes has allowed a separate investigation of the whole and the shallower part of the implanted region. The mean valence state of Cu depends on the implant dose, yielding Cu(2+) in the 1 x 10(16) Cu/cm(2) samples and a mixture of mainly Cu(+) and Cu(0) in 5 x 10(16) Cu/cm(2) samples. More reduced ions are present in the surface part of the implanted layer. In the ionic phase Cu has a well defined first coordination shell consisting of 3-4 O atoms at a distance between 0.186 +/- 0.002 and 0.192 +/- 0.002 nm, Metallic Cu crystalline clusters are found only in samples implanted with larger doses.